DB2 Version 9.

1 for z/OS



Application Programming and SQL Guide

SC18-9841-05
DB2 Version 9.1 for z/OS



Application Programming and SQL Guide

SC18-9841-05
Note
Before using this information and the product it supports, be sure to read the general information under “Notices” at the
end of this information.

Sixth edition (October 2009)

This edition applies to DB2 Version 9.1 for z/OS (DB2 V9.1 for z/OS), product number 5635-DB2, and to any
subsequent releases until otherwise indicated in new editions. Make sure you are using the correct edition for the
level of the product.
Specific changes are indicated by a vertical bar to the left of a change. A vertical bar to the left of a figure caption
indicates that the figure has changed. Editorial changes that have no technical significance are not noted.
© Copyright International Business Machines Corporation 1983, 2009.
US Government Users Restricted Rights – Use, duplication or disclosure restricted by GSA ADP Schedule Contract
with IBM Corp.
Contents
About this information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Who should read this information . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
DB2 Utilities Suite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Terminology and citations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
Accessibility features for DB2 Version 9.1 for z/OS . . . . . . . . . . . . . . . . . . . . . . xiv
How to send your comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
How to read syntax diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Chapter 1. Planning for and designing DB2 applications . . . . . . . . . . . . . . . 1

| Application and SQL release incompatibilities . . . . . . . . . . . . . . . . . . . . . . . . 1
Determining the value of any SQL processing options that affect the design of your program . . . . . . . . 13
Determining the binding method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Changes that invalidate plans or packages . . . . . . . . . . . . . . . . . . . . . . . . 16
Determining the value of any bind options that affect the design of your program . . . . . . . . . . . 18
Designing your application to promote concurrency . . . . . . . . . . . . . . . . . . . . . . 18
Designing your application for recovery . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Unit of work in TSO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Unit of work in CICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Planning for program recovery in IMS programs . . . . . . . . . . . . . . . . . . . . . . 21
Undoing selected changes within a unit of work by using savepoints . . . . . . . . . . . . . . . 28
| Planning for recovery of table spaces that are not logged . . . . . . . . . . . . . . . . . . . 30
Designing your application to access distributed data . . . . . . . . . . . . . . . . . . . . . 31
Remote servers and distributed data . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Advantages of DRDA access. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Preparing for coordinated updates to two or more data sources . . . . . . . . . . . . . . . . . 33
Forcing restricted system rules in your program . . . . . . . . . . . . . . . . . . . . . . 34
Maximizing the performance of an application that accesses distributed data . . . . . . . . . . . . 34

Chapter 2. Connecting to DB2 from your application program . . . . . . . . . . . . 45

Invoking the call attachment facility . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Call attachment facility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
Making the CAF language interface (DSNALI) available . . . . . . . . . . . . . . . . . . .52
Requirements for programs that use CAF . . . . . . . . . . . . . . . . . . . . . . . .53
How CAF modifies the content of registers . . . . . . . . . . . . . . . . . . . . . . . .54
Implicit connections to CAF . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
CALL DSNALI statement parameter list . . . . . . . . . . . . . . . . . . . . . . . . .55
Summary of CAF behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
CAF connection functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
Turning on a CAF trace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69
CAF return codes and reason codes . . . . . . . . . . . . . . . . . . . . . . . . . .69
Sample CAF scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
Examples of invoking CAF . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
Invoking the Resource Recovery Services attachment facility . . . . . . . . . . . . . . . . . . .77
Resource Recovery Services attachment facility . . . . . . . . . . . . . . . . . . . . . .79
Making the RRSAF language interface (DSNRLI) available . . . . . . . . . . . . . . . . . .83
Requirements for programs that use RRSAF . . . . . . . . . . . . . . . . . . . . . . .85
How RRSAF modifies the content of registers . . . . . . . . . . . . . . . . . . . . . . .85
Implicit connections to RRSAF . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
CALL DSNRLI statement parameter list . . . . . . . . . . . . . . . . . . . . . . . . .86
Summary of RRSAF behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
RRSAF connection functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
RRSAF return codes and reason codes . . . . . . . . . . . . . . . . . . . . . . . . . 119
Sample RRSAF scenarios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Program examples for RRSAF . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Controlling the CICS attachment facility from an application . . . . . . . . . . . . . . . . . . 124

© Copyright IBM Corp. 1983, 2009 iii

Detecting whether the CICS attachment facility is operational . . . . . . . . . . . . . . . . . 124
Improving thread reuse in CICS applications . . . . . . . . . . . . . . . . . . . . . . . 125

Chapter 3. Coding SQL statements in application programs: General information . . . 127

Declaring table and view definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . 128
DCLGEN (declarations generator) . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Generating table and view declarations by using DCLGEN . . . . . . . . . . . . . . . . . . 129
Including declarations from DCLGEN in your program . . . . . . . . . . . . . . . . . . . 137
Example: Adding DCLGEN declarations to a library . . . . . . . . . . . . . . . . . . . . 137
Defining the items that your program can use to check whether an SQL statement executed successfully . . . . 141
Defining SQL descriptor areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Declaring host variables and indicator variables . . . . . . . . . . . . . . . . . . . . . . . 142
Host variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Host variable arrays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Host structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Indicator variables, arrays, and structures . . . . . . . . . . . . . . . . . . . . . . . . 145
Setting the CCSID for host variables. . . . . . . . . . . . . . . . . . . . . . . . . . 146
Determining what caused an error when retrieving data into a host variable . . . . . . . . . . . . 147
Compatibility of SQL and language data types . . . . . . . . . . . . . . . . . . . . . . . 148
Embedding SQL statements in your application . . . . . . . . . . . . . . . . . . . . . . . 151
Delimiting an SQL statement . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Rules for host variables in an SQL statement . . . . . . . . . . . . . . . . . . . . . . . 151
Retrieving a single row of data into host variables . . . . . . . . . . . . . . . . . . . . . 152
Determining whether a retrieved value in a host variable is null or truncated . . . . . . . . . . . . 154
Determining whether a column value is null . . . . . . . . . . . . . . . . . . . . . . . 156
Updating data by using host variables . . . . . . . . . . . . . . . . . . . . . . . . . 157
Inserting a single row by using a host variable . . . . . . . . . . . . . . . . . . . . . . 158
Inserting null values into columns by using indicator variables or arrays . . . . . . . . . . . . . 158
Host variable arrays in an SQL statement . . . . . . . . . . . . . . . . . . . . . . . . 159
Retrieving multiple rows of data into host variable arrays . . . . . . . . . . . . . . . . . . 160
Inserting multiple rows of data from host variable arrays. . . . . . . . . . . . . . . . . . . 160
Retrieving a single row of data into a host structure . . . . . . . . . . . . . . . . . . . . 161
Including dynamic SQL in your program . . . . . . . . . . . . . . . . . . . . . . . . 162
Keeping prepared statements after commit points . . . . . . . . . . . . . . . . . . . . . 198
Limiting CPU time for dynamic SQL statements by using the resource limit facility . . . . . . . . . . 200
Checking the execution of SQL statements. . . . . . . . . . . . . . . . . . . . . . . . . 202
Checking the execution of SQL statements by using the SQLCA . . . . . . . . . . . . . . . . 203
Checking the execution of SQL statements by using SQLCODE and SQLSTATE . . . . . . . . . . . 207
Checking the execution of SQL statements by using the WHENEVER statement . . . . . . . . . . . 208
Checking the execution of SQL statements by using the GET DIAGNOSTICS statement . . . . . . . . 209
Handling SQL error codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Arithmetic and conversion errors . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
Writing applications that enable users to create and modify tables. . . . . . . . . . . . . . . . . 216
Saving SQL statements that are translated from end user requests . . . . . . . . . . . . . . . . . 216
XML data in embedded SQL applications . . . . . . . . . . . . . . . . . . . . . . . . . 217
Host variable data types for XML data in embedded SQL applications . . . . . . . . . . . . . . 217
XML column updates in embedded SQL applications . . . . . . . . . . . . . . . . . . . . 222
XML data retrieval in embedded SQL applications . . . . . . . . . . . . . . . . . . . . . 224
Programming examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
Examples of programs that call stored procedures . . . . . . . . . . . . . . . . . . . . . . 228

Chapter 4. Coding SQL statements in assembler application programs . . . . . . . 229

Defining the SQL communications area, SQLSTATE, and SQLCODE in assembler . . . . . . . . . . . 229
Defining SQL descriptor areas in assembler . . . . . . . . . . . . . . . . . . . . . . . . 230
Declaring host variables and indicator variables in assembler . . . . . . . . . . . . . . . . . . 230
Host variables in assembler . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Indicator variables in assembler . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Equivalent SQL and assembler data types . . . . . . . . . . . . . . . . . . . . . . . . . 236
SQL statements in assembler programs . . . . . . . . . . . . . . . . . . . . . . . . . . 241
Delimiters in SQL statements in assembler programs . . . . . . . . . . . . . . . . . . . . 246

iv Application Programming and SQL Guide

Macros for assembler applications . . . . . . . . . . . . . . . . . . . . . . . . . . 246
Programming examples in assembler . . . . . . . . . . . . . . . . . . . . . . . . . 247

Chapter 5. Coding SQL statements in C application programs . . . . . . . . . . . 249

Defining the SQL communications area, SQLSTATE, and SQLCODE in C . . . . . . . . . . . . . . 249
Defining SQL descriptor areas in C . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
Declaring host variables and indicator variables in C . . . . . . . . . . . . . . . . . . . . . 251
Host variables in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
Host variable arrays in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262
Host structures in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
Indicator variables, indicator arrays, and host structure indicator arrays in C . . . . . . . . . . . . 270
Referencing pointer host variables in C programs . . . . . . . . . . . . . . . . . . . . . 272
Declaring pointer host variables in C programs . . . . . . . . . . . . . . . . . . . . . . 273
Equivalent SQL and C data types. . . . . . . . . . . . . . . . . . . . . . . . . . . . 275
SQL statements in C programs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 280
Delimiters in SQL statements in C programs . . . . . . . . . . . . . . . . . . . . . . . 284
Programming examples in C . . . . . . . . . . . . . . . . . . . . . . . . . . . . 284

Chapter 6. Coding SQL statements in COBOL application programs. . . . . . . . . 295

Defining the SQL communications area, SQLSTATE, and SQLCODE in COBOL . . . . . . . . . . . . 295
Defining SQL descriptor areas in COBOL . . . . . . . . . . . . . . . . . . . . . . . . . 296
Declaring host variables and indicator variables in COBOL . . . . . . . . . . . . . . . . . . . 297
Host variables in COBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
Host variable arrays in COBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . 307
Host structures in COBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
Indicator variables, indicator arrays, and host structure indicator arrays in COBOL . . . . . . . . . . 319
Controlling the CCSID for COBOL host variables . . . . . . . . . . . . . . . . . . . . . 320
Equivalent SQL and COBOL data types . . . . . . . . . . . . . . . . . . . . . . . . . 322
SQL statements in COBOL programs . . . . . . . . . . . . . . . . . . . . . . . . . . 326
Delimiters in SQL statements in COBOL programs . . . . . . . . . . . . . . . . . . . . . 332
Object-oriented extensions in COBOL . . . . . . . . . . . . . . . . . . . . . . . . . 333
Programming examples in COBOL . . . . . . . . . . . . . . . . . . . . . . . . . . 333

Chapter 7. Coding SQL statements in Fortran application programs . . . . . . . . . 363

Defining the SQL communications area, SQLSTATE, and SQLCODE in Fortran . . . . . . . . . . . . 363
Defining SQL descriptor areas in Fortran . . . . . . . . . . . . . . . . . . . . . . . . . 364
Declaring host variables and indicator variables in Fortran . . . . . . . . . . . . . . . . . . . 365
Host variables in Fortran . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365
Indicator variables in Fortran . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368
Equivalent SQL and Fortran data types. . . . . . . . . . . . . . . . . . . . . . . . . . 369
SQL statements in Fortran programs. . . . . . . . . . . . . . . . . . . . . . . . . . . 371
Delimiters in SQL statements in Fortran programs . . . . . . . . . . . . . . . . . . . . . 374

Chapter 8. Coding SQL statements in PL/I application programs . . . . . . . . . . 375

Defining the SQL communications area, SQLSTATE, and SQLCODE in PL/I . . . . . . . . . . . . . 375
Defining SQL descriptor areas in PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . 376
Declaring host variables and indicator variables in PL/I . . . . . . . . . . . . . . . . . . . . 376
Host variables in PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377
Host variable arrays in PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382
Host structures in PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 386
Indicator variables in PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388
Equivalent SQL and PL/I data types . . . . . . . . . . . . . . . . . . . . . . . . . . 389
SQL statements in PL/I programs . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
Delimiters in SQL statements in PL/I programs . . . . . . . . . . . . . . . . . . . . . . 397
Programming examples in PL/I . . . . . . . . . . . . . . . . . . . . . . . . . . . 397

Chapter 9. Coding SQL statements in REXX application programs . . . . . . . . . 403

Defining the SQL communications area, SQLSTATE, and SQLCODE in REXX . . . . . . . . . . . . . 403
Defining SQL descriptor areas in REXX. . . . . . . . . . . . . . . . . . . . . . . . . . 403
Equivalent SQL and REXX data types . . . . . . . . . . . . . . . . . . . . . . . . . . 404

Contents v
SQL statements in REXX programs . . . . . . . . . . . . . . . . . . . . . . . . . . . 405
Delimiters in SQL statements in REXX programs . . . . . . . . . . . . . . . . . . . . . 408
Accessing the DB2 REXX language support application programming interfaces . . . . . . . . . . . 409
Ensuring that DB2 correctly interprets character input data in REXX programs . . . . . . . . . . . 410
Passing the data type of an input data type to DB2 for REXX programs . . . . . . . . . . . . . . 411
Setting the isolation level of SQL statements in a REXX procedure. . . . . . . . . . . . . . . . 411
Retrieving data from DB2 tables in REXX programs . . . . . . . . . . . . . . . . . . . . 412
Cursors and statement names in REXX . . . . . . . . . . . . . . . . . . . . . . . . . 413
Programming examples in REXX . . . . . . . . . . . . . . . . . . . . . . . . . . . 414

Chapter 10. Creating and modifying DB2 objects . . . . . . . . . . . . . . . . . 425

Creating tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 425
Data types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 426
Storing LOB data in a table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428
Identity columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 431
Creating tables for data integrity . . . . . . . . . . . . . . . . . . . . . . . . . . . 433
Creating work tables for the EMP and DEPT sample tables . . . . . . . . . . . . . . . . . . 442
Creating created temporary tables . . . . . . . . . . . . . . . . . . . . . . . . . . 443
Creating declared temporary tables . . . . . . . . . . . . . . . . . . . . . . . . . . 445
Providing a unique key for a table . . . . . . . . . . . . . . . . . . . . . . . . . . . 447
| Fixing tables with incomplete definitions . . . . . . . . . . . . . . . . . . . . . . . . . 448
Dropping tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449
Defining a view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 449
Views . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450
Dropping a view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Creating a common table expression. . . . . . . . . . . . . . . . . . . . . . . . . . . 451
Common table expressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 452
Examples of recursive common table expressions . . . . . . . . . . . . . . . . . . . . . 453
Creating triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
Invoking stored procedures and user-defined functions from triggers. . . . . . . . . . . . . . . 465
| Inserting, updating, and deleting data in views by using INSTEAD OF triggers . . . . . . . . . . . 466
Trigger packages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 467
Trigger cascading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468
Order of multiple triggers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 469
Interactions between triggers and referential constraints . . . . . . . . . . . . . . . . . . . 470
Interactions between triggers and tables that have multilevel security with row-level granularity . . . . . 471
Triggers that return inconsistent results. . . . . . . . . . . . . . . . . . . . . . . . . 472
Sequence objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 474
DB2 object relational extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476
Creating a distinct type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476
Distinct types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 477
Example of distinct types, user-defined functions, and LOBs . . . . . . . . . . . . . . . . . 478
Defining a user-defined function . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480
User-defined functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
Components of a user-defined function definition . . . . . . . . . . . . . . . . . . . . . 485
Writing an external user-defined function . . . . . . . . . . . . . . . . . . . . . . . . 487
Making a user-defined function reentrant . . . . . . . . . . . . . . . . . . . . . . . . 510
Using special registers in a user-defined function or a stored procedure . . . . . . . . . . . . . . 511
Accessing transition tables in a user-defined function or stored procedure . . . . . . . . . . . . . 513
Preparing an external user-defined function for execution . . . . . . . . . . . . . . . . . . 517
Abnormal termination of an external user-defined function . . . . . . . . . . . . . . . . . . 517
Saving information between invocations of a user-defined function by using a scratchpad. . . . . . . . 517
Example of creating and using a user-defined scalar function . . . . . . . . . . . . . . . . . 519
User-defined function samples that ship with DB2 . . . . . . . . . . . . . . . . . . . . . 519
Determining the authorization cache size for stored procedures and user-defined functions . . . . . . . 520
Creating a stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 520
Stored procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 521
Setting up the stored procedures environment . . . . . . . . . . . . . . . . . . . . . . 533
| Creating a native SQL procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 534
| Migrating an external SQL procedure to a native SQL procedure . . . . . . . . . . . . . . . . 559
Changing an existing version of a native SQL procedure . . . . . . . . . . . . . . . . . . . 560

vi Application Programming and SQL Guide

Regenerating an existing version of a native SQL procedure . . . . . . . . . . . . . . . . . . 560
Removing an existing version of a native SQL procedure . . . . . . . . . . . . . . . . . . . 561
| Creating an external SQL procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 561
Creating an external stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . 577
Creating multiple versions of external procedures and external SQL procedures . . . . . . . . . . . 598
COMMIT and ROLLBACK statements in a stored procedure . . . . . . . . . . . . . . . . . 598
Special registers in a stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . 599
Restrictions for stored procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 599
Writing a program or stored procedure to receive the result sets from a stored procedure . . . . . . . . 600

Chapter 11. Adding and modifying data . . . . . . . . . . . . . . . . . . . . . 605

Inserting data into tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 605
Inserting rows by using the INSERT statement . . . . . . . . . . . . . . . . . . . . . . 605
| Inserting data and updating data in a single operation . . . . . . . . . . . . . . . . . . . 611
Selecting values while inserting data . . . . . . . . . . . . . . . . . . . . . . . . . 613
Adding data to the end of a table . . . . . . . . . . . . . . . . . . . . . . . . . . . 619
Storing data that does not have a tabular format . . . . . . . . . . . . . . . . . . . . . . 620
Updating table data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 620
| Selecting values while updating data . . . . . . . . . . . . . . . . . . . . . . . . . 621
Updating thousands of rows . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
Deleting data from tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 622
| Selecting values while deleting data . . . . . . . . . . . . . . . . . . . . . . . . . . 624

Chapter 12. Accessing data . . . . . . . . . . . . . . . . . . . . . . . . . . 627

Determining which tables you have access to. . . . . . . . . . . . . . . . . . . . . . . . 627
Displaying information about the columns for a given table . . . . . . . . . . . . . . . . . . . 627
Retrieving data by using the SELECT statement . . . . . . . . . . . . . . . . . . . . . . . 628
Selecting derived columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
| Selecting XML data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 631
Formatting the result table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632
| Combining result tables from multiple SELECT statements . . . . . . . . . . . . . . . . . . 637
Summarizing group values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 642
| Finding rows that were changed within a specified period of time . . . . . . . . . . . . . . . 644
Joining data from more than one table . . . . . . . . . . . . . . . . . . . . . . . . . 644
Optimizing retrieval for a small set of rows . . . . . . . . . . . . . . . . . . . . . . . 655
Creating recursive SQL by using common table expressions . . . . . . . . . . . . . . . . . . 656
Updating data as it is retrieved from the database . . . . . . . . . . . . . . . . . . . . . 657
Avoiding decimal arithmetic errors . . . . . . . . . . . . . . . . . . . . . . . . . . 657
Implications of using SELECT * . . . . . . . . . . . . . . . . . . . . . . . . . . . 658
Subqueries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 659
Restrictions when using distinct types with UNION, EXCEPT, and INTERSECT . . . . . . . . . . . 667
Comparison of distinct types . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668
Nested SQL statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 669
Retrieving a set of rows by using a cursor . . . . . . . . . . . . . . . . . . . . . . . . . 670
Cursors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 671
Accessing data by using a row-positioned cursor . . . . . . . . . . . . . . . . . . . . . 675
Accessing data by using a rowset-positioned cursor . . . . . . . . . . . . . . . . . . . . 680
Retrieving rows by using a scrollable cursor . . . . . . . . . . . . . . . . . . . . . . . 685
| Accessing XML or LOB data quickly by using FETCH WITH CONTINUE . . . . . . . . . . . . . 690
Determining the attributes of a cursor by using the SQLCA . . . . . . . . . . . . . . . . . . 693
Determining the attributes of a cursor by using the GET DIAGNOSTICS statement . . . . . . . . . . 694
Scrolling through previously retrieved data . . . . . . . . . . . . . . . . . . . . . . . 694
Updating previously retrieved data . . . . . . . . . . . . . . . . . . . . . . . . . . 696
FETCH statement interaction between row and rowset positioning . . . . . . . . . . . . . . . 696
Examples of fetching rows by using cursors . . . . . . . . . . . . . . . . . . . . . . . 697
Specifying direct row access by using row IDs . . . . . . . . . . . . . . . . . . . . . . . 702
ROWID columns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704
Ways to manipulate LOB data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704
LOB host variable, LOB locator, and LOB file reference variable declarations . . . . . . . . . . . . 705
LOB materialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 711

Contents vii
Saving storage when manipulating LOBs by using LOB locators . . . . . . . . . . . . . . . . 711
Deferring evaluation of a LOB expression to improve performance . . . . . . . . . . . . . . . 713
| LOB file reference variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 715
Referencing a sequence object . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 717
Retrieving thousands of rows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 718
| Determining when a row was changed . . . . . . . . . . . . . . . . . . . . . . . . . . 718
| Checking whether an XML column contains a certain value . . . . . . . . . . . . . . . . . . . 719
Accessing DB2 data that is not in a table . . . . . . . . . . . . . . . . . . . . . . . . . 719
Ensuring that queries perform sufficiently . . . . . . . . . . . . . . . . . . . . . . . . . 720
Items to include in a batch DL/I program . . . . . . . . . . . . . . . . . . . . . . . . . 720

Chapter 13. Invoking a user-defined function . . . . . . . . . . . . . . . . . . . 723

Determining the authorization ID for invoking user-defined functions . . . . . . . . . . . . . . . 724
Ensuring that DB2 executes the intended user-defined function. . . . . . . . . . . . . . . . . . 725
How DB2 resolves functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 726
Checking how DB2 resolves functions by using DSN_FUNCTION_TABLE . . . . . . . . . . . . . 729
Restrictions when passing arguments with distinct types to functions . . . . . . . . . . . . . . . 732
Cases when DB2 casts arguments for a user-defined function . . . . . . . . . . . . . . . . . . 733

Chapter 14. Calling a stored procedure from your application . . . . . . . . . . . 735

Parameter list for stored procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . 740
Linkage conventions for stored procedures . . . . . . . . . . . . . . . . . . . . . . . . 741
Passing large output parameters to stored procedures by using indicator variables . . . . . . . . . . . 756
Data types for calling stored procedures . . . . . . . . . . . . . . . . . . . . . . . . . 757
Calling a stored procedure from a REXX procedure . . . . . . . . . . . . . . . . . . . . . 757
Preparing a client program for a stored procedure . . . . . . . . . . . . . . . . . . . . . . 760
How DB2 determines which stored procedure to run . . . . . . . . . . . . . . . . . . . . . 761
Calling different versions of a stored procedure from a single application . . . . . . . . . . . . . . 762
Invoking multiple instances of a stored procedure . . . . . . . . . . . . . . . . . . . . . . 763
Stored procedures that access non-DB2 resources . . . . . . . . . . . . . . . . . . . . . . 764
Designating the active version of a native SQL procedure . . . . . . . . . . . . . . . . . . . 765
Temporarily overriding the active version of a native SQL procedure . . . . . . . . . . . . . . . . 765
Specifying the number of stored procedures that can run concurrently . . . . . . . . . . . . . . . 766
DB2-supplied stored procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 766
WLM_REFRESH stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 774
| WLM_SET_CLIENT_INFO stored procedure . . . . . . . . . . . . . . . . . . . . . . . 776
DSNACICS stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 778
DSNAIMS stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 786
| DSNAEXP stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 791
Deprecated: DXXMQINSERT stored procedure . . . . . . . . . . . . . . . . . . . . . . 794
Deprecated: DXXMQSHRED stored procedure . . . . . . . . . . . . . . . . . . . . . . 796
Deprecated: DXXMQINSERTCLOB stored procedure . . . . . . . . . . . . . . . . . . . . 798
Deprecated: DXXMQSHREDCLOB stored procedure . . . . . . . . . . . . . . . . . . . . 801
Deprecated: DXXMQINSERTALL stored procedure . . . . . . . . . . . . . . . . . . . . . 803
Deprecated: DXXMQSHREDALL stored procedure . . . . . . . . . . . . . . . . . . . . . 806
Deprecated: DXXMQSHREDALLCLOB stored procedure . . . . . . . . . . . . . . . . . . . 808
Deprecated: DXXMQINSERTALLCLOB stored procedure . . . . . . . . . . . . . . . . . . . 810
Deprecated: DXXMQGEN stored procedure . . . . . . . . . . . . . . . . . . . . . . . 813
Deprecated: DXXMQRETRIEVE stored procedure . . . . . . . . . . . . . . . . . . . . . 816
Deprecated: DXXMQGENCLOB stored procedure . . . . . . . . . . . . . . . . . . . . . 820
Deprecated: DXXMQRETRIEVECLOB stored procedure . . . . . . . . . . . . . . . . . . . 823
XSR_REGISTER stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 827
XSR_ADDSCHEMADOC stored procedure . . . . . . . . . . . . . . . . . . . . . . . 829
XSR_COMPLETE stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 830
XSR_REMOVE stored procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . 832
Deprecated: XDBDECOMPXML stored procedure . . . . . . . . . . . . . . . . . . . . . 833

Chapter 15. Coding methods for distributed data . . . . . . . . . . . . . . . . . 835

Accessing distributed data by using three-part table names . . . . . . . . . . . . . . . . . . . 835
Accessing remote declared temporary tables by using three-part table names . . . . . . . . . . . . 837

viii Application Programming and SQL Guide

Accessing distributed data by using explicit CONNECT statements . . . . . . . . . . . . . . . . 837
Specifying a location alias name for multiple sites . . . . . . . . . . . . . . . . . . . . . 838
Releasing connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 839
Transmitting mixed data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 839
Identifying the server at run time . . . . . . . . . . . . . . . . . . . . . . . . . . . 840
SQL limitations at dissimilar servers. . . . . . . . . . . . . . . . . . . . . . . . . . . 840
Support for executing long SQL statements in a distributed environment . . . . . . . . . . . . . . 840
Distributed queries against ASCII or Unicode tables . . . . . . . . . . . . . . . . . . . . . 841
Restrictions when using scrollable cursors to access distributed data . . . . . . . . . . . . . . . . 841
Restrictions when using rowset-positioned cursors to access distributed data . . . . . . . . . . . . . 842
WebSphere MQ with DB2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 842
WebSphere MQ messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 842
DB2 MQ functions and DB2 MQ XML stored procedures . . . . . . . . . . . . . . . . . . . 846
| Generating XML documents from existing tables and sending them to an MQ message queue . . . . . . 852
| Shredding XML documents from an MQ message queue . . . . . . . . . . . . . . . . . . . 852
| DB2 MQ tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 853
| Converting applications to use the MQI functions . . . . . . . . . . . . . . . . . . . . . 861
Basic messaging with WebSphere MQ . . . . . . . . . . . . . . . . . . . . . . . . . 862
Sending messages with WebSphere MQ . . . . . . . . . . . . . . . . . . . . . . . . 863
Retrieving messages with WebSphere MQ . . . . . . . . . . . . . . . . . . . . . . . . 863
Application to application connectivity with WebSphere MQ . . . . . . . . . . . . . . . . . 865
Asynchronous messaging in DB2 for z/OS . . . . . . . . . . . . . . . . . . . . . . . 868

Chapter 16. DB2 as a Web services consumer and provider . . . . . . . . . . . . 881

The SOAPHTTPV and SOAPHTTPC user-defined functions . . . . . . . . . . . . . . . . . . . 881
| The SOAPHTTPNV and SOAPHTTPNC user-defined functions . . . . . . . . . . . . . . . . . 883
SQLSTATEs for DB2 as a Web services consumer . . . . . . . . . . . . . . . . . . . . . . 883

Chapter 17. Preparing an application to run on DB2 for z/OS . . . . . . . . . . . . 887

Setting the DB2I defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 889
Processing SQL statements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890
Processing SQL statements by using the DB2 precompiler . . . . . . . . . . . . . . . . . . 892
| Processing SQL statements by using the DB2 coprocessor. . . . . . . . . . . . . . . . . . . 898
Translating command-level statements in a CICS program . . . . . . . . . . . . . . . . . . 901
Differences between the DB2 precompiler and the DB2 coprocessor . . . . . . . . . . . . . . . 902
Options for SQL statement processing . . . . . . . . . . . . . . . . . . . . . . . . . 904
Program preparation options for remote packages . . . . . . . . . . . . . . . . . . . . . 913
Compiling and link-editing an application. . . . . . . . . . . . . . . . . . . . . . . . . 915
Binding an application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 916
Binding a DBRM to a package. . . . . . . . . . . . . . . . . . . . . . . . . . . . 917
Binding an application plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . 922
Bind process for remote access . . . . . . . . . . . . . . . . . . . . . . . . . . . 926
Binding a batch program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 930
Converting an existing plan into packages to run remotely . . . . . . . . . . . . . . . . . . 931
Setting the program level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 931
DYNAMICRULES bind option . . . . . . . . . . . . . . . . . . . . . . . . . . . 932
Determining the authorization cache size for plans . . . . . . . . . . . . . . . . . . . . . 934
Determining the authorization cache size for packages . . . . . . . . . . . . . . . . . . . 934
Dynamic plan selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 934
Rebinding an application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 936
Rebinding a package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 936
Rebinding a plan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 938
Rebinding lists of plans and packages . . . . . . . . . . . . . . . . . . . . . . . . . 938
Generating lists of REBIND commands . . . . . . . . . . . . . . . . . . . . . . . . . 938
Automatic rebinding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 944
Specifying the rules that apply to SQL behavior at run time . . . . . . . . . . . . . . . . . . . 946
DB2 program preparation overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 947
Input and output data sets for DL/I batch jobs . . . . . . . . . . . . . . . . . . . . . . . 949
DB2-supplied JCL procedures for preparing an application . . . . . . . . . . . . . . . . . . . 952
JCL to include the appropriate interface code when using the DB2-supplied JCL procedures . . . . . . . 952

Contents ix
Tailoring DB2-supplied JCL procedures for preparing CICS programs . . . . . . . . . . . . . . 953
DB2I primary option menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 955
DB2I panels that are used for program preparation . . . . . . . . . . . . . . . . . . . . . . 956
DB2 Program Preparation panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 957
DB2I Defaults Panel 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 961
DB2I Defaults Panel 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 963
Precompile panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 964
Bind Package panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 967
Bind Plan panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 969
Defaults for Bind Package panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 973
Defaults for Bind Plan panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 976
System Connection Types panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 980
Panels for entering lists of values. . . . . . . . . . . . . . . . . . . . . . . . . . . 981
Program Preparation: Compile, Link, and Run panel . . . . . . . . . . . . . . . . . . . . 982
DB2I panels that are used to rebind and free plans and packages . . . . . . . . . . . . . . . . . 984
Bind/Rebind/Free Selection panel . . . . . . . . . . . . . . . . . . . . . . . . . . 985
Rebind Package panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 986
Rebind Trigger Package panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 988
Rebind Plan panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 990
Free Package panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 992
Free Plan panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 993

Chapter 18. Running an application on DB2 for z/OS . . . . . . . . . . . . . . . 995

DSN command processor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 995
DB2I Run panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 996
Running a program in TSO foreground. . . . . . . . . . . . . . . . . . . . . . . . . . 997
Running a DB2 REXX application . . . . . . . . . . . . . . . . . . . . . . . . . . . 998
Invoking programs through the Interactive System Productivity Facility . . . . . . . . . . . . . . . 998
ISPF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 999
Invoking a single SQL program through ISPF and DSN . . . . . . . . . . . . . . . . . . . 1000
Invoking multiple SQL programs through ISPF and DSN . . . . . . . . . . . . . . . . . . 1001
Loading and running a batch program . . . . . . . . . . . . . . . . . . . . . . . . . 1002
Authorization for running a batch DL/I program . . . . . . . . . . . . . . . . . . . . . 1003
Restarting a batch program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1003
| Running stored procedures from the command line processor . . . . . . . . . . . . . . . . . . 1006
| Command line processor CALL statement . . . . . . . . . . . . . . . . . . . . . . . 1006
Example of running a batch DB2 application in TSO . . . . . . . . . . . . . . . . . . . . . 1007
Example of calling applications in a command procedure . . . . . . . . . . . . . . . . . . . 1008

Chapter 19. Testing and debugging an application program on DB2 for z/OS . . . . 1009
Designing a test data structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1009
Analyzing application data needs . . . . . . . . . . . . . . . . . . . . . . . . . . 1009
Authorization for test tables and applications . . . . . . . . . . . . . . . . . . . . . . 1010
Example SQL statements to create a comprehensive test structure . . . . . . . . . . . . . . . 1011
Populating the test tables with data . . . . . . . . . . . . . . . . . . . . . . . . . . 1012
Methods for testing SQL statements . . . . . . . . . . . . . . . . . . . . . . . . . . 1012
Executing SQL by using SPUFI . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1013
SPUFI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1016
Content of a SPUFI input data set . . . . . . . . . . . . . . . . . . . . . . . . . . 1017
The SPUFI panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1017
Changing SPUFI defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1019
Setting the SQL terminator character in a SPUFI input data set . . . . . . . . . . . . . . . . 1024
Controlling toleration of warnings in SPUFI . . . . . . . . . . . . . . . . . . . . . . . 1025
Output from SPUFI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1025
Testing an external user-defined function . . . . . . . . . . . . . . . . . . . . . . . . . 1027
Testing a user-defined function by using the Debug Tool for z/OS . . . . . . . . . . . . . . . 1027
Testing a user-defined function by routing the debugging messages to SYSPRINT . . . . . . . . . . 1029
Testing a user-defined function by using driver applications . . . . . . . . . . . . . . . . . 1029
Testing a user-defined function by using SQL INSERT statements . . . . . . . . . . . . . . . 1030
| Debugging stored procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1030

x Application Programming and SQL Guide

| Debugging stored procedures with the Debug Tool and IBM VisualAge COBOL . . . . . . . . . . 1031
| Debugging a C language stored procedure with the Debug Tool and C/C++ Productivity Tools for z/OS 1032
| Debugging stored procedures by using the Unified Debugger . . . . . . . . . . . . . . . . . 1033
| Debugging stored procedures with the Debug Tool for z/OS . . . . . . . . . . . . . . . . . 1034
| Recording stored procedure debugging messages in a file . . . . . . . . . . . . . . . . . . 1036
| Driver applications for debugging procedures . . . . . . . . . . . . . . . . . . . . . . 1036
| DB2 tables that contain debugging information. . . . . . . . . . . . . . . . . . . . . . 1036
Debugging an application program. . . . . . . . . . . . . . . . . . . . . . . . . . . 1037
Locating the problem in an application . . . . . . . . . . . . . . . . . . . . . . . . 1037
Techniques for debugging programs in TSO . . . . . . . . . . . . . . . . . . . . . . . 1042
Techniques for debugging programs in IMS . . . . . . . . . . . . . . . . . . . . . . . 1042
Techniques for debugging programs in CICS . . . . . . . . . . . . . . . . . . . . . . 1043
Finding a violated referential or check constraint . . . . . . . . . . . . . . . . . . . . . . 1047

Chapter 20. DB2 sample applications and data . . . . . . . . . . . . . . . . . 1049

DB2 sample tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1049
Activity table (DSN8910.ACT) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1049
Department table (DSN8910.DEPT) . . . . . . . . . . . . . . . . . . . . . . . . . . 1050
Employee table (DSN8910.EMP) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1051
Employee photo and resume table (DSN8910.EMP_PHOTO_RESUME) . . . . . . . . . . . . . . 1055
Project table (DSN8910.PROJ) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1056
Project activity table (DSN8910.PROJACT) . . . . . . . . . . . . . . . . . . . . . . . 1057
Employee to project activity table (DSN8910.EMPPROJACT) . . . . . . . . . . . . . . . . . 1058
Unicode sample table (DSN8910.DEMO_UNICODE) . . . . . . . . . . . . . . . . . . . . 1059
Relationships among the sample tables . . . . . . . . . . . . . . . . . . . . . . . . 1060
Views on the sample tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1061
Storage of sample application tables . . . . . . . . . . . . . . . . . . . . . . . . . 1065
DB2 sample applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1069
Types of sample applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1071
Application languages and environments for the sample applications . . . . . . . . . . . . . . 1073
Sample applications in TSO . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1074
Sample applications in IMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1076
Sample applications in CICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1077
DSNTIAUL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1077
DSNTIAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1083
DSNTEP2 and DSNTEP4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1084

Information resources for DB2 for z/OS and related products . . . . . . . . . . . 1091

How to obtain DB2 information . . . . . . . . . . . . . . . . . . . . . . . . 1097

How to use the DB2 library . . . . . . . . . . . . . . . . . . . . . . . . . . 1101

Notices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1105
Programming Interface Information . . . . . . . . . . . . . . . . . . . . . . . . . . 1106
General-use Programming Interface and Associated Guidance Information . . . . . . . . . . . . 1107
Product-sensitive Programming Interface and Associated Guidance Information . . . . . . . . . . . 1107
Trademarks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1107

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1109

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1153

Contents xi
xii Application Programming and SQL Guide
About this information
This information discusses how to design and write application programs that
access DB2® for z/OS® (DB2), a highly flexible relational database management
system (DBMS).

Visit the following Web site for information about ordering DB2 books and
obtaining other valuable information about DB2 for z/OS: http://
publib.boulder.ibm.com/infocenter/imzic

This information assumes that your DB2 subsystem is running in Version 9.1
new-function mode. Generally, new functions that are described, including changes
to existing functions, statements, and limits, are available only in new-function
mode. Two exceptions to this general statement are new and changed utilities and
optimization enhancements, which are also available in conversion mode unless
stated otherwise.

Who should read this information

This information is for DB2 application developers who are familiar with
Structured Query Language (SQL) and who know one or more programming
languages that DB2 supports.

DB2 Utilities Suite

Important: In this version of DB2 for z/OS, the DB2 Utilities Suite is available as
an optional product. You must separately order and purchase a license to such
utilities, and discussion of those utility functions in this publication is not intended
to otherwise imply that you have a license to them.

The DB2 Utilities Suite is designed to work with the DFSORT™ program, which
you are licensed to use in support of the DB2 utilities even if you do not otherwise
license DFSORT for general use. If your primary sort product is not DFSORT,
consider the following informational APARs mandatory reading:
v II14047/II14213: USE OF DFSORT BY DB2 UTILITIES
v II13495: HOW DFSORT TAKES ADVANTAGE OF 64-BIT REAL
ARCHITECTURE
These informational APARs are periodically updated.
Related information
DB2 utilities packaging (Utility Guide)

Terminology and citations

In this information, DB2 Version 9.1 for z/OS is referred to as ″DB2 for z/OS.″ In
cases where the context makes the meaning clear, DB2 for z/OS is referred to as
″DB2.″ When this information refers to titles of DB2 for z/OS books, a short title is
used. (For example, ″See DB2 SQL Reference″ is a citation to IBM® DB2 Version 9.1
for z/OS SQL Reference.)

© Copyright IBM Corp. 1983, 2009 xiii

When referring to a DB2 product other than DB2 for z/OS, this information uses
the product’s full name to avoid ambiguity.

The following terms are used as indicated:

DB2 Represents either the DB2 licensed program or a particular DB2 subsystem.
OMEGAMON®
Refers to any of the following products:
v IBM Tivoli® OMEGAMON XE for DB2 Performance Expert on z/OS
v IBM Tivoli OMEGAMON XE for DB2 Performance Monitor on z/OS
v IBM DB2 Performance Expert for Multiplatforms and Workgroups
v IBM DB2 Buffer Pool Analyzer for z/OS
C, C++, and C language
Represent the C or C++ programming language.
| CICS® Represents CICS Transaction Server for z/OS.
IMS™ Represents the IMS Database Manager or IMS Transaction Manager.
MVS™ Represents the MVS element of the z/OS operating system, which is
equivalent to the Base Control Program (BCP) component of the z/OS
operating system.
RACF®
Represents the functions that are provided by the RACF component of the
z/OS Security Server.

Accessibility features for DB2 Version 9.1 for z/OS

Accessibility features help a user who has a physical disability, such as restricted
mobility or limited vision, to use information technology products successfully.

Accessibility features

The following list includes the major accessibility features in z/OS products,
including DB2 Version 9.1 for z/OS. These features support:
v Keyboard-only operation.
v Interfaces that are commonly used by screen readers and screen magnifiers.
v Customization of display attributes such as color, contrast, and font size

Tip: The Information Management Software for z/OS Solutions Information

Center (which includes information for DB2 Version 9.1 for z/OS) and its related
publications are accessibility-enabled for the IBM Home Page Reader. You can
operate all features using the keyboard instead of the mouse.

Keyboard navigation

You can access DB2 Version 9.1 for z/OS ISPF panel functions by using a keyboard
or keyboard shortcut keys.

For information about navigating the DB2 Version 9.1 for z/OS ISPF panels using
TSO/E or ISPF, refer to the z/OS TSO/E Primer, the z/OS TSO/E User’s Guide, and
the z/OS ISPF User’s Guide. These guides describe how to navigate each interface,
including the use of keyboard shortcuts or function keys (PF keys). Each guide
includes the default settings for the PF keys and explains how to modify their
functions.

xiv Application Programming and SQL Guide

Related accessibility information

Online documentation for DB2 Version 9.1 for z/OS is available in the Information
Management Software for z/OS Solutions Information Center, which is available at
the following Web site: http://publib.boulder.ibm.com/infocenter/dzichelp

IBM and accessibility

See the IBM Accessibility Center at http://www.ibm.com/able for more information

about the commitment that IBM has to accessibility.

How to send your comments

Your feedback helps IBM to provide quality information. Please send any
comments that you have about this book or other DB2 for z/OS documentation.
You can use the following methods to provide comments:
v Send your comments by e-mail to db2zinfo@us.ibm.com and include the name
of the product, the version number of the product, and the number of the book.
If you are commenting on specific text, please list the location of the text (for
example, a chapter and section title or a help topic title).
v You can send comments from the Web. Visit the DB2 for z/OS - Technical
Resources Web site at:

http://www.ibm.com/support/docview.wss?&uid=swg27011656

This Web site has an online reader comment form that you can use to send
comments.
v You can also send comments by using the feedback link at the footer of each
page in the Information Management Software for z/OS Solutions Information
Center at http://publib.boulder.ibm.com/infocenter/db2zhelp.

How to read syntax diagrams

Certain conventions apply to the syntax diagrams that are used in IBM
documentation.

Apply the following rules when reading the syntax diagrams that are used in DB2
for z/OS documentation:
v Read the syntax diagrams from left to right, from top to bottom, following the
path of the line.
The

─── symbol indicates the beginning of a statement.
The ───
symbol indicates that the statement syntax is continued on the next
line.
The
─── symbol indicates that a statement is continued from the previous line.
The ───
 symbol indicates the end of a statement.
v Required items appear on the horizontal line (the main path).

required_item


v Optional items appear below the main path.

About this information xv

required_item

optional_item

If an optional item appears above the main path, that item has no effect on the
execution of the statement and is used only for readability.

optional_item


required_item


v If you can choose from two or more items, they appear vertically, in a stack.
If you must choose one of the items, one item of the stack appears on the main
path.

required_item required_choice1

required_choice2

If choosing one of the items is optional, the entire stack appears below the main
path.

required_item

optional_choice1
optional_choice2

If one of the items is the default, it appears above the main path and the
remaining choices are shown below.

default_choice


required_item

optional_choice
optional_choice

v An arrow returning to the left, above the main line, indicates an item that can be
repeated.

required_item  repeatable_item


If the repeat arrow contains a comma, you must separate repeated items with a
comma.

required_item  repeatable_item


A repeat arrow above a stack indicates that you can repeat the items in the
stack.
| v Sometimes a diagram must be split into fragments. The syntax fragment is
| shown separately from the main syntax diagram, but the contents of the
| fragment should be read as if they are on the main path of the diagram.

|

required_item fragment-name

|

xvi Application Programming and SQL Guide

| fragment-name:

| required_item
optional_name
|
| v With the exception of XPath keywords, keywords appear in uppercase (for
| example, FROM). Keywords must be spelled exactly as shown. XPath keywords
| are defined as lowercase names, and must be spelled exactly as shown. Variables
appear in all lowercase letters (for example, column-name). They represent
user-supplied names or values.
v If punctuation marks, parentheses, arithmetic operators, or other such symbols
are shown, you must enter them as part of the syntax.

About this information xvii

xviii Application Programming and SQL Guide
Chapter 1. Planning for and designing DB2 applications
Whether you are writing a new DB2 application or migrating an existing
application from a previous release of DB2, you need to make some planning and
design decisions before you write or run the program.

If you are migrating an existing application from a previous release of DB2, read
the application and SQL release incompatibilities and make any necessary changes
in the application.

If you are writing a new DB2 application, first determine the following items:
v the value of some of the SQL processing options
v the binding method
v the value of some of the bind options

Then make sure that your program implements the appropriate recommendations
so that it promotes concurrency, can handle recovery and restart situations, and can
efficiently access distributed data.

| Application and SQL release incompatibilities

| When you migrate to Version 9.1, be aware of the application and SQL release
| incompatibilities.

| Plan for the following changes in Version 9.1 that might affect your migration.

| Changes in BIND PACKAGE and BIND PLAN defaults

| The default value for bind option CURRENTDATA is changed from YES to NO.
| This applies to the BIND PLAN and the BIND PACKAGE subcommands, as well
| as the CREATE TRIGGER for trigger packages, and the CREATE PROCEDURE and
| the ALTER PROCEDURE ADD VERSION SQL statements for SQL PL procedure
| packages. Specifying NO for CURRENTDATA is the best option for performance.

| The default value for bind option ISOLATION is changed from RR to CS. This
| applies to the BIND PLAN and the remote BIND PACKAGE subcommands. For
| the BIND PACKAGE subcommand, the current default (plan value) stays. The
| default change does not apply to implicitly-built CTs (for example, DISTSERV CTs).

| Although you can specify DBPROTOCOL(PRIVATE) for the DBPROTOCOL

| parameter of the BIND option, DB2 issues a new warning message, DSNT226I.

| All BIND statements for plans and packages that are bound during the installation
| or migration process specify the ISOLATION parameter explicitly, except for
| routines that do not fetch data. The current settings are maintained for
| compatibility.

| Plan for the XML data type

| Drop any user-defined data types with the name XML to prevent problems with
| the new Version 9.1 built-in XML data type. You can re-create the existing
| user-defined data types with new names.

© Copyright IBM Corp. 1983, 2009 1

| Changes to XMLNAMESPACES

| In DB2 Version 8, in the XMLNAMESPACES function, if the XML-namespace-uri

| argument has a value of http://www.w3.org/XML/1998/namespace or
| http://www.w3.org/2000/xmlns/, DB2 does not issue an error. In Version 9.1,
| starting in conversion mode, DB2 issues an error.

| Changes to serialization of empty elements

| In Version 8, DB2 serializes empty XML elements in a different way than it

| serializes them in Version 9.1. In Version 8, empty element ″a″ is serialized as
| <a></a>. In Version 9.1, starting in conversion mode, empty element ″a″ is
| serialized as <a/>.

| Availability of LOB or XML values in JDBC or SQLJ applications

| with progressive streaming

| In previous releases, if a JDBC or SQLJ application retrieves LOB data into an

| application variable, the contents of the application variable are still available after
| the cursor is moved or closed. DB2 Version 9.1 for z/OS supports streaming. The
| IBM Data Server Driver for JDBC and SQLJ uses progressive streaming as the
| default for retrieval of LOB or XML values. When progressive streaming is in
| effect, the contents of LOB or XML variables are no longer available after the
| cursor is moved or closed.

| Adjust applications that depend on error information that is

| returned from DB2-supplied stored procedures

| Adjust any applications that call one of the following stored procedures and then
| check and process the specific SQLCODE or SQLSTATE that is returned by the
| CALL statement:
| v SQLJ.INSTALL_JAR
| v SQLJ.REMOVE_JAR
| v SQLJ.REPLACE_JAR
| v SQLJ.DB2_INSTALL_JAR
| v SQLJ.DB2_REPLACE_JAR
| v SQLJ.DB2_REMOVE_JAR
| v SQLJ.DB2_UPDATEJARINFO

| In Version 9.1, these stored procedures return more meaningful SQLCODEs and
| SQLSTATEs than they return in previous releases of DB2. The other input and
| output parameters of these stored procedures have not changed.

| For example, the following application needs to change because -20201 is no longer
| the SQLCODE that is returned. Successful execution (SQLCODE 0) is not affected.
| CALL SQLJ.REMOVE_JAR(...)
| IF (SQLCODE = -20201) THEN
| DO;
| ...
| END;

2 Application Programming and SQL Guide

| Some materialized query tables should be dropped

| Before migrating to conversion mode, drop all materialized query tables that are
| based on the SYSIBM.SYSROUTINES catalog table. During migration, if any
| materialized query tables are based on the SYSIBM.SYSROUTINES catalog table,
| SQLCODE -750 is issued.

| Before converting to enabling-new-function mode, drop all materialized query

| tables that are based on the SYSIBM.SYSPACKSTMT catalog table. During
| conversion, if any materialized query tables are based on the
| SYSIBM.SYSPACKSTMT catalog table, SQLCODE -750 is issued.

| Fully define objects

| Ensure that you do not have any incomplete object definitions in your DB2 Version
| 8 catalog. For example, if a table has a primary or unique key defined but the
| enforcing primary or unique key index does not exist, the table definition is
| considered incomplete. You need to complete or drop all such objects before you
| begin migration because their behavior will be different in Version 9.1. For
| example, if you attempt to create an enforcing primary key index to complete a
| table definition in Version 9.1 and the residing table space is implicitly created, the
| index is treated as a regular index instead of an enforcing index.

| SQL reserved words

| Version 9.1 has several new SQL reserved words. Refer to Reserved words (SQL
| Reference) for the list, and adjust your applications accordingly.

| Changes to PL/I applications with no DECLARE VARIABLE

| statements

| For PL/I applications with no DECLARE VARIABLE statements, the rules for host
| variables and string constants in the FROM clause of a PREPARE or EXECUTE
| IMMEDIATE statement have changed. A host variable must be a varying-length
| string variable that is preceded by a colon. A PL/I string cannot be preceded by a
| colon.

| Automatic rebind of plans and packages created before DB2

| Version 4

| If you have plans and packages that were bound before DB2 Version 4 and you
| specified YES or COEXIST in the AUTO BIND field of panel DSNTIPO, DB2
| Version 9.1 autobinds these packages. Thus, you might experience an execution
| delay the first time that such a plan is loaded. Also, DB2 might change the access
| path due to the autobind, potentially resulting in a more efficient access path.

| If you specify NO in the AUTO BIND field of panel DSNTIPO, DB2 Version 9.1
| returns SQLCODE -908, SQLSTATE 23510 for each attempt to use such a package
| or plan until it is rebound.

| Changed behavior of the INSERT statement with the

| OVERRIDING USER VALUES clause

| When the INSERT statement is specified with the OVERRIDING USER VALUES
| clause, the value for the insert operation is ignored for columns that are defined
| with the GENERATED BY DEFAULT attribute.

Chapter 1. Planning for and designing DB2 applications 3

| DESCRIBE no longer returns LONG type values

| Because DB2 no longer stores LONG type values in the catalog, when you execute
| a DESCRIBE statement against a column with a LONG VARCHAR or LONG
| VARGRAPHIC data type, the DESCRIBE statement returns the values as
| VARCHAR or VARGRAPHIC data type.

| The DSNTIAUL sample program was updated through APAR PK46518 to account
| for this change. You need to apply APAR PK46518 and precompile, bind compile,
| and link-edit DSNTIAUL to make it compatible with the changed DESCRIBE
| behavior.

| DB2 enforces the restrictions about where a host variable array

| can be specified

| host-variable-array is the meta-variable for host variable arrays in syntax diagrams.

| host-variable-array is included only in the syntax for multi-row FETCH, multi-row
| INSERT, multi-row MERGE, and EXECUTE in support of a dynamic multi-row
| INSERT or MERGE statement. host-variable-array is not included in the syntax
| diagram for expression, so a host variable array cannot be used in other contexts. In
| previous releases, if you specified host-variable-array in an unsupported context, you
| received no errors. In Version 9.1, if a host variable array is referenced in an
| unsupported context, DB2 issues an error.

| For more information about where you can specify the host-variable-array variable,
| see DB2 SQL Reference.

| DEBUGSESSION system privilege required for continued

| debugging of SQL procedures

| After you migrate to new-function mode, users that debug external SQL
| procedures need the DEBUGSESSION system privilege. (External SQL procedures
| were previously called SQL procedures in Version 8.) Only users of the new
| Unified Debugger enabled client platforms need this system privilege. Users of the
| Version 8 SQL Debugger-enabled client platforms do not need this system
| privilege.

| Changes to the result length of the DECRYPT function

| The result length of the DECRYPT function is shortened to 8 bytes less than the
| length of the input value. If the result expands because of a difference between
| input and result CCSIDs, you must cast the encrypted data to a larger VARCHAR
| value before the DECRYPT function is run.

| COLTYPE column in SYSIBM.SYSCOLUMNS and

| SYSIBM.SYSCOLUMNS_HIST for LONG column types

| When new tables are created with LONG VARCHAR or LONG VARGRAPHIC
| columns, the COLTYPE values in SYSIBM.SYSCOLUMNS and
| SYSIBM.SYSCOLUMNS_HIST contain VARCHAR or VARG.

4 Application Programming and SQL Guide

| CREATEDBY column in SYSIBM.SYSDATATYPES,
| SYSIBM.SYSROUTINES, SYSIBM.SYSSEQUENCES, and
| SYSIBM.SYSTRIGGERS

| The CREATEDBY column might contain a different value than in previous releases
| of DB2. The column might contain a different value in static CREATE statements
| for distinct types, functions, and procedures or when a dynamic SQL statement
| sets the CURRENT SQLID value to a value other than USER.

| Drop and re-create SYSPROC.DSNWZP

| Drop and re-create SYSPROC.DSNWZP as part of running job DSNTIJSG or alter it

| to specify READS SQL DATA, as shown in the following SQL statement:
| ALTER PROCEDURE SYSPROC.DSNWZP READS SQL DATA;

| On data sharing systems, SYSPROC.DSNWZP needs to be dropped and re-created

| as part of migrating the first member, but not for subsequent members. DSNTIJSG
| grants execute access on DSNWZP to PUBLIC. If necessary, change PUBLIC to a
| specific authorization ID.

| DB2 returns all DSNWZP output in the same format as DB2

| parameters

| In previous releases, DSNWZP returned the current setting of several system

| parameters in a format other than the one used by the system parameter macros.
| For example, DSN6SPRM expected the setting for EDMPOOL in kilobytes, and
| DSNWZP returned it in bytes. In Version 9.1, DB2 returns all DSNWZP output in
| the same format as DB2 parameters. Modify programs that call DSNWZP if they
| compensate for the format differences.

| DB2 enforces the restriction that row IDs are not compatible with
| character strings when they are used with a set operator

| In previous releases, DB2 did not always enforce the restriction that row IDs are
| not compatible with character strings. In Version 9.1, DB2 enforces the restriction
| that row IDs are not compatible with string types when they are used with a set
| operator (UNION, INTERSECT, or EXCEPT).

| You can no longer explicitly create a database name as

| DSNxxxxx

| After you migrate to conversion mode, if you explicitly create a database name
| with eight characters that begins with DSN and is followed by exactly five digits,
| DB2 issues an SQLCODE -20074 (SQLSTATE 42939).

| Database privileges on the DSNDB04 database now give you

| those privileges on all implicitly created databases

| Because database privileges on the DSNDB04 database now give you those
| privileges on all implicitly created databases, careful consideration is needed before
| you grant database privileges on DSNDB04. For example, in Version 9.1, if you
| have the STOPDB privilege on DSNDB04, you also have the STOPDB privilege on
| all implicitly created databases.

Chapter 1. Planning for and designing DB2 applications 5

| Implicitly created objects that are associated with LOB columns
| require additional privileges

| In previous releases, implicitly created objects that are associated with LOB
| columns do not require CREATETAB and CREATETS privileges on the database of
| the base table. Those implicitly created objects also do not require the USE
| privilege on the buffer pool and storage group that is used by the LOB objects. In
| Version 9.1, these privileges are required.

| Adjust applications to use LRHCLR instead of LGDISCLR

| The LGDISCLR field in the DSNDQJ00 macro has been removed. Update
| applications that use the LGDISCLR value in the DSNDQJ00 mapping macro to
| determine whether a log record is a compensation log record to use the LRHCLR
| value instead.

| Changed behavior for the CREATE statement

| You can no longer create databases with the AS TEMP clause or table spaces that
| specify TEMP as the target database. The TEMP database is no longer used by
| DB2. The WORKFILE database is the only temporary database.

| The DECLARE statement and the work file database

| If you have applications in Version 8 that issue DECLARE SENSITIVE STATIC

| SCROLL CURSOR or DECLARE GLOBAL TEMPORARY TABLE statements,
| ensure that the work file database exists and that it has at least one table space
| with a 32 KB page size to avoid errors.

| Adjust monitor programs that access OP buffers

| Adjust assignment strategies of monitor programs that access OP buffers. In

| Version 8, traces are left in a disabled state, which consumes CPU for trace data
| that cannot be retrieved. In Version 9.1, traces that are started with a destination of
| OPX choose the next available buffer that is not in use and traces are no longer left
| in a disabled state.

| In addition, in Version 8, when the thread that owns an OP buffer terminates, OP

| traces are left in a disabled state and can be reactivated by starting another trace to
| that buffer. In Version 9.1, if an OP buffer terminates and the only destinations for
| the trace records are OP buffers, the traces that are started to that buffer are
| stopped. If an OP buffer terminates and the trace is started to both OP and non-OP
| destinations, the traces that are started to that buffer are modified to use non-OP
| destinations only.

| The message format of DSNW128I and DSNW129I has changed, so modify

| automation that is based on those message formats.

| Changed behavior for system-required objects

| After you migrate to Version 9.1 new-function mode, if the containing table space
| is implicitly created, you cannot drop any system-required objects, except for the
| LOB table space, even if you explicitly created these objects in a previous release.
| The following statements will not work properly if the system-required objects
| were implicitly created by DB2:

6 Application Programming and SQL Guide

| CREATE AUXILIARY TABLE
| If you issue a CREATE AUXILIARY TABLE statement and an auxiliary
| table that was implicitly created by DB2 already exists for the same base
| table, the CREATE AUXILIARY TABLE statement fails and DB2 issues
| SQLCODE -646, SQLSTATE 55017, and reason code 3.
| CREATE LOB TABLESPACE
| If you issue a CREATE LOB TABLESPACE statement to create a LOB table
| space in an implicitly created database, the CREATE LOB TABLESPACE
| statement fails and DB2 issues SQLCODE -20355, SQLSTATE 429BW, and
| reason code 1.
| CREATE DATABASE
| If you specify a database name with eight characters that begins with DSN
| and is followed by exactly five digits in a CREATE DATABASE statement,
| the CREATE DATABASE statement fails and DB2 issues SQLCODE -20074,
| SQLSTATE 42939.
| CREATE INDEX
| If you create an index on a primary key, unique key, or ROWID column
| that is defined as GENERATED BY DEFAULT, the index will be treated as
| a regular index instead of an enforcing index.
| CREATE AUXILIARY INDEX
| If you issue a CREATE AUXILIARY INDEX statement and an auxiliary
| index that was implicitly created by DB2 already exists for the same base
| table, the CREATE AUXILIARY INDEX statement fails and DB2 issues
| SQLCODE -748, SQLCODE 54048, and reason code 3.
| CREATE
| If you issue a CREATE statement and do not specify an IN clause or table
| space name, and the default buffer pool is not large enough, DB2 chooses a
| 4-KB, 8-KB, 16-KB, or 32-KB buffer pool, depending on the record size. If
| you issue a CREATE statement and do not specify an IN clause or table
| space name, DB2 implicitly creates a partitioned-by-growth table space. If
| you drop the table, DB2 also drops the containing table space.
| DROP TABLE
| If you issue a DROP TABLE statement to drop an auxiliary table from a
| table space that was implicitly created by DB2, the DROP TABLE statement
| fails and DB2 issues SQLCODE -20355, SQLSTATE 429BW, and reason code
| 2.
| DROP TABLESPACE
| If you issue a DROP TABLESPACE statement to drop an implicitly-created
| LOB table space, the DROP TABLESPACE statement fails and DB2 issues
| SQLCODE -20355, SQLSTATE 429BW, and reason code 2.
| DROP INDEX
| If you issue a DROP INDEX statement to drop an enforcing primary key,
| unique key, or ROWID index from a table space that was implicitly
| created, the DROP INDEX statement fails and DB2 issues SQLCODE -669,
| SQLSTATE 42917, and reason code 2. If you issue a DROP INDEX
| statement to drop an auxiliary index from a table space that was implicitly
| created, the DROP INDEX statement fails and DB2 issues SQLCODE
| -20355, SQLSTATE 429BW, and reason code 2.

Chapter 1. Planning for and designing DB2 applications 7

| Changes to INSERT, UPDATE, or DELETE statements on some
| indexes

| In Version 9.1, you cannot execute INSERT, UPDATE, or DELETE statements that
| affect an index in the same commit scope as ALTER INDEX statements on that
| index.

| LOBs with a maximum length greater than 1 GB can now be

| logged

| In previous releases, only LOBs with a maximum length of 1 GB or less could be

| logged. In Version 9.1, LOBs with a maximum length that is greater than 1 GB can
| be logged.

| DB2 returns an error when a LOB value is specified for an

| argument to a stored procedure and the argument value is
| longer than the target parameter and the excess is not trailing
| blanks

| In previous releases, DB2 did not return an error when a LOB value was specified
| for an argument to a stored procedure and the argument value was longer than the
| target parameter and the excess was not trailing blanks. DB2 truncated the data
| and the procedure executed. In Version 9.1, DB2 returns an error.

| Changes to VARCHAR function formatting of decimal data

| In Version 9.1, the formatting of decimal data has changed for the VARCHAR
| function and CAST specification with a VARCHAR result type. When the input
| data is decimal, any leading zeroes in the input value are removed, and leading
| zeroes are not added to an input value that did not already contain leading zeroes.

| Changes to VARCHAR_FORMAT function length attribute

| In Version 9.1, the length attribute of the result is the length attribute of the format
| string, up to a maximum of 100.

| ’W’ is no longer recognized as a valid format element of the

| VARCHAR_FORMAT function format string

| DB2 Version 9.1 no longer recognizes ’W’ as a valid format element of the
| VARCHAR_FORMAT function format string. Version 8 never recognized ’W’ as a
| valid format element.

| Use WW instead. Drop and re-create existing views and materialized queries that
| are defined with Version 9.1 and that use the ’W’ format element with the
| VARCHAR_FORMAT function. Rebind existing bound statements that are bound
| with Version 9.1 and that use the ’W’ format element with the
| VARCHAR_FORMAT function.

| Leading or trailing blanks from the VARCHAR_FORMAT function

| format string are no longer removed

| Leading or trailing blanks from the format string for the VARCHAR_FORMAT
| function are no longer removed. Existing view definitions are recalculated as part
| of Version 9.1, so the new rules take effect. You can continue to use existing
| materialized query statements, but they use the old rules and remove leading and

8 Application Programming and SQL Guide

| trailing blanks. Existing references to the VARCHAR_FORMAT function in bound
| statements only get the new behavior when they have been bound or rebound in
| Version 9.1.

| DB2 issues warnings when some BEFORE or AFTER triggers are

| created

| DB2 Version 9.1 for z/OS issues a warning when a BEFORE or AFTER trigger is
| created and a trigger transition variable is passed as an argument for a parameter
| on a CALL statement that is within the trigger body.

| DB2 drops certain indexes when a unique constraint is dropped

| In previous releases, if a unique constraint was dropped, DB2 did not drop the
| index that enforced uniqueness. In Version 9.1, if a table is in an implicitly-created
| table space, and a unique constraint on that table is dropped, DB2 drops the index
| that enforces uniqueness.

| Changes to the upper limit to the size of the row that is used by
| sort to evaluate column functions

| The maximum limit of a row (data and key columns) that is used by sort to
| evaluate MULTIPLE DISTINCT and GROUP BY column functions is decreased to
| 32600. If you exceed the limit, DB2 issues an error.

| DB2 enforces restriction on specifying a CAST FROM clause for

| some forms of CREATE FUNCTION statements

| The CAST FROM clause is included only in the syntax diagram for the CREATE
| FUNCTION statement for an external scalar function. The CAST FROM clause is
| not included in the syntax diagrams for the other variations of CREATE
| FUNCTION (external table function, sourced function, or SQL function); the clause
| cannot be used for these other variations. In previous releases, if you specified a
| CAST FROM clause in an unsupported context, you received no errors. In Version
| 9.1 if a CAST FROM clause is specified in an unsupported context, DB2 issues an
| error.

| DB2 enforces restrictions on specifying the AS LOCATOR clause

| and TABLE LIKE clause

| The AS LOCATOR clause for LOBs is included in the syntax diagram for the
| CREATE FUNCTION statement for an SQL function. This clause is not supported
| in other contexts when identifying an existing SQL function such as in an ALTER,
| COMMENT, DROP, GRANT, or REVOKE statement. In previous releases, if you
| specified an AS LOCATOR clause for LOBs in an unsupported context, you might
| not have received an error. In Version 9.1 if an AS LOCATOR clause for LOBs is
| specified in an unsupported context, DB2 issues an error.

| The TABLE LIKE clause for a trigger transition table is included only in the syntax
| diagram for the CREATE FUNCTION statement for an external scalar function,
| external table function, or sourced function. This clause is not supported for SQL
| functions or in other contexts when identifying an existing function such as in an
| ALTER, COMMENT, DROP, GRANT, or REVOKE statement, or in the SOURCE
| clause of a CREATE FUNCTION statement. In previous releases, if you specified a
| TABLE LIKE clause for a trigger transition table in an unsupported context, you
| might not have received an error. In Version 9.1 if a TABLE LIKE clause for a

Chapter 1. Planning for and designing DB2 applications 9

| trigger transition table is specified in an unsupported context, DB2 issues an error.

| DB2 enforces restriction on the CCSID parameter for the

| DECRYPT_BIT and DECRYPT_BINARY functions

| The CCSID parameter is not supported by the DECRYPT_BIT and

| DECRYPT_BINARY built-in functions. In previous releases, if you specified an
| argument for the CCSID parameter for these functions, you received no errors. In
| Version 9.1 if an argument is specified for the CCSID parameter in an unsupported
| context, DB2 issues an error.

| Changed behavior of CREATE PROCEDURE for an SQL

| procedure

| With the introduction of native SQL procedures in Version 9, the semantics of the
| CREATE PROCEDURE statement for an SQL procedure has changed. Starting in
| Version 9, all SQL procedures that are created without the FENCED option or the
| EXTERNAL option in the CREATE PROCEDURE statement are native SQL
| procedures. In previous releases of DB2, if you did not specify either of these
| options, the procedures were created as external SQL procedures.

| If you do specify FENCED or EXTERNAL, the meanings are the same as in

| previous releases of DB2. Both of these keywords mean that an external SQL
| procedure is to be created.

| Explicitly qualify names of variables, parameters, and columns in

| SQL procedures

| As of Version 9, the rules that are used for name resolution within a native SQL
| procedure differ from the rules that were used for SQL procedures in prior
| releases. Because an SQL parameter or SQL variable can have the same name as a
| column name, you should explicitly qualify the names of any SQL parameters,
| SQL variables or columns that have non-unique names. For more information
| about how the names of these items are resolved, see References to SQL
| parameters and SQL variables (SQL Reference). The rules that are used for name
| resolution within external SQL procedures remain unchanged.

| Make any necessary program changes for possibly different

| values for RETURNED_SQLSTATE and
| DB2_RETURNED_SQLCODE

| In Version 9.1, when an SQL statement other than GET DIAGNOSTICS or

| compound-statement is processed, the current diagnostics area is cleared before
| DB2 processes the SQL statement. Clearing of the diagnostics area can result in
| different values being returned for RETURNED_SQLSTATE and
| DB2_RETURNED_SQLCODE for a GET DIAGNOSTICS statement than what
| would be returned if the GET DIAGNOSTICS statement were issued from within
| an external SQL procedure. Additionally, there might be some differences in the
| values returned for the SQLSTATE and SQLCODE SQL variables than would have
| been returned from an external SQL procedure. (External SQL procedures were
| previously called SQL procedures in Version 8.)

10 Application Programming and SQL Guide

| SQLSTATE and SQLCODE SQL variables after a GET
| DIAGNOSTICS statement

| In Version 9.1, the SQLSTATE and SQLCODE SQL variables are not cleared
| following a GET DIAGNOSTICS statement.

| Coding multiple SQL statements in a handler body

| Previous releases of DB2 did not allow for a compound statement within a handler.
| A workaround to include multiple statements within a handler (without support
| for a compound statement in a handler) was to use another control statement, such
| as an IF statement, which in turn contained multiple statements. Version 9.1 now
| supports a compound statement within a handler body. The compound statement
| is recommended for including multiple statements within a handler body.

| Unhandled warnings

| In Version 9.1, when a native SQL procedure completes processing with an

| unhandled warning, DB2 returns the unhandled warning to the calling application.
| The behavior of an external SQL procedure is unchanged from releases prior to
| Version 9.1. When such a procedure completes processing with an unhandled
| warning, DB2 does not return the unhandled warning to the calling application.

| Change your programs to handle any changed messages from

| SQL procedures

| In Version 9.1, DB2 issues different messages for the new native SQL procedures
| than it does for external SQL procedures. (External SQL procedures were
| previously called SQL procedures in Version 8.) For external SQL procedures, DB2
| continues to issue DSNHxxxx messages. For native SQL procedures, DB2 issues
| SQL return codes. The relationship between these messages is shown in the
| following table:
| Table 1. Relationship between DSNHxxxx messages that are issued for external SQL
| procedures and SQLCODEs that are issued for native SQL procedures
| DSNHxxxx message1 SQLCODE2
| DSNH051I -051
| DSNH385I +385
| DSNH590I -590
| DSNH4408I -408
| DSNH4777I n/a
| DSNH4778I -778
| DSNH4779I -779
| DSNH4780I -780
| DSNH4781I -781
| DSNH4782I -782
| DSNH4785I -785
| DSNH4787I -787
|

| Note:

Chapter 1. Planning for and designing DB2 applications 11

| 1. These messages are used for external SQL procedures, which can be defined by
| specifying EXTERNAL or FENCED in Version 9.1.
| 2. These messages are used for native SQL procedures in Version 9.1.

| Enhanced data type checking for zero-length characters

| In Version 9.1, when you specify a CHAR data type with a length of 0 in the
| SQLDA, DB2 issues SQLCODE -804 regardless of the null indicator value.

| Adding a column generates a new table space version

| In previous releases, adding a column to a table did not generate a new table space
| version. In Version 9.1, adding a column to a table with an ALTER TABLE ADD
| COLUMN statement generates a new table space version.

| You cannot add a column and issue SELECT, INSERT, UPDATE,

| DELETE, or MERGE statements in the same commit scope

| You cannot have a version-generating ALTER TABLE ADD COLUMN statement

| and SELECT, INSERT, UPDATE, DELETE, or MERGE statements in the same
| commit scope. If a version-generating ALTER TABLE ADD COLUMN statement
| follows SELECT, INSERT, UPDATE, DELETE, or MERGE statements in the same
| commit scope, SQLCODE -910 is issued. SQLCODE -910 is also issued if SELECT,
| INSERT, UPDATE, DELETE, or MERGE statements follow a version-generating
| ALTER TABLE ADD COLUMN statement in the same commit scope.

| CAST FROM clause of CREATE FUNCTION statement for SQL

| functions is no longer supported

| The CAST FROM clause of the CREATE FUNCTION statement for SQL functions
| is no longer supported. If you issue a CREATE FUNCTION statement for an SQL
| function with a CAST FROM clause, DB2 issues an error.

| GRAPHIC and NOGRAPHIC SQL processing options are

| deprecated

| If you specify the SQL processing options GRAPHIC or NOGRAPHIC, DB2 ignores
| them. These options are superseded by the CCSID SQL processing option.

| Specifying ALTER DATABASE STOGROUP for work file

| databases

| In previous releases of DB2, you could not execute ALTER DATABASE

| STOGROUP on a work file database. Beginning with DB2 Version 9.1 conversion
| mode, this restriction is removed.

| DB2 enforces restrictions about where an INTO clause can be

| specified

| The INTO clause (as related to queries) is included only in the syntax diagram for
| the SELECT INTO statement. The INTO clause is not included in the syntax
| diagrams for select-clause, subselect, fullselect, or select-statement. In previous
| releases, if you specified an INTO clause in an unsupported context in a query, you
| might not have received an error. In Version 9.1, if an INTO clause is specified in
| an unsupported context, DB2 issues an error.

12 Application Programming and SQL Guide

| Pre-compilation for unsupported compilers

| For some COBOL and PL/I compilers that are no longer supported, you can use a
| version of the precompiler that allows you to precompile applications that have
| dependencies on these unsupported compilers. You can use this version of the
| precompiler with the following unsupported compilers:
| v OS/VS COBOL V1.2.4
| v OS PL/I 1.5 (PL/I Opt. V1.5.1)
| v VS/COBOL II V1R4
| v OS PL/I 2.3

| The load module for this precompiler is DSNHPC7. This precompiler is meant
| only to ease the transition from unsupported compilers to supported compilers.
| This precompiler has the following restrictions:
| v There is no corresponding DB2 coprocessor function to match this precompiler.
| v The precompiler does not support SQL procedures.
| v Only COBOL and PL/I are supported.
| v The SQL flagger is not supported.
| v The precompiler produces Version 7 DBRMs, and does not support any
| capability that is newer than Version 7.

| Qualify user-defined function names

| If you use a user-defined function that has the same name as a built-in function
| that has been added to Version 9.1, ensure that you fully qualify the function
| name. If the function name is unqualified and “SYSIBM” precedes the schema that
| you used for this function in the SQL path, DB2 invokes one of the built-in
| functions.

| For a list of built-in functions, including those that have been added in Version 9.1,
| see Functions (SQL Reference).

Determining the value of any SQL processing options that affect the
design of your program
When you process SQL statements in an application program, you can specify
options that describe the basic characteristics of the program or indicate how you
want the output listings to look. Although most of these options do not affect how
you design or code the program, a few options do.

SQL processing options specify program characteristics such as the following items:
v The host language in which the program is written
v The maximum precision of decimal numbers in the program
v How many lines are on a page of the precompiler listing
In many cases, you may want to accept the default value provided.

To determine the value of any SQL processing options that affect the design of
your program:

Review the list of SQL processing options and decide the values for any options
that affect the way that you write your program. For example, you need to know if
you are using NOFOR or STDSQL(YES) before you begin coding.

Chapter 1. Planning for and designing DB2 applications 13

Related concepts
“DB2 program preparation overview” on page 947
Related reference
“Descriptions of SQL processing options” on page 904

Determining the binding method

Before you can run an application, you must bind a plan. You can bind all of your
database request modules (DBRMs) into a single application plan or you can first
bind packages and then bind those packages into a plan. The bind method that
you choose can affect your application design.

You can choose one of the following binding methods:

v Bind all of your DBRMs into a single application plan.
v Bind all of your DBRMs into separate packages. Then bind all those packages
into a single application plan.
v Bind some of your DBRMs into separate packages. Then bind those packages
and any other DBRMs for that program into an application plan.

The use of packages affects your application design. For example, you might
decide to put certain SQL statements together in the same program, precompile
them into the same DBRM, and then bind them into a single package.

To determine the binding method:

Consider the advantages and disadvantages of each binding method, which are
described in the following table.
Table 2. Advantages and disadvantages of each binding method
Binding method Advantages Disadvantages
Bind all of your DBRMs This method has fewer steps and is appropriate in Maintenance is difficult. This
into a single application some cases. This method is suitable for small method has the disadvantage
plan. applications that are unlikely to change or that require that a change to one DBRM
all resources to be acquired when the plan is allocated, requires rebinding the entire
rather than when your program first uses them. plan, even though most DBRMs
are unchanged.

14 Application Programming and SQL Guide

Table 2. Advantages and disadvantages of each binding method (continued)
Binding method Advantages Disadvantages
Bind all of your DBRMs Maintenance is easier. When you use packages, you do Too many packages might be
into separate packages. not need to bind the entire plan again when you difficult to track. Input to
Then bind all those change one SQL statement. You need to bind only the binding a package is a single
packages into a single package that is associated with the changed SQL DBRM only. A one-to-one
application plan statement. correspondence between
programs and packages might
You can incrementally develop your program without easily enable you to keep track
rebinding the plan. A collection is a group of associated of each. However, your
packages. Binding packages into package collections application might consist of too
enables you to add packages to an existing application many packages to track easily.
plan without having to bind the plan again. If you
include a collection name in the package list when you
bind a plan, any package in the collection becomes
available to the plan. The collection can be empty when
you first bind the plan. Later, you can add packages to
the collection and drop or replace existing packages
without binding the plan again.

You can maintain several versions of a package within

the same plan. Maintaining several versions of a plan
without using packages requires a separate plan for
each version, and therefore, separate plan names and
RUN commands. Isolating separate versions of a
program into packages requires only one plan and
helps to simplify program migration and fallback. For
example, you can maintain separate development, test,
and production levels of a program by binding each
level of the program as a separate version of a package,
all within a single plan. You cannot bind or rebind a
package or a plan while it is running. However, you
can bind a different version of a package that is
running.

You can use different bind options for different

DBRMs. The options of the BIND PLAN command
apply to all DBRMs that are bound directly to the plan.
The options of the BIND PACKAGE command apply to
only the single DBRM that is bound to that package.
The package options need not all be the same as the
plan options, and they need not be the same as the
options for other packages that are used by the same
plan.

You can use different name qualifiers for different

groups of SQL statements. You can use a bind option
to name a qualifier for the unqualified object names in
SQL statements in a plan or package. By using
packages, you can use different qualifiers for SQL
statements in different parts of your application. By
rebinding, you can redirect your SQL statements, for
example, from a test table to a production table.

Unused packages are not locked. Packages and plans

are locked when you bind or run them. Packages that
run under a plan are not locked until the plan uses
them. If you run a plan and some packages in the
package list never run, those packages are never
locked.

Chapter 1. Planning for and designing DB2 applications 15

Table 2. Advantages and disadvantages of each binding method (continued)
Binding method Advantages Disadvantages
Bind some of your This method helps you migrate to using packages. Depending on your application
DBRMs into separate Binding DBRMs directly to the plan and specifying a design, you might not gain some
packages. Then bind package list is a suitable method for maintaining of the advantages of using
those packages and any existing applications. You can add a package list when packages.
other DBRMs for that you rebind an existing plan. To migrate gradually to
program into an the use of packages, bind DBRMs as packages when
application plan. you need to make changes.

Related concepts
“DB2 program preparation overview” on page 947
Related tasks
“Binding an application” on page 916

Changes that invalidate plans or packages

Changes to your program or database objects can invalidate plans and packages.
Consider the effect of these changes when you determine the binding method for
your program.

A change to your program probably invalidates one or more of your packages and
perhaps your entire plan. For some changes, you must bind a new object; for
others, rebinding is sufficient.

A plan or package can also become invalid for reasons that do not depend on
operations in your program. For example, when an index is dropped that is used
in an access path by one of your queries, a plan or package can become invalid. In
those cases, DB2 might rebind the plan or package automatically the next time that
the plan or package is used.

The following table lists the actions that you must take when changes are made to
your program or database objects.
Table 3. Changes that require plans or packages to be rebound.
Change made Required action
Run RUNSTATS to update catalog statistics Rebind the package or plan by using the
REBIND command. Rebinding might
improve the access path that DB2 uses.
Add an index to a table Rebind the package or plan by using the
REBIND command. Rebinding causes DB2 to
consider using the index when accessing this
table.
1
Change the bind options Rebind the package or plan by using the
REBIND command and specifying the new
value for the bind option. If the option that
you want to change is not available for the
REBIND command, issue the BIND
command with ACTION(REPLACE) instead.
Change both statements in the host language Precompile, compile, and link the application
and SQL statements program. Issue the BIND command with
ACTION(REPLACE) for the package or plan.

16 Application Programming and SQL Guide

Table 3. Changes that require plans or packages to be rebound. (continued)
Change made Required action
Drop a table, index, or other object, and If a table with a trigger is dropped, recreate
recreate the object the trigger if you recreate the table.
Otherwise, no change is required. DB2
attempts to automatically rebind the plan or
package the next time it is run.
Drop an object that a package depends on No action is required. If the package or plan
becomes invalid, DB2 automatically rebinds
the plan or package the next time that it is
allocated.

The package might become invalid according

to the following criteria:
v If the package is not appended to any
running plan, the package becomes
invalid.
v If the package is appended to a running
plan, and the drop occurs within that plan,
the package becomes invalid. However, if
the package is appended to a running
plan, and the drop occurs outside of that
plan, the object is not dropped, and the
package does not become invalid.

In all cases, the plan does not become invalid

until it has a DBRM that references the
dropped object.
Revoke an authorization to use an object No action is required. DB2 attempts to
automatically rebind the plan or package the
next time it is run. Automatic rebind fails if
authorization is still not available. In this
case, you must rebind the package or plan by
using the REBIND command.
Rename a column in a table on which a plan No action is required. DB2 automatically
or package is dependent rebinds invalidated plans and packages. If
automatic rebind is unsuccessful, modify,
recompile, and rebind the affected
applications.
| RUN REPAIR DBD REBUILD on a database Trigger packages in the database are
| invalidated. Rebind all trigger packages in
| the database

Note:
1. In the case of changing the bind options, the change is not actually made until
you perform the required action.

Chapter 1. Planning for and designing DB2 applications 17

Related concepts
“Automatic rebinding” on page 944
“Trigger packages” on page 467
Related tasks
“Rebinding an application” on page 936

Determining the value of any bind options that affect the design of
your program
Several options of the BIND PACKAGE and BIND PLAN commands can affect
your program design. For example, you can use a bind option to ensure that a
package or plan can run only from a particular CICS connection or IMS region;
your code does not need to enforce this situation.

To determine the value of any bind options that affect the design of your program:

Review the list of bind options and decide the values for any options that affect
the way that you write your program. For example, you should decide the values
of the ACQUIRE and RELEASE options before you write your program. These
options determine when your application acquires and releases locks on the objects
it uses.
Related reference
BIND and REBIND options (DB2 Command Reference)

Designing your application to promote concurrency

You should design your program so that it protects the integrity of the data, but
does not prevent other processes from accessing the same data for long periods of
time.

Concurrency is the ability of more than one application process to access the same
data at essentially the same time. Concurrency must be controlled to prevent lost
updates and such possibly undesirable effects as unrepeatable reads and access to
uncommitted data.

To design your application to promote concurrency:

1. Understand the techniques that DB2 uses to control concurrency.
One basic way that DB2 controls concurrency is by using locks for units of
work. When a unit of work completes, all locks that were implicitly acquired
by that unit of work are released, which enables a new unit of work to begin.
The amount of processing time that is used by a unit of work in your program
affects the length of time that DB2 prevents other users from accessing that
locked data. When several programs try to use the same data concurrently, each
program’s unit of work should be as short as possible to minimize the
interference between the programs.
Other techniques are discussed in the performance information about
improving concurrency.
2. Follow the recommendations for application design for concurrency.

18 Application Programming and SQL Guide

Related tasks
Programming for concurrency (DB2 Performance)
Programming your applications for concurrency (DB2 Performance)

Designing your application for recovery

If your application fails or DB2 terminates abnormally, you need to ensure the
integrity of any data that was manipulated in your application. You should
consider possible recovery situations when you design your application.

To design your application for recovery:

1. Put any changes that logically need to be made at the same time in the same
unit of work. This action ensures that in case DB2 terminates abnormally or
your application fails, the data is left in a consistent state.
A unit of work is a logically distinct procedure that contains steps that change
the data. If all the steps complete successfully, you want the data changes to
become permanent. But, if any of the steps fail, you want all modified data to
return to the original value before the procedure began. For example, suppose
two employees in the sample table DSN8910.EMP exchange offices. You need to
exchange their office phone numbers in the PHONENO column. You need to
use two UPDATE statements to make each phone number current. Both
statements, taken together, are a unit of work. You want both statements to
complete successfully. For example, if only one statement is successful, you
want both phone numbers rolled back to their original values before attempting
another update.
2. Consider how often you should commit any changes to the data.
If your program abends or the system fails, DB2 backs out all uncommitted
data changes. Changed data returns to its original condition without interfering
with other system activities.
For IMS and CICS applications, if the system fails, DB2 data does not always
return to a consistent state immediately. DB2 does not process indoubt data
(data that is neither uncommitted nor committed) until you restart IMS or the
CICS attachment facility. To ensure that DB2 and IMS are synchronized, restart
both DB2 and IMS. To ensure that DB2 and CICS are synchronized, restart both
DB2 and the CICS attachment facility.
3. Consider whether your application should intercept abends.
If your application intercepts abends, DB2 commits work, because it is unaware
that an abend has occurred. If you want DB2 to roll back work automatically
when an abend occurs in your program, do not let the program or run-time
environment intercept the abend. If your program uses Language
Environment®, and you want DB2 to roll back work automatically when an
abend occurs in the program, specify the run-time options
ABTERMENC(ABEND) and TRAP(ON).
4. For TSO applications only: Issue COMMIT statements before you connect to
another DBMS.
If the system fails at this point, DB2 cannot know whether your transaction is
complete. In this case, as in the case of a failure during a one-phase commit
operation for a single subsystem, you must make your own provision for
maintaining data integrity.
5. For TSO applications only: Determine if you want to provide an abend exit
routine in your program.

Chapter 1. Planning for and designing DB2 applications 19

If you provide this routine, it must use tracking indicators to determine if an
abend occurs during DB2 processing. If an abend does occur when DB2 has
control, you must allow task termination to complete. DB2 detects task
termination and terminates the thread with the ABRT parameter. Do not re-run
the program.
Allowing task termination to complete is the only action that you can take for
abends that are caused by the CANCEL command or by DETACH. You cannot
use additional SQL statements at this point. If you attempt to execute another
SQL statement from the application program or its recovery routine,
unexpected errors can occur.
Related concepts
Unit of work (SQL Reference)

Unit of work in TSO

Applications that use the TSO attachment facility can explicitly define units of
work by using the SQL COMMIT and ROLLBACK statements.

In TSO applications, a unit of work starts when the first updates of a DB2 object
occur. A unit of work ends when one of the following conditions occurs:
v The program issues a subsequent COMMIT statement. At this point in the
processing, your program has determined that the data is consistent; all data
changes that were made since the previous commit point were made correctly.
v The program issues a subsequent ROLLBACK statement. At this point in the
processing, your program has determined that the data changes were not made
correctly and, therefore, should not be permanent. A ROLLBACK statement
causes any data changes that were made since the last commit point to be
backed out.
v The program terminates and returns to the DSN command processor, which
returns to the TSO Terminal Monitor Program (TMP).

The first and third conditions in the preceding list are called a commit point. A
commit point occurs when you issue a COMMIT statement or your program
terminates normally.
Related reference
COMMIT (SQL Reference)
ROLLBACK (SQL Reference)

Unit of work in CICS

CICS applications can explicitly define units of work by using the CICS
SYNCPOINT command. Alternatively, units of work are defined implicitly by
several logic breaking points.

All the processing that occurs in your program between two commit points is
known as a logical unit of work (LUW) or unit of work. In CICS applications, a
unit of work is marked as complete by a commit or synchronization (sync) point,
which is defined in one of following ways:
v Implicitly at the end of a transaction, which is signaled by a CICS RETURN
command at the highest logical level.
v Explicitly by CICS SYNCPOINT commands that the program issues at logically
appropriate points in the transaction.
v Implicitly through a DL/I PSB termination (TERM) call or command.

20 Application Programming and SQL Guide

v Implicitly when a batch DL/I program issues a DL/I checkpoint call. This call
can occur when the batch DL/I program shares a database with CICS
applications through the database sharing facility.

For example, consider a program that subtracts the quantity of items sold from an
inventory file and then adds that quantity to a reorder file. When both transactions
complete (and not before) and the data in the two files is consistent, the program
can then issue a DL/I TERM call or a SYNCPOINT command. If one of the steps
fails, you want the data to return to the value it had before the unit of work began.
That is, you want it rolled back to a previous point of consistency. You can achieve
this state by using the SYNCPOINT command with the ROLLBACK option.

By using a SYNCPOINT command with the ROLLBACK option, you can back out
uncommitted data changes. For example, a program that updates a set of related
rows sometimes encounters an error after updating several of them. The program
can use the SYNCPOINT command with the ROLLBACK option to undo all of the
updates without giving up control.

The SQL COMMIT and ROLLBACK statements are not valid in a CICS
environment. You can coordinate DB2 with CICS functions that are used in
programs, so that DB2 and non-DB2 data are consistent.

Planning for program recovery in IMS programs

To be prepared for recovery situations for IMS programs that access DB2 data, you
need to make several design decisions that are specific to IMS programs. These
decisions are in addition to the general recommendations that you should follow
when designing your application for recovery.

Both IMS and DB2 handle recovery in an IMS application program that accesses
DB2 data. IMS coordinates the process, and DB2 handles recovery for DB2 data.

To plan for program recovery in IMS programs:

1. For a program that processes messages as its input, decide whether to specify
single-mode or multiple-mode transactions on the TRANSACT statement of the
APPLCTN macro for the program.
Single-mode
Indicates that a commit point in DB2 occurs each time the program
issues a call to retrieve a new message. Specifying single-mode can
simplify recovery; if the program abends, you can restart the program
from the most recent call for a new message. When IMS restarts the
program, the program starts by processing the next message.
Multiple-mode
Indicates that a commit point occurs when the program issues a
checkpoint call or when it terminates normally. Those two events are
the only times during the program that IMS sends the program’s
output messages to their destinations. Because fewer commit points are
processed in multiple-mode programs than in single-mode programs,
multiple-mode programs could perform slightly better than
single-mode programs. When a multiple-mode program abends, IMS
can restart it only from a checkpoint call. Instead of having only the
most recent message to reprocess, a program might have several
messages to reprocess. The number of messages to process depends on
when the program issued the last checkpoint call.

Chapter 1. Planning for and designing DB2 applications 21

DB2 does some processing with single- and multiple-mode programs. When a
multiple-mode program issues a call to retrieve a new message, DB2 performs
an authorization check and closes all open cursors in the program.
2. Decide whether to issue checkpoint calls (CHKP) and if so, how often to issue
them. Each call indicates to IMS that the program has reached a sync point and
establishes a place in the program from which you can restart the program.
Consider the following factors when deciding when to use checkpoint calls:
v How long it takes to back out and recover that unit of work. The program
must issue checkpoints frequently enough to make the program easy to back
out and recover.
v How long database resources are locked in DB2 and IMS.
v For multiple-mode programs: How you want the output messages grouped.
Checkpoint calls establish how a multiple-mode program groups its output
messages. Programs must issue checkpoints frequently enough to avoid
building up too many output messages.

Restriction: You cannot use SQL COMMIT and ROLLBACK statements in the
DB2 DL/I batch support environment, because IMS coordinates the unit of
work.
3. Issue CLOSE CURSOR statements before any checkpoint calls or GU calls to
the message queue, not after.
4. After any checkpoint calls, set the value of any special registers that were reset
if their values are needed after the checkpoint:
A CHKP call causes IMS to sign on to DB2 again, which resets the special
registers that are shown in the following table.
Table 4. Special registers that are reset by a checkpoint call.
Value to which it is reset after a checkpoint
Special register call
CURRENT PACKAGESET blanks
CURRENT SERVER blanks
CURRENT SQLID blanks
CURRENT DEGREE 1

5. After any commit points, reopen the cursors that you want and re-establish
positioning
6. Decide whether to specify the WITH HOLD option for any cursors. This option
determines whether the program retains the position of the cursor in the DB2
database after you issue IMS CHKP calls. You always lose the program
database positioning in DL/I after an IMS CHKP call.
The program database positioning in DB2 is affected according to the following
criteria:
v If you do not specify the WITH HOLD option for a cursor, you lose the
position of that cursor.
v If you specify the WITH HOLD option for a cursor and the application is
message-driven, you lose the position of that cursor.
v If you specify the WITH HOLD option for a cursor and the application is
operating in DL/I batch or DL/I BMP, you retain the position of that cursor.
7. Use IMS rollback calls, ROLL and ROLB, to back out DB2 and DL/I changes to
the last commit point. These options have the following differences:

22 Application Programming and SQL Guide

ROLL
Specifies that all changes since the last commit point are to be backed out
and the program is to be terminated. IMS terminates the program with user
abend code U0778 and without a storage dump.
When you issue a ROLL call, the only option you supply is the call
function, ROLL.
ROLLB
Specifies that all changes since the last commit point are to be backed out
and control is to be returned to the program so that it can continue
processing.
A ROLB call has the following options:
v The call function, ROLB
v The name of the I/O PCB
How ROLL and ROLB calls effect DL/I changes in a batch environment
depends on the IMS system log and back out options that are specified, as
shown in the following table.
Table 5. Effects of ROLL and ROLLB calls on DL/I changes in a batch environment
Options specified
Rollback call System log option Backout option Result
ROLL tape any DL/I does not back
out updates, and
abend U0778 occurs.
disk BKO=NO DB2 backs out
updates to the
previous checkpoint.
disk BKO=YES DL/I backs out
updates, and abend
U0778 occurs. DB2
backs out updates to
the previous
checkpoint.

Chapter 1. Planning for and designing DB2 applications 23

Table 5. Effects of ROLL and ROLLB calls on DL/I changes in a batch
environment (continued)
Options specified
Rollback call System log option Backout option Result
ROLB tape any DL/I does not back
out updates, and an
AL status code is
returned in the PCB.
DB2 backs out
updates to the
disk BKO=NO previous checkpoint.
The DB2 DL/I
support causes the
application program
to abend when ROLB
fails.
disk BKO=YES DL/I backs out
database updates,
and control is passed
back to the
application program.
DB2 backs out
updates to the
previous checkpoint.
Restriction: You
cannot specify the
address of an I/O
area as one of the
options on the call; if
you do, your
program receives an
AD status code.
However, you must
have an I/O PCB for
your program.
Specify CMPAT=YES
on the CMPAT
keyword in the
PSBGEN statement
for your program’s
PSB.

Related concepts
“Checkpoints in IMS programs” on page 26

Unit of work in IMS online programs

IMS applications can explicitly define units of work by using a CHKP, SYNC,
ROLL, or ROLB call, or, for single-mode transactions, a GU call.

In IMS, a unit of work starts when one of the following events occurs:
v When the program starts
v After a CHKP, SYNC, ROLL, or ROLB call has completed
v For single-mode transactions, when a GU call is issued to the I/O PCB

A unit of work ends when one of the following events occurs:

24 Application Programming and SQL Guide

v The program issues either a subsequent CHKP or SYNC call, or, for single-mode
transactions, a GU call to the I/O PCB. At this point in the processing, the data
is consistent. All data changes that were made since the previous commit point
are made correctly.
v The program issues a subsequent ROLB or ROLL call. At this point in the
processing, your program has determined that the data changes are not correct
and, therefore, that the data changes should not become permanent.
v The program terminates.

Restriction: The SQL COMMIT and ROLLBACK statements are not valid in an
IMS environment.

A commit point occurs in a program as the result of any one of the following
events:
v The program terminates normally. Normal program termination is always a
commit point.
v The program issues a checkpoint call. Checkpoint calls are a program’s means of
explicitly indicating to IMS that it has reached a commit point in its processing.
v The program issues a SYNC call. A SYNC call is a Fast Path system service call
to request commit-point processing. You can use a SYNC call only in a
non-message-driven Fast Path program.
v For a program that processes messages as its input, a commit point can occur
when the program retrieves a new message. This behavior depends on the mode
that you specify in the APPLCTN macro for the program:
– If you specify single-mode transactions, a commit point in DB2 occurs each
time the program issues a call to retrieve a new message.
– If you specify multiple-mode transactions or you do not specify a mode, a
commit point occurs when the program issues a checkpoint call or when it
terminates normally.

At the time of a commit point, the following actions occur:

v IMS and DB2 can release locks that the program has held since the last commit
point. Releasing these locks makes the data available to other application
programs and users. However, when you define a cursor as WITH HOLD in a
BMP program, DB2 holds those locks until the cursor closes or the program
ends.
v DB2 closes any open cursors that the program has been using.
v IMS and DB2 make the program’s changes to the database permanent.
v If the program processes messages, IMS sends the output messages that the
application program produces to their final destinations. Until the program
reaches a commit point, IMS holds the program’s output messages at a
temporary destination.

If the program abends before reaching the commit point, the following actions
occur:
v Both IMS and DB2 back out all the changes the program has made to the
database since the last commit point.
v IMS deletes any output messages that the program has produced since the last
commit point (for nonexpress PCBs).
v If the program processes messages, people at terminals and other application
programs receive information from the terminating application program.

Chapter 1. Planning for and designing DB2 applications 25

If the system fails, a unit of work resolves automatically when DB2 and IMS batch
programs reconnect. Any indoubt units of work are resolved at reconnect time.

Specifying checkpoint frequency in IMS programs

A checkpoint indicates a commit point in IMS programs. You should specify
checkpoint frequency in your program in a way that makes changing it easy in
case the frequency you initially specify is not right.

To specify checkpoint frequency in IMS programs:

1. Use a counter in your program to keep track of one of the following items:
v Elapsed time
v The number of root segments that your program accesses
v The number of updates that your program performs
2. Issue a checkpoint call after a certain time interval, number of root segments, or
number of updates.

Checkpoints in IMS programs:

Issuing checkpoint calls releases locked resources and establishes a place in the
program from which you can restart the program. The decision about whether
your program should issue checkpoints (and if so, how often) depends on your
program.

Generally, the following types of programs should issue checkpoint calls:

v Multiple-mode programs
v Batch-oriented BMPs
v Nonmessage-driven Fast Path programs. (These programs can use a special Fast
Path call, but they can also use symbolic checkpoint calls.)
v Most batch programs
v Programs that run in a data sharing environment. (Data sharing makes it
possible for online and batch application programs in separate IMS systems, in
the same or separate processors, to access databases concurrently. Issuing
checkpoint calls frequently in programs that run in a data sharing environment
is important, because programs in several IMS systems access the database.)

You do not need to issue checkpoints in the following types of programs:

v Single-mode programs
v Database load programs
v Programs that access the database in read-only mode (defined with the
processing option GO during a PSBGEN) and are short enough to restart from
the beginning
v Programs that, by their nature, must have exclusive use of the database

A CHKP call causes IMS to perform the following actions:

v Inform DB2 that the changes that your program made to the database can
become permanent. DB2 makes the changes to DB2 data permanent, and IMS
makes the changes to IMS data permanent.
v Send a message that contains the checkpoint identification that is given in the
call to the system console operator and to the IMS master terminal operator.
v Return the next input message to the program’s I/O area if the program
processes input messages. In MPPs and transaction-oriented BMPs, a checkpoint
call acts like a call for a new message.

26 Application Programming and SQL Guide

v Sign on to DB2 again.

Programs that issue symbolic checkpoint calls can specify as many as seven data
areas in the program that is to be restored at restart. DB2 always recovers to the
last checkpoint. You must restart the program from that point.

If you use symbolic checkpoint calls, you can use a restart call (XRST) to restart a
program after an abend. This call restores the program’s data areas to the way they
were when the program terminated abnormally, and it restarts the program from
the last checkpoint call that the program issued before terminating abnormally.

Restriction: For BMP programs that process DB2 databases, you can restart the
program only from the latest checkpoint and not from any checkpoint, as in IMS.

Checkpoints in MPPs and transaction-oriented BMPs

In single-mode programs, checkpoint calls and message retrieval calls (called

get-unique calls) both establish commit points. The checkpoint calls retrieve input
messages and take the place of get-unique calls. BMPs that access non-DL/I
databases and MPPs can issue both get unique calls and checkpoint calls to
establish commit points. However, message-driven BMPs must issue checkpoint
calls rather than get-unique calls to establish commit points, because they can
restart from a checkpoint only. If a program abends after issuing a get-unique call,
IMS backs out the database updates to the most recent commit point, which is the
get-unique call.

In multiple-mode BMPs and MPPs, the only commit points are the checkpoint calls
that the program issues and normal program termination. If the program abends
and it has not issued checkpoint calls, IMS backs out the program’s database
updates and cancels the messages that it has created since the beginning of the
program. If the program has issued checkpoint calls, IMS backs out the program’s
changes and cancels the output messages it has created since the most recent
checkpoint call.

Checkpoints in batch-oriented BMPs

If a batch-oriented BMP does not issue checkpoints frequently enough, IMS can
abend that BMP or another application program for one of the following reasons:
v Other programs cannot get to the data that they need within a specified amount
of time.
If a BMP retrieves and updates many database records between checkpoint calls,
it can monopolize large portions of the databases and cause long waits for other
programs that need those segments. (The exception to this situation is a BMP
with a processing option of GO; IMS does not enqueue segments for programs
with this processing option.) Issuing checkpoint calls releases the segments that
the BMP has enqueued and makes them available to other programs.
v Not enough storage is available for the segments that the program has read and
updated.
If IMS is using program isolation enqueuing, the space that is needed to
enqueue information about the segments that the program has read and updated
must not exceed the amount of storage that is defined for the IMS system. (The
amount of storage available is specified during IMS system definition. ) If a BMP
enqueues too many segments, the amount of storage that is needed for the
enqueued segments can exceed the amount of available storage. In that case,

Chapter 1. Planning for and designing DB2 applications 27

IMS terminates the program abnormally. You then need to increase the
program’s checkpoint frequency before rerunning the program.

When you issue a DL/I CHKP call from an application program that uses DB2
databases, IMS processes the CHKP call for all DL/I databases, and DB2 commits
all the DB2 database resources. No checkpoint information is recorded for DB2
databases in the IMS log or the DB2 log. The application program must record
relevant information about DB2 databases for a checkpoint, if necessary. One way
to record such information is to put it in a data area that is included in the DL/I
CHKP call.

Performance might be slowed by the commit processing that DB2 does during a
DL/I CHKP call, because the program needs to re-establish position within a DB2
database. The fastest way to re-establish a position in a DB2 database is to use an
index on the target table, with a key that matches one-to-one with every column in
the SQL predicate.

Recovering data in IMS programs

In an online IMS system, recovery and restart are part of the IMS system. For a
batch region, your location’s operational procedures control recovery and restart.

To recover data in IMS programs:

Take one or more of the following actions depending on the type of program:

Program type Recommended action

DL/I batch applications Use the DL/I batch backout utility to back
out DL/I changes. DB2 automatically backs
out changes whenever the application
program abends.
Applications that use symbolic checkpoints Use a restart call (XRST) to restart a program
after an abend. This call restores the
program’s data areas to the way they were
when the program terminated abnormally,
and it restarts the program from the last
checkpoint call that the program issued
before terminating abnormally.
BMP programs that access DB2 databases Restart the program from the latest
checkpoint.
Restriction: You can restart the program
only from the latest checkpoint and not from
any checkpoint, as in IMS.
Applications that use online IMS systems No action needed. Recovery and restart are
part of the IMS system
Applications that reside in the batch region Follow your location’s operational
procedures to control recovery and restart.

Undoing selected changes within a unit of work by using

savepoints
Savepoints enable you to undo selected changes within a unit of work. Your
application can set any number of savepoints and then specify a specific savepoint
to indicate which changes to undo within the unit of work.

To undo selected changes within a unit of work by using savepoints:

28 Application Programming and SQL Guide

1. Set any savepoints by using SQL SAVEPOINT statements. Savepoints set a
point to which you can undo changes within a unit of work.
Consider the following abilities and restrictions when setting savepoints:
v You can set a savepoint with the same name multiple times within a unit of
work. Each time that you set the savepoint, the new value of the savepoint
replaces the old value.
v If you do not want a savepoint to have different values within a unit of
work, use the UNIQUE option in the SAVEPOINT statement. If an
application executes a SAVEPOINT statement with the same name as a
savepoint that was previously defined as unique, an SQL error occurs.
v If you set a savepoint before you execute a CONNECT statement, the scope
of that savepoint is the local site. If you set a savepoint after you execute the
CONNECT statement, the scope of that savepoint is the site to which you are
connected.
v When savepoints are active, which they are until the unit of work completes,
you cannot access remote sites by using three-part names or aliases for
three-part names. You can, however, use DRDA® access with explicit
CONNECT statements.
v You cannot use savepoints in global transactions, triggers, user-defined
functions, or stored procedures that are nested within triggers or
user-defined functions.
2. Specify the changes that you want to undo within a unit of work by using the
SQL ROLLBACK TO SAVEPOINT statement.
DB2 undoes all changes since the specified savepoint. If you do not specify a
savepoint name, DB2 rolls back work to the most recently created savepoint.
3. Optional: If you no longer need a savepoint, delete it by using the SQL
RELEASE SAVEPOINT statement.

Recommendation: If you no longer need a savepoint before the end of a

transaction, release it. Otherwise, savepoints are automatically released at the
end of a unit of work. Releasing savepoints is essential if you need to use
three-part names to access remote locations, because you cannot perform this
action while savepoints are active.

Examples

Rolling back to the most recently created savepoint: When the ROLLBACK TO
SAVEPOINT statement is executed in the following code, DB2 rolls back work to
savepoint B.
EXEC SQL SAVEPOINT A;
...
EXEC SQL SAVEPOINT B;
...
EXEC SQL ROLLBACK TO SAVEPOINT;

Setting savepoints during distributed processing: An application performs the

following tasks:
1. Sets savepoint C1.
2. Does some local processing.
3. Executes a CONNECT statement to connect to a remote site.
4. Sets savepoint C2.

Chapter 1. Planning for and designing DB2 applications 29

Because savepoint C1 is set before the application connects to a remote site,
savepoint C1 is known only at the local site. However, because savepoint C2 is set
after the application connects to the remote site, savepoint C2 is known only at the
remote site.

Setting multiple savepoints with the same name: Suppose that the following
actions occur within a unit of work:
1. Application A sets savepoint S.
2. Application A calls stored procedure P.
3. Stored procedure P sets savepoint S.
4. Stored procedure P executes the following statement: ROLLBACK TO SAVEPOINT S
When DB2 executes the ROLLBACK statement, DB2 rolls back work to the
savepoint that was set in the stored procedure, because that value is the most
recent value of savepoint S.
Related reference
RELEASE SAVEPOINT (SQL Reference)
ROLLBACK (SQL Reference)
SAVEPOINT (SQL Reference)

| Planning for recovery of table spaces that are not logged

| To suppress logging, you can specify the NOT LOGGED option when you create
| or alter a table space. However, because logs are generally used in recovery,
| planning for recovery of table spaces for which changes are not logged requires
| some additional planning.

| Although you can plan for recovery, you still need to take some corrective actions
| after any system failures to recover the data and fix any affected table spaces. For
| example, if a table space that is not logged was open for update at the time that
| DB2 terminates, the subsequent restart places that table space in LPL and marks it
| with RECOVER-pending status. You need to take corrective action to clear the
| RECOVER-pending status.

| To plan for recovery of table spaces that are not logged:

| 1. Ensure that you can recover lost data by performing one of the following
| actions:
| v Ensure that you have a data recovery source that does not rely on a log
| record to recreate any lost data.
| v Limit modifications that are not logged to easily repeatable changes that can
| be quickly repeated.
| 2. Avoid placing a table space that is not logged in a RECOVER-pending status.
| The following actions place a table space in RECOVER-pending status:
| v Issuing a ROLLBACK statement or ROLLBACK TO SAVEPOINT statement
| after modifying a table in a table space that is not logged.
| v Causing duplicate keys or referential integrity violations when you modify a
| table space that is not logged.
| If the table space is placed in RECOVER-pending status, it is unavailable until
| you manually fix it.
| 3. For table spaces that are not logged and have associated LOB or XML table
| spaces, take image copies as a recovery set.

30 Application Programming and SQL Guide

| This action ensures that the base table space and all the associated LOB or XML
| table spaces are copied at the same point in time. A subsequent RECOVER TO
| LASTCOPY operation for the entire set results in consistent data across the base
| table space and all of the associated LOB and XML table spaces.
| Related tasks
| Clearing the RECOVER-pending status (DB2 Administration Guide)
| Related reference
| RECOVER (DB2 Utilities)

Designing your application to access distributed data

For applications that access data on another database management system (DBMS)
other than your local system, use DRDA access. You should also consider the
limitations and recommendations for such programs when designing them.

If your system is not already set up to use DRDA access, you must first prepare
your system to use DRDA access. One of the tools that can help you during this
process is the private to DRDA protocol REXX™ tool (DSNTP2DP).

To design your application to access distributed data:

1. Ensure that the appropriate authorization ID has been granted authorization at
the remote server to connect to that server and use resources from it.
2. If your application contains SQL statements that run at the requester, include at
the requester a database request module (DBRM) that is bound either directly
to a plan or to a package that is included in the plan’s package list.
3. Include a package at the remote server for any SQL statements that run at that
server.
4. For TSO and batch applications that update data at a remote server, ensure that
one of the following conditions is true:
v No other connections exist.
v All existing connections are to servers that are restricted to read-only
operations.

Restriction: If neither of these conditions are met, the application is restricted

to read-only operations.
If one of these conditions is met, and if the first connection in a logical unit of
work is to a server that supports two-phase commit, that server and all servers
that support two-phase commit can update data. However, if the first
connection is to a server that does not support two-phase commit, only that
server is allowed to update data.
5. For programs that access at least one restricted system, ensure that your
program does not violate any of the limitations for accessing restricted systems.
A restricted system is a DBMS that does not implement two-phase commit
processing.
Accessing restricted systems has the following limitations:
v For programs that access CICS or IMS, you cannot update data on restricted
systems.
v Within a unit of work, you cannot update a restricted system after updating
a non-restricted system.
v Within a unit of work, if you update a restricted system, you cannot update
any other systems.

Chapter 1. Planning for and designing DB2 applications 31

If you are accessing a mixture of systems, some of which might be restricted,
you can perform the following actions:
v Read from any of the systems at any time.
v Update any one system many times in one unit of work.
v Update many systems, including CICS or IMS, in one unit of work, provided
that none of them is a restricted system. If the first system you update in a
unit of work is not restricted, any attempt to update a restricted system in
that unit of work returns an error.
v Update one restricted system in a unit of work, provided that you do not try
to update any other system in the same unit of work. If the first system you
update in a unit of work is restricted, any attempt to update any other
system in that unit of work returns an error.
Related tasks
Preparing your system for DRDA access (DB2 Installation and Migration)
Related reference
The private to DRDA protocol REXX tool (DSNTP2DP) (DB2 Installation and
Migration)

Remote servers and distributed data

Distributed data is data that resides on a database management system (DBMS)
other than your local system. Your local DBMS is the one on which you bind your
application plan. All other DBMSs are remote.

If you are requesting services from a remote DBMS, that DBMS is a server, and
your local system is a requester or client.

Your application can be connected to many DBMSs at one time; the one that is
currently performing work is the current server. When the local system is
performing work, it also is called the current server.

A remote server can be physically remote, or it can be another subsystem of the

same operating system that your local DBMS runs under. A remote server might be
an instance of DB2 for z/OS, or it might be an instance of one of another product.

A DBMS, whether local or remote, is known to your DB2 system by its location
name. The location name of a remote DBMS is recorded in the communications
database.
Related tasks
Choosing names for the local subsystem (DB2 Installation and Migration)

Advantages of DRDA access

Programs that access distributed data should use DRDA access. Not only does
DRDA access have many advantages over DB2 private protocol access, but also
private protocol support will be removed in a future release of DB2.

DRDA access has the following advantages over DB2 private protocol access:
v Integration: DRDA access is available to all DBMSs that implement Distributed
Relational Database Architecture™ (DRDA). Those DBMSs include supported
releases of DB2 for z/OS, other members of the DB2 family of IBM products,
and many products of other companies.

32 Application Programming and SQL Guide

DB2 private protocol access is available only to supported releases of DB2 for
z/OS.
v SQL compatibility: DRDA access allows any SQL statement that the server can
execute.
DB2 private protocol access supports only data manipulation statements:
INSERT, UPDATE, DELETE, SELECT, OPEN, FETCH, and CLOSE. In addition,
you cannot use any syntax of an SQL statement that was introduced after DB2
Version 5. You also cannot invoke user-defined functions and stored procedures
or use LOBs or distinct types.
v Reduced network load: DRDA access uses a more compact format for sending
data over the network. This process improves the performance on slow network
links.
v Reduced bind processing: A DBRM for statements that are executed by DRDA
access is bound to a package at the server only once. Those statements can
include PREPARE and EXECUTE, so your application can accept dynamic
statements that are to be executed at the server.
Queries that are executed by DB2 private protocol access are bound at the server
whenever they are first executed in a unit of work. Repeated binds can reduce
the performance of a query that is executed often.
v Stored procedures: You can use stored procedures with DRDA access. Because
stored procedures require no message traffic over the network while they are
running, they reduce the biggest obstacle to high performance for distributed
data.
v Scrollable cursors: You can use scrollable cursors if you use DRDA access.
v Savepoints: You can set savepoints only if you use DRDA access with explicit
CONNECT statements. If you set a savepoint and then execute an SQL
statement with a three-part name, an SQL error occurs.
Related tasks
“Undoing selected changes within a unit of work by using savepoints” on page 28

Preparing for coordinated updates to two or more data

sources
Two or more updates are coordinated if they must all commit or all roll back in the
same unit of work.

This situation is common in banking. Suppose that an amount is subtracted from

one account and added to another. The two actions must either both commit or
both roll back at the end of the unit of work.

To prepare for coordinated updates to two or more data sources:

Ensure that all systems that your program accesses implement two-phase commit
processing. This processing ensures that updates to two or more DBMSs are
coordinated automatically.
For example, DB2 and IMS, and DB2 and CICS, jointly implement a two-phase
commit process. You can update an IMS database and a DB2 table in the same unit
of work. If a system or communication failure occurs between committing the
work on IMS and on DB2, the two programs restore the two systems to a
consistent point when activity resumes.
You cannot do true coordinated updates within a DBMS that does not implement
two-phase commit processing, because DB2 prevents you from updating such a
DBMS and any other system within the same unit of work. In this context, update
includes the statements INSERT, UPDATE, MERGE, DELETE, CREATE, ALTER,

Chapter 1. Planning for and designing DB2 applications 33

DROP, GRANT, REVOKE, RENAME, COMMENT, and LABEL.
However, if you cannot implement two-phase commit processing on all systems
that your program accesses, you can simulate the effect of coordinated updates by
performing the following actions:
1. Update one system and commit that work.
2. Update the second system and commit its work.
3. Ensure that your program has code to undo the first update if a failure occurs
after the first update is committed and before the second update is committed.
No automatic provision exists for bringing the two systems back to a consistent
point.
Related concepts
Two-phase commit process (DB2 Administration Guide)

Forcing restricted system rules in your program

A restricted system is a DBMS that does not implement two-phase commit
processing. These systems have a number of update restrictions. You can restrict
your program completely to the rules for these restricted systems, regardless of
whether the program is accessing restricted systems or non-restricted systems.

Accessing restricted systems has the following limitations:

v For programs that access CICS or IMS, you cannot update data on restricted
systems.
v Within a unit of work, you cannot update a restricted system after updating a
non-restricted system.
v Within a unit of work, if you update a restricted system, you cannot update any
other systems.

To force restricted system rules in your program:

When you prepare your program, specify the SQL processing option
CONNECT(1). This option applies type 1 CONNECT statement rules.

Restriction: Do not use packages that are precompiled with the CONNECT(1)
option and packages that are precompiled with the CONNECT(2) option in the
same package list. The first CONNECT statement that is executed by your
program determines which rules are in effect for the entire execution: type 1 or
type 2. If your program attempts to execute a later CONNECT statement that is
precompiled with the other type, DB2 returns an error.
Related concepts
“Options for SQL statement processing” on page 904

Maximizing the performance of an application that accesses

distributed data
The key to improving the performance of applications that access remote data is to
limit the number of network transmissions. You should consider if any of the
recommendations for reducing these transmissions makes sense for your
application.

To maximize the performance of an application that accesses distributed data:

1. Write any queries that access distributed data according to the following
recommendations to limit the number of messages that these queries send over
the network:
34 Application Programming and SQL Guide
v Reduce the number of columns and rows in the result table by keeping the
select lists as short as possible and using the WHERE, GROUP BY, and
HAVING clauses to eliminate unwanted data at the remote server.
v Specify the FOR FETCH ONLY or FOR READ ONLY clause when possible.
Retrieving thousands of rows as a continuous stream is reasonable. Sending a
separate message for each one can be significantly slower.
However, be aware the a query that is sent to a remote subsystem almost
always takes longer to execute than the same query that accesses tables of the
same size on the local subsystem for the following reasons:
v Overhead processing, including startup, negotiating session limits, and, for
DB2 private protocol access, the bind required at the remote location
v The time required to send messages across the network
2. For any of the following situations, use the OPTIMIZE FOR n ROWS clause in
your SELECT statements and query result sets from stored procedures:
v The application fetches only a small number of rows from the query result
set.
v The application fetches a large number of rows from a read-only query.
v The application rarely closes the SQL cursor before fetching the entire query
result set.
v The application does not issue statements other than the FETCH statement to
the DB2 server while the SQL cursor is open.
v The application does not execute FETCH statements for multiple cursors that
are open concurrently and defined with the OPTIMIZE FOR n ROWS clause.
v The application does not need to scroll randomly through the data.
The OPTIMIZE FOR n ROWS clause limits the number of data rows that the
server returns on each DRDA network transmission.

Restriction: This clause has no effect on scrollable cursors.

In a DRDA environment, if you specify 1, 2, or 3 for n , DB2 uses the value 16
(instead of n) for network blocking and prefetches 16 rows. As a result,
network usage is more efficient even though DB2 uses the small value of n for
query optimization.
For example, the following SQL statement causes DB2 to prefetch 16 rows of
the result table even though n has a value of 1.
SELECT * FROM EMP OPTIMIZE FOR 1 ROW ONLY;
3. For queries that have potentially large result tables, but need only a limited
number of rows, specify the FETCH FIRST n ROWS ONLY clause. This clause
limits the number of rows that are returned to a client program.
For example, suppose that you need only one row of the result table. You can
add the FETCH FIRST 1 ROW ONLY clause, as shown in the following
example:
SELECT * FROM EMP OPTIMIZE FOR 1 ROW ONLY FETCH FIRST 1 ROW ONLY;

In this case, the FETCH FIRST 1 ROW ONLY clause prevents 15 unnecessary
prefetches.
4. If your program accesses LOB columns in a remote table, use the following
techniques to minimize the number of bytes that are transferred between the
client and the server:
v Use LOB locators instead of LOB host variables.
If you need to store only a portion of a LOB value at the client, or if your
client program manipulates the LOB data but does not need a copy of it,

Chapter 1. Planning for and designing DB2 applications 35

LOB locators are a good choice. When a client program retrieves a LOB
column from a server into a locator, DB2 transfers only the 4-byte locator
value to the client, not the entire LOB value.
v Use stored procedure result sets.
When you return LOB data to a client program from a stored procedure, use
result sets rather than passing the LOB data to the client in parameters.
Using result sets to return data causes less LOB materialization and less
movement of data among address spaces.
v Set the CURRENT RULES special register to DB2.
When a DB2 server receives an OPEN request for a cursor, the server uses
the value in the CURRENT RULES special register to determine the type of
host variables that the associated statement uses to retrieve LOB values. If
you specify a value of DB2 for the CURRENT RULES special register before
you perform a CONNECT, and the first FETCH statement for the cursor uses
a LOB locator to retrieve LOB column values, DB2 lets you use only LOB
locators for all subsequent FETCH statements for that column until you close
the cursor. If the first FETCH statement uses a host variable, DB2 lets you
use only host variables for all subsequent FETCH statements for that column
until you close the cursor. However, if you set the value of CURRENT
RULES to STD, DB2 lets you use the same open cursor to fetch a LOB
column into either a LOB locator or a host variable.
Although a value of STD for the CURRENT RULES special register gives you
more programming flexibility when you retrieve LOB data, you get better
performance if you use a value of DB2. With the STD option, the server must
send and receive network messages for each FETCH statement to indicate
whether the data that is being transferred is a LOB locator or a LOB value.
With the DB2 option, the server knows the size of the LOB data after the first
FETCH, so an extra message about LOB data size is unnecessary. The server
can send multiple blocks of data to the requester at one time, which reduces
the total time for data transfer.
For example, suppose that an end user wants to browse through a large set of
employee records and look at pictures of only a few of those employees. At the
server, you set the CURRENT RULES special register to DB2. In the application,
you declare and open a cursor to select employee records. The application then
fetches all picture data into 4-byte LOB locators. Because DB2 knows that 4
bytes of LOB data is returned for each FETCH statement, DB2 can fill the
network buffers with locators for many pictures. When a user wants to see a
picture for a particular person, the application can retrieve the picture from the
server by assigning the value that is referenced by the LOB locator to a LOB
host variable. This situation is implemented in the following code:
SQL TYPE IS BLOB my_blob[1M];
SQL
. TYPE IS BLOB AS LOCATOR my_loc;
.
.
FETCH
. C1 INTO :my_loc; /* Fetch BLOB into LOB locator */
.
.
SET :my_blob = :my_loc; /* Assign BLOB to host variable */

Restriction: You must use DRDA access to access LOB columns in a remote
table.
5. Minimize the use of parameter markers.
When using DRDA access, DB2 can streamline the processing of dynamic
queries that do not have parameter markers. When a DB2 requester encounters
a PREPARE statement for such a query, it anticipates that the application is
going to open a cursor. DB2 therefore sends a single message to the server that

36 Application Programming and SQL Guide

contains a combined request for the PREPARE, DESCRIBE, and OPEN
operations. A server that receives this message sequence returns a reply
message sequence that includes the output from the PREPARE, DESCRIBE, and
OPEN operations. As a result, the number of network messages sent and
received for these operations is reduced from two to one. DB2 combines
messages for these queries regardless of whether the bind option
DEFER(PREPARE) is specified.
6. Ensure that each cursor meets one of the following conditions when possible,
so that DB2 uses block fetch to minimize the number of messages that are sent
across the network:
v The cursor is declared with either the FOR FETCH ONLY or FOR READ
ONLY clause.
v The cursor is a non-scrollable cursor, and the result table of the cursor is
read-only.
v The cursor is a scrollable cursor that is declared as INSENSITIVE, and the
result table of the cursor is read-only.
v The cursor is a scrollable cursor that is declared as SENSITIVE, the result
table of the cursor is read-only, and the value of the CURRENTDATA bind
option is NO.
v The result table of the cursor is not read-only, but the cursor is ambiguous,
and the value of the CURRENTDATA bind option is NO.
A cursor is ambiguous when any of the following conditions are true:
– It is not defined with the clauses FOR FETCH ONLY, FOR READ ONLY,
or FOR UPDATE.
– It is not defined on a read-only result table.
– It is not the target of a WHERE CURRENT clause on an SQL UPDATE or
DELETE statement.
– It is in a plan or package that contains the SQL statements PREPARE or
EXECUTE IMMEDIATE.
7. For ODBC and JDBC applications, use the rowset parameter to limit the
number of rows that are returned from a fetch operation.
If a DRDA requester sends the rowset parameter to a DB2 server, the server
performs the following actions:
v Returns no more than the number of rows in the rowset parameter
v Returns extra query blocks if the value of the EXTRA BLOCKS SRV field on
the DISTRIBUTED DATA FACILITY PANEL 2 installation panel on the server
allows extra query blocks to be returned
v Processes the FETCH FIRST n ROWS ONLY clause, if it is specified
v Does not process the OPTIMIZE FOR n ROWS clause
8. Use the recommended values for the following bind options:
Table 6. Recommended bind option values for applications that access distributed data
Bind option Recommended value and actions Reason
CURRENTDATA CURRENTDATA(NO) Use this bind option to force block fetch for
ambiguous queries.

Chapter 1. Planning for and designing DB2 applications 37

Table 6. Recommended bind option values for applications that access distributed data (continued)
Bind option Recommended value and actions Reason
DBPROTOCOL DBPROTOCOL(DRDA) If the value of the installation default
database protocol is not DRDA, use this
bind option to cause DB2 to use DRDA
access to execute SQL statements with
three-part names. Statements that use
DRDA access perform better at execution
time for the following reasons:
v Binding occurs when the package is
bound, not during program execution.
v DB2 does not destroy static statement
information at commit time, as it does
with DB2 private protocol access. With
DRDA access, if a commit occurs
between two executions of a statement,
DB2 does not need to prepare the
statement twice.
ISOLATION Anything but ISOLATION (RR) When possible, do not bind application
plans and packages with ISOLATION(RR).
If your application does not need to
reference rows that it has already read,
another isolation level might reduce lock
contention and message overhead during
commit processing.
KEEPDYNAMIC KEEPDYNAMIC(YES) Use this bind option to improve
performance for queries that use cursors
that are defined with the WITH HOLD
option. With KEEPDYNAMIC(YES), DB2
automatically closes the cursor when no
more data exists for retrieval. The client
does not need to send a network message
to tell DB2 to close the cursor.
NODEFER and DEFER DEFER(PREPARE) This option reduces network traffic, because
the PREPARE and EXECUTE statements
and responses are transmitted together.

38 Application Programming and SQL Guide

Table 6. Recommended bind option values for applications that access distributed data (continued)
Bind option Recommended value and actions Reason
PKLIST and NOPKLIST PKLIST The order in which you specify package
collections in a package list can affect the
Specify the package collections for this bind performance of your application program.
option according to the following When a local instance of DB2 attempts to
recommendations: execute an SQL statement at a remote
v Reduce the number of packages per server, the local DB2 subsystem must
collection that DB2 must search. The determine which package collection the
following example specifies only one SQL statement is in. DB2 must send a
package in each collection: message to the server to request that the
PKLIST(S1.COLLA.PGM1, S1.COLLB.PGM2) server check each collection ID for the SQL
statement until the statement is found or no
v Reduce the number of package more collection IDs are in the package list.
collections at each location that DB2 must You can reduce the amount of network
search. The following example specifies traffic, and thereby improve performance,
only one package collection at each by reducing the number of package
location: collections that each server must search.
PKLIST(S1.COLLA.*, S2.COLLB.*)
v Reduce the number of collections that are As an alternative to specifying the package
used for each application. The following collections on the PKLIST bind option, you
example specifies only one collection to can specify the package collection that is
search: associated with an SQL statement in your
application program. Execute the SET
PKLIST(*.COLLA.*) CURRENT PACKAGESET statement before
Requirement: When you specify the you execute an SQL statement to tell DB2
DEFER(PREPARE) bind option with DRDA which package collection to search for the
access, the package that contains the statement.
statements whose preparation you want to
defer must be the first qualifying entry in
the package search sequence that DB2 uses.

For example, assume that the package list

for a plan contains two entries:
PKLIST(LOCB.COLLA.*, LOCB.COLLB.*)

If the intended package is in collection

COLLB, ensure that DB2 searches that
collection first by executing the following
SQL statement:
SET CURRENT PACKAGESET = 'COLLB';

Alternatively, you can list COLLB first in

the PKLIST bind option:
PKLIST(LOCB.COLLB.*, LOCB.COLLA.*)

For the NODEFER(PREPARE) bind option,

the collections in the package list can be in
any order, but if the package is not found
in the first qualifying PKLIST entry,
significant network overhead might result
from DB2 searching through the list.

Chapter 1. Planning for and designing DB2 applications 39

Table 6. Recommended bind option values for applications that access distributed data (continued)
Bind option Recommended value and actions Reason
REOPT Use the following guidelines to decide Because of performance costs when DB2
which option to choose: reoptimizes the access path at run time,
| v Use the REOPT(AUTO) option when the minimize reoptimization when possible.
| following conditions are true:
| – You are using the dynamic statement
| cache.
| – You want DB2 to decide if a new
| access path is needed.
| – Your dynamic SQL statements are
| executed many times with possibly
| different input variables.
| – Similar input variables tend to be
| executed consecutively.
v Use the REOPT(ALWAYS) option on only
packages or plans that contain statements
that perform poorly because of a bad
access path. If you specify
REOPT(ALWAYS) when you bind a plan
that contains statements that use DB2
private protocol access to access remote
data, DB2 prepares those statements
twice.
v Use the REOPT(ONCE) option when the
following conditions are true:
– You are using the dynamic statement
cache.
– You have plans or packages that
contain dynamic SQL statements that
perform poorly because of access path
selection.
– Your dynamic SQL statements are
executed many times with possibly
different input variables.
v Use the REOPT(NONE) option when you
bind a plan or package that contains
statements that use DB2 private protocol
access.

40 Application Programming and SQL Guide

Related concepts
“How DB2 identifies packages at run time” on page 924
Block fetch (DB2 Performance)
Related tasks
“Saving storage when manipulating LOBs by using LOB locators” on page 711
Fetching a limited number of rows: FETCH FIRST n ROWS ONLY (DB2
Performance)
Related reference
BIND and REBIND options (DB2 Command Reference)
fetch-first-clause (SQL Reference)

The effect of the OPTIMIZE FOR n ROWS clause in distributed

applications
You can specify the OPTIMIZE FOR n ROWS clause to improve the performance of
certain queries. For queries that access distributed data, this clause can have a
significant performance impact, because it helps limit the amount of data that is
sent over the network and the number of network transmissions.

When you specify the OPTIMIZE FOR n ROWS clause in your query, the number
of rows that DB2 transmits on each network transmission depends on the
following factors:
v If n rows of the SQL result set fit within a single DRDA query block, a DB2
server can send n rows to any DRDA client. In this case, DB2 sends n rows in
each network transmission until the entire query result set is returned.
v If n rows of the SQL result set exceed a single DRDA query block, the number of
rows that are contained in each network transmission depends on the client’s
DRDA software level and configuration. The following conditions apply:
– If the client does not support extra query blocks, the DB2 server automatically
reduces the value of n to match the number of rows that fit within a DRDA
query block.
– If the client supports extra query blocks, the DRDA client can choose to
accept multiple DRDA query blocks in a single data transmission. DRDA
allows the client to establish an upper limit on the number of DRDA query
blocks in each network transmission.
The number of rows that a DB2 server sends is the smaller of the following
values:
- n rows
- the number of rows that fit within the maximum number of extra DRDA
query blocks that the DB2 server returns to a client in a single network
transmission. (This value is specified in the EXTRA BLOCKS SRV field on
installation panel DSNTIP5 at the DB2 server.)
- the number of rows that fit within the client’s extra query block limit,
which is obtained from the DDM MAXBLKEXT parameter that is received
from the client. (When DB2 acts as a DRDA client, the DDM MAXBLKEXT
parameter is set to the value of EXTRA BLOCKS REQ on installation panel
DSNTIP5.)

Depending on the value that you specify for n, the OPTIMIZE FOR n ROWS clause
can improve performance in the following ways:

Chapter 1. Planning for and designing DB2 applications 41

v If n is less than the number of rows that fit in the DRDA query block,
OPTIMIZE FOR n ROWS can improve performance by preventing the DB2
server from fetching rows that might never be used by the DRDA client
application.
v If n is greater than the number of rows that fit in a DRDA query block,
OPTIMIZE FOR n ROWS lets the DRDA client request multiple blocks of query
data on each network transmission. This use of OPTIMIZE FOR n ROWS can
significantly improve elapsed time for applications that download large amounts
of data.

Although the OPTIMIZE FOR n ROWS clause can improve performance, this same
function can degrade performance if you do not use it properly. The following
examples demonstrate the performance problems that can occur when you do not
use this clause judiciously.

In the following figure, the DRDA client opens a cursor and fetches rows from the
cursor. At some point before all rows in the query result set are returned, the
application issues an SQL INSERT statement.

DRDA client DB2 server

DECLARE C1 CURSOR
FOR SELECT * FROM T1
FOR FETCH ONLY;
OPEN C1; SQL cursor is opened

Query block with 100

rows is returned
FETCH C1 INTO ...;

FETCH C1 INTO ...;

INSERT INTO ...; Server processes

INSERT statement

Figure 1. Message flows without the OPTIMIZE FOR n ROWS clause

In this case, DB2 uses normal DRDA message blocking, which has the following
advantages over the message blocking that is used for the OPTIMIZE FOR n
ROWS clause:
v If the application issues an SQL statement other than FETCH (for example, an
INSERT statement in this case), the DRDA client can transmit the SQL statement
immediately, because the DRDA connection is not in use after the SQL OPEN.
v The DRDA query block size places an upper limit on the number of rows that
are fetched unnecessarily. If the SQL application closes the cursor before fetching
all the rows in the query result set, the server fetches only the number of rows
that fit in one query block, which is 100 rows of the result set.

In the following figure, the DRDA client opens a cursor and fetches rows from the
cursor by using OPTIMIZE FOR n ROWS clause. Both the DRDA client and the
DB2 server are configured to support multiple DRDA query blocks. At some time
before the end of the query result set, the application issues an SQL INSERT.

42 Application Programming and SQL Guide

DRDA client DB2 server

DECLARE C1 CURSOR
FOR SELECT * FROM T1
OPTIMIZE FOR
1000 ROWS;

OPEN C1; SQL cursor is opened

Query block with 100

FETCH C1 INTO ...; rows is returned
Query block with 100
FETCH C1 INTO ...;
. rows is returned
.
. Query block with 100
INSERT INTO ...; rows is returned
Query block with 100
rows is returned
Query block with 100
rows is returned
Query block with 100
rows is returned
Query block with 100
rows is returned
Query block with 100
rows is returned
Query block with 100
rows is returned
Query block with 100
rows is returned
Server processes
INSERT statement

Figure 2. Message flows with the OPTIMIZE FOR 1000 ROWS clause

Because the query uses the OPTIMIZE FOR n ROWS clause, the DRDA connection
is not available when the SQL INSERT is issued. The connection is still being used
to receive the DRDA query blocks for 1000 rows of data. This situation causes the
following performance problems:
v Application elapsed time can increase if the DRDA client waits for a large query
result set to be transmitted before the DRDA connection can be used for other
SQL statements. In this example, the SQL INSERT statement is delayed because
of a large query result set.
v If the application closes the cursor before fetching all the rows in the SQL result
set, the server might fetch a large number of rows unnecessarily.
Related concepts
Minimizing overhead for retrieving few rows: OPTIMIZE FOR n ROWS (DB2
Performance)
Related reference
optimize-for-clause (SQL Reference)

Fast implicit close

When you specify the FETCH FIRST n ROWS ONLY clause in a distributed query,
DB2 might use a fast implicit close to improve performance. Fast implicit close is the
process of DB2 closing a cursor after prefetching thenth row or when no more
rows are to be returned.

Chapter 1. Planning for and designing DB2 applications 43

Fast implicit close can improve query performance, because it saves an additional
network transmission between the client and the server.

DB2 uses fast implicit close when all of the following conditions are true:
v The query uses limited block fetch.
v The query does not retrieve any LOBs.
v The cursor is not a scrollable cursor.
v Either of the following conditions is true:
– The cursor is defined with the WITH HOLD option, and the package or plan
that contains the cursor is bound with the KEEPDYNAMIC(YES) option.
– The cursor is not defined with the WITH HOLD option.
Related concepts
Block fetch (DB2 Performance)

44 Application Programming and SQL Guide

Chapter 2. Connecting to DB2 from your application program
Application programs communicate to DB2 through an attachment facility. You
must invoke an attachment facility, either implicitly or explicitly, before your
program can interact with DB2.

You can use the following attachment facilities in a z/OS environment:

CICS attachment facility
Use this facility to access DB2 from CICS application programs.
IMS attachment facility
Use this facility to access DB2 from IMS application programs.
Time Sharing Option (TSO) attachment facility
Use this facility in a TSO or batch environment to communicate to a local
DB2 subsystem. This facility invokes the DSN command processor.
Call attachment facility (CAF)
Use this facility as an alternative to the TSO attachment facility when your
application needs tight control over the session environment.
Resource Recovery Services attachment facility (RRSAF)
Use this facility for stored procedures that run in a WLM-established
address space or as an alternative to the CAF. This facility has more
capabilities than CAF.

For distributed applications, use the distributed data facility (DDF).

Requirement: Ensure that any application that requests DB2 services satisfies the
following environment characteristics, regardless of the attachment facility that you
use:
v The application must be running in TCB mode. SRB mode is not supported.
v An application task cannot have any Enabled Unlocked Task (EUT) functional
recovery routines (FRRs) active when requesting DB2 services. If an EUT FRR is
active, the DB2 functional recovery can fail, and your application can receive
some unpredictable abends.
v Different attachment facilities cannot be active concurrently within the same
address space. Specifically, the following requirements exist:
– An application must not use CAF or RRSAF in an CICS or IMS address
space.
– An application that runs in an address space that has a CAF connection to
DB2 cannot connect to DB2 by using RRSAF.
– An application that runs in an address space that has an RRSAF connection to
DB2 cannot connect to DB2 by using CAF.
– An application cannot invoke the z/OS AXSET macro after executing the CAF
CONNECT call and before executing the CAF DISCONNECT call.
v One attachment facility cannot start another. For example, your CAF or RRSAF
application cannot use DSN, and a DSN RUN subcommand cannot call your
CAF or RRSAF application.

© Copyright IBM Corp. 1983, 2009 45

v The language interface modules for CAF and RRSAF, DSNALI and DSNRLI, are
shipped with the linkage attributes AMODE(31) and RMODE(ANY). If your
applications load CAF or RRSAF below the 16-MB line, you must link-edit
DSNALI or DSNRLI again.
Related concepts
DB2 attachment facilities (Introduction to DB2 for z/OS)
Distributed data facility (Introduction to DB2 for z/OS)

Invoking the call attachment facility

Invoke the call attachment facility (CAF) when you want your application program
to establish and control its own connection to DB2. Applications that use CAF can
explicitly control the state of their connections to DB2 by using connection
functions that CAF supplies.

Before you can invoke CAF, perform the following actions:

v Ensure that the CAF language interface (DSNALI) is available.
v Ensure that your application satisfies the requirements for programs that access
CAF.
v Ensure that your application satisfies the general environment characteristics for
connecting to DB2.
v Ensure that you are familiar with the following z/OS concepts and facilities:
– The CALL macro and standard module linkage conventions
– Program addressing and residency options (AMODE and RMODE)
– Creating and controlling tasks; multitasking
– Functional recovery facilities such as ESTAE, ESTAI, and FRRs
– Asynchronous events and TSO attention exits (STAX)
– Synchronization techniques such as WAIT/POST.

Applications that use CAF can be written in assembler language, C, COBOL,

Fortran, and PL/I. When choosing a language to code your application in, consider
the following restrictions:
v If you need to use z/OS macros (ATTACH, WAIT, POST, and so on), use a
programming language that supports them or embed them in modules that are
written in assembler language.
v The CAF TRANSLATE function is not available in Fortran. To use this function,
code it in a routine that is written in another language, and then call that routine
from Fortran.

Recommendations: For IMS and DSN applications, consider the following

recommendations:
v For IMS batch applications, do not use CAF. Instead use the DB2 DL/I batch
support. Although it is possible for IMS batch applications to access DB2
databases through CAF, that method does not coordinate the commitment of
work between the IMS and DB2 systems.
v For DSN applications, do not use CAF unless you provide an application
controller to manage the DSN application and replace any needed DSN
functions. You might also have to change the application to communicate
connection failures to the controller correctly. Running DSN applications with
CAF is not advantageous, and the loss of DSN services can affect how well your
program runs.

46 Application Programming and SQL Guide

To invoke CAF:

Perform one of the following actions:

v Explicitly invoke CAF by including in your program CALL DSNALI statements
with the appropriate options.
The first option is a CAF connection function, which describes the action that
you want CAF to take. The effect of any function depends in part on what
functions the program has already run.

Requirement: For C and PL/I applications, you must also include in your
program the compiler directives that are listed in the following table, because
DSNALI is an assembler language program.
Table 7. Compiler directives to include in C and PL/I applications that contain CALL DSNALI
statements
Language Compiler directive to include
C #pragma linkage(dsnali, OS)
C++ extern "OS" {
int DSNALI(
char * functn,
...); }
PL/I DCL DSNALI ENTRY OPTIONS(ASM,INTER,RETCODE;

v Implicitly invoke CAF by including SQL statements or IFI calls in your program
just as you would in any program. The CAF facility establishes the connections
to DB2 with the default values for the subsystem name and plan name.

Restriction: If your program can make its first SQL call from different modules
with different DBRMs, you cannot use a default plan name and thus, you cannot
implicitly invoke CAF. Instead, you must explicitly invoke CAF by using the
OPEN function.

Requirement: If your application includes both SQL and IFI calls, you must
issue at least one SQL call before you issue any IFI calls. This action ensures that
your application uses the correct plan.
Although doing so is not recommended, you can run existing DSN applications
with CAF by allowing them to make implicit connections to DB2. For DB2 to
make an implicit connection successfully, the plan name for the application must
be the same as the member name of the database request module (DBRM) that
DB2 produced when you precompiled the source program that contains the first
SQL call. You must also substitute the DSNALI language interface module for
the TSO language interface module, DSNELI.
If you do not specify the return code and reason code parameters in your CAF
calls or you invoked CAF implicitly, CAF puts a return code in register 15 and a
reason code in register 0.
To determine if an implicit connection was successful, the application program
should examine the return and reason codes immediately after the first executable
SQL statement in the application program by performing one of the following
actions:
v Examining registers 0 and 15 directly.
v Examining the SQLCA, and if the SQLCODE is -991, obtain the return and
reason code from the message text. The return code is the first token, and the
reason code is the second token.

Chapter 2. Connecting to DB2 from your application program 47

If the implicit connection was successful, the application can examine the
SQLCODE for the first, and subsequent, SQL statements.

Examples

Example of a CAF configuration: The following figure shows an conceptual

example of invoking and using CAF. The application contains statements to load
DSNALI, DSNHLI2, and DSNWLI2. The application accesses DB2 by using the
CAF Language Interface. It calls DSNALI to handle CAF requests, DSNWLI to
handle IFI calls, and DSNHLI to handle SQL calls.

Application CAF CAF

Load
Language Mainline
LOAD DSNALI
Interface Code
LOAD DSNHLI2
LOAD DSNWLI2
Call
CALL DSNALI
( CONNECT ) DSNALI
( OPEN )
( CLOSE )
( DISCONNECT )

CALL DSNWLI
(IFI calls) (Process
CALL DSNHLI connection
(SQL calls) requests)

DSNHLI (dummy DB2

application
entry point)

CALL DSNHLI2 DSNHLI2

(Transfer calls (Process
to real CAF SQL SQL stmts)
entry point)

DSNWLI (dummy
application
entry point)

CALL DSNWLI2 DSNWLI

(Transfer calls
to real CAF
IFI)

Figure 3. Sample call attachment facility configuration

Sample programs that use CAF: You can find a sample assembler program
(DSN8CA) and a sample COBOL program (DSN8CC) that use the CAF in library
prefix.SDSNSAMP. A PL/I application (DSN8SPM) calls DSN8CA, and a COBOL
application (DSN8SCM) calls DSN8CC.

48 Application Programming and SQL Guide

Related concepts
“DB2 sample applications” on page 1069
Related reference
“CAF connection functions” on page 58

Call attachment facility

An attachment facility enables programs to communicate with DB2. The call
attachment facility (CAF) provides such a connection for programs that run in
z/OS batch, TSO foreground, and TSO background and need tight control over the
session environment.

A program that uses CAF can perform the following actions:

v Access DB2 from z/OS address spaces where TSO, IMS, or CICS do not exist.
v Access DB2 from multiple z/OS tasks in an address space.
v Access the DB2 IFI.
v Run when DB2 is down.

Restriction: The application cannot run SQL when DB2 is down.

v Run with or without the TSO terminal monitor program (TMP).
v Run without being a subtask of the DSN command processor or of any DB2
code.
v Run above or below the 16-MB line. (The CAF code resides below the line.)
v Establish an explicit connection to DB2, through a CALL interface, with control
over the exact state of the connection.
v Establish an implicit connection to DB2, by using SQL statements or IFI calls
without first calling CAF, with a default plan name and subsystem identifier.
v Verify that the application is using the correct release of DB2.
v Supply event control blocks (ECBs), for DB2 to post, that signal startup or
termination.
v Intercept return codes, reason codes, and abend codes from DB2 and translate
them into messages as desired.

Any task in an address space can establish a connection to DB2 through CAF. Only
one connection can exist for each task control block (TCB). A DB2 service request
that is issued by a program that is running under a given task is associated with
that task’s connection to DB2. The service request operates independently of any
DB2 activity under any other task.

Each connected task can run a plan. Multiple tasks in a single address space can
specify the same plan, but each instance of a plan runs independently from the
others. A task can terminate its plan and run a different plan without fully
breaking its connection to DB2.

CAF does not generate task structures.

When you design your application, consider that using multiple simultaneous
connections can increase the possibility of deadlocks and DB2 resource contention.

A tracing facility provides diagnostic messages that aid in debugging programs

and diagnosing errors in the CAF code. In particular, attempts to use CAF
incorrectly cause error messages in the trace stream.

Chapter 2. Connecting to DB2 from your application program 49

Restriction: CAF does not provide attention processing exits or functional recovery
routines. You can provide whatever attention handling and functional recovery
your application needs, but you must use ESTAE/ESTAI type recovery routines
and not Enabled Unlocked Task (EUT) FRR routines.

Properties of CAF connections

CAF enables programs to communicate with DB2. A CAF connection joins any task
in an address space to DB2.

The connection that CAF makes with DB2 has the basic properties that are listed in
the following table.
Table 8. Properties of CAF connections
Property Value Comments
Connection name DB2CALL You can use the DISPLAY
THREAD command to list
CAF applications that have
the connection name
DB2CALL.
Connection type BATCH BATCH connections use a
single phase commit process
that is coordinated by DB2.
Application programs can
also control when statements
are committed by using the
SQL COMMIT and
ROLLBACK statements.
Authorization IDs Authorization IDs that are DB2 establishes authorization
associated with the address IDs for each task’s connection
space when it processes that
connection. For the BATCH
connection type, DB2 creates
a list of authorization IDs
based on the authorization ID
that is associated with the
address space. This list is the
same for every task. A
location can provide a DB2
connection authorization exit
routine to change the list of
IDs.
Scope CAF processes connections as none
if each task is entirely
isolated. When a task
requests a function, the CAF
passes the functions to DB2
and is unaware of the
connection status of other
tasks in the address space.
However, the application
program and the DB2
subsystem are aware of the
connection status of multiple
tasks in an address space.

If a connected task terminates normally before the CLOSE function deallocates the
plan, DB2 commits any database changes that the thread made since the last

50 Application Programming and SQL Guide

commit point. If a connected task abends before the CLOSE function deallocates
the plan, DB2 rolls back any database changes since the last commit point. In
either case, DB2 deallocates the plan, if necessary, and terminates the task’s
connection before it allows the task to terminate.

If DB2 abnormally terminates while an application is running, the application is

rolled back to the last commit point. If DB2 terminates while processing a commit
request, DB2 either commits or rolls back any changes at the next restart. The
action taken depends on the state of the commit request when DB2 terminates.
Related concepts
Connection routines and sign-on routines (DB2 Administration Guide)

Attention exit routines for CAF

An attention exit routine enables you to regain control from DB2 during
long-running or erroneous requests. CAF has no attention exit routines, but you
can provide your own if necessary.

An attention exit routine works by detaching the TCB that is currently waiting on
an SQL or IFI request to complete. After the TCB is detached, DB2 detects the
resulting abend and performs termination processing for that task. The termination
processing includes any necessary rollback of transactions.

You can provide your own attention exit routines. However, your routine might
not get control if you request attention while DB2 code is running, because DB2
uses enabled unlocked task (EUT) functional recovery routines (FRRs).

Recovery routines for CAF

You can use abend recovery routines and functional recovery routines (FRRs) to
handle unexpected errors. An abend recovery routine controls what happens when
an abend occurs while DB2 has control. A functional recovery routine can obtain
information about and recover from program errors.

The CAF has no abend recovery routines, but you can provide your own. Any
abend recovery routines that you provide must use tracking indicators to
determine if an abend occurred during DB2 processing. If an abend occurs while
DB2 has control, the recovery routine can take one of the following actions:
v Allow task termination to complete. Do not retry the program. DB2 detects task
termination and terminates the thread with the ABRT parameter. You lose all
database changes back to the last sync point or commit point.
This action is the only action that you can take for abends that are caused by the
CANCEL command or by DETACH. You cannot use additional SQL statements.
If you attempt to execute another SQL statement from the application program
or its recovery routine, you receive a return code of +256 and a reason code of
X’00F30083’.
v In an ESTAE routine, issue a CLOSE function call with the ABRT parameter
followed by a DISCONNECT function call. The ESTAE exit routine can retry so
that you do not need to reinstate the application task.

FRRs must comply with the following requirements and restrictions:

v You can use only enabled unlocked task (EUT) FRRs in your routines that call
DB2. The standard z/OS functional recovery routines (FRRs) apply to only code
that runs in service request block (SRB) mode, and DB2 does not support calls
from SRB mode routines.

Chapter 2. Connecting to DB2 from your application program 51

v Do not have an EUT FRR active when using CAF, processing SQL requests, or
calling IFI. With z/OS, if you have an active EUT FRR, all DB2 requests fail,
including the initial CONNECT or OPEN request. The requests fail because DB2
always creates an ARR-type ESTAE, and z/OS does not allow the creation of
ARR-type ESTAEs when an FRR is active.
v An EUT FRR cannot retry failing DB2 requests. An EUT FRR retry bypasses
ESTAE routines from DB2. The next DB2 request of any type, including a
DISCONNECT request, fails with a return code of +256 and a reason code of
X’00F30050’.

Making the CAF language interface (DSNALI) available

Before you can invoke the call attachment facility (CAF), you must first make
DSNALI available.

Part of CAF is a DB2 load module, DSNALI, which is also known as the CAF
language interface. DSNALI has the alias names DSNHLI2 and DSNWLI2. The
module has five entry points: DSNALI, DSNHLI, DSNHLI2, DSNWLI, and
DSNWLI2. These entry points serve the following functions:
v Entry point DSNALI handles explicit DB2 connection service requests.
v DSNHLI and DSNHLI2 handle SQL calls. Use DSNHLI if your application
program link-edits DSNALI. Use DSNHLI2 if your application program loads
DSNALI.
v DSNWLI and DSNWLI2 handle IFI calls. Use DSNWLI if your application
program link-edits DSNALI. Use DSNWLI2 if your application program loads
DSNALI.

To make DSNALI available:

1. Decide which of the following methods you want to use to make DSNALI
available:
v Explicitly issuing LOAD requests when your program runs.
By explicitly loading the DSNALI module, you beneficially isolate the
maintenance of your application from future IBM maintenance to the
language interface. If the language interface changes, the change will
probably not affect your load module.
v Including the DSNALI module in your load module when you link-edit your
program.
If you do not need explicit calls to DSNALI for CAF functions, link-editing
DSNALI into your load module has some advantages. When you include
DSNALI during the link-edit, you do not need to code a dummy DSNHLI
entry point in your program or specify the precompiler option ATTACH.
Module DSNALI contains an entry point for DSNHLI, which is identical to
DSNHLI2, and an entry point DSNWLI, which is identical to DSNWLI2.
A disadvantage to link-editing DSNALI into your load module is that any
IBM maintenance to DSNALI requires a new link-edit of your load module.
2. Depending on the method that you chose in step 1, perform one of the
following actions:
v If you want to explicitly issue LOAD requests when your program runs:
In your program, issue z/OS LOAD service requests for entry points
DSNALI and DSNHLI2. If you use IFI services, you must also load
DSNWLI2. The entry point addresses that LOAD returns are saved for later
use with the CALL macro. Indicate to DB2 which entry point to use in one of
the following two ways:

52 Application Programming and SQL Guide

– Specify the precompiler option ATTACH(CAF).
This option causes DB2 to generate calls that specify entry point
DSNHLI2.

Restriction: You cannot use this option if your application is written in

Fortran.
– Code a dummy entry point named DSNHLI within your load module.
If you do not specify the precompiler option ATTACH, the DB2
precompiler generates calls to entry point DSNHLI for each SQL request.
The precompiler does not know about and is independent of the different
DB2 attachment facilities. When the calls generated by the DB2
precompiler pass control to DSNHLI, your code that corresponds to the
dummy entry point must preserve the option list that was passed in R1
and specify the same option list when it calls DSNHLI2.
v If you want to include the DSNALI module in your load module when
you link-edit your program:
Include DSNALI in your load module during a link-edit step. The module
must be in a load module library, which is included either in the SYSLIB
concatenation or another INCLUDE library that is defined in the linkage
editor JCL. Because all language interface modules contain an entry point
declaration for DSNHLI, the linkage editor JCL must contain an INCLUDE
linkage editor control statement for DSNALI; for example, INCLUDE
DB2LIB(DSNALI). By coding these options, you avoid inadvertently picking up
the wrong language interface module.
Related concepts
“LOB file reference variables” on page 715
“Examples of invoking CAF” on page 71
Related tasks
“Saving storage when manipulating LOBs by using LOB locators” on page 711

Requirements for programs that use CAF

The call attachment facility (CAF) enables programs to communicate with DB2.
Before you invoke CAF in your program, ensure that your program satisfies any
requirements for using CAF.

When you write programs that use CAF, ensure that they meet the following
requirements:
v The program accounts for the size of the CAF code. The CAF code requires
about 16 KB of virtual storage per address space and an additional 10 KB for
each TCB that uses CAF.
v If your local environment intercepts and replaces the z/OS LOAD SVC that CAF
uses, you must ensure that your version of LOAD manages the load list element
(LLE) and contents directory entry (CDE) chains like the standard z/OS LOAD
macro. CAF uses z/OS SVC LOAD to load two modules as part of the
initialization after your first service request. Both modules are loaded into
fetch-protected storage that has the job-step protection key.
v If you use CAF from IMS batch, you must write data to only one system in any
one unit of work. If you write to both systems within the same unit, a system
failure can leave the two databases inconsistent with no possibility of automatic
recovery. To end a unit of work in DB2, execute the SQL COMMIT statement. To
end a unit of work in IMS, issue the SYNCPOINT command.

Chapter 2. Connecting to DB2 from your application program 53

You can prepare application programs to run in CAF similar to how you prepare
applications to run in other environments, such as CICS, IMS, and TSO. You can
prepare a CAF application either in the batch environment or by using the DB2
program preparation process. You can use the program preparation system either
through DB2I or through the DSNH CLIST.
Related tasks
Chapter 17, “Preparing an application to run on DB2 for z/OS,” on page 887

How CAF modifies the content of registers

If you do not specify the return code and reason code parameters in your CAF
function calls or you invoke CAF implicitly, CAF puts a return code in register 15
and a reason code in register 0. The contents of registers 2 through 14 are
preserved across calls.

The following table lists the standard calling conventions for registers R1, R13, R14,
and R15.
Table 9. Standard usage of registers R1, R13, R14, and R15
Register Usage
R1 CALL DSNALI parameter list pointer
R13 Address of caller’s save area
R14 Caller’s return address
R15 CAF entry point address

Your CAF program should respect these register conventions.

CAF also supports high-level languages that cannot examine the contents of
individual registers.
Related concepts
“CALL DSNALI statement parameter list” on page 55

Implicit connections to CAF

If the CAF language interface (DSNALI) is available and you do not explicitly
specify CALL DSNALI statements in your application, CAF initiates implicit
CONNECT and OPEN requests to DB2. These requests are subject to the same DB2
return codes and reason codes as explicitly specified requests.

Implicit connections use the following defaults:

Subsystem name
The default name that is specified in the module DSNHDECP. CAF uses
the installation default DSNHDECP, unless your own DSNHDECP module
is in a library in a STEPLIB statement of a JOBLIB concatenation or in the
link list. In a data sharing group, the default subsystem name is the group
attachment name.
Be certain that you know what the default name is and that it names the
specific DB2 subsystem you want to use.
Plan name
The member name of the database request module (DBRM) that DB2
produced when you precompiled the source program that contains the first
SQL call.

54 Application Programming and SQL Guide

Different types of implicit connections exist. The simplest is for an application to
call neither the CONNECT nor OPEN functions. You can also use the CONNECT
function only or the OPEN function only. Each of these calls implicitly connects
your application to DB2. To terminate an implicit connection, you must use the
proper calls.
Related concepts
“Summary of CAF behavior” on page 57

CALL DSNALI statement parameter list

The CALL DSNALI statement explicitly invokes CAF. When you include CALL
DSNALI statements in your program, you must specify all parameters that come
before the return code parameter.

For CALL DSNALI statements, use a standard z/OS CALL parameter list. Register
1 points to a list of fullword addresses that point to the actual parameters. The last
address must contain a 1 in the high-order bit.

In CALL DSNALI statements, you cannot omit any of parameters that come before
the return code parameter by coding zeros or blanks. No defaults exist for those
parameters for explicit connection requests. Defaults are provided for only implicit
connections. All parameters starting with the return code parameter are optional.

When you want to use the default value for a parameter but specify subsequent
parameters, code the CALL DSNALI statement as follows:
| v For C-language, when you code CALL DSNALI statements in C, you need to
| specify the address of every required parameter, using the “address of” operator
| (&), and not the parameter itself. For example, to pass the startecb parameter on
| CONNECT, specify the address of the 4-byte integer (&secb).
| functn char[13] = "CONNECT ";
| ssid char[ 5] = "DB2A";
| int tecb = 0;
| int secb = 0;
| ptr ribptr;
| int retcode;
| int reascode;
| ptr eibptr;
|
| fnret = dsnali(&functn[0], &ssid[0], &tecb, &secb, &ribptr, &retcode, &reascode,
| NULL, &eibptr);
v For other languages except assembler language, code zero for that parameter in
the CALL DSNALI statement. For example, suppose that you are coding a
CONNECT call in a COBOL program, and you want to specify all parameters
except the return code parameter. You can write a statement similar to the
following statement:
CALL 'DSNALI' USING FUNCTN SSID TECB SECB RIBPTR
BY CONTENT ZERO BY REFERENCE REASCODE SRDURA EIBPTR.
v For assembler language, code a comma for that parameter in the CALL DSNALI
statement. For example, to specify all optional parameters except the return code
parameter write a statement similar to the following statement:
CALL DSNALI,(FUNCTN,SSID,TERMECB,STARTECB,RIBPTR,,REASCODE,SRDURA,EIBPTR,
GROUPOVERRIDE)

The following figure shows a sample parameter list structure for the CONNECT
function.

Chapter 2. Connecting to DB2 from your application program 55

Figure 4. The parameter list for a CONNECT call

The preceding figure illustrates how you can omit parameters for the CALL
DSNALI statement to control the return code and reason code fields after a
CONNECT call. You can terminate the parameter list at any of the following
points. These termination points apply to all CALL DSNALI statement parameter
lists.
1. Terminates the parameter list without specifying the parameters retcode,
reascodeand srdura and places the return code in register 15 and the reason code
in register 0.
Terminating the parameter list at this point ensures compatibility with CAF
programs that require a return code in register 15 and a reason code in register
0.
2. Terminates the parameter list after the parameter retcode and places the return
code in the parameter list and the reason code in register 0.
Terminating the parameter list at this point enables the application program to
take action, based on the return code, without further examination of the
associated reason code.
3. Terminates the parameter list after the parameter reascode and places the return
code and the reason code in the parameter list.
Terminating the parameter list at this point provides support to high-level
languages that are unable to examine the contents of individual registers.

56 Application Programming and SQL Guide

If you code your CAF application in assembler language, you can specify the
reason code parameter and omit the return code parameter.
4. Terminates the parameter list after the parameter srdura.
If you code your CAF application in assembler language, you can specify this
parameter and omit the retcode and reascode parameters.
5. Terminates the parameter list after the parameter eibptr.
If you code your CAF application in assembler language, you can specify this
parameter and omit the retcode, reascode, or srdura parameters.
6. Terminates the parameter list after the parameter groupoverride.
If you code your CAF application in assembler language, you can specify this
parameter and omit the retcode, reascode,srdura, or eibptr parameters.

Even if you specify that the return code be placed in the parameter list, it is also
placed in register 15 to accommodate high-level languages that support special
return code processing.
Related concepts
“How CAF modifies the content of registers” on page 54

Summary of CAF behavior

The effect of any CAF function depends in part on what functions the program has
already run. You should plan the CAF function calls that your program makes to
avoid any errors and major structural problems in your application.

The following table summarizes CAF behavior after various inputs from
application programs. The top row lists the possible CAF functions that programs
can call. The first column lists the task’s most recent history of connection requests.
For example, the value “CONNECT followed by OPEN” in the first column means
that the task issued CONNECT and then OPEN with no other CAF calls in
between. The intersection of a row and column shows the effect of the next call if
it follows the corresponding connection history. For example, if the call is OPEN
and the connection history is CONNECT, the effect is OPEN; the OPEN function is
performed. If the call is SQL and the connection history is empty (meaning that the
SQL call is the first CAF function the program), the effect is that implicit
CONNECT and OPEN functions are performed, followed by the SQL function.
Table 10. Effects of CAF calls, as dependent on connection history
Next function
Previous
function CONNECT OPEN SQL CLOSE DISCONNECT TRANSLATE
1
Empty: first call CONNECT OPEN CONNECT, Error 203 Error 2041 Error 2051
OPEN, followed
by the SQL or
IFI call
CONNECT Error 2011 OPEN OPEN, followed Error 2031 DISCONNECT TRANSLATE
by the SQL or
IFI call
CONNECT Error 2011 Error 2021 The SQL or IFI CLOSE2 DISCONNECT TRANSLATE
followed by call
OPEN
CONNECT Error 2011 Error 2021 The SQL or IFI CLOSE2 DISCONNECT TRANSLATE
followed by SQL call
or IFI call

Chapter 2. Connecting to DB2 from your application program 57

Table 10. Effects of CAF calls, as dependent on connection history (continued)
Next function
Previous
function CONNECT OPEN SQL CLOSE DISCONNECT TRANSLATE
1 1 2
OPEN Error 201 Error 202 The SQL or IFI CLOSE Error 2041 TRANSLATE
call
SQL or IFI call Error 2011 Error 2021 The SQL or IFI CLOSE2 Error 2041 TRANSLATE3
call

Notes:
1. An error is shown in this table as Error nnn. The corresponding reason code is
X’00C10nnn’. The message number is DSNAnnnI or DSNAnnnE.
2. The task and address space connections remain active. If the CLOSE call fails
because DB2 was down, the CAF control blocks are reset, the function produces
return code 4 and reason code X’00C10824’, and CAF is ready for more
connection requests when DB2 is up.
3. A TRANSLATE request is accepted, but in this case it is redundant. CAF
automatically issues a TRANSLATE request when an SQL or IFI request fails.
Related reference
“CAF return codes and reason codes” on page 69

CAF connection functions

A CAF connection function specifies the action that you want CAF to take. You
specify these functions when you invoke CAF through CALL DSNALI statements.

You can specify the following CAF functions in a CALL DSNALI statement:
CONNECT
Establishes the task (TCB) as a user of the named DB2 subsystem. When
the first task within an address space issues a connection request, the
address space is also initialized as a user of DB2.
OPEN Allocates a DB2 plan. You must allocate a plan before DB2 can process SQL
statements. If you did not request the CONNECT function, the OPEN
function implicitly establishes the task, and optionally the address space, as
a user of DB2.
CLOSE
Commits or abnormally terminates any database changes and deallocates
the plan. If the OPEN function implicitly requests the CONNECT function,
the CLOSE function removes the task, and possibly the address space, as a
user of DB2.
DISCONNECT
Removes the task as a user of DB2 and, if this task is the last or only task
in the address space with a DB2 connection, terminates the address space
connection to DB2.
TRANSLATE
Returns an SQL code and printable text that describe a DB2 hexadecimal
error reason code. This information is returned to the SQLCA.

Restriction: You cannot call the TRANSLATE function from the Fortran
language.

58 Application Programming and SQL Guide

Recommendation: Because the effect of any CAF function depends on what
functions the program has already run, carefully plan the calls that your program
makes to these CAF connection functions. Read about the summary of CAF
behavior and make these function calls accordingly.
Related concepts
“Summary of CAF behavior” on page 57
“CALL DSNALI statement parameter list” on page 55

CONNECT function for CAF

The CAF CONNECT function initializes a connection to DB2. This function is
different than the SQL CONNECT statement that accesses a remote location within
DB2.

The CONNECT function establishes the caller’s task as a user of DB2 services. If
no other task in the address space currently holds a connection with the specified
subsystem, the CONNECT function also initializes the address space for
communication to the DB2 address spaces. The CONNECT function establishes the
address space’s cross memory authorization to DB2 and builds address space
control blocks. You can issue a CONNECT request from any or all tasks in the
address space, but the address space level is initialized only once when the first
task connects.

Using the CONNECT function is optional. If you do not call the CONNECT
function, the first request from a task, either an OPEN request or an SQL or IFI
call, causes CAF to issue an implicit CONNECT request. If a task is connected
implicitly, the connection to DB2 is terminated either when you call the CLOSE
function or when the task terminates.

Call the CONNECT function in all of the following situations:

v You need to specify a particular subsystem name (ssnm) other than the default
subsystem name.
v You need the value of the CURRENT DEGREE special register to last as long as
the connection (srdura).
v You need to monitor the DB2 startup ECB (startecb), the DB2 termination ECB
(termecb), or the DB2 release level.
v You plan to have multiple tasks in the address space open and close plans or a
single task in the address space open and close plans more than once.
Establishing task and address space level connections involves significant
overhead. Using the CONNECT function to establish a task connection explicitly
minimizes this overhead by ensuring that the connection to DB2 remains after
the CLOSE function deallocates a plan. In this case, the connection terminates
only when you use the DISCONNECT function or when the task terminates.

The CONNECT function also enables the caller to learn the following items:
v That the operator has issued a STOP DB2 command. When this event occurs,
DB2 posts the termination ECB, termecb. Your application can either wait on or
just look at the ECB.
v That DB2 is abnormally terminating. When this event occurs happens, DB2 posts
the termination ECB, termecb.
v That DB2 is available again after a connection attempt that failed because DB2
was down. Your application can either wait or look at the startup ECB, startecb.
DB2 ignores this ECB if it was active at the time of the CONNECT request.

Chapter 2. Connecting to DB2 from your application program 59

v The current release level of DB2. To find this information, access the RIBREL
field in the release information block (RIB).

Restriction: Do not issue CONNECT requests from a TCB that already has an
active DB2 connection.

Recommendation: Do not mix explicit CONNECT and OPEN requests with

implicitly established connections in the same address space. Either explicitly
specify which DB2 subsystem you want to use or allow all requests to use the
default subsystem.

The following diagram shows the syntax for the CONNECT function.

DSNALI CONNECT function

CALL DSNALI ( function, ssnm, termecb, startecb, ribptr

)

,retcode
,reascode
,srdura
,eibptr
,groupoverride

Parameters point to the following areas:

function
A 12-byte area that contains CONNECT followed by five blanks.
ssnm
A 4-byte DB2 subsystem name or group attachment name (if used in a data
sharing group) to which the connection is made.
If ssnm is less than four characters long, pad it on the right with blanks to a
length of four characters.
termecb
A 4-byte integer representing the application’s event control block (ECB) for
DB2 termination. DB2 posts this ECB when the operator enters the STOP DB2
command or when DB2 is abnormally terminating. The ECB indicates the type
of termination by a POST code, as shown in the following table:
Table 11. POST codes and related termination types
POST code Termination type
8 QUIESCE
12 FORCE
16 ABTERM

Before you check termecb in your CAF application program, first check the
return code and reason code from the CONNECT call to ensure that the call
completed successfully.
startecb
A 4-byte integer representing the application’s startup ECB. If DB2 has not yet

60 Application Programming and SQL Guide

started when the application issues the call, DB2 posts the ECB when it
successfully completes its startup processing. DB2 posts at most one startup
ECB per address space. The ECB is the one associated with the most recent
CONNECT call from that address space. Your application program must
examine any nonzero CAF and DB2 reason codes before issuing a WAIT on
this ECB.
If ssnm is a group attachment name, the first DB2 subsystem that starts on the
local z/OS system and matches the specified group attachment name posts the
ECB.
ribptr
A 4-byte area in which CAF places the address of the release information block
(RIB) after the call. You can determine what release level of DB2 you are
currently running by examining the RIBREL field. You can determine the
modification level within the release level by examining the RIBCNUMB and
RIBCINFO fields. If the value in the RIBCNUMB field is greater than zero,
check the RIBCINFO field for modification levels.
If the RIB is not available (for example, if you name a subsystem that does not
exist), DB2 sets the 4-byte area to zeros.
The area to which ribptr points is below the 16-MB line.
Your program does not have to use the release information block, but it cannot
omit the ribptr parameter.
Macro DSNDRIB maps the release information block (RIB). It can be found in
prefix.SDSNMACS(DSNDRIB).
retcode
A 4-byte area in which CAF places the return code.
This field is optional. If you do not specify retcode, CAF places the return code
in register 15 and the reason code in register 0.
reascode
A 4-byte area in which CAF places a reason code.
This field is optional. If you do not specify reascode, CAF places the reason
code in register 0. If you specify reascode, you must also specify retcode.
srdura
A 10-byte area that contains the string ’SRDURA(CD)’. This field is optional. If
you specify srdura, the value in the CURRENT DEGREE special register stays
in effect from the time of the CONNECT call until the time of the
DISCONNECT call. If you do not specify srdura, the value in the CURRENT
DEGREE special register stays in effect from the time of the OPEN call until
the time of the CLOSE call. If you specify this parameter in any language
except assembler, you must also specify retcode and reascode. In assembler
language, you can omit these parameters by specifying commas as
placeholders.
eibptr
A 4-byte area in which CAF puts the address of the environment information
block (EIB). The EIB contains information that you can use if you are
connecting to a DB2 subsystem that is part of a data sharing group. For
example, you can determine the name of the data sharing group, the member
to which you are connecting, and whether the subsystem is in new-function
mode. If the DB2 subsystem that you connect to is not part of a data sharing

Chapter 2. Connecting to DB2 from your application program 61

group, the fields in the EIB that are related to data sharing are blank. If the EIB
is not available (for example, if you name a subsystem that does not exist),
DB2 sets the 4-byte area to zeros.
| The area to which eibptr points is above the 16-MB line.
You can omit this parameter when you make a CONNECT call.
If you specify this parameter in any language except assembler, you must also
specify retcode, reascode, and srdura. In assembler language, you can omit
retcode, reascode, and srdura by specifying commas as placeholders.
Macro DSNDEIB maps the EIB. It can be found in
prefix.SDSNMACS(DSNDEIB).
| groupoverride
| An 8-byte area that the application provides. This parameter is optional. If you
| do not want group attach to be attempted, specify ’NOGROUP’. This string
| indicates that the subsystem name that is specified by ssnm is to be used as a
| DB2 subsystem name, even if ssnm matches a group attachment name. If
| groupoverride is not provided, ssnm is used as the group attachment name if it
| matches a group attachment name.
| If you specify this parameter in any language except assembler, you must also
| specify retcode, reascode, srdura, and eibptr. In assembler language, you can omit
| retcode, reascode, srdura, and eibptr by specifying commas as placeholders.

| Recommendation: Avoid using the groupoverride parameter when possible,

| because it limits the ability to do dynamic workload routing in a Parallel
| Sysplex®. However, you should use this parameter in a data sharing
| environment when you want to connect to a specific member of a data sharing
| group, and the subsystem name of that member is the same as the group
| attachment name.

Example of CAF CONNECT function calls

The following table shows a CONNECT call in each language.

Table 12. Examples of CAF CONNECT function calls
Language Call example
Assembler CALL
DSNALI,(FUNCTN,SSID,TERMECB,STARTECB,RIBPTR,RETCODE,REASCODE,SRDURA,
EIBPTR, GRPOVER)
C1 fnret=dsnali(&functn[0],&ssid[0], &tecb, &secb,&ribptr,&retcode, &reascode, &srdura[0],
&eibptr, &grpover[0]);
COBOL CALL 'DSNALI' USING FUNCTN SSID TERMECB STARTECB RIBPTR RETCODE REASCODE SRDURA
EIBPTR GRPOVER.
Fortran CALL
DSNALI(FUNCTN,SSID,TERMECB,STARTECB,RIBPTR,RETCODE,REASCODE,SRDURA,
EIBPTR,GRPOVER)
PL/I1 CALL
DSNALI(FUNCTN,SSID,TERMECB,STARTECB,RIBPTR,RETCODE,REASCODE,SRDURA,
EIBPTR,GRPOVER)

Note:
v For C and PL/I applications, you must include the appropriate compiler
directives, because DSNALI is an assembler language program. These compiler
directives are described in the instructions for invoking CAF.
62 Application Programming and SQL Guide
Related concepts
“Examples of invoking CAF” on page 71
Related tasks
“Invoking the call attachment facility” on page 46
Related information
Synchronizing Tasks (WAIT, POST, and EVENTS Macros) (MVS Programming:
Assembler Services Guide)

OPEN function for CAF

The OPEN function allocates DB2 resources that are needed to run the specified
plan or issue IFI requests. If the requesting task does not already have a connection
to the named DB2 subsystem, the OPEN function establishes it.

Using the OPEN function is optional. If you do not call the OPEN function, the
actions that the OPEN function perform occur implicitly on the first SQL or IFI call
from the task.

Restriction: Do not use the OPEN function if the task already has a plan allocated.

The following diagram shows the syntax for the OPEN function.

DSNALI OPEN function

CALL DSNALI ( function, ssnm, plan

)

, retcode
, reascode
, groupoverride

Parameters point to the following areas:

function
A 12-byte area that contains the word OPEN followed by eight blanks.
ssnm
A 4-byte DB2 subsystem name or group attachment name (if used in a data
sharing group). The OPEN function allocates the specified plan to this DB2
subsystem. Also, if the requesting task does not already have a connection to
the named DB2 subsystem, the OPEN function establishes it.
You must specify the ssnm parameter, even if the requesting task also issues a
CONNECT call. If a task issues a CONNECT call followed by an OPEN call,
the subsystem names for both calls must be the same.
If ssnm is less than four characters long, pad it on the right with blanks to a
length of four characters.
plan
An 8-byte DB2 plan name.
retcode
A 4-byte area in which CAF places the return code.

Chapter 2. Connecting to DB2 from your application program 63

This field is optional. If you do not specify retcode,CAF places the return code
in register 15 and the reason code in register 0.
reascode
A 4-byte area in which CAF places a reason code.
This field is optional. If you do not specify reascode, CAF places the reason
code in register 0. If you specify reascode, you must also specify retcode.
| groupoverride
An 8-byte area that the application provides. This field is optional. If you do
not want group attach to be attempted, specify ’NOGROUP’. This string
indicates that the subsystem name that is specified by ssnm is to be used as a
DB2 subsystem name, even if ssnm matches a group attachment name. If you
do not specify groupoverride, ssnm is used as the group attachment name if it
matches a group attachment name. If you specify this parameter in any
language except assembler, you must also specify retcode and reascode. In
assembler language, you can omit these parameters by specifying commas as
placeholders.

Recommendation: Avoid using the groupoverride parameter when possible,

because it limits the ability to do dynamic workload routing in a Parallel
Sysplex. However, you should use this parameter in a data sharing
environment when you want to connect to a specific member of a data sharing
group, and the subsystem name of that member is the same as the group
attachment name.

Examples of CAF OPEN calls

The following table shows an OPEN call in each language.

Table 13. Examples of CAF OPEN calls
Language Call example
Assembler CALL DSNALI,(FUNCTN,SSID,PLANNAME, RETCODE,REASCODE,GRPOVER)
1
C fnret=dsnali(&functn[0],&ssid[0], &planname[0],&retcode, &reascode,&grpover[0]);
COBOL CALL 'DSNALI' USING FUNCTN SSID PLANNAME RETCODE REASCODE GRPOVER.
Fortran CALL DSNALI(FUNCTN,SSID,PLANNAME, RETCODE,REASCODE,GRPOVER)
1
PL/I CALL DSNALI(FUNCTN,SSID,PLANNAME, RETCODE,REASCODE,GRPOVER);

Note:
v For C and PL/I applications, you must include the appropriate compiler
directives, because DSNALI is an assembler language program. These compiler
directives are described in the instructions for invoking CAF.
Related concepts
“Implicit connections to CAF” on page 54
Related tasks
“Invoking the call attachment facility” on page 46

CLOSE function for CAF

The CAF CLOSE function deallocates the plan that was created either explicitly by
a call to the OPEN function or implicitly at the first SQL call. Optionally, the
CLOSE function also disconnects the task, and possibly the address space, from
DB2.

64 Application Programming and SQL Guide

If you did not issue an explicit CONNECT call for the task, the CLOSE function
deletes the task’s connection to DB2. If no other task in the address space has an
active connection to DB2, DB2 also deletes the control block structures that were
created for the address space and removes the cross memory authorization.

Using the CLOSE function is optional. Consider the following rules and
recommendations about when to use and not use the CLOSE function:
v Do not use the CLOSE function when your current task does not have a plan
allocated.
v If you want to use a new plan, you must issue an explicit CLOSE call, followed
by an OPEN call with the new plan name.
v When shutting down your application you can improve the performance of this
shut down by explicitly calling the CLOSE function before the task terminates. If
you omit the CLOSE call, DB2 performs an implicit CLOSE. In this case, DB2
performs the same actions when your task terminates, by using the SYNC
parameter if termination is normal and the ABRT parameter if termination is
abnormal.
v If DB2 terminates, issue an explicit CLOSE call for any task that did not issue a
CONNECT call. This action enables CAF to reset its control blocks to allow for
future connections. This CLOSE call returns the reset accomplished return code
(+004) and reason code X’00C10824’. If you omit the CLOSE call in this case,
when DB2 is back on line, the task’s next connection request fails. You get either
the message YOUR TCB DOES NOT HAVE A CONNECTION, with X’00F30018’
in register 0, or the CAF error message DSNA201I or DSNA202I, depending on
what your application tried to do. The task must then issue a CLOSE call before
it can reconnect to DB2.
v A task that issued an explicit CONNECT call should issue a DISCONNECT call
instead of a CLOSE call. This action causes CAF to reset its control blocks when
DB2 terminates.

The following diagram shows the syntax for the CLOSE function.

DSNALI CLOSE function

CALL DSNALI ( function, termop )


, retcode
, reascode

Parameters point to the following areas:

function
A 12-byte area that contains the word CLOSE followed by seven blanks.
termop
A 4-byte terminate option, with one of the following values:
SYNC Specifies that DB2 is to commit any modified data.
ABRT Specifies that DB2 is to roll back data to the previous commit point.
retcode
A 4-byte area in which CAF is to place the return code.

Chapter 2. Connecting to DB2 from your application program 65

This field is optional. If you do not specify retcode, CAF places the return code
in register 15 and the reason code in register 0.
reascode
A 4-byte area in which CAF places a reason code.
This field is optional. If you do not specify reascode, CAF places the reason
code in register 0. If you specify reascode, you must also specify retcode.

Examples of CAF CLOSE calls

The following table shows a CLOSE call in each language.

Table 14. Examples of CAF CLOSE calls
Language Call example
Assembler CALL DSNALI,(FUNCTN,TERMOP,RETCODE, REASCODE)
1
C fnret=dsnali(&functn[0], &termop[0], &retcode,&reascode);
COBOL CALL 'DSNALI' USING FUNCTN TERMOP RETCODE REASCODE.
Fortran CALL DSNALI(FUNCTN,TERMOP, RETCODE,REASCODE)
1
PL/I CALL DSNALI(FUNCTN,TERMOP, RETCODE,REASCODE);

Note:
v For C and PL/I applications, you must include the appropriate compiler
directives, because DSNALI is an assembler language program. These compiler
directives are described in the instructions for invoking CAF.
Related tasks
“Invoking the call attachment facility” on page 46

DISCONNECT function for CAF

The CAF DISCONNECT function terminates a connection to DB2.

DISCONNECT removes the calling task’s connection to DB2. If no other task in the
address space has an active connection to DB2, DB2 also deletes the control block
structures that were created for the address space and removes the cross memory
authorization.

If an OPEN call is in effect, which means that a plan is allocated, when the
DISCONNECT call is issued, CAF issues an implicit CLOSE with the SYNC
parameter.

Using the DISCONNECT function is optional. Consider the following rules and
recommendations about when to use and not use the DISCONNECT function:
v Only those tasks that explicitly issued a CONNECT call can issue a
DISCONNECT call. If a CONNECT call was not used, a DISCONNECT call
causes an error.
v When shutting down your application you can improve the performance of this
shut down by explicitly calling the DISCONNECT function before the task
terminates. If you omit the DISCONNECT call, DB2 performs an implicit
DISCONNECT. In this case, DB2 performs the same actions when your task
terminates.
v If DB2 terminates, any task that issued a CONNECT call must issue a
DISCONNECT call to reset the CAF control blocks. The DISCONNECT function

66 Application Programming and SQL Guide

returns the reset accomplished return codes and reason codes (+004 and
X’00C10824’). This action ensures that future connection requests from the task
work when DB2 is back on line.
v A task that did not explicitly issue a CONNECT call must issue a CLOSE call
instead of a DISCONNECT call. This action resets the CAF control blocks when
DB2 terminates.

The following diagram shows the syntax for the DISCONNECT function.

DSNALI DISCONNECT function

CALL DSNALI ( function )


, retcode
, reascode

The single parameter points to the following area:

function
A 12-byte area that contains the word DISCONNECT followed by two blanks.
retcode
A 4-byte area in which CAF places the return code.
This field is optional. If you do not specify retcode, CAF places the return code
in register 15 and the reason code in register 0.
reascode
A 4-byte area in which CAF places a reason code.
This field is optional. If you do not specify reascode, CAF places the reason
code in register 0. If you specify reascode, you must also specify retcode.

Examples of CAF DISCONNECT calls

The following table shows a DISCONNECT call in each language.

Table 15. Examples of CAF DISCONNECT calls
Language Call example
Assembler CALL DSNALI(,FUNCTN,RETCODE,REASCODE)
1
C fnret=dsnali(&functn[0], &retcode, &reascode);
COBOL CALL 'DSNALI' USING FUNCTN RETCODE REASCODE.
Fortran CALL DSNALI(FUNCTN,RETCODE,REASCODE)
1
PL/I CALL DSNALI(FUNCTN,RETCODE,REASCODE);

Note:
v For C and PL/I applications, you must include the appropriate compiler
directives, because DSNALI is an assembler language program. These compiler
directives are described in the instructions for invoking CAF.

Chapter 2. Connecting to DB2 from your application program 67

Related tasks
“Invoking the call attachment facility” on page 46

TRANSLATE function for CAF

The TRANSLATE function converts a DB2 hexadecimal error reason code from a
failed OPEN request into an SQL error code and printable error message text. DB2
places the information into the SQLCODE and SQLSTATE host variables or related
fields of the caller’s SQLCA.

The DB2 error reason code that is converted is read from register 0. The
TRANSLATE function does not change the contents of registers 0 and 15, unless
the TRANSLATE request fails; in that case, register 0 is set to X’C10205’ and
register 15 is set to 200.

Consider the following rules and recommendations about when to use and not use
the TRANSLATE function:
v You cannot call the TRANSLATE function from the Fortran language.
v The TRANSLATE function is useful only if you used an explicit CONNECT call
before an OPEN request that fails. For errors that occur during SQL or IFI
requests, the TRANSLATE function performs automatically.
v The TRANSLATE function can translate those codes that begin with X’00F3’, but
it does not translate CAF reason codes that begin with X’00C1’.

If you receive error reason code X’00F30040’ (resource unavailable) after an OPEN
request, the TRANSLATE function returns the name of the unavailable database
object in the last 44 characters of the SQLERRM field.

If the TRANSLATE function does not recognize the error reason code, it returns
SQLCODE -924 (SQLSTATE ’58006’) and places a printable copy of the original
DB2 function code and the return and error reason codes in the SQLERRM field.

The following diagram shows the syntax for the TRANSLATE function.

DSNALI TRANSLATE function

CALL DSNALI ( function, sqlca )


, retcode
, reascode

Parameters point to the following areas:

function
A 12-byte area the contains the word TRANSLATE followed by three blanks.
sqlca
The program’s SQL communication area (SQLCA).
retcode
A 4-byte area in which CAF places the return code.
This field is optional. If you do not specify retcode, CAF places the return code
in register 15 and the reason code in register 0.

68 Application Programming and SQL Guide

reascode
A 4-byte area in which CAF places a reason code.
This field is optional. If you do not specify reascode, CAF places the reason
code in register 0. If you specify reascode, you must also specify retcode.

Examples of CAF TRANSLATE calls

The following table shows a TRANSLATE call in each language.

Table 16. Examples of CAF TRANSLATE calls
Language Call example
Assembler CALL DSNALI,(FUNCTN,SQLCA,RETCODE, REASCODE)
1
C fnret=dsnali(&functn[0], &sqlca, &retcode, &reascode);
COBOL CALL 'DSNALI' USING FUNCTN SQLCA RETCODE REASCODE.
1
PL/I CALL DSNALI(FUNCTN,SQLCA,RETCODE, REASCODE);

Note:
v For C and PL/I applications, you must include the appropriate compiler
directives, because DSNALI is an assembler language program. These compiler
directives are described in the instructions for invoking CAF.
Related tasks
“Invoking the call attachment facility” on page 46

Turning on a CAF trace

CAF does not capture any diagnostic trace messages unless you tell it to by
turning on a trace.

To turn on a CAF trace:

Allocate a DSNTRACE data set either dynamically or by including a DSNTRACE

DD statement in your JCL. CAF writes diagnostic trace messages to that data set.
The trace message numbers contain the last three digits of the reason codes.
Related concepts
“Examples of invoking CAF” on page 71

CAF return codes and reason codes

CAF provides the return codes and reason codes either to the corresponding
parameters that are specified in a CAF function call or, if you choose not to use
those parameters, to registers 15 and 0.

When the reason code begins with X’00F3’ except for X’00F30006’, you can use the
CAF TRANSLATE function to obtain error message text that can be printed and
displayed. These reason codes are issued by the subsystem support for allied
memories, a part of the DB2 subsystem support subcomponent that services all
DB2 connection and work requests.

For SQL calls, CAF returns standard SQL codes in the SQLCA. CAF returns IFI
return codes and reason codes in the instrumentation facility communication area
(IFCA).

The following table lists the CAF return codes and reason codes.

Chapter 2. Connecting to DB2 from your application program 69

Table 17. CAF return codes and reason codes
Return code Reason code Explanation
0 X’00000000’ Successful completion.
4 X’00C10824’ CAF reset complete. CAF is ready to make a new connection.
8 X’00C10831’ Release level mismatch between DB2 and the CAF code.
1
200 X’00C10201’ Received a second CONNECT request from the same TCB. The first
CONNECT request could have been implicit or explicit.
2001 X’00C10202’ Received a second OPEN request from the same TCB. The first
OPEN request could have been implicit or explicit.
2001 X’00C10203’ CLOSE request issued when no active OPEN request exists.
1
200 X’00C10204’ DISCONNECT request issued when no active CONNECT request
exists, or the AXSET macro was issued between the CONNECT
request and the DISCONNECT request.
2001 X’00C10205’ TRANSLATE request issued when no connection to DB2 exists.
1
200 X’00C10206’ Incorrect number of parameters was specified or the end-of-list bit
was off.
2001 X’00C10207’ Unrecognized function parameter.
1
200 X’00C10208’ Received requests to access two different DB2 subsystems from the
same TCB.
2
204 CAF system error. Probable error in the attach or DB2.
Notes:
1. A CAF error probably caused by errors in the parameter lists from the application programs. CAF errors do not
change the current state of your connection to DB2; you can continue processing with a corrected request.
2. System errors cause abends. If tracing is on, a descriptive message is written to the DSNTRACE data set just
before the abend.

Sample CAF scenarios

One or more tasks can use CAF to connect to DB2. This connection can be made
either implicitly or explicitly. For explicit connections, a task calls one or more of
the CAF connection functions.

A single task with implicit connections

The simplest connection scenario is a single task that makes calls to DB2 without
using explicit CALL DSNALI statements. The task implicitly connects to the
default subsystem name and uses the default plan name.

When the task terminates, the following events occur:

v If termination was normal, any database changes are committed.
v If termination was abnormal, any database changes are rolled back.
v The active plan and all database resources are deallocated.
v The task and address space connections to DB2 are terminated.

A single task with explicit connections

The following example pseudocode illustrates a more complex scenario with a

single task.

70 Application Programming and SQL Guide

CONNECT
OPEN allocate a plan
SQL or IFI call
•••
CLOSE deallocate the current plan
OPEN allocate a new plan
SQL or IFI call
•••
CLOSE
DISCONNECT

A task can have a connection to only one DB2 subsystem at any point in time. A
CAF error occurs if the subsystem name in the OPEN call does not match the
subsystem name in the CONNECT call. To switch to a different subsystem, the
application must first disconnect from the current subsystem and then issue a
connect request with a new subsystem name.

Multiple tasks
In the following scenario, multiple tasks within the address space use DB2 services.
Each task must explicitly specify the same subsystem name on either the
CONNECT function request or the OPEN function request. Task 1 makes no SQL
or IFI calls. Its purpose is to monitor the DB2 termination and startup ECBs and to
check the DB2 release level.
TASK 1 TASK 2 TASK 3 TASK n

CONNECT
OPEN OPEN OPEN
SQL SQL SQL
... ... ...
CLOSE CLOSE CLOSE
OPEN OPEN OPEN
SQL SQL SQL
... ... ...
CLOSE CLOSE CLOSE
DISCONNECT

Examples of invoking CAF

The call attachment facility (CAF) enables programs to communicate with DB2. If
you explicitly invoke CAF in your program, you can use the CAF connection
functions to control the state of the connection.

Example JCL for invoking CAF

The following sample JCL shows how to use CAF in a batch (non-TSO)
environment. The DSNTRACE statement in this example is optional.
//jobname JOB z/OS_jobcard_information
//CAFJCL EXEC PGM=CAF_application_program
//STEPLIB DD DSN=application_load_library
// DD DSN=DB2_load_library
.
.
.

//SYSPRINT DD SYSOUT=*
//DSNTRACE DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*

Chapter 2. Connecting to DB2 from your application program 71

Example of assembler code that invokes CAF

The following examples show parts of a sample assembler program that uses CAF.
They demonstrate the basic techniques for making CAF calls, but do not show the
code and z/OS macros needed to support those calls. For example, many
applications need a two-task structure so that attention-handling routines can
detach connected subtasks to regain control from DB2. This structure is not shown
in the following code examples. Also, these code examples assume the existence of
a WRITE macro. Wherever this macro is included in the example, substitute code
of your own. You must decide what you want your application to do in those
situations; you probably do not want to write the error messages shown.

Example of loading and deleting the CAF language interface: The following code
segment shows how an application can load entry points DSNALI and DSNHLI2
for the CAF language interface. Storing the entry points in variables LIALI and
LISQL ensures that the application has to load the entry points only once. When
the module is done with DB2, you should delete the entries.
****************************** GET LANGUAGE INTERFACE ENTRY ADDRESSES
LOAD EP=DSNALI Load the CAF service request EP
ST R0,LIALI Save this for CAF service requests
LOAD EP=DSNHLI2 Load the CAF SQL call Entry Point
ST R0,LISQL Save this for SQL calls
* .
* . Insert connection service requests and SQL calls here
* .
DELETE EP=DSNALI Correctly maintain use count
DELETE EP=DSNHLI2 Correctly maintain use count

Example of connecting to DB2 with CAF: The following example code shows
how to issue explicit requests for certain actions, such as CONNECT, OPEN,
CLOSE, DISCONNECT, and TRANSLATE, and uses the CHEKCODE subroutine to
check the return reason codes from CAF.
****************************** CONNECT ********************************
L R15,LIALI Get the Language Interface address
MVC FUNCTN,CONNECT Get the function to call
CALL (15),(FUNCTN,SSID,TECB,SECB,RIBPTR),VL,MF=(E,CAFCALL)
BAL R14,CHEKCODE Check the return and reason codes
CLC CONTROL,CONTINUE Is everything still OK
BNE EXIT If CONTROL not 'CONTINUE', stop loop
USING R8,RIB Prepare to access the RIB
L R8,RIBPTR Access RIB to get DB2 release level
WRITE 'The current DB2 release level is' RIBREL

****************************** OPEN ***********************************

L R15,LIALI Get the Language Interface address
MVC FUNCTN,OPEN Get the function to call
CALL (15),(FUNCTN,SSID,PLAN),VL,MF=(E,CAFCALL)
BAL R14,CHEKCODE Check the return and reason codes

****************************** SQL ************************************

* Insert your SQL calls here. The DB2 Precompiler
* generates calls to entry point DSNHLI. You should
* specify the precompiler option ATTACH(CAF), or code
* a dummy entry point named DSNHLI to intercept
* all SQL calls. A dummy DSNHLI is shown below.
****************************** CLOSE **********************************
CLC CONTROL,CONTINUE Is everything still OK?
BNE EXIT If CONTROL not 'CONTINUE', shut down
MVC TRMOP,ABRT Assume termination with ABRT parameter
L R4,SQLCODE Put the SQLCODE into a register
C R4,CODE0 Examine the SQLCODE
BZ SYNCTERM If zero, then CLOSE with SYNC parameter

72 Application Programming and SQL Guide

C R4,CODE100 See if SQLCODE was 100
BNE DISC If not 100, CLOSE with ABRT parameter
SYNCTERM MVC TRMOP,SYNC Good code, terminate with SYNC parameter
DISC DS 0H Now build the CAF parmlist
L R15,LIALI Get the Language Interface address
MVC FUNCTN,CLOSE Get the function to call
CALL (15),(FUNCTN,TRMOP),VL,MF=(E,CAFCALL)
BAL R14,CHEKCODE Check the return and reason codes

****************************** DISCONNECT *****************************

CLC CONTROL,CONTINUE Is everything still OK
BNE EXIT If CONTROL not 'CONTINUE', stop loop
L R15,LIALI Get the Language Interface address
MVC FUNCTN,DISCON Get the function to call
CALL (15),(FUNCTN),VL,MF=(E,CAFCALL)
BAL R14,CHEKCODE Check the return and reason codes

This example code does not show a task that waits on the DB2 termination ECB. If
you want such a task, you can code it by using the z/OS WAIT macro to monitor
the ECB. You probably want this task to detach the sample code if the termination
ECB is posted. That task can also wait on the DB2 startup ECB. This sample waits
on the startup ECB at its own task level.

This example code assumes that the variables in the following table are already set:
Table 18. Variables that preceding example assembler code assumes are set
Variable Usage
LIALI The entry point that handles DB2 connection
service requests.
LISQL The entry point that handles SQL calls.
SSID The DB2 subsystem identifier.
TECB The address of the DB2 termination ECB.
SECB The address of the DB2 startup ECB.
RIBPTR A fullword that CAF sets to contain the RIB
address.
PLAN The plan name to use in the OPEN call.
CONTROL This variable is used to shut down
processing because of unsatisfactory return
or reason codes. The CHECKCODE
subroutine sets this value.
CAFCALL List-form parameter area for the CALL
macro.

Example of checking return codes and reason codes when using CAF: The
following example code illustrates a way to check the return codes and the DB2
termination ECB after each connection service request and SQL call. The routine
sets the variable CONTROL to control further processing within the module.
***********************************************************************
* CHEKCODE PSEUDOCODE *
***********************************************************************
*IF TECB is POSTed with the ABTERM or FORCE codes
* THEN
* CONTROL = 'SHUTDOWN'
* WRITE 'DB2 found FORCE or ABTERM, shutting down'
* ELSE /* Termination ECB was not POSTed */
* SELECT (RETCODE) /* Look at the return code */
* WHEN (0) ; /* Do nothing; everything is OK */

Chapter 2. Connecting to DB2 from your application program 73

* WHEN (4) ; /* Warning */
* SELECT (REASCODE) /* Look at the reason code */
* WHEN ('00C10824'X) /* Ready for another CAF call */
* CONTROL = 'RESTART' /* Start over, from the top */
* OTHERWISE
* WRITE 'Found unexpected R0 when R15 was 4'
* CONTROL = 'SHUTDOWN'
* END INNER-SELECT
* WHEN (8,12) /* Connection failure */
* SELECT (REASCODE) /* Look at the reason code */
* WHEN ('00C10831'X) /* DB2 / CAF release level mismatch*/
* WRITE 'Found a mismatch between DB2 and CAF release levels'
* WHEN ('00F30002'X, /* These mean that DB2 is down but */
* '00F30012'X) /* will POST SECB when up again */
* DO
* WRITE 'DB2 is unavailable. I'll tell you when it's up.'
* WAIT SECB /* Wait for DB2 to come up */
* WRITE 'DB2 is now available.'
* END
* /**********************************************************/
* /* Insert tests for other DB2 connection failures here. */
* /* CAF Externals Specification lists other codes you can */
* /* receive. Handle them in whatever way is appropriate */
* /* for your application. */
* /**********************************************************/
* OTHERWISE /* Found a code we're not ready for*/
* WRITE 'Warning: DB2 connection failure. Cause unknown'
* CALL DSNALI ('TRANSLATE',SQLCA) /* Fill in SQLCA */
* WRITE SQLCODE and SQLERRM
* END INNER-SELECT
* WHEN (200)
* WRITE 'CAF found user error. See DSNTRACE dataset'
* WHEN (204)
* WRITE 'CAF system error. See DSNTRACE data set'
* OTHERWISE
* CONTROL = 'SHUTDOWN'
* WRITE 'Got an unrecognized return code'
* END MAIN SELECT
* IF (RETCODE > 4) THEN /* Was there a connection problem?*/
* CONTROL = 'SHUTDOWN'
* END CHEKCODE
***********************************************************************
* Subroutine CHEKCODE checks return codes from DB2 and Call Attach.
* When CHEKCODE receives control, R13 should point to the caller's
* save area.
***********************************************************************
CHEKCODE DS 0H
STM R14,R12,12(R13) Prolog
ST R15,RETCODE Save the return code
ST R0,REASCODE Save the reason code
LA R15,SAVEAREA Get save area address
ST R13,4(,R15) Chain the save areas
ST R15,8(,R13) Chain the save areas
LR R13,R15 Put save area address in R13
* ********************* HUNT FOR FORCE OR ABTERM ***************
TM TECB,POSTBIT See if TECB was POSTed
BZ DOCHECKS Branch if TECB was not POSTed
CLC TECBCODE(3),QUIESCE Is this "STOP DB2 MODE=FORCE"
BE DOCHECKS If not QUIESCE, was FORCE or ABTERM
MVC CONTROL,SHUTDOWN Shutdown
WRITE 'Found found FORCE or ABTERM, shutting down'
B ENDCCODE Go to the end of CHEKCODE
DOCHECKS DS 0H Examine RETCODE and REASCODE
* ********************* HUNT FOR 0 *****************************
CLC RETCODE,ZERO Was it a zero?
BE ENDCCODE Nothing to do in CHEKCODE for zero
* ********************* HUNT FOR 4 *****************************

74 Application Programming and SQL Guide

CLC RETCODE,FOUR Was it a 4?
BNE HUNT8 If not a 4, hunt eights
CLC REASCODE,C10831 Was it a release level mismatch?
BNE HUNT824 Branch if not an 831
WRITE 'Found a mismatch between DB2 and CAF release levels'
B ENDCCODE We are done. Go to end of CHEKCODE
HUNT824 DS 0H Now look for 'CAF reset' reason code
CLC REASCODE,C10824 Was it 4? Are we ready to restart?
BNE UNRECOG If not 824, got unknown code
WRITE 'CAF is now ready for more input'
MVC CONTROL,RESTART Indicate that we should re-CONNECT
B ENDCCODE We are done. Go to end of CHEKCODE
UNRECOG DS 0H
WRITE 'Got RETCODE = 4 and an unrecognized reason code'
MVC CONTROL,SHUTDOWN Shutdown, serious problem
B ENDCCODE We are done. Go to end of CHEKCODE
* ********************* HUNT FOR 8 *****************************
HUNT8 DS 0H
CLC RETCODE,EIGHT Hunt return code of 8
BE GOT8OR12
CLC RETCODE,TWELVE Hunt return code of 12
BNE HUNT200
GOT8OR12 DS 0H Found return code of 8 or 12
WRITE 'Found RETCODE of 8 or 12'
CLC REASCODE,F30002 Hunt for X'00F30002'
BE DB2DOWN
CLC REASCODE,F30012 Hunt for X'00F30012'
BE DB2DOWN
WRITE 'DB2 connection failure with an unrecognized REASCODE'
CLC SQLCODE,ZERO See if we need TRANSLATE
BNE A4TRANS If not blank, skip TRANSLATE
* ********************* TRANSLATE unrecognized RETCODEs ********
WRITE 'SQLCODE 0 but R15 not, so TRANSLATE to get SQLCODE'
L R15,LIALI Get the Language Interface address
CALL (15),(TRANSLAT,SQLCA),VL,MF=(E,CAFCALL)
C R0,C10205 Did the TRANSLATE work?
BNE A4TRANS If not C10205, SQLERRM now filled in
WRITE 'Not able to TRANSLATE the connection failure'
B ENDCCODE Go to end of CHEKCODE
A4TRANS DS 0H SQLERRM must be filled in to get here
* Note: your code should probably remove the X'FF'
* separators and format the SQLERRM feedback area.
* Alternatively, use DB2 Sample Application DSNTIAR
* to format a message.
WRITE 'SQLERRM is:' SQLERRM
B ENDCCODE We are done. Go to end of CHEKCODE
DB2DOWN DS 0H Hunt return code of 200
WRITE 'DB2 is down and I will tell you when it comes up'
WAIT ECB=SECB Wait for DB2 to come up
WRITE 'DB2 is now available'
MVC CONTROL,RESTART Indicate that we should re-CONNECT
B ENDCCODE
* ********************* HUNT FOR 200 ***************************
HUNT200 DS 0H Hunt return code of 200
CLC RETCODE,NUM200 Hunt 200
BNE HUNT204
WRITE 'CAF found user error, see DSNTRACE data set'
B ENDCCODE We are done. Go to end of CHEKCODE
* ********************* HUNT FOR 204 ***************************
HUNT204 DS 0H Hunt return code of 204
CLC RETCODE,NUM204 Hunt 204
BNE WASSAT If not 204, got strange code
WRITE 'CAF found system error, see DSNTRACE data set'
B ENDCCODE We are done. Go to end of CHEKCODE
* ********************* UNRECOGNIZED RETCODE *******************
WASSAT DS 0H
WRITE 'Got an unrecognized RETCODE'

Chapter 2. Connecting to DB2 from your application program 75

MVC CONTROL,SHUTDOWN Shutdown
BE ENDCCODE We are done. Go to end of CHEKCODE
ENDCCODE DS 0H Should we shut down?
L R4,RETCODE Get a copy of the RETCODE
C R4,FOUR Have a look at the RETCODE
BNH BYEBYE If RETCODE <= 4 then leave CHEKCODE
MVC CONTROL,SHUTDOWN Shutdown
BYEBYE DS 0H Wrap up and leave CHEKCODE
L R13,4(,R13) Point to caller's save area
RETURN (14,12) Return to the caller

Example of invoking CAF when you do not specify the precompiler option
ATTACH(CAF): Each of the four DB2 attachment facilities contains an entry point
named DSNHLI. When you use CAF but do not specify the precompiler option
ATTACH(CAF), SQL statements result in BALR instructions to DSNHLI in your
program. To find the correct DSNHLI entry point without including DSNALI in
your load module, code a subroutine with entry point DSNHLI that passes control
to entry point DSNHLI2 in the DSNALI module. DSNHLI2 is unique to DSNALI
and is at the same location in DSNALI as DSNHLI. DSNALI uses 31-bit
addressing. If the application that calls this intermediate subroutine uses 24-bit
addressing, this subroutine should account for the difference.

In the following example, LISQL is addressable because the calling CSECT used
the same register 12 as CSECT DSNHLI. Your application must also establish
addressability to LISQL.
***********************************************************************
* Subroutine DSNHLI intercepts calls to LI EP=DSNHLI
***********************************************************************
DS 0D
DSNHLI CSECT Begin CSECT
STM R14,R12,12(R13) Prologue
LA R15,SAVEHLI Get save area address
ST R13,4(,R15) Chain the save areas
ST R15,8(,R13) Chain the save areas
LR R13,R15 Put save area address in R13
L R15,LISQL Get the address of real DSNHLI
BASSM R14,R15 Branch to DSNALI to do an SQL call
* DSNALI is in 31-bit mode, so use
* BASSM to assure that the addressing
* mode is preserved.
L R13,4(,R13) Restore R13 (caller's save area addr)
L R14,12(,R13) Restore R14 (return address)
RETURN (1,12) Restore R1-12, NOT R0 and R15 (codes)

Example of variable declarations when using CAF: The following example code
shows declarations for some of the variables that were used in the previous
subroutines.
****************************** VARIABLES ******************************
SECB DS F DB2 Startup ECB
TECB DS F DB2 Termination ECB
LIALI DS F DSNALI Entry Point address
LISQL DS F DSNHLI2 Entry Point address
SSID DS CL4 DB2 Subsystem ID. CONNECT parameter
PLAN DS CL8 DB2 Plan name. OPEN parameter
TRMOP DS CL4 CLOSE termination option (SYNC|ABRT)
FUNCTN DS CL12 CAF function to be called
RIBPTR DS F DB2 puts Release Info Block addr here
RETCODE DS F Chekcode saves R15 here
REASCODE DS F Chekcode saves R0 here
CONTROL DS CL8 GO, SHUTDOWN, or RESTART
SAVEAREA DS 18F Save area for CHEKCODE
****************************** CONSTANTS ******************************
SHUTDOWN DC CL8'SHUTDOWN' CONTROL value: Shutdown execution

76 Application Programming and SQL Guide

RESTART DC CL8'RESTART ' CONTROL value: Restart execution
CONTINUE DC CL8'CONTINUE' CONTROL value: Everything OK, cont
CODE0 DC F'0' SQLCODE of 0
CODE100 DC F'100' SQLCODE of 100
QUIESCE DC XL3'000008' TECB postcode: STOP DB2 MODE=QUIESCE
CONNECT DC CL12'CONNECT ' Name of a CAF service. Must be CL12!
OPEN DC CL12'OPEN ' Name of a CAF service. Must be CL12!
CLOSE DC CL12'CLOSE ' Name of a CAF service. Must be CL12!
DISCON DC CL12'DISCONNECT ' Name of a CAF service. Must be CL12!
TRANSLAT DC CL12'TRANSLATE ' Name of a CAF service. Must be CL12!
SYNC DC CL4'SYNC' Termination option (COMMIT)
ABRT DC CL4'ABRT' Termination option (ROLLBACK)
****************************** RETURN CODES (R15) FROM CALL ATTACH ****
ZERO DC F'0' 0
FOUR DC F'4' 4
EIGHT DC F'8' 8
TWELVE DC F'12' 12 (Call Attach return code in R15)
NUM200 DC F'200' 200 (User error)
NUM204 DC F'204' 204 (Call Attach system error)
****************************** REASON CODES (R00) FROM CALL ATTACH ****
C10205 DC XL4'00C10205' Call attach could not TRANSLATE
C10831 DC XL4'00C10831' Call attach found a release mismatch
C10824 DC XL4'00C10824' Call attach ready for more input
F30002 DC XL4'00F30002' DB2 subsystem not up
F30011 DC XL4'00F30011' DB2 subsystem not up
F30012 DC XL4'00F30012' DB2 subsystem not up
F30025 DC XL4'00F30025' DB2 is stopping (REASCODE)
*
* Insert more codes here as necessary for your application
*
****************************** SQLCA and RIB **************************
EXEC SQL INCLUDE SQLCA
DSNDRIB Get the DB2 Release Information Block
****************************** CALL macro parm list *******************
CAFCALL CALL ,(*,*,*,*,*,*,*,*,*),VL,MF=L

Invoking the Resource Recovery Services attachment facility

The Resource Recovery Services attachment facility (RRSAF) enables your program
to communicate with DB2. Invoke RRSAF as an alternative to invoking CAF or
when using stored procedures that run in a WLM-established address space.
RRSAF has more capabilities than CAF.

Before you invoke RRSAF, perform the following actions:

v Ensure that the RRSAF language interface load module, DSNRLI, is available.
v Ensure that your application satisfies the requirements for programs that access
RRSAF.
v Ensure that your application satisfies the general environment characteristics for
connecting to DB2.
v Ensure that you are familiar with the following z/OS concepts and facilities:
– The CALL macro and standard module linkage conventions
– Program addressing and residency options (AMODE and RMODE)
– Creating and controlling tasks; multitasking
– Functional recovery facilities such as ESTAE, ESTAI, and FRRs
– Synchronization techniques such as WAIT/POST
– z/OS RRS functions, such as SRRCMIT and SRRBACK

Applications that use RRSAF can be written in assembler language, C, COBOL,

Fortran, and PL/I. When choosing a language to code your application in, consider
the following restrictions:

Chapter 2. Connecting to DB2 from your application program 77

v If you use z/OS macros (ATTACH, WAIT, POST, and so on), choose a
programming language that supports them.
v The RRSAF TRANSLATE function is not available in Fortran. To use this
function, code it in a routine that is written in another language, and then call
that routine from Fortran.

To invoke RRSAF:
1. Perform one of the following actions:
v Explicitly invoke RRSAF by including in your program CALL DSNRLI
statements with the appropriate options.
The first option is an RRSAF connection function, which describes the action
that you want RRSAF to take. The effect of any function depends in part on
what functions the program has already performed.
To code RRSAF functions in C, COBOL, Fortran, or PL/I, follow the
individual language’s rules for making calls to assembler language routines.
Specify the return code and reason code parameters in the parameter list for
each RRSAF call.

Requirement: For C, C++, and PL/I applications, you must also include in
your program the compiler directives that are listed in the following table,
because DSNRLI is an assembler language program.
Table 19. Compiler directives to include in C, C++, and PL/I applications that contain CALL
DSNRLI statements
Language Compiler directive to include
C #pragma linkage(dsnrli, OS)
C++ extern "OS" {
int DSNRLI(
char * functn,
...); }
PL/I DCL DSNRLI ENTRY OPTIONS(ASM,INTER,RETCODE);

v Implicitly invoke RRSAF by including SQL statements or IFI calls in your

program just as you would in any program. The RRSAF facility establishes
the connection to DB2 with the default values for the subsystem name, plan
name and authorization ID.

Restriction: If your program can make its first SQL call from different
modules with different DBRMs, you cannot use a default plan name and
thus, you cannot implicitly invoke RRSAF. Instead, you must explicitly
invoke RRSAF by calling the CREATE THREAD function.

Requirement: If your application includes both SQL and IFI calls, you must
issue at least one SQL call before you issue any IFI calls. This action ensures
that your application uses the correct plan.
2. If you implicitly invoked RRSAF, determine if the implicit connection was
successful by examining the return code and reason code immediately after the
first executable SQL statement within the application program. Your program
can check these codes by performing one of the following actions:
v Examine registers 0 and 15 directly.
v Examine the SQLCA, and if the SQLCODE is -981, obtain the return and
reason code from the message text. The return code is the first token, and the
reason code is the second token.

78 Application Programming and SQL Guide

If the implicit connection is successful, the application can examine the
SQLCODE for the first, and subsequent, SQL statements.

Example of an RRSAF configuration

The following figure shows an conceptual example of invoking and using RRSAF.

Figure 5. Sample RRSAF configuration

Resource Recovery Services attachment facility

An attachment facility enables programs to communicate with DB2. The Resource
Recovery Services attachment facility (RRSAF) provides such a connection for
programs that run in z/OS batch, TSO foreground, and TSO background. The
RRSAF is an alternative to CAF and has more functionality.

Chapter 2. Connecting to DB2 from your application program 79

An application program using RRSAF can perform the following actions:
v Use DB2 to process SQL statements, commands, or instrumentation facility
interface (IFI) calls.
v Coordinate DB2 updates with updates made by all other resource managers that
also use z/OS RRS in an z/OS system.
v Use the z/OS System Authorization Facility and an external security product,
such as RACF, to sign on to DB2 with the authorization ID of an end user.
v Sign on to DB2 using a new authorization ID and an existing connection and
plan.
v Access DB2 from multiple z/OS tasks in an address space.
v Switch a DB2 thread among z/OS tasks within a single address space.
v Access the DB2 IFI.
v Run with or without the TSO terminal monitor program (TMP).
v Run without being a subtask of the DSN command processor (or of any DB2
code).
v Run above or below the 16-MB line.
v Establish an explicit connection to DB2, through a call interface, with control
over the exact state of the connection.
v Establish an implicit connection to DB2 (with a default subsystem identifier and
a default plan name) by using SQL statements or IFI calls without first calling
RRSAF.
v Supply event control blocks (ECBs), for DB2 to post, that signal start-up or
termination.
v Intercept return codes, reason codes, and abend codes from DB2 and translate
them into messages as desired.

RRSAF uses z/OS Transaction Management and Recoverable Resource Manager

Services (z/OS RRS).

Any task in an address space can establish a connection to DB2 through RRSAF.
Each task control block (TCB) can have only one connection to DB2. A DB2 service
request that is issued by a program that runs under a given task is associated with
that task’s connection to DB2. The service request operates independently of any
DB2 activity under any other task.

Each connected task can run a plan. Tasks within a single address space can
specify the same plan, but each instance of a plan runs independently from the
others. A task can terminate its plan and run a different plan without completely
breaking its connection to DB2.

RRSAF does not generate task structures.

When you design your application, consider that using multiple simultaneous
connections can increase the possibility of deadlocks and DB2 resource contention.

Restriction: RRSAF does not provide attention processing exits or functional

recovery routines. You can provide whatever attention handling and functional
recovery your application needs, but you must use ESTAE/ESTAI type recovery
routines only.

80 Application Programming and SQL Guide

A tracing facility provides diagnostic messages that help you debug programs and
diagnose errors in the RRSAF code. The trace information is available only in a
SYSABEND or SYSUDUMP dump.

To commit work in RRSAF applications, use the CPIC SRRCMIT function or the
DB2 COMMIT statement. To roll back work, use the CPIC SRRBACK function or
the DB2 ROLLBACK statement.

Use the following guidelines to decide whether to use the DB2 statements or the
CPIC functions for commit and rollback operations:
v Use DB2 COMMIT and ROLLBACK statements when all of the following
conditions are true:
– The only recoverable resource that is accessed by your application is DB2 data
that is managed by a single DB2 instance.
DB2 COMMIT and ROLLBACK statements fail if your RRSAF application
accesses recoverable resources other than DB2 data that is managed by a
single DB2 instance.
– The address space from which syncpoint processing is initiated is the same as
the address space that is connected to DB2.
v If your application accesses other recoverable resources, or syncpoint processing
and DB2 access are initiated from different address spaces, use SRRCMIT and
SRRBACK.
Related reference
COMMIT (SQL Reference)
ROLLBACK (SQL Reference)
Related information
z/OS Internet Library at ibm.com

Properties of RRSAF connections

RRSAF enables programs to communicate with DB2 to process SQL statements,
commands, or IFI calls. An RRSAF connection joins any task in an address space to
DB2.

Restriction: Do not mix RRSAF connections with other connection types in a

single address space. The first connection that is made from an address space to
DB2 determines the type of connection allowed.

The connection that RRSAF makes with DB2 has the basic properties that are listed
in the following table.
Table 20. Properties of RRSAF connections
Property Value Comments
Connection name RRSAF You can use the DISPLAY
THREAD command to list
RRSAF applications that have
the connection name RRSAF.
Connection type RRSAF None.

Chapter 2. Connecting to DB2 from your application program 81

Table 20. Properties of RRSAF connections (continued)
Property Value Comments
Authorization ID Authorization IDs that are A connection must have a
associated with each DB2 primary ID and can have one
connection or more secondary IDs. Those
identifiers are used for the
following purposes:
v Validating access to DB2
v Checking privileges on
DB2 objects
v Assigning ownership of
DB2 objects
v Identifying the user of a
connection for audit,
performance, and
accounting traces.

RRSAF relies on the z/OS

System Authorization Facility
(SAF) and a security product,
such as RACF, to verify and
authorize the authorization
IDs. An application that
connects to DB2 through
RRSAF must pass those
identifiers to SAF for
verification and authorization
checking. RRSAF retrieves
the identifiers from SAF.

A location can provide an

authorization exit routine for
a DB2 connection to change
the authorization IDs and to
indicate whether the
connection is allowed. The
actual values that are
assigned to the primary and
secondary authorization IDs
can differ from the values
that are provided by a
SIGNON or AUTH SIGNON
request. A site’s DB2 signon
exit routine can access the
primary and secondary
authorization IDs and can
modify the IDs to satisfy the
site’s security requirements.
The exit routine can also
indicate whether the signon
request should be accepted.

82 Application Programming and SQL Guide

Table 20. Properties of RRSAF connections (continued)
Property Value Comments
Scope RRSAF processes connections None.
as if each task is entirely
isolated. When a task
requests a function, RRSAF
passes the function to DB2,
regardless of the connection
status of other tasks in the
address space. However, the
application program and the
DB2 subsystem have access
to the connection status of
multiple tasks in an address
space.

If an application that is connected to DB2 through RRSAF terminates normally

before the TERMINATE THREAD or TERMINATE IDENTIFY functions deallocate
the plan, RRS commits any changes made after the last commit point. If the
application terminates abnormally before the TERMINATE THREAD or
TERMINATE IDENTIFY functions deallocate the plan, z/OS RRS rolls back any
changes made after the last commit point. In either case, DB2 deallocates the plan,
if necessary, and terminates the application’s connection.

If DB2 abends while an application is running, DB2 rolls back changes to the last
commit point. If DB2 terminates while processing a commit request, DB2 either
commits or rolls back any changes at the next restart. The action taken depends on
the state of the commit request when DB2 terminates.

Making the RRSAF language interface (DSNRLI) available

Before you can invoke the Resource Recovery Services attachment facility (RRSAF),
you must first make available the RRSAF language interface load module,
DSNRLI.

Part of RRSAF is a DB2 load module, DSNRLI, which is also known as the RRSAF
language interface module. DSNRLI has the alias names DSNHLIR and DSNWLIR.
The module has five entry points: DSNRLI, DSNHLI, DSNHLIR, DSNWLI, and
DSNWLIR. These entry points serve the following functions:
v Entry point DSNRLI handles explicit DB2 connection service requests.
v DSNHLI and DSNHLIR handle SQL calls. Use DSNHLI if your application
program link-edits RRSAF. Use DSNHLIR if your application program loads
RRSAF.
v DSNWLI and DSNWLIR handle IFI calls. Use DSNWLI if your application
program link-edits RRSAF. Use DSNWLIR if your application program loads
RRSAF.

To make DSNRLI available:

1. Decide which of the following methods you want to use to make DSNRLI
available:
v Explicitly issuing LOAD requests when your program runs.

Chapter 2. Connecting to DB2 from your application program 83

By explicitly loading the DSNRLI module, you can isolate the maintenance of
your application from future IBM maintenance to the language interface. If
the language interface changes, the change will probably not affect your load
module.
v Including the DSNRLI module in your load module when you link-edit your
program.
A disadvantage of link-editing DSNRLI into your load module is that if IBM
makes a change to DSNRLI, you must link-edit your program again.
2. Depending on the method that you chose in step 1, perform one of the
following actions:
v If you want to explicitly issue LOAD requests when your program runs:
In your program, issue z/OS LOAD service requests for entry points
DSNRLI and DSNHLIR. If you use IFI services, you must also load
DSNWLIR. Save the entry point address that LOAD returns and use it in the
CALL macro.
Indicate to DB2 which entry point to use in one of the following two ways:
– Specify the precompiler option ATTACH(RRSAF).
This option causes DB2 to generate calls that specify entry point
DSNHLIR.

Restriction: You cannot use this option if your application is written in

Fortran.
– Code a dummy entry point named DSNHLI within your load module.
If you do not specify the precompiler option ATTACH, the DB2
precompiler generates calls to entry point DSNHLI for each SQL request.
The precompiler does not know about and is independent of the different
DB2 attachment facilities. When the calls that are generated by the DB2
precompiler pass control to DSNHLI, your code that corresponds to the
dummy entry point must preserve the option list that is passed in register
1 and call DSNHLIR with the same option list.
v If you want to include the DSNRLI module in your load module when
you link-edit your program:
Include DSNRLI in your load module during a link-edit step. For example,
you can use a linkage editor control statement that is similar to the following
statement in your JCL:
INCLUDE DB2LIB(DSNRLI).

By coding this statement, you avoid inadvertently picking up the wrong

language interface module.
When you include the DSNRLI module during the link-edit, do not include a
dummy DSNHLI entry point in your program or specify the precompiler
option ATTACH. Module DSNRLI contains an entry point for DSNHLI,
which is identical to DSNHLIR, and an entry point for DSNWLI, which is
identical to DSNWLIR.

84 Application Programming and SQL Guide

Related concepts
“Program examples for RRSAF” on page 121
Related tasks
“Making the CAF language interface (DSNALI) available” on page 52

Requirements for programs that use RRSAF

The Resource Recovery Services attachment facility (RRSAF) enables programs to
communicate with DB2. Before you invoke RRSAF in your program, ensure that
your program satisfies any requirements for using RRSAF.

When you write programs that use RRSAF, ensure that they meet the following
requirements:
v The program accounts for the size of the RRSAF code. The RRSAF code requires
about 10 KB of virtual storage per address space and an additional 10 KB for
each TCB that uses RRSAF.
v If your local environment intercepts and replaces the z/OS LOAD SVC that
RRSAF uses, you must ensure that your version of LOAD manages the load list
element (LLE) and contents directory entry (CDE) chains like the standard z/OS
LOAD macro. RRSAF uses z/OS SVC LOAD to load a module as part of the
initialization after your first service request. The module is loaded into
fetch-protected storage that has the job-step protection key.

You can prepare application programs to run in RRSAF similar to how you prepare
applications to run in other environments, such as CICS, IMS, and TSO. You can
prepare an RRSAF application either in the batch environment or by using the DB2
program preparation process. You can use the program preparation system either
through DB2I or through the DSNH CLIST.
Related tasks
Chapter 17, “Preparing an application to run on DB2 for z/OS,” on page 887

How RRSAF modifies the content of registers

If you do not specify the return code and reason code parameters in your RRSAF
function calls or you invoke RRSAF implicitly, RRSAF puts a return code in
register 15 and a reason code in register 0. RRSAF preserves the contents of
registers 2 through 14.

If you specify the return code and reason code parameters, RRSAF places the
return code in register 15 and in the return code parameter to accommodate
high-level languages that support special return code processing.

The following table summarizes the register conventions for RRSAF calls.
Table 21. Register conventions for RRSAF calls
Register Usage
R1 Parameter list pointer
R13 Address of caller’s save area
R14 Caller’s return address
R15 RRSAF entry point address

Chapter 2. Connecting to DB2 from your application program 85

Implicit connections to RRSAF
RRSAF establishes an implicit connection to DB2 if the RRSAF language interface
load module (DSNRLI) is available, you do not explicitly specify the IDENTIFY
function in a CALL DSNRLI statement in your program, and the application
includes SQL statements or IFI calls.

An implicit connection causes RRSAF to initiate implicit IDENTIFY and CREATE

THREAD requests to DB2. These requests are subject to the same DB2 return codes
and reason codes as explicitly specified requests.

Implicit connections use the following defaults:

Subsystem name
The default name that is specified in the module DSNHDECP. RRSAF uses
the installation default DSNHDECP, unless your own DSNHDECP module
is in a library in a STEPLIB statement of the JOBLIB concatenation or in
the link list. In a data sharing group, the default subsystem name is the
group attachment name.
Be certain that you know what the default name is and that it names the
specific DB2 subsystem that you want to use.
Plan name
The member name of the database request module (DBRM) that DB2
produced when you precompiled the source program that contains the first
SQL call.
Authorization ID
The 7-byte user ID that is associated with the address space, unless an
authorized function has built an Accessor Environment Element (ACEE)
for the address space. If an authorized function has built an ACEE, DB2
passes the 8-byte user ID from the ACEE.

For an implicit connection request, your application should not explicitly specify
either the IDENTIFY function or the CREATE THREAD function. Your application
can execute other explicit RRSAF calls after the implicit connection is made. An
implicit connection does not perform any SIGNON processing. Your application
can execute the SIGNON function at any point of consistency. To terminate an
implicit connection, you must use the proper function calls.

For implicit connection requests, register 15 contains the return code, and register 0
contains the reason code. The return code and reason code are also in the message
text for SQLCODE -981.
Related concepts
“Summary of RRSAF behavior” on page 87

CALL DSNRLI statement parameter list

The CALL DSNRLI statement explicitly invokes RRSAF. When you include CALL
DSNRLI statements in your program, you must specify all parameters that come
before the return code parameter.

In CALL DSNRLI statements, you cannot omit any of parameters that come before
the return code parameter by coding zeros or blanks. No defaults exist for those
parameters for explicit connection requests. Defaults are provided for only implicit
connections. All parameters starting with the return code parameter are optional.

86 Application Programming and SQL Guide

When you want to use the default value for a parameter but specify subsequent
parameters, code the CALL DSNRLI statement as follows:
| v For C-language, when you code CALL DSNRLI statements in C, you need to
| specify the address of every parameter, using the ″address of″ operator (&), and
| not the parameter itself. For example, to pass the pklistptr parameter on the
| ″CREATE THREAD″ specify the address of the 4-byte pointer to the structure
| (&pklistptr):
| fnret=dsnrli(&crthrdfn[0], &plan[0], &collid[0], &reuse[0],
| &retcode, &reascode, &pklistptr);
v For all languages except assembler language, code zero for that parameter in the
CALL DSNRLI statement. For example, suppose that you are coding an
IDENTIFY call in a COBOL program, and you want to specify all parameters
except the return code parameter. You can write a statement similar to the
following statement:
CALL 'DSNRLI' USING IDFYFN SSNM RIBPTR EIBPTR TERMECB STARTECB
BY CONTENT ZERO BY REFERENCE REASCODE.
v For assembler language, code a comma for that parameter in the CALL DSNRLI
statement. For example, suppose that you are coding an IDENTIFY call, and you
want to specify all parameters except the return code parameter. You can write a
statement similar to the following statement:
CALL DSNRLI,(IDFYFN,SSNM,RIBPTR,EIBPTR,TERMECB,STARTECB,,REASCODE)

For assembler programs that invoke RRSAF, use a standard parameter list for an
z/OS CALL. Register 1 must contain the address of a list of pointers to the
parameters. Each pointer is a 4-byte address. The last address must contain the
value 1 in the high-order bit.

Summary of RRSAF behavior

The effect of any RRSAF function depends in part on what functions the program
has already run. You should plan the RRSAF function calls that your program
makes to avoid any errors and major structural problems in your application.

The following tables summarize RRSAF behavior after various inputs from
application programs. The contents of each table cell indicate the result of calling
the function in the first column for that row followed by the function in the
current column heading. For example, if you issue TERMINATE THREAD and
then IDENTIFY, RRSAF returns reason code X’00C12201’. Use these tables to
understand the order in which your application must issue RRSAF calls, SQL
statements, and IFI requests.

| The RRSAF FIND_DB2_SYSTEMS function is omitted from these tables, because it

| does not affect the operation of any of the other functions

The following table summarizes RRSAF behavior when the next call is to the
IDENTIFY function, the SWITCH TO function, the SIGNON function, or the
CREATE THREAD function.
Table 22. Effect of call order when next call is IDENTIFY, SWITCH TO, SIGNON, or CREATE THREAD
Next function
SIGNON, AUTH SIGNON,
Previous function IDENTIFY SWITCH TO or CONTEXT SIGNON CREATE THREAD
Empty: first call IDENTIFY X’00C12205’1 X’00C12204’1 X’00C12204’1
IDENTIFY X’00F30049’1 Switch to ssnm Signon 2
X’00C12217’1

Chapter 2. Connecting to DB2 from your application program 87

Table 22. Effect of call order when next call is IDENTIFY, SWITCH TO, SIGNON, or CREATE THREAD (continued)
Next function
SIGNON, AUTH SIGNON,
Previous function IDENTIFY SWITCH TO or CONTEXT SIGNON CREATE THREAD
2
SWITCH TO IDENTIFY Switch to ssnm Signon CREATE THREAD
1 2
SIGNON, AUTH SIGNON, X’00F30049’ Switch to ssnm Signon CREATE THREAD
or CONTEXT SIGNON
CREATE THREAD X’00F30049’1 Switch to ssnm Signon 2
X’00C12202’1
TERMINATE THREAD X’00C12201’1 Switch to ssnm Signon 2
CREATE THREAD
1 2
IFI X’00F30049’ Switch to ssnm Signon X’00C12202’1
SQL X’00F30049’1 Switch to ssnm X’00F30092’13 X’00C12202’1
SRRCMIT or SRRBACK X’00F30049’1 Switch to ssnm Signon 2
X’00C12202’1
Notes:
1. Errors are identified by the DB2 reason code that RRSAF returns.
2. Signon means either the SIGNON function, the AUTH SIGNON function, or the CONTEXT SIGNON function.
3. The SIGNON, AUTH SIGNON, or CONTEXT SIGNON functions are not allowed if any SQL operations are
requested after the CREATE THREAD function or after the last SRRCMIT or SRRBACK request.

| The following table summarizes RRSAF behavior when the next call is an SQL
| statement or an IFI call or to the TERMINATE THREAD function, the TERMINATE
| IDENTIFY function, or the TRANSLATE function.
Table 23. Effect of call order when next call is SQL or IFI, TERMINATE THREAD, TERMINATE IDENTIFY, or
TRANSLATE
Next function
Previous function SQL or IFI TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE
4
Empty: first call SQL or IFI call X’00C12204’1 X’00C12204’1 X’00C12204’1
IDENTIFY SQL or IFI call4 X’00C12203’1 TERMINATE IDENTIFY TRANSLATE
4
SWITCH TO SQL or IFI call TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE
4
SIGNON, AUTH SIGNON, SQL or IFI call TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE
or CONTEXT SIGNON
CREATE THREAD SQL or IFI call4 TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE
4 1
TERMINATE THREAD SQL or IFI call X’00C12203’ TERMINATE IDENTIFY TRANSLATE
4
IFI SQL or IFI call TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE
4 12 13
SQL SQL or IFI call X’00F30093’ X’00F30093’ TRANSLATE
4
SRRCMIT or SRRBACK SQL or IFI call TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE

88 Application Programming and SQL Guide

Table 23. Effect of call order when next call is SQL or IFI, TERMINATE THREAD, TERMINATE IDENTIFY, or
TRANSLATE (continued)
Next function
Previous function SQL or IFI TERMINATE THREAD TERMINATE IDENTIFY TRANSLATE
Notes:
1. Errors are identified by the DB2 reason code that RRSAF returns.
2. TERMINATE THREAD is not allowed if any SQL operations are requested after the CREATE THREAD function
or after the last SRRCMIT or SRRBACK request.
3. TERMINATE IDENTIFY is not allowed if any SQL operations are requested after the CREATE THREAD function
or after the last SRRCMIT or SRRBACK request.
4. If you are using an implicit connection to RRSAF and issue SQL or IFI calls, RRSAF issues implicit IDENTIFY and
CREATE THREAD requests. If you continue with explicit RRSAF statements, you must follow the standard order
of explicit RRSAF calls. Implicitly connecting to RRSAF does not cause an implicit SIGNON request. Therefore,
you might need to issue an explicit SIGNON request to satisfy the standard order requirement. For example, an
SQL statement followed by an explicit TERMINATE THREAD request results in an error. You must issue an
explicit SIGNON request before issuing the TERMINATE THREAD request.

Related concepts
X’F3......’ codes (DB2 Codes)

RRSAF connection functions

An RRSAF connection function specifies the action that you want RRSAF to take.
You specify these functions when you invoke RRSAF through CALL DSNRLI
statements.
Related concepts
“CALL DSNRLI statement parameter list” on page 86
“Summary of RRSAF behavior” on page 87

IDENTIFY function for RRSAF

The RRSAF IDENTIFY function initializes a connection to DB2.

The IDENTIFY function establishes the caller’s task as a user of DB2 services. If no
other task in the address space currently is connected to the specified subsystem,
the IDENTIFY function also initializes the address space to communicate with the
DB2 address spaces. The IDENTIFY function establishes the cross-memory
authorization of the address space to DB2 and builds address space control blocks.

The following diagram shows the syntax for the IDENTIFY function.

DSNRLI IDENTIFY function

CALL DSNRLI ( function , ssnm , ribptr , eibptr , termecb ,

startecb

|
)

, retcode
, reascode
, groupoverride
, decpptr

Chapter 2. Connecting to DB2 from your application program 89

Parameters point to the following areas:
function
An 18-byte area that contains IDENTIFY followed by 10 blanks.
ssnm
A 4-byte DB2 subsystem name or group attachment name (if used in a data
sharing group) to which the connection is made. If ssnm is less than four
characters long, pad it on the right with blanks to a length of four characters.
ribptr
A 4-byte area in which RRSAF places the address of the release information
block (RIB) after the call. You can use the RIB to determine the release level of
the DB2 subsystem to which the application is connected. You can determine
the modification level within the release level by examining the RIBCNUMB
and RIBCINFO fields. If the value in the RIBCNUMB field is greater than zero,
check the RIBCINFO field for modification levels.
If the RIB is not available (for example, if ssnm names a subsystem that does
not exist), DB2 sets the 4-byte area to zeros.
The area to which ribptr points is below the 16-MB line.
This parameter is required. However, the application does not need to refer to
the returned information.
eibptr
A 4-byte area in which RRSAF places the address of the environment
information block (EIB) after the call. The EIB contains environment
information, such as the data sharing group, the name of the DB2 member to
which the IDENTIFY request was issued, and whether the subsystem is in
new-function mode. If the DB2 subsystem is not in a data sharing group,
RRSAF sets the data sharing group and member names to blanks. If the EIB is
not available (for example, if ssnm names a subsystem that does not exist),
RRSAF sets the 4-byte area to zeros.
The area to which eibptr points is above the 16-MB line.
This parameter is required. However, the application does not need to refer to
the returned information.
termecb
The address of the application’s event control block (ECB) that is used for DB2
termination. DB2 posts this ECB when the system operator enters the STOP
DB2 command or when DB2 is terminating abnormally. Specify a value of 0 if
you do not want to use a termination ECB.
RRSAF puts a POST code in the ECB to indicate the type of termination as
shown in the following table.
Table 24. Post codes for types of DB2 termination
POST code Termination type
8 QUIESCE
12 FORCE
16 ABTERM

startecb
The address of the application’s startup ECB. If DB2 has not started when the
application issues the IDENTIFY call, DB2 posts the ECB when DB2 has
started. Enter a value of zero if you do not want to use a startup ECB. DB2

90 Application Programming and SQL Guide

posts no more than one startup ECB per address space. The ECB that is posted
is associated with the most recent IDENTIFY call from that address space. The
application program must examine any nonzero RRSAF or DB2 reason codes
before issuing a WAIT request on this ECB.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places a reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode or its default. You can
specify a default for retcode by specifying a comma or zero, depending on the
language.
groupoverride
| An 8-byte area that the application provides. This parameter is optional. If you
| do not want group attach to be attempted, specify ’NOGROUP’. This string
| indicates that the subsystem name that is specified by ssnm is to be used as a
| DB2 subsystem name, even if ssnm matches a group attachment name. If
| groupoverride is not provided, ssnm is used as the group attachment name if it
| matches a group attachment name.
| If you specify this parameter in any language except assembler, you must also
| specify the retcode and reascode parameters. In assembler language, you can
| omit the retcode and reascode parameters by specifying commas as
| place-holders.

| Recommendation: Avoid using the groupoverride parameter when possible,

| because it limits the ability to do dynamic workload routing in a Parallel
| Sysplex. However, you should use this parameter in a data sharing
| environment when you want to connect to a specific member of a data sharing
| group, and the subsystem name of that member is the same as the group
| attachment name.
| decpptr
| A 4-byte area in which RRSAF is to put the address of the DSNHDECP control
| block that was loaded by subsystem ssnm when that subsystem was started.
| This 4-byte area is a 31-bit pointer. If ssnm is not found, the 4-byte area is set to
| 0.
| The area to which decpptr points is above the 16-MB line.
| If you specify this parameter in any language except assembler, you must also
| specify the retcode, reascode, and groupoverride parameters. In assembler
| language, you can omit the retcode, reascode, and groupoverride parameters by
| specifying commas as placeholders.

Example of RRSAF IDENTIFY function calls

The following table shows an IDENTIFY call in each language.

Chapter 2. Connecting to DB2 from your application program 91

Table 25. Examples of RRSAF IDENTIFY calls
Language Call example
Assembler CALL DSNRLI,(IDFYFN,SSNM,RIBPTR,EIBPTR,TERMECB,STARTECB, RETCODE,REASCODE,GRPOVER,DECPPTR)
1
C fnret=dsnrli(&idfyfn[0],&ssnm[0], &ribptr, &eibptr, &termecb, &startecb, &retcode,
&reascode,&grpover[0],&decpptr);
COBOL CALL 'DSNRLI' USING IDFYFN SSNM RIBTPR EIBPTR TERMECB STARTECB RETCODE REASCODE GRPOVER
DECPPTR.
Fortran CALL DSNRLI(IDFYFN,SSNM,RIBPTR,EIBPTR,TERMECB,STARTECB, RETCODE,REASCODE,GRPOVER,DECPPTR)
1
PL/I CALL DSNRLI(IDFYFN,SSNM,RIBPTR,EIBPTR,TERMECB,STARTECB, RETCODE,REASCODE,GRPOVER,DECPPTR);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.

Internal processing for the IDENTIFY function

| When you call the IDENTIFY function, DB2 performs the following steps:
| 1. DB2 determines whether the user address space is authorized to connect to
| DB2. DB2 invokes the z/OS SAF and passes a primary authorization ID to SAF.
| That authorization ID is the 7-byte user ID that is associated with the address
| space, unless an authorized function has built an ACEE for the address space.
| If an authorized function has built an ACEE, DB2 passes the 8-byte user ID
| from the ACEE. SAF calls an external security product, such as RACF, to
| determine if the task is authorized to use the following items:
| v The DB2 resource class (CLASS=DSNR)
| v The DB2 subsystem (SUBSYS=ssnm)
| v Connection type RRSAF
| 2. If that check is successful, DB2 calls the DB2 connection exit routine to perform
| additional verification and possibly change the authorization ID.
| 3. DB2 searches for a matching trusted context in the system cache and then the
| catalog based on the following criteria:
| v The primary authorization ID matches a trusted context SYSTEM AUTHID.
| v The job or started task name matches the JOBNAME attribute that is defined
| for the identified trusted context.
| If a trusted context is defined, DB2 checks if SECURITY LABEL is defined in
| the trusted context. If SECURITY LABEL is defined, DB2 verifies the SECURITY
| LABEL with RACF by using the RACROUTE VERIFY request. This security
| label is used to verify multi-level security for SYSTEM AUTHID.If a matching
| trusted context is defined, DB2 establishes the connection as trusted. Otherwise,
| the connection is established without any additional privileges.
| 4. DB2 then sets the connection name to RRSAF and the connection type to
| RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

SWITCH TO function for RRSAF

The RRSAF SWITCH TO function directs RRSAF, SQL, or IFI requests to a
specified DB2 subsystem. Use the SWITCH TO function to establish connections to
multiple DB2 subsystems from a single task.

92 Application Programming and SQL Guide

The SWITCH TO function is useful only after a successful IDENTIFY call. If you
have established a connection with one DB2 subsystem, you must issue a SWITCH
TO call before you make an IDENTIFY call to another DB2 subsystem. Otherwise,
DB2 returns return code X’200’ and reason code X’00C12201’.

The first time that you make a SWITCH TO call to a new DB2 subsystem, DB2
returns return code 4 and reason code X’00C12205’ as a warning to indicate that
the current task has not yet been identified to the new DB2 subsystem.

The following diagram shows the syntax for the SWITCH TO function.

DSNRLI SWITCH TO function

CALL DSNRLI ( function,ssnm

)

, retcode
, reascode
, groupoverride

Parameters point to the following areas:

function
An 18-byte area that contains SWITCH TO followed by nine blanks.
ssnm
A 4-byte DB2 subsystem name or group attachment name (if used in a data
sharing group) to which the connection is made. If ssnm is less than four
characters long, pad it on the right with blanks to a length of four characters.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify this parameter, you must also specify retcode.
groupoverride
| An 8-byte area that the application provides. This parameter is optional. If you
| do not want group attach to be attempted, specify ’NOGROUP’. This string
| indicates that the subsystem name that is specified by ssnm is to be used as a
| DB2 subsystem name, even if ssnm matches a group attachment name. If
| groupoverride is not provided, ssnm is used as the group attachment name if it
| matches a group attachment name.
| If you specify this parameter in any language except assembler, you must also
| specify the retcode and reascode parameters. In assembler language, you can
| omit the retcode and reascode parameters by specifying commas as
| place-holders.

Chapter 2. Connecting to DB2 from your application program 93

| Recommendation: Avoid using the groupoverride parameter when possible,
| because it limits the ability to do dynamic workload routing in a Parallel
| Sysplex. However, you should use this parameter in a data sharing
| environment when you want to connect to a specific member of a data sharing
| group, and the subsystem name of that member is the same as the group
| attachment name.

Examples

Examples of RRSAF SWITCH TO calls: The following table shows a SWITCH TO

call in each language.
Table 26. Examples of RRSAF SWITCH TO calls
Language Call example
Assembler CALL DSNRLI,(SWITCHFN,SSNM,RETCODE,REASCODE,GRPOVER)
1
C fnret=dsnrli(&switchfn[0], &ssnm[0], &retcode, &reascode,&grpover[0]);
COBOL CALL 'DSNRLI' USING SWITCHFN RETCODE REASCODE GRPOVER.
Fortran CALL DSNRLI(SWITCHFN,RETCODE,REASCODE,GRPOVER)
1
PL/I CALL DSNRLI(SWITCHFN,RETCODE,REASCODE,GRPOVER);

1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.

Example of using the SWITCH TO function to interact with multiple DB2

subsystems: The following example shows how you can use the SWITCH TO
function to interact with three DB2 subsystems.
| RRSAF calls for subsystem db21:
| IDENTIFY
| SIGNON
| CREATE THREAD
| Execute SQL on subsystem db21
| SWITCH TO db22
| IF retcode = 4 AND reascode = '00C12205'X THEN
| DO;
| RRSAF calls on subsystem db22:
| IDENTIFY
| SIGNON
| CREATE THREAD
| END;
| Execute SQL on subsystem db22
| SWITCH TO db23
| IF retcode = 4 AND reascode = '00C12205'X THEN
| DO;
| RRSAF calls on subsystem db23:
| IDENTIFY
| SIGNON
| CREATE THREAD
| END;
| Execute SQL on subsystem 23
| SWITCH TO db21
| Execute SQL on subsystem 21
| SWITCH TO db22
| Execute SQL on subsystem 22
| SWITCH TO db21
| Execute SQL on subsystem 21
| SRRCMIT (to commit the UR)
| SWITCH TO db23
| Execute SQL on subsystem 23

94 Application Programming and SQL Guide

| SWITCH TO db22
| Execute SQL on subsystem 22
| SWITCH TO db21
| Execute SQL on subsystem 21
| SRRCMIT (to commit the UR)
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

SIGNON function for RRSAF

The RRSAF SIGNON function establishes a primary authorization ID and,
optionally, one or more secondary authorization IDs for a connection.

Requirement: Your program does not need to be an authorized program to issue

the SIGNON call. For that reason, before you issue the SIGNON call, you must
issue the RACF external security interface macro RACROUTE REQUEST=VERIFY
to perform the following actions:
v Define and populate an ACEE to identify the user of the program.
v Associate the ACEE with the user’s TCB.
v Verify that the user is defined to RACF and authorized to use the application.

Generally, you issue a SIGNON call after an IDENTIFY call and before a CREATE
THREAD call. You can also issue a SIGNON call if the application is at a point of
consistency, and one of the following conditions is true:
v The value of reuse in the CREATE THREAD call was RESET.
v The value of reuse in the CREATE THREAD call was INITIAL, no held cursors
are open, the package or plan is bound with KEEPDYNAMIC(NO), and all
special registers are at their initial state. If open held cursors exist or the package
or plan is bound with KEEPDYNAMIC(YES), you can issue a SIGNON call only
if the primary authorization ID has not changed.

| After you issue a SIGNON call, subsequent SQL statements return an error
| (SQLCODE -900) if the both of following conditions are true:
| v The connection was established as trusted when it was initialized.
| v The primary authorization ID that was used when you issued the SIGNON call
| is not allowed to use the trusted connection.

| If a trusted context is defined, DB2 checks if SECURITY LABEL is defined in the

| trusted context. If SECURITY LABEL is defined, DB2 verifies the security label
| with RACF by using the RACROUTE VERIFY request. This security label is used
| to verify multi-level security for SYSTEM AUTHID.

The following diagram shows the syntax for the SIGNON function.

Chapter 2. Connecting to DB2 from your application program 95

DSNRLI SIGNON function

CALL DSNRLI ( function, correlation-id, accounting-token, accounting-interval

)

,retcode
,reascode
,user
,appl
,ws
,xid
,accounting-string

Parameters point to the following areas:

function
An 18-byte area that contains SIGNON followed by twelve blanks.
correlation-id
A 12-byte area in which you can put a DB2 correlation ID. The correlation ID is
displayed in DB2 accounting and statistics trace records. You can use the
correlation ID to correlate work units. This token appears in the output from
the DISPLAY THREAD command. If you do not want to specify a correlation
ID, fill the 12-byte area with blanks.
accounting-token
A 22-byte area in which you can put a value for a DB2 accounting token. This
value is displayed in DB2 accounting and statistics trace records in the
QWHCTOKEN field, which is mapped by DSNDQWHC DSECT. Setting the
value of the accounting token sets the value of the CURRENT
CLIENT_ACCTNG special register. If accounting-token is less than 22 characters
long, you must pad it on the right with blanks to a length of 22 characters. If
you do not want to specify an accounting token, fill the 22-byte area with
blanks.
Alternatively, you change the value of the DB2 accounting token with RRSAF
functions AUTH SIGNON, CONTEXT SIGNON or SET_CLIENT_ID. You can
retrieve the DB2 accounting token with the CURRENT CLIENT_ACCTNG
special register only if the DDF accounting string is not set.
accounting-interval
A 6-byte area that specifies when DB2 writes an accounting record.
| If you specify COMMIT in that area, DB2 writes an accounting record each
| time that the application issues SRRCMIT without open held cursors. If the
| accounting interval is COMMIT and an SRRCMIT is issued while a held cursor
| is open, the accounting interval spans that commit and ends at the next valid
| accounting interval end point (such as the next SRRCMIT that is issued
| without open held cursors, application termination, or SIGNON with a new
| authorization ID).
If you specify any other value, DB2 writes an accounting record when the
application terminates or when you call the SIGNON function with a new
authorization ID.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.

96 Application Programming and SQL Guide

reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify this parameter, you must also specify retcode.
user
A 16-byte area that contains the user ID of the client end user. You can use this
parameter to provide the identity of the client end user for accounting and
monitoring purposes. DB2 displays this user ID in the output from the
DISPLAY THREAD command and in DB2 accounting and statistics trace
records. Setting the user ID sets the value of the CURRENT CLIENT_USERID
special register. If user is less than 16 characters long, you must pad it on the
right with blanks to a length of 16 characters.
This parameter is optional. If you specify user, you must also specify retcode
and reascode. If you do not specify user, no user ID is associated with the
connection.
appl
A 32-byte area that contains the application or transaction name of the end
user’s application. You can use this parameter to provide the identity of the
client end user for accounting and monitoring purposes. DB2 displays the
application name in the output from the DISPLAY THREAD command and in
DB2 accounting and statistics trace records. Setting the application name sets
the value of the CURRENT CLIENT_APPLNAME special register. If appl is less
than 32 characters long, you must pad it on the right with blanks to a length of
32 characters.
This parameter is optional. If you specify appl, you must also specify retcode,
reascode, and user. If you do not specify appl, no application or transaction is
associated with the connection.
ws An 18-byte area that contains the workstation name of the client end user. You
can use this parameter to provide the identity of the client end user for
accounting and monitoring purposes. DB2 displays the workstation name in
the output from the DISPLAY THREAD command and in DB2 accounting and
statistics trace records. Setting the workstation name sets the value of the
CURRENT CLIENT_WRKSTNNAME special register. If ws is less than 18
characters long, you must pad it on the right with blanks to a length of 18
characters.
This field is optional. If you specify ws, you must also specify retcode, reascode,
user, and appl. If you do not specify ws, no workstation name is associated with
the connection.
xid
A 4-byte area that indicates whether the thread is part of a global transaction.
A DB2 thread that is part of a global transaction can share locks with other
DB2 threads that are part of the same global transaction and can access and
modify the same data. A global transaction exists until one of the threads that
is part of the global transaction is committed or rolled back.
You can specify one of the following values for xid:
0 Indicates that the thread is not part of a global transaction. The value 0
must be specified as a binary integer.
1 Indicates that the thread is part of a global transaction and that DB2
should retrieve the global transaction ID from RRS. If a global

Chapter 2. Connecting to DB2 from your application program 97

transaction ID already exists for the task, the thread becomes part of
the associated global transaction. Otherwise, RRS generates a new
global transaction ID. The value 1 must be specified as a binary
integer. Alternatively, if you want DB2 to return the generated global
transaction ID to the caller, specify an address instead of 1.
address The 4-byte address of an area in which you enter a global transaction
ID for the thread. If the global transaction ID already exists, the thread
becomes part of the associated global transaction. Otherwise, RRS
creates a new global transaction with the ID that you specify.
Alternatively, if you want DB2 to generate and return a global
transaction ID, pass the address of a null global transaction ID by
setting the format ID field of the global transaction ID to binary -1
(’FFFFFFF’X). DB2 then replaces the contents of the area with the
generated transaction ID. The area at the specified address must be in
writable storage and have a length of at least 140 bytes to
accommodate the largest possible transaction ID value.
The following table shows the format of a global transaction ID.
Table 27. Format of a user-created global transaction ID
Field description Length in bytes Data type
Format ID 4 Integer
Global transaction ID length 4 Integer
(1 - 64)
Branch qualifier length (1 - 4 Integer
64)
Global transaction ID 1 to 64 Character
Branch qualifier 1 to 64 Character

accounting-string
A one-byte length field and a 255-byte area in which you can put a value for a
DB2 accounting string. This value is placed in the DDF accounting trace
records in the QMDASQLI field, which is mapped by DSNDQMDA DSECT. If
accounting-string is less than 255 characters, you must pad it on the right with
zeros to a length of 255 bytes. The entire 256 bytes is mapped by DSNDQMDA
DSECT.
This parameter is optional. If you specify accounting-string, you must also
specify retcode, reascode, user, appl and xid. If you do not specify
accounting-string, no accounting string is associated with the connection.
You can also change the value of the accounting string with RRSAF functions
AUTH SIGNON, CONTEXT SIGNON, or SET_CLIENT_ID.
You can retrieve the DDF suffix portion of the accounting string with the
CURRENT CLIENT_ACCTNG special register. The suffix portion of
accounting-string can contain a maximum of 200 characters. The QMDASFLN
field contains the accounting suffix length, and the QMDASUFX field contains
the accounting suffix value. If the DDF accounting string is set, you cannot
query the accounting token with the CURRENT CLIENT_ACCTNG special
register.

Example of RRSAF SIGNON calls

The following table shows a SIGNON call in each language.

98 Application Programming and SQL Guide

Table 28. Examples of RRSAF SIGNON calls
Language Call example
assembler CALL DSNRLI,(SGNONFN,CORRID,ACCTTKN,ACCTINT, RETCODE,REASCODE,USERID,APPLNAME,WSNAME,XIDPTR)
1
C fnret=dsnrli(&sgnonfn[0], &corrid[0], &accttkn[0], &acctint[0], &retcode, &reascode,
&userid[0], &applname[0], &wsname[0], &xidptr);
COBOL CALL 'DSNRLI' USING SGNONFN CORRID ACCTTKN ACCTINT RETCODE REASCODE USERID APPLNAME WSNAME
XIDPTR.
Fortran CALL DSNRLI(SGNONFN,CORRID,ACCTTKN,ACCTINT, RETCODE,REASCODE,USERID,APPLNAME,WSNAME,XIDPTR)
1
PL/I CALL DSNRLI(SGNONFN,CORRID,ACCTTKN,ACCTINT, RETCODE,REASCODE,USERID,APPLNAME,WSNAME,XIDPTR);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77
Related information
z/OS Internet Library at ibm.com

AUTH SIGNON function for RRSAF

The RRSAF AUTH SIGNON function enables an APF-authorized program to pass
to DB2 either a primary authorization ID and, optionally, one or more secondary
authorization IDs, or an ACEE that is used for authorization checking. These IDs
are then associated with the connection.

Generally, you issue an AUTH SIGNON call after an IDENTIFY call and before a
CREATE THREAD call. You can also issue an AUTH SIGNON call if the
application is at a point of consistency, and one of the following conditions is true:
v The value of reuse in the CREATE THREAD call was RESET.
v The value of reuse in the CREATE THREAD call was INITIAL, no held cursors
are open, the package or plan is bound with KEEPDYNAMIC(NO), and all
special registers are at their initial state. If open held cursors exist or the package
or plan is bound with KEEPDYNAMIC(YES), a SIGNON call is permitted only if
the primary authorization ID has not changed.

The following diagram shows the syntax for the AUTH SIGNON function.

DSNRLI AUTH SIGNON function

CALL DSNRLI ( function, correlation-id, accounting-token,

accounting-interval, primary-authid, ACEE-address, secondary-authid

)

,retcode
,reascode
,user
,appl
,ws
,xid
,accounting-string

Chapter 2. Connecting to DB2 from your application program 99

Parameters point to the following areas:
function
An 18-byte area that contains AUTH SIGNON followed by seven blanks.
correlation-id
A 12-byte area in which you can put a DB2 correlation ID. The correlation ID is
displayed in DB2 accounting and statistics trace records. You can use the
correlation ID to correlate work units. This token appears in output from the
DISPLAY THREAD command. If you do not want to specify a correlation ID,
fill the 12-byte area with blanks.
accounting-token
A 22-byte area in which you can put a value for a DB2 accounting token. This
value is displayed in DB2 accounting and statistics trace records in the
QWHCTOKEN field, which is mapped by DSNDQWHC DSECT. Setting the
value of the accounting token sets the value of the CURRENT
CLIENT_ACCTNG special register. If accounting-token is less than 22 characters
long, you must pad it on the right with blanks to a length of 22 characters. If
you do not want to specify an accounting token, fill the 22-byte area with
blanks.
You can also change the value of the DB2 accounting token with RRSAF
functions SIGNON, CONTEXT SIGNON or SET_CLIENT_ID. You can retrieve
the DB2 accounting token with the CURRENT CLIENT_ACCTNG special
register only if the DDF accounting string is not set.
accounting-interval
A 6-byte area with that specifies when DB2 writes an accounting record.
| If you specify COMMIT in that area, DB2 writes an accounting record each
| time that the application issues SRRCMIT without open held cursors. If the
| accounting interval is COMMIT and an SRRCMIT is issued while a held cursor
| is open, the accounting interval spans that commit and ends at the next valid
| accounting interval end point (such as the next SRRCMIT that is issued
| without open held cursors, application termination, or SIGNON with a new
| authorization ID).
If you specify any other value, DB2 writes an accounting record when the
application terminates or when you call the SIGNON function with a new
authorization ID.
primary-authid
An 8-byte area in which you can put a primary authorization ID. If you are not
passing the authorization ID to DB2 explicitly, put X’00’ or a blank in the first
byte of the area.
ACEE-address
The 4-byte address of an ACEE that you pass to DB2. If you do not want to
provide an ACEE, specify 0 in this field.
secondary-authid
An 8-byte area in which you can put a secondary authorization ID. If you do
not pass the authorization ID to DB2 explicitly, put X’00’ or a blank in the first
byte of the area. If you enter a secondary authorization ID, you must also enter
a primary authorization ID.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.

100 Application Programming and SQL Guide

reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascoder, you must also specify retcode.
user
A 16-byte area that contains the user ID of the client end user. You can use this
parameter to provide the identity of the client end user for accounting and
monitoring purposes. DB2 displays this user ID in the output from the
DISPLAY THREAD command and in DB2 accounting and statistics trace
records. Setting the user ID sets the value of the CURRENT CLIENT_USERID
special register. If user is less than 16 characters long, you must pad it on the
right with blanks to a length of 16 characters.
This parameter is optional. If you specify user, you must also specify retcode
and reascode. If you do not specify this parameter, no user ID is associated with
the connection.
appl
A 32-byte area that contains the application or transaction name of the end
user’s application. You can use this parameter to provide the identity of the
client end user for accounting and monitoring purposes. DB2 displays the
application name in the output from the DISPLAY THREAD command and in
DB2 accounting and statistics trace records. Setting the application name sets
the value of the CURRENT CLIENT_APPLNAME special register. If appl is less
than 32 characters long, you must pad it on the right with blanks to a length of
32 characters.
This parameter is optional. If you specify appl, you must also specify retcode,
reascode, and user. If you do not specify this parameter, no application or
transaction is associated with the connection.
ws An 18-byte area that contains the workstation name of the client end user. You
can use this parameter to provide the identity of the client end user for
accounting and monitoring purposes. DB2 displays the workstation name in
the output from the DISPLAY THREAD command and in DB2 accounting and
statistics trace records. Setting the workstation name sets the value of the
CURRENT CLIENT_WRKSTNNAME special register. If ws is less than 18
characters long, you must pad it on the right with blanks to a length of 18
characters.
This parameter is optional. If you specify ws, you must also specify retcode,
reascode, user, and appl. If you do not specify this parameter, no workstation
name is associated with the connection.
You can also change the value of the workstation name with RRSAF functions
SIGNON, CONTEXT SIGNON or SET_CLIENT_ID. You can retrieve the
workstation name with the CURRENT CLIENT_WRKSTNNAME special
register.
xid
A 4-byte area that indicates whether the thread is part of a global transaction.
A DB2 thread that is part of a global transaction can share locks with other
DB2 threads that are part of the same global transaction and can access and
modify the same data. A global transaction exists until one of the threads that
is part of the global transaction is committed or rolled back.
You can specify one of the following values for xid:

Chapter 2. Connecting to DB2 from your application program 101

0 Indicates that the thread is not part of a global transaction. The value 0
must be specified as a binary integer.
1 Indicates that the thread is part of a global transaction and that DB2
should retrieve the global transaction ID from RRS. If a global
transaction ID already exists for the task, the thread becomes part of
the associated global transaction. Otherwise, RRS generates a new
global transaction ID. The value 1 must be specified as a binary
integer. Alternatively, if you want DB2 to return the generated global
transaction ID to the caller, specify an address instead of 1.
address The 4-byte address of an area into which you enter a global transaction
ID for the thread. If the global transaction ID already exists, the thread
becomes part of the associated global transaction. Otherwise, RRS
creates a new global transaction with the ID that you specify.
Alternatively, if you want DB2 to generate and return a global
transaction ID, pass the address of a null global transaction ID by
setting the format ID field of the global transaction ID to binary -1
(’FFFFFFF’X). DB2 then replaces the contents of the area with the
generated transaction ID. The area at the specified address must be in
writable storage and have a length of at least 140 bytes to
accommodate the largest possible transaction ID value.
The format of a global transaction ID is shown in the description of the
RRSAF SIGNON function.
accounting-string
A one-byte length field and a 255-byte area in which you can put a value for a
DB2 accounting string. This value is placed in the DDF accounting trace
records in the QMDASQLI field, which is mapped by DSNDQMDA DSECT. If
accounting-string is less than 255 characters, you must pad it on the right with
zeros to a length of 255 bytes. The entire 256 bytes is mapped by DSNDQMDA
DSECT.
This parameter is optional. If you specify this accounting-string, you must also
specify retcode, reascode, user, appl and xid. If you do not specify this parameter,
no accounting string is associated with the connection.
You can also change the value of the accounting string with RRSAF functions
AUTH SIGNON, CONTEXT SIGNON, or SET_CLIENT_ID.
You can retrieve the DDF suffix portion of the accounting string with the
CURRENT CLIENT_ACCTNG special register. The suffix portion of
accounting-string can contain a maximum of 200 characters. The QMDASFLN
field contains the accounting suffix length, and the QMDASUFX field contains
the accounting suffix value. If the DDF accounting string is set, you cannot
query the accounting token with the CURRENT CLIENT_ACCTNG special
register.

Example of RRSAF AUTH SIGNON calls

The following table shows a AUTH SIGNON call in each language.

Table 29. Examples of RRSAF AUTH SIGNON calls
Language Call example
Assembler CALL DSNRLI,(ASGNONFN,CORRID,ACCTTKN,ACCTINT,PAUTHID,ACEEPTR, SAUTHID,RETCODE,REASCODE,
USERID,APPLNAME,WSNAME,XIDPTR)

102 Application Programming and SQL Guide

Table 29. Examples of RRSAF AUTH SIGNON calls (continued)
Language Call example
1
C fnret=dsnrli(&asgnonfn[0], &corrid[0], &accttkn[0], &acctint[0], &pauthid[0], &aceeptr,
&sauthid[0], &retcode, &reascode, &userid[0], &applname[0], &wsname[0], &xidptr);
COBOL CALL 'DSNRLI' USING ASGNONFN CORRID ACCTTKN ACCTINT PAUTHID ACEEPTR SAUTHID RETCODE REASCODE
USERID APPLNAME WSNAME XIDPTR.
Fortran CALL DSNRLI(ASGNONFN,CORRID,ACCTTKN,ACCTINT,PAUTHID,ACEEPTR, SAUTHID,RETCODE,REASCODE,USERID,
APPLNAME,WSNAME,XIDPTR)
PL/I1 CALL DSNRLI(ASGNONFN,CORRID,ACCTTKN,ACCTINT,PAUTHID,ACEEPTR, SAUTHID,RETCODE,REASCODE,USERID,
APPLNAME,WSNAME,XIDPTR);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77
Related reference
“SIGNON function for RRSAF” on page 95

CONTEXT SIGNON function for RRSAF

The RRSAF CONTEXT SIGNON function establishes a primary authorization ID
and one or more secondary authorization IDs for a connection.

Requirement: Before you invoke CONTEXT SIGNON, you must have called the
RRS context services function Set Context Data (CTXSDTA) to store a primary
authorization ID and optionally, the address of an ACEE in the context data whose
context key you supply as input to CONTEXT SIGNON.

The CONTEXT SIGNON function uses the context key to retrieve the primary
authorization ID from data that is associated with the current RRS context. DB2
uses the RRS context services function Retrieve Context Data (CTXRDTA) to
retrieve context data that contains the authorization ID and ACEE address. The
context data must have the following format:
Version number
A 4-byte area that contains the version number of the context data. Set this
area to 1.
Server product name
An 8-byte area that contains the name of the server product that set the
context data.
ALET A 4-byte area that can contain an ALET value. DB2 does not reference this
area.
ACEE address
A 4-byte area that contains an ACEE address or 0 if an ACEE is not
provided. DB2 requires that the ACEE is in the home address space of the
task.
If you pass an ACEE address, the CONTEXT SIGNON function uses the
value in ACEEGRPN as the secondary authorization ID if the length of the
group name (ACEEGRPL) is not 0.

Chapter 2. Connecting to DB2 from your application program 103

primary-authid
An 8-byte area that contains the primary authorization ID to be used. If the
authorization ID is less than 8 bytes in length, pad it on the right with
blank characters to a length of 8 bytes.
If the new primary authorization ID is not different than the current
primary authorization ID (which was established when the IDENTIFY
function was invoked or at a previous SIGNON invocation), DB2 invokes
only the signon exit. If the value has changed, DB2 establishes a new
primary authorization ID and new SQL authorization ID and then invokes
the signon exit.

Generally, you issue a CONTEXT SIGNON call after an IDENTIFY call and before
a CREATE THREAD call. You can also issue a CONTEXT SIGNON call if the
application is at a point of consistency, and one of the following conditions is true:
v The value of reuse in the CREATE THREAD call was RESET.
v The value of reuse in the CREATE THREAD call was INITIAL, no held cursors
are open, the package or plan is bound with KEEPDYNAMIC(NO), and all
special registers are at their initial state. If open held cursors exist or the package
or plan is bound with KEEPDYNAMIC(YES), a SIGNON call is permitted only if
the primary authorization ID has not changed.

The following diagram shows the syntax for the CONTEXT SIGNON function.

DSNRLI CONTEXT SIGNON function

CALL DSNRLI ( function, correlation-id, accounting-token, accounting-interval, context-key

)

,retcode
,reascode
,user
,appl
,ws
,xid
,accounting-string

Parameters point to the following areas:

function
An 18-byte area that contains CONTEXT SIGNON followed by four blanks.
correlation-id
A 12-byte area in which you can put a DB2 correlation ID. The correlation ID is
displayed in DB2 accounting and statistics trace records. You can use the
correlation ID to correlate work units. This token appears in output from the
DISPLAY THREAD command. If you do not want to specify a correlation ID,
fill the 12-byte area with blanks.
accounting-token
A 22-byte area in which you can put a value for a DB2 accounting token. This
value is displayed in DB2 accounting and statistics trace records in the
QWHCTOKEN field, which is mapped by DSNDQWHC DSECT. Setting the
value of the accounting token sets the value of the CURRENT
CLIENT_ACCTNG special register. If accounting-token is less than 22 characters

104 Application Programming and SQL Guide

long, you must pad it on the right with blanks to a length of 22 characters. If
you do not want to specify an accounting token, fill the 22-byte area with
blanks.
You can also change the value of the DB2 accounting token with RRSAF
functions SIGNON, AUTH SIGNON, or SET_CLIENT_ID. You can retrieve the
DB2 accounting token with the CURRENT CLIENT_ACCTNG special register
only if the DDF accounting string is not set.
accounting-interval
A 6-byte area that specifies when DB2 writes an accounting record.
| If you specify COMMIT in that area, DB2 writes an accounting record each
| time that the application issues SRRCMIT without open held cursors. If the
| accounting interval is COMMIT and an SRRCMIT is issued while a held cursor
| is open, the accounting interval spans that commit and ends at the next valid
| accounting interval end point (such as the next SRRCMIT that is issued
| without open held cursors, application termination, or SIGNON with a new
| authorization ID).
If you specify any other value, DB2 writes an accounting record when the
application terminates or when you call the SIGNON function with a new
authorization ID.
context-key
A 32-byte area in which you put the context key that you specified when you
called the RRS Set Context Data (CTXSDTA) service to save the primary
authorization ID and an optional ACEE address.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.
user
A 16-byte area that contains the user ID of the client end user. You can use this
parameter to provide the identity of the client end user for accounting and
monitoring purposes. DB2 displays this user ID in the output from the
DISPLAY THREAD command and in DB2 accounting and statistics trace
records. Setting the user ID sets the value of the CURRENT CLIENT_USERID
special register. If user is less than 16 characters long, you must pad it on the
right with blanks to a length of 16 characters.
This parameter is optional. If you specify user, you must also specify retcode
and reascode. If you do not specify user, no user ID is associated with the
connection.
appl
A 32-byte area that contains the application or transaction name of the end
user’s application. You can use this parameter to provide the identity of the
client end user for accounting and monitoring purposes. DB2 displays the
application name in the output from the DISPLAY THREAD command and in
DB2 accounting and statistics trace records. Setting the application name sets

Chapter 2. Connecting to DB2 from your application program 105

the value of the CURRENT CLIENT_APPLNAME special register. If appl is less
than 32 characters long, you must pad it on the right with blanks to a length of
32 characters.
This parameter is optional. If you specify appl, you must also specify retcode,
reascode, and user. If you do not specify appl, no application or transaction is
associated with the connection.
ws An 18-byte area that contains the workstation name of the client end user. You
can use this parameter to provide the identity of the client end user for
accounting and monitoring purposes. DB2 displays the workstation name in
the output from the DISPLAY THREAD command and in DB2 accounting and
statistics trace records. Setting the workstation name sets the value of the
CURRENT CLIENT_WRKSTNNAME special register. If ws is less than 18
characters long, you must pad it on the right with blanks to a length of 18
characters.
This parameter is optional. If you specify ws, you must also specify retcode,
reascode, user, and appl. If you do not specify ws, no workstation name is
associated with the connection.
You can also change the value of the workstation name with the RRSAF
functions SIGNON, AUTH SIGNON, or SET_CLIENT_ID. You can retrieve the
workstation name with the CLIENT_WRKSTNNAME special register.
xid
A 4-byte area that indicates whether the thread is part of a global transaction.
A DB2 thread that is part of a global transaction can share locks with other
DB2 threads that are part of the same global transaction and can access and
modify the same data. A global transaction exists until one of the threads that
is part of the global transaction is committed or rolled back.
You can specify one of the following values for xid:
0 Indicates that the thread is not part of a global transaction. The value 0
must be specified as a binary integer.
1 Indicates that the thread is part of a global transaction and that DB2
should retrieve the global transaction ID from RRS. If a global
transaction ID already exists for the task, the thread becomes part of
the associated global transaction. Otherwise, RRS generates a new
global transaction ID. The value 1 must be specified as a binary
integer. Alternatively, if you want DB2 to return the generated global
transaction ID to the caller, specify an address instead of 1.
address The 4-byte address of an area into which you enter a global transaction
ID for the thread. If the global transaction ID already exists, the thread
becomes part of the associated global transaction. Otherwise, RRS
creates a new global transaction with the ID that you specify.
Alternatively, if you want DB2 to generate and return a global
transaction ID, pass the address of a null global transaction ID by
setting the format ID field of the global transaction ID to binary -1
(’FFFFFFF’X). DB2 then replaces the contents of the area with the
generated transaction ID. The area at the specified address must be in
writable storage and have a length of at least 140 bytes to
accommodate the largest possible transaction ID value.
The format of a global transaction ID is shown in the description of the
RRSAF SIGNON function.

106 Application Programming and SQL Guide

accounting-string
A one-byte length field and a 255-byte area in which you can put a value for a
DB2 accounting string. This value is placed in the DDF accounting trace
records in the QMDASQLI field, which is mapped by DSNDQMDA DSECT. If
accounting-string is less than 255 characters, you must pad it on the right with
zeros to a length of 255 bytes. The entire 256 bytes is mapped by DSNDQMDA
DSECT.
This parameter is optional. If you specify this accounting-string, you must also
specify retcode, reascode, user, appl and xid. If you do not specify this parameter,
no accounting string is associated with the connection.
You can also change the value of the accounting string with RRSAF functions
AUTH SIGNON, CONTEXT SIGNON, or SET_CLIENT_ID.
You can retrieve the DDF suffix portion of the accounting string with the
CURRENT CLIENT_ACCTNG special register. The suffix portion of
accounting-string can contain a maximum of 200 characters. The QMDASFLN
field contains the accounting suffix length, and the QMDASUFX field contains
the accounting suffix value. If the DDF accounting string is set, you cannot
query the accounting token with the CURRENT CLIENT_ACCTNG special
register.

Example of RRSAF CONTEXT SIGNON calls

The following table shows a CONTEXT SIGNON call in each language.

Table 30. Examples of RRSAF CONTEXT SIGNON calls
Language Call example
Assembler CALL DSNRLI,(CSGNONFN,CORRID,ACCTTKN,ACCTINT,CTXTKEY, RETCODE,REASCODE,USERID,APPLNAME,
WSNAME,XIDPTR)
C1 fnret=dsnrli(&csgnonfn[0], &corrid[0], &accttkn[0], &acctint[0], &ctxtkey[0], &retcode,
&reascode, &userid[0], &applname[0], &wsname[0], &xidptr);
COBOL CALL 'DSNRLI' USING CSGNONFN CORRID ACCTTKN ACCTINT CTXTKEY RETCODE REASCODE USERID APPLNAME
WSNAME XIDPTR.
Fortran CALL DSNRLI(CSGNONFN,CORRID,ACCTTKN,ACCTINT,CTXTKEY, RETCODE,REASCODE, USERID,APPLNAME,
WSNAME,XIDPTR)
PL/I1 CALL DSNRLI(CSGNONFN,CORRID,ACCTTKN,ACCTINT,CTXTKEY, RETCODE,REASCODE,USERID,APPLNAME,
WSNAME,XIDPTR);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77
Related reference
“SIGNON function for RRSAF” on page 95

SET_ID function for RRSAF

The RRSAF SET_ID function sets a new value for the client program ID that can be
used to identify the end user. The function then passes this information to DB2
when the next SQL request is processed.

The following diagram shows the syntax of the SET_ID function.

Chapter 2. Connecting to DB2 from your application program 107

DSNRLI SET_ID function

CALL DSNRLI ( function, program-id )


, retcode
, reascode

Parameters point to the following areas:

function
An 18-byte area that contains SET_ID followed by 12 blanks.
program-id
An 80-byte area that contains the caller-provided string to be passed to DB2. If
program-id is less than 80 characters, you must pad it with blanks on the right
to a length of 80 characters.
DB2 places the contents of program-id into IFCID 316 records, along with other
statistics, so that you can identify which program is associated with a
particular SQL statement.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.

Example of RRSAF SET_ID calls

The following table shows a SET_ID call in each language.

Table 31. Examples of RRSAF SET_ID calls
Language Call example
Assembler CALL DSNRLI,(SETIDFN,PROGID,RETCODE,REASCODE)
1
C fnret=dsnrli(&setidfn[0], &progid[0], &retcode, &reascode);
COBOL CALL 'DSNRLI' USING SETIDFN PROGID RETCODE REASCODE.
Fortran CALL DSNRLI(SETIDFN,PROGID,RETCODE,REASCODE)
1
PL/I CALL DSNRLI(SETIDFN,PROGID,RETCODE,REASCODE);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.

108 Application Programming and SQL Guide

Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

SET_CLIENT_ID function for RRSAF

The RRSAF SET_CLIENT_ID function sets new values for the client user ID, the
application program name, the workstation name, the accounting token, and the
DDF client accounting string. The function then passes this information to DB2
when the next SQL request is processed.

These values can be used to identify the end user. The calling program defines the
contents of these parameters. DB2 places the parameter values in the output from
the DISPLAY THREAD command and in DB2 accounting and statistics trace
records.

The following diagram shows the syntax of the SET_CLIENT_ID function.

DSNRLI SET_CLIENT_ID function

CALL DSNRLI ( function, accounting-token, user, appl, ws

)

,retcode
,reascode
,accounting-string

Parameters point to the following areas:

function
An 18-byte area that contains SET_CLIENT_ID followed by 5 blanks.
accounting-token
A 22-byte area in which you can put a value for a DB2 accounting token. This
value is placed in the DB2 accounting and statistics trace records in the
QWHCTOKEN field, which is mapped by DSNDQWHC DSECT. If
accounting-token is less than 22 characters long, you must pad it on the right
with blanks to a length of 22 characters.
You can omit this parameter by specifying a value of 0 in the parameter list.
Alternatively, you can change the value of the DB2 accounting token with the
RRSAF functions SIGNON, AUTH SIGNON, or CONTEXT SIGNON. You can
retrieve the DB2 accounting token with the CURRENT CLIENT_ACCTNG
special register only if the DDF accounting string is not set.
user
A 16-byte area that contains the user ID of the client end user. You can use this
parameter to provide the identity of the client end user for accounting and
monitoring purposes. DB2 places this user ID in the output from the DISPLAY
THREAD command and in DB2 accounting and statistics trace records. If user
is less than 16 characters long, you must pad it on the right with blanks to a
length of 16 characters.
You can omit this parameter by specifying a value of 0 in the parameter list.

Chapter 2. Connecting to DB2 from your application program 109

You can also change the value of the client user ID with the RRSAF functions
SIGNON, AUTH SIGNON, or CONTEXT SIGNON. You can retrieve the client
user ID with the CLIENT_USERID special register.
appl
An 32-byte area that contains the application or transaction name of the end
user’s application. You can use this parameter to provide the identity of the
client end user for accounting and monitoring purposes. DB2 places the
application name in the output from the DISPLAY THREAD command and in
DB2 accounting and statistics trace records. If appl is less than 32 characters,
you must pad it on the right with blanks to a length of 32 characters.
You can omit this parameter by specifying a value of 0 in the parameter list.
You can also change the value of the application name with the RRSAF
functions SIGNON, AUTH SIGNON, or CONTEXT SIGNON. You can retrieve
the application name with the CLIENT_APPLNAME special register.
ws An 18-byte area that contains the workstation name of the client end user. You
can use this parameter to provide the identity of the client end user for
accounting and monitoring purposes. DB2 places this workstation name in the
output from the DISPLAY THREAD command and in DB2 accounting and
statistics trace records. If ws is less than 18 characters, you must pad it on the
right with blanks to a length of 18 characters.
You can omit this parameter by specifying a value of 0 in the parameter list.
You can also change the value of the workstation name with the RRSAF
functions SIGNON, AUTH SIGNON, or CONTEXT SIGNON. You can retrieve
the workstation name with the CLIENT_WRKSTNNAME special register.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.
accounting-string
A one-byte length field and a 255-byte area in which you can put a value for a
DB2 accounting string. This value is placed in the DDF accounting trace
records in the QMDASQLI field, which is mapped by DSNDQMDA DSECT. If
accounting-string is less than 255 characters, you must pad it on the right with
zeros to a length of 255 bytes. The entire 256 bytes is mapped by DSNDQMDA
DSECT.
This parameter is optional. If you specify this accounting-string, you must also
specify retcode, reascode, user, appl and xid. If you do not specify this parameter,
no accounting string is associated with the connection.
You can also change the value of the accounting string with RRSAF functions
AUTH SIGNON, CONTEXT SIGNON, or SET_CLIENT_ID.
You can retrieve the DDF suffix portion of the accounting string with the
CURRENT CLIENT_ACCTNG special register. The suffix portion of
accounting-string can contain a maximum of 200 characters. The QMDASFLN

110 Application Programming and SQL Guide

field contains the accounting suffix length, and the QMDASUFX field contains
the accounting suffix value. If the DDF accounting string is set, you cannot
query the accounting token with the CURRENT CLIENT_ACCTNG special
register.

Example of RRSAF SET_CLIENT_ID calls

The following table shows a SET_CLIENT_ID call in each language.

Table 32. Examples of RRSAF SET_CLIENT_ID calls
Language Call example
Assembler CALL DSNRLI,(SECLIDFN,ACCT,USER,APPL,WS,RETCODE,REASCODE)
1
C fnret=dsnrli(&seclidfn[0], &acct[0], &user[0], &appl[0], &ws[0], &retcode, &reascode);
COBOL CALL 'DSNRLI' USING SECLIDFN ACCT USER APPL WS RETCODE REASCODE.
Fortran CALL DSNRLI(SECLIDFN,ACCT,USER,APPL,WS,RETCODE,REASCODE)
1
PL/I CALL DSNRLI(SECLIDFN,ACCT,USER,APPL,WS,RETCODE,REASCODE);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

CREATE THREAD function for RRSAF

The RRSAF CREATE THREAD function allocates the DB2 resources that are
required for an application to issue SQL or IFI requests. This function must
complete before the application can execute SQL statements or IFI requests.

The following diagram shows the syntax of the CREATE THREAD function.

DSNRLI CREATE THREAD function

CALL DSNRLI ( function, plan, collection, reuse

)

, retcode
, reascode
, pklistptr

Parameters point to the following areas:

function
An 18-byte area that contains CREATE THREAD followed by five blanks.
plan
An 8-byte DB2 plan name. RRSAF allocates the named plan.
If you provide a collection name instead of a plan name, specify the question
mark character (?) in the first byte of this field. DB2 then allocates a special

Chapter 2. Connecting to DB2 from your application program 111

plan named ?RRSAF and uses the value that you specify for collection . When
DB2 allocates a plan named ?RRSAF, DB2 checks authorization to execute the
package in the same way as it checks authorization to execute a package from
a requester other than DB2 for z/OS.
If you do not provide a collection name in the collection field, you must enter a
valid plan name in this field.
collection
An 18-byte area in which you enter a collection name. DB2 uses the collection
names to locate a package that is associated with the first SQL statement in the
program.
When you provide a collection name and put the question mark character (?)
in the plan field, DB2 allocates a plan named ?RRSAF and a package list that
contains the following two entries:
v The specified collection name.
v An entry that contains * for the location, collection name, and package name.
(This entry lets the application access remote locations and access packages
in collections other than the default collection that is specified at create
thread time.)
The application can use the SET CURRENT PACKAGESET statement to change
the collection ID that DB2 uses to locate a package.
If you provide a plan name in the plan field, DB2 ignores the value in the
collection field.
reuse
An 8-byte area that controls the action that DB2 takes if a SIGNON call is
issued after a CREATE THREAD call. Specify one of the following values in
this field:
RESET
Releases any held cursors and reinitializes the special registers
INITIAL
Does not allow the SIGNON call

This parameter is required. If the 8-byte area does not contain either RESET or
INITIAL, the default value is INITIAL.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.
pklistptr
A 4-byte field that contains a pointer to a user-supplied data area that contains
a list of collection IDs. A collection ID is an SQL identifier of 1 to 128 letters,
digits, or the underscore character that identifies a collection of packages. The
length of the data area is a maximum of 2050 bytes. The data area contains a
2-byte length field, followed by up to 2048 bytes of collection ID entries,
separated by commas.

112 Application Programming and SQL Guide

When you specify pklistptr and the question mark character (?) in the plan field,
DB2 allocates a special plan named ?RRSAF and a package list that contains
the following entries:
v The collection names that you specify in the data area to which pklistptr
points
v An entry that contains * for the location, collection ID, and package name
If you also specify collection, DB2 ignores that value.
Each collection entry must be of the form collection-ID.*, *.collection-ID.*, or *.*.*.
collection-ID and must follow the naming conventions for a collection ID, as
described in the description of the BIND and REBIND options.
DB2 uses the collection names to locate a package that is associated with the
first SQL statement in the program. The entry that contains *.*.* lets the
application access remote locations and access packages in collections other
than the default collection that is specified at create thread time.
The application can use the SET CURRENT PACKAGESET statement to change
the collection ID that DB2 uses to locate a package.
This parameter is optional. If you specify this parameter, you must also specify
retcode and reascode.
If you provide a plan name in the plan field, DB2 ignores the pklistptr value.

Recommendation: Using a package list can have a negative impact on

performance. For better performance, specify a short package list.

Example of RRSAF CREATE THREAD calls

The following table shows a CREATE THREAD call in each language.

Table 33. Examples of RRSAF CREATE THREAD calls
Language Call example
Assembler CALL DSNRLI,(CRTHRDFN,PLAN,COLLID,REUSE,RETCODE,REASCODE,PKLISTPTR)
C1 fnret=dsnrli(&crthrdfn[0], &plan[0], &collid[0], &reuse[0], &retcode, &reascode, &pklistptr);
COBOL CALL 'DSNRLI' USING CRTHRDFN PLAN COLLID REUSE RETCODE REASCODE PKLSTPTR.
Fortran CALL DSNRLI(CRTHRDFN,PLAN,COLLID,REUSE,RETCODE,REASCODE,PKLSTPTR)
PL/I1 CALL DSNRLI(CRTHRDFN,PLAN,COLLID,REUSE,RETCODE,REASCODE,PKLSTPTR);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.

Chapter 2. Connecting to DB2 from your application program 113

Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77
Authorizing plan or package access through applications (DB2 Administration
Guide)
Related reference
BIND and REBIND options (DB2 Command Reference)

TERMINATE THREAD function for RRSAF

The RRSAF TERMINATE THREAD function deallocates DB2 resources that are
associated with a plan and were previously allocated for an application by the
CREATE THREAD function. You can then use the CREATE THREAD function to
allocate another plan with the same connection.

If you call the TERMINATE THREAD function and the application is not at a point
of consistency, RRSAF returns reason code X’00C12211’.

The following diagram shows the syntax of the TERMINATE THREAD function.

DSNRLI TERMINATE THREAD function

CALL DSNRLI ( function, )


, retcode
, reascode

Parameters point to the following areas:

function
An 18-byte area the contains TERMINATE THREAD followed by two blanks.
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.

Example of RRSAF TERMINATE THREAD calls

The following table shows a TERMINATE THREAD call in each language.

Table 34. Examples of RRSAF TERMINATE THREAD calls
Language Call example
Assembler CALL DSNRLI,(TRMTHDFN,RETCODE,REASCODE)
C1 fnret=dsnrli(&trmthdfn[0], &retcode, &reascode);
COBOL CALL 'DSNRLI' USING TRMTHDFN RETCODE REASCODE.

114 Application Programming and SQL Guide

Table 34. Examples of RRSAF TERMINATE THREAD calls (continued)
Language Call example
Fortran CALL DSNRLI(TRMTHDFN,RETCODE,REASCODE)
1
PL/I CALL DSNRLI(TRMTHDFN,RETCODE,REASCODE);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

TERMINATE IDENTIFY function for RRSAF

The RRSAF TERMINATE IDENTIFY function terminates a connection to DB2.
Calling the TERMINATE IDENTIFY function is optional. If you do not call it, DB2
performs the same functions when the task terminates.

If DB2 terminates, the application must issue TERMINATE IDENTIFY to reset the
RRSAF control blocks. This action ensures that future connection requests from the
task are successful when DB2 restarts.

The TERMINATE IDENTIFY function removes the calling task’s connection to DB2.
If no other task in the address space has an active connection to DB2, DB2 also
deletes the control block structures that were created for the address space and
removes the cross-memory authorization.

If the application is not at a point of consistency when you call the TERMINATE
IDENTIFY function, RRSAF returns reason code X’00C12211’.

If the application allocated a plan, and you call the TERMINATE IDENTIFY
function without first calling the TERMINATE THREAD function, DB2 deallocates
the plan before terminating the connection.

The following diagram shows the syntax of the TERMINATE IDENTIFY function.

DSNRLI TERMINATE IDENTIFY function

CALL DSNRLI ( function )


, retcode
, reascode

Parameters point to the following areas:

function
An 18-byte area that contains TERMINATE IDENTIFY.
retcode
A 4-byte area in which RRSAF places the return code.

Chapter 2. Connecting to DB2 from your application program 115

This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.

Example of RRSAF TERMINATE IDENTIFY calls

The following table shows a TERMINATE IDENTIFY call in each language.

Table 35. Examples of RRSAF TERMINATE IDENTIFY calls
Language Call example
Assembler CALL DSNRLI,(TMIDFYFN,RETCODE,REASCODE)
1
C fnret=dsnrli(&tmidfyfn[0], &retcode, &reascode);
COBOL CALL 'DSNRLI' USING TMIDFYFN RETCODE REASCODE.
Fortran CALL DSNRLI(TMIDFYFN,RETCODE,REASCODE)
1
PL/I CALL DSNRLI(TMIDFYFN,RETCODE,REASCODE);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

TRANSLATE function for RRSAF

The RRSAF TRANSLATE function converts a hexadecimal reason code for a DB2
error into a signed integer SQL code and a printable error message. The SQL code
and message text are placed in the SQLCODE and SQLSTATE host variables or
related fields of the SQLCA.

Consider the following rules and recommendations about when to use and not use
the TRANSLATE function:
v You cannot call the TRANSLATE function from the Fortran language.
v Call the TRANSLATE function only after a successful IDENTIFY operation. For
errors that occur during SQL or IFI requests, the TRANSLATE function performs
automatically.
v The TRANSLATE function translates codes that begin with X’00F3’, but it does
not translate RRSAF reason codes that begin with X’00C1’.

If you receive error reason code X’00F30040’ (resource unavailable) after an OPEN
request, the TRANSLATE function returns the name of the unavailable database
object in the last 44 characters of the SQLERRM field.

If the TRANSLATE function does not recognize the error reason code, it returns
SQLCODE -924 (SQLSTATE ’58006’) and places a printable copy of the original
DB2 function code and the return and error reason codes in the SQLERRM field.
The contents of registers 0 and 15 do not change, unless TRANSLATE fails. In this
case, register 0 is set to X’00C12204’, and register 15 is set to 200.
116 Application Programming and SQL Guide
The following diagram shows the syntax of the TRANSLATE function.

DSNRLI TRANSLATE function

CALL DSNRLI ( function, sqlca )


, retcode
, reascode

Parameters point to the following areas:

function
An 18-byte area that contains the word TRANSLATE followed by nine blanks.
sqlca
The program’s SQL communication area (SQLCA).
retcode
A 4-byte area in which RRSAF places the return code.
This parameter is optional. If you do not specify retcode, RRSAF places the
return code in register 15 and the reason code in register 0.
reascode
A 4-byte area in which RRSAF places the reason code.
This parameter is optional. If you do not specify reascode, RRSAF places the
reason code in register 0.
If you specify reascode, you must also specify retcode.

Example of RRSAF TRANSLATE calls

The following table shows a TRANSLATE call in each language.

Table 36. Examples of RRSAF TRANSLATE calls
Language Call example
Assembler CALL DSNRLI,(XLATFN,SQLCA,RETCODE,REASCODE)
1
C fnret=dsnrli(&connfn[0], &sqlca, &retcode, &reascode);
COBOL CALL 'DSNRLI' USING XLATFN SQLCA RETCODE REASCODE.
1
PL/I CALL DSNRLI(XLATFN,SQLCA,RETCODE,REASCODE);

Note:
1. For C, C++, and PL/I applications, you must include the appropriate compiler
directives, because DSNRLI is an assembler language program. These compiler
directives are described in the instructions for invoking RRSAF.
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77

| FIND_DB2_SYSTEMS function for RRSAF

| The RRSAF FIND_DB2_SYSTEMS function identifies all active DB2 subsystems on
| a z/OS LPAR.

Chapter 2. Connecting to DB2 from your application program 117

| The following diagram shows the syntax of the FIND_DB2_SYSTEMS function.

| DSNRLI FIND_DB2_SYSTEMS function

|

CALL DSNRLI ( function , ssnma , activea , arraysz ,

|
|
)

| , retcode
, reascode
|
||

| Parameters point to the following areas:

| function
| An 18-byte area that contains FIND_DB2_SYSTEMS followed by two blanks.
| ssnma
| A storage area for an array of 4-byte character strings into which RRSAF places
| the names of all the DB2 subsystems (SSIDs) that are defined for the current
| LPAR. You must provide the storage area. If the array is larger than the
| number of DB2 subsystems, RRSAF returns the value ' ' (four blanks) in
| all unused array members.
| activea
| A storage area for an array of 4-byte values into which RRSAF returns an
| indication of whether a defined subsystem is active. Each value is represented
| as a fixed 31-bit integer. The value 1 means that the subsystem is active. The
| value 0 means that the subsystem is not active. The size of this array must be
| the same as the size of the ssnma array. If the array is larger than the number
| of DB2 subsystems, RRSAF returns the value -1 in all unused array members.
| The information in the activea array is the information that is available at the
| point in time that you requested it and might change at any time.
| arraysz
| A 4-byte area, represented as a fixed 31-bit integer, that specifies the number of
| entries for the ssnma and activea arrays. If the number of array entries is
| insufficient to contain all of the subsystems defined on the current LPAR,
| RRSAF uses all available entries and returns return code 4.
| retcode
| A 4-byte area in which RRSAF is to place the return code for this call to the
| FIND_DB2_SYSTEMS function.
| This parameter is optional. If you do not retcode, RRSAF places the return code
| in register 15 and the reason code in register 0.
| reascode
| A 4-byte area in which RRSAF is to place the reason code for this call to the
| FIND_DB2_SYSTEMS function.
| This parameter is optional. If you do not specify reascode, RRSAF places the
| reason code in register 0.

118 Application Programming and SQL Guide

| Example values that the FIND_DB2_SYSTEMS function returns

| Assume that two subsystems are defined on the current LPAR. Subsystem DB2A is
| active, and subsystem DB2B is stopped. Suppose that you invoke RRSAF with the
| function FIND_DB2_SYSTEMS and a value of 3 for arraysz. The ssnma array and
| activea array are set to the following values:
| Table 37. Example values returned in the ssnma and activeaarrays
| Array element number Values in ssnma array Values in activea array
| 1 DB2A 1
| 2 DB2B 0
| 3 (four blanks) -1
|
| Related tasks
| “Invoking the Resource Recovery Services attachment facility” on page 77

RRSAF return codes and reason codes

If you specify return code and reason code parameters in an RRSAF function call,
RRSAF returns the return code and reason code in those parameters. If you do not
specify those parameters or implicitly invoke RRSAF, RRSAF puts the return code
in register 15 and the reason code in register 0.

When the reason code begins with X’00F3’, except for X’00F30006’, you can use the
RRSAF TRANSLATE function to obtain error message text that can be printed and
displayed.

For SQL calls, RRSAF returns standard SQL return codes in the SQLCA. RRSAF
returns IFI return codes and reason codes in the instrumentation facility
communication area (IFCA).

The following table lists the RRSAF return codes.

Table 38. RRSAF return codes
Return code Explanation
0 The call completed successfully.
4 Status information is available. See the
reason code for details.
>4 The call failed. See the reason code for
details.

Related reference
“TRANSLATE function for RRSAF” on page 116

Sample RRSAF scenarios

One or more tasks can use RRSAF to connect to DB2. This connection can be made
either implicitly or explicitly. For explicit connections, a task calls one or more of
the RRSAF connection functions.

A single task

The following example pseudocode illustrates a single task running in an address

space that explicitly connects to DB2 through RRSAF. z/OS RRS controls commit
processing when the task terminates normally.
Chapter 2. Connecting to DB2 from your application program 119
IDENTIFY
SIGNON
CREATE THREAD
SQL
. or IFI
.
.
TERMINATE IDENTIFY

Multiple tasks

In the following scenario, multiple tasks in an address space explicitly connect to

DB2 through RRSAF. Task 1 executes no SQL statements and makes no IFI calls. Its
purpose is to monitor DB2 termination and startup ECBs and to check the DB2
release level.
TASK 1 TASK 2 TASK 3 TASK n

IDENTIFY IDENTIFY IDENTIFY IDENTIFY

SIGNON SIGNON SIGNON
CREATE THREAD CREATE THREAD CREATE THREAD
SQL SQL SQL
... ... ...
SRRCMIT SRRCMIT SRRCMIT
SQL SQL SQL
... ... ...
SRRCMIT SRRCMIT SRRCMIT
... ... ...
TERMINATE IDENTIFY

Reusing a DB2 thread

The following example pseudocode shows a DB2 thread that is reused by another
user at a point of consistency. When the application calls the SIGNON function for
user B, DB2 reuses the plan that is allocated by the CREATE THREAD function for
user A.
IDENTIFY
SIGNON user A
CREATE THREAD
SQL
...
SRRCMIT
SIGNON user B
SQL
...
SRRCMIT

Switching DB2 threads between tasks

The following scenario shows how you can switch the threads for four users (A, B,
C, and D) among two tasks (1 and 2).
Task 1 Task 2

CTXBEGC (create context a) CTXBEGC (create context b)

CTXSWCH(a,0) CTXSWCH(b,0)
IDENTIFY IDENTIFY
SIGNON user A SIGNON user B
CREATE THREAD (Plan A) CREATE THREAD (plan B)
SQL SQL
... ...
CTXSWCH(0,a) CTXSWCH(0,b)

CTXBEGC (create context c) CTXBEGC (create context d)

CTXSWCH(c,0) CTXSWCH(d,0)

120 Application Programming and SQL Guide

IDENTIFY IDENTIFY
SIGNON user C SIGNON user D
CREATE THREAD (plan C) CREATE THREAD (plan D)
SQL SQL
... ...
CTXSWCH(b,c) CTXSWCH(0,d)
SQL (plan B) ...
... CTXSWCH(a,0)
SQL (plan A)

The applications perform the following steps:

v Task 1 creates context a, switches contexts so that context a is active for task 1,
and calls the IDENTIFY function to initialize a connection to a subsystem. A task
must always call the IDENTIFY function before a context switch can occur. After
the IDENTIFY operation is complete, task 1 allocates a thread for user A, and
performs SQL operations.
At the same time, task 2 creates context b, switches contexts so that context b is
active for task 2, calls the IDENTIFY function to initialize a connection to the
subsystem, allocates a thread for user B, and performs SQL operations.
When the SQL operations complete, both tasks perform RRS context switch
operations. Those operations disconnect each DB2 thread from the task under
which it was running.
v Task 1 then creates context c, calls the IDENTIFY function to initialize a
connection to the subsystem, switches contexts so that context c is active for task
1, allocates a thread for user C, and performs SQL operations for user C.
Task 2 does the same operations for user D.
v When the SQL operations for user C complete, task 1 performs a context switch
operation to perform the following actions:
– Switch the thread for user C away from task 1.
– Switch the thread for user B to task 1.
For a context switch operation to associate a task with a DB2 thread, the DB2
thread must have previously performed an IDENTIFY operation. Therefore,
before the thread for user B can be associated with task 1, task 1 must have
performed an IDENTIFY operation.
v Task 2 performs two context switch operations to perform the following actions:
– Disassociate the thread for user D from task 2.
– Associate the thread for user A with task 2.

Program examples for RRSAF

The Resource Recovery Services attachment facility (RRSAF) enables programs to
communicate with DB2. You can use RRSAF as an alternative to CAF.

Example JCL for invoking RRSAF

The following sample JCL shows how to use RRSAF in a batch environment. The
DSNRRSAF DD statement starts the RRSAF trace. Use that DD statement only if
you are diagnosing a problem.
//jobname JOB z/OS_jobcard_information
//RRSJCL EXEC PGM=RRS_application_program
//STEPLIB DD DSN=application_load_library
// DD DSN=DB2_load_library

Chapter 2. Connecting to DB2 from your application program 121

.
.
.

//SYSPRINT DD SYSOUT=*
//DSNRRSAF DD DUMMY
//SYSUDUMP DD SYSOUT=*

Example of loading and deleting the RRSAF language interface

The following code segment shows how an application loads entry points DSNRLI
and DSNHLIR of the RRSAF language interface. Storing the entry points in
variables LIRLI and LISQL ensures that the application loads the entry points only
once. Delete the loaded modules when the application no longer needs to access
DB2.
****************************** GET LANGUAGE INTERFACE ENTRY ADDRESSES
LOAD EP=DSNRLI Load the RRSAF service request EP
ST R0,LIRLI Save this for RRSAF service requests
LOAD EP=DSNHLIR Load the RRSAF SQL call Entry Point
ST R0,LISQL Save this for SQL calls
* .
* . Insert connection service requests and SQL calls here
* .
DELETE EP=DSNRLI Correctly maintain use count
DELETE EP=DSNHLIR Correctly maintain use count

Example of using dummy entry point DSNHLI for RRSAF

Each of the DB2 attachment facilities contains an entry point named DSNHLI.
When you use RRSAF but do not specify the ATTACH(RRSAF) precompiler
option, the precompiler generates BALR instructions to DSNHLI for SQL
statements in your program. To find the correct DSNHLI entry point without
including DSNRLI in your load module, code a subroutine, with entry point
DSNHLI, that passes control to entry point DSNHLIR in the DSNRLI module.
DSNHLIR is unique to DSNRLI and is at the same location as DSNHLI in
DSNRLI. DSNRLI uses 31-bit addressing. If the application that calls this
intermediate subroutine uses 24-bit addressing, the intermediate subroutine must
account for the difference.

In the following example, LISQL is addressable because the calling CSECT used
the same register 12 as CSECT DSNHLI. Your application must also establish
addressability to LISQL.
***********************************************************************
* Subroutine DSNHLI intercepts calls to LI EP=DSNHLI
***********************************************************************
DS 0D
DSNHLI CSECT Begin CSECT
STM R14,R12,12(R13) Prologue
LA R15,SAVEHLI Get save area address
ST R13,4(,R15) Chain the save areas
ST R15,8(,R13) Chain the save areas
LR R13,R15 Put save area address in R13
L R15,LISQL Get the address of real DSNHLI
BASSM R14,R15 Branch to DSNRLI to do an SQL call
* DSNRLI is in 31-bit mode, so use
* BASSM to assure that the addressing
* mode is preserved.
L R13,4(,R13) Restore R13 (caller's save area addr)
L R14,12(,R13) Restore R14 (return address)
RETURN (1,12) Restore R1-12, NOT R0 and R15 (codes)

122 Application Programming and SQL Guide

Example of connecting to DB2 with RRSAF

This example uses the variables that are declared in the following code.
****************** VARIABLES SET BY APPLICATION ***********************
LIRLI DS F DSNRLI entry point address
LISQL DS F DSNHLIR entry point address
SSNM DS CL4 DB2 subsystem name for IDENTIFY
CORRID DS CL12 Correlation ID for SIGNON
ACCTTKN DS CL22 Accounting token for SIGNON
ACCTINT DS CL6 Accounting interval for SIGNON
PLAN DS CL8 DB2 plan name for CREATE THREAD
COLLID DS CL18 Collection ID for CREATE THREAD. If
* PLAN contains a plan name, not used.
REUSE DS CL8 Controls SIGNON after CREATE THREAD
CONTROL DS CL8 Action that application takes based
* on return code from RRSAF
****************** VARIABLES SET BY DB2 *******************************
STARTECB DS F DB2 startup ECB
TERMECB DS F DB2 termination ECB
EIBPTR DS F Address of environment info block
RIBPTR DS F Address of release info block
****************************** CONSTANTS ******************************
CONTINUE DC CL8'CONTINUE' CONTROL value: Everything OK
IDFYFN DC CL18'IDENTIFY ' Name of RRSAF service
SGNONFN DC CL18'SIGNON ' Name of RRSAF service
CRTHRDFN DC CL18'CREATE THREAD ' Name of RRSAF service
TRMTHDFN DC CL18'TERMINATE THREAD ' Name of RRSAF service
TMIDFYFN DC CL18'TERMINATE IDENTIFY' Name of RRSAF service
****************************** SQLCA and RIB **************************
EXEC SQL INCLUDE SQLCA
DSNDRIB Map the DB2 Release Information Block
******************* Parameter list for RRSAF calls ********************
RRSAFCLL CALL ,(*,*,*,*,*,*,*,*),VL,MF=L

The following example code shows how to issue requests for the RRSAF functions
IDENTIFY, SIGNON, CREATE THREAD, TERMINATE THREAD, and
TERMINATE IDENTIFY. This example does not show a task that waits on the DB2
termination ECB. You can code such a task and use the z/OS WAIT macro to
monitor the ECB. The task that waits on the termination ECB should detach the
sample code if the termination ECB is posted. That task can also wait on the DB2
startup ECB. This example waits on the startup ECB at its own task level.
***************************** IDENTIFY ********************************
L R15,LIRLI Get the Language Interface address
CALL (15),(IDFYFN,SSNM,RIBPTR,EIBPTR,TERMECB,STARTECB),VL,MF=X
(E,RRSAFCLL)
BAL R14,CHEKCODE Call a routine (not shown) to check
* return and reason codes
CLC CONTROL,CONTINUE Is everything still OK
BNE EXIT If CONTROL not 'CONTINUE', stop loop
USING R8,RIB Prepare to access the RIB
L R8,RIBPTR Access RIB to get DB2 release level
WRITE 'The current DB2 release level is' RIBREL
***************************** SIGNON **********************************
L R15,LIRLI Get the Language Interface address
CALL (15),(SGNONFN,CORRID,ACCTTKN,ACCTINT),VL,MF=(E,RRSAFCLL)
BAL R14,CHEKCODE Check the return and reason codes
*************************** CREATE THREAD *****************************
L R15,LIRLI Get the Language Interface address
CALL (15),(CRTHRDFN,PLAN,COLLID,REUSE),VL,MF=(E,RRSAFCLL)
BAL R14,CHEKCODE Check the return and reason codes
****************************** SQL ************************************
* Insert your SQL calls here. The DB2 Precompiler
* generates calls to entry point DSNHLI. You should
* code a dummy entry point of that name to intercept

Chapter 2. Connecting to DB2 from your application program 123

* all SQL calls. A dummy DSNHLI is shown in the following
* section.
************************ TERMINATE THREAD *****************************
CLC CONTROL,CONTINUE Is everything still OK?
BNE EXIT If CONTROL not 'CONTINUE', shut down
L R15,LIRLI Get the Language Interface address
CALL (15),(TRMTHDFN),VL,MF=(E,RRSAFCLL)
BAL R14,CHEKCODE Check the return and reason codes
************************ TERMINATE IDENTIFY ***************************
CLC CONTROL,CONTINUE Is everything still OK
BNE EXIT If CONTROL not 'CONTINUE', stop loop
L R15,LIRLI Get the Language Interface address
CALL (15),(TMIDFYFN),VL,MF=(E,RRSAFCLL)
BAL R14,CHEKCODE Check the return and reason codes

Controlling the CICS attachment facility from an application

Use the CICS attachment facility to access DB2 from CICS application programs.

You can start and stop the CICS attachment facility from within an application
program.

To control the CICS attachment facility:

1. To start the CICS attachment facility, perform one of the following actions:
v Include the following statement in your application:
EXEC CICS LINK PROGRAM('DSN2COM0')
v Use the system programming interface SET DB2CONN for the CICS
Transaction Server.
2. To stop the CICS attachment facility, perform one of the following actions:
v Include the following statement in your application:
EXEC CICS LINK PROGRAM('DSN2COM2')
v Use the system programming interface SET DB2CONN for the CICS
Transaction Server.
Related information
CICS Transaction Server Library at ibm.com

Detecting whether the CICS attachment facility is operational

Before you execute SQL in a CICS program, you should test if the CICS attachment
facility is available. You do not need to do this test if the CICS attachment facility
is started and you are using standby mode.

When an SQL statement is executed, and the CICS attachment facility is in standby
mode, the attachment issues SQLCODE -923 with a reason code that indicates that
DB2 is not available.

To detect whether the CICS attachment facility is operational:

Use the INQUIRE EXITPROGRAM command for the CICS Transaction Server in
your application.
The following example shows how to use this command. In this example, the
INQUIRE EXITPROGRAM command tests whether the resource manager for SQL,
DSNCSQL, is up and running. CICS returns the results in the EIBRESP field of the
EXEC interface block (EIB) and in the field whose name is the argument of the
CONNECTST parameter (in this case, STST). If the EIBRESP value indicates that

124 Application Programming and SQL Guide

the command completed normally and the STST value indicates that the resource
manager is available, you can then execute SQL statements.
STST DS F
ENTNAME DS CL8
EXITPROG
. DS CL8
.
.
MVC ENTNAME,=CL8'DSNCSQL'
MVC EXITPROG,=CL8'DSN2EXT1'
EXEC CICS INQUIRE EXITPROGRAM(EXITPROG) X
ENTRYNAME(ENTNAME) CONNECTST(STST) NOHANDLE
CLC EIBRESP,DFHRESP(NORMAL)
BNE NOTREADY
CLC STST,DFHVALUE(CONNECTED)
BNE NOTREADY
UPNREADY DS 0H
attach is up
NOTREADY DS 0H
attach isn't up yet

If you use the INQUIRE EXITPROGRAM command to avoid AEY9 abends and the
CICS attachment facility is down, the storm drain effect can occur. The storm drain
effect is a condition that occurs when a system continues to receive work, even
though that system is down.
Related concepts
Storm-drain effect (DB2 Data Sharing Planning and Administration)
Related information
CICS Transaction Server Library at ibm.com
-923 (DB2 Codes)

Improving thread reuse in CICS applications

In general, you want transactions to reuse threads whenever possible, because each
thread creation is associated with a high processor cost.

To improve thread reuse in CICS applications:

Close all cursors that are declared with the WITH HOLD option before each sync
point. DB2 does not automatically close them. A thread for an application that
contains an open cursor cannot be reused. You should close all cursors
immediately after you finish using them.
Related concepts
“Held and non-held cursors” on page 673

Chapter 2. Connecting to DB2 from your application program 125

126 Application Programming and SQL Guide
Chapter 3. Coding SQL statements in application programs:
General information
A query is an SQL statement that returns data from a DB2 database. Your program
can communicate this SQL statement to DB2 in one of several ways. After
processing the statement, DB2 sends back a return code, which your program
should then test to determine the result of the operation.

To include DB2 queries in an application program:

1. Choose one of the following methods for communicating with DB2:
v Static SQL
v Embedded dynamic SQL
v Open Database Connectivity (ODBC)
v JDBC application support
v SQLJ application support
ODBC lets you access data through ODBC function calls in your application.
You execute SQL statements by passing them to DB2 through a ODBC function
call. ODBC eliminates the need for precompiling and binding your application
and increases the portability of your application by using the ODBC interface.
If you are writing your applications in Java™, you can use JDBC application
support to access DB2. JDBC is similar to ODBC but is designed specifically for
use with Java. In addition to using JDBC, you can use SQLJ application support
to access DB2. SQLJ is designed to simplify the coding of DB2 calls for Java
applications.
2. Optional: Declare the tables and views that you use. You can use DCLGEN to
generate these declarations.
3. Define the items that your program can use to check whether an SQL statement
executed successfully. You can either define an SQL communications area
(SQLCA) or declare SQLSTATE and SQLCODE host variables.
4. Define at least one SQL descriptor area (SQLDA).
5. Declare any of the following data items for passing data between DB2 and a
host language:
v host variables
v host variable arrays
v host structures
Ensure that you use the appropriate data types.
6. Code SQL statements to access DB2 data. Ensure that you delimit these
statements properly.
Consider using cursors to select a set of rows and then process the set either
one row at a time or one rowset at a time.
7. Check the execution of the SQL statements.
8. Handle any SQL error codes.

© Copyright IBM Corp. 1983, 2009 127

Related concepts
“Dynamic SQL” on page 162
JDBC application programming (Programming for Java)
SQLJ application programming (Programming for Java)
Introduction to DB2 ODBC (Programming for ODBC)
Related tasks
“Delimiting an SQL statement” on page 151
“Retrieving a set of rows by using a cursor” on page 670

Declaring table and view definitions

Before your program issues SQL statements that select, insert, update, or delete
data, the program should declare the tables and views that those statements access.

Your program is not required to declare tables or views, but doing so offers the
following advantages:
v Clear documentation in the program
The declaration specifies the structure of the table or view and the data type of
each column. You can refer to the declaration for the column names and data
types in the table or view.
v Assurance that your program uses the correct column names and data types
The DB2 precompiler uses your declarations to make sure that you have used
correct column names and data types in your SQL statements. The DB2
precompiler issues a warning message when the column names and data types
in SQL statements do not correspond to the table and view declarations in your
program.

To declare table and view definitions:

Perform one of the following actions:

v Include an SQL DECLARE TABLE statement in your program. Specify the name
of the table or view and list each column and its data type.
When you declare a table or view that contains a column with a distinct type,
declare that column with the source type of the distinct type rather than with
the distinct type itself. When you declare the column with the source type, DB2
can check embedded SQL statements that reference that column at precompile
time.
In a COBOL program, code the DECLARE TABLE statement in the
WORKING-STORAGE SECTION or LINKAGE SECTION within the DATA
DIVISION.

Example DECLARE statement in a COBOL program: The following DECLARE

TABLE statement in a COBOL program defines the DSN8910.DEPT table:
EXEC SQL
DECLARE DSN8910.DEPT TABLE
(DEPTNO CHAR(3) NOT NULL,
DEPTNAME VARCHAR(36) NOT NULL,
MGRNO CHAR(6) ,
ADMRDEPT CHAR(3) NOT NULL,
LOCATION CHAR(16) )
END-EXEC.

128 Application Programming and SQL Guide

v Use DCLGEN, the declarations generator that is supplied with DB2, to create
these declarations for you and then include them in your program.

Restriction: You can use DCLGEN for only C, COBOL, and PL/I programs.
Related reference
DECLARE TABLE (SQL Reference)

DCLGEN (declarations generator)

Your program should declare the tables and views that it accesses. DCLGEN, the
declarations generator that is supplied with DB2, produces these DECLARE
statements for C, COBOL, and PL/I programs, so that you do not need to code the
statements yourself. DCLGEN also generates corresponding host variable
structures.

DCLGEN generates a table or view declaration and puts it into a member of a

partitioned data set that you can include in your program. When you use
DCLGEN to generate a table declaration, DB2 gets the relevant information from
the DB2 catalog. The catalog contains information about the table or view
definition and the definition of each column within the table or view. DCLGEN
uses this information to produce an SQL DECLARE TABLE statement for the table
or view and a corresponding PL/I or C structure declaration or COBOL record
description.
Related reference
DCLGEN (DECLARATIONS GENERATOR) (DSN) (DB2 Command Reference)

Generating table and view declarations by using DCLGEN

Your program should declare the tables and views that it accesses. For C, COBOL,
and PL/I programs you can use DCLGEN to produce these declarations, so that
you do not need to code the statements yourself. DCLGEN also generates
corresponding host variable structures.

Requirements:
v DB2 must be active before you can use DCLGEN.
v You can use DCLGEN for table declarations only if the table or view that you
are declaring already exists.
v If you use DCLGEN, you must use it before you precompile your program.

To generate table and view declarations by using DCLGEN:

1. Invoke DCLGEN by performing one of the following actions:
v To start DCLGEN from ISPF through DB2I: Select the DCLGEN option on
the DB2I Primary Option Menu panel. Then follow the detailed instructions
for generating table and view declarations by using DCLGEN from DB2I.
v To start DCLGEN directly from TSO: Sign on to TSO, issue the TSO
command DSN, and then issue the subcommand DCLGEN.
v To start DCLGEN directly from a CLIST: From a CLIST, running in TSO
foreground or background, issue DSN and then DCLGEN.
v To start DCLGEN with JCL: Supply the required information in JCL and run
DCLGEN in batch. Use the sample jobs DSNTEJ2C and DSNTEJ2P in the
prefix.SDSNSAMP library as models.

Chapter 3. Coding SQL statements in application programs: General information 129

Requirement: If you want to start DCLGEN in the foreground and your
table names include DBCS characters, you must provide and display
double-byte characters. If you do not have a terminal that displays DBCS
characters, you can enter DBCS characters by using the hex mode of ISPF
edit.
DCLGEN creates the declarations in the specified data set.
DCLGEN generates a table or column name in the DECLARE statement as a
non-delimited identifier unless at least one of the following conditions is true:
v The name contains special characters and is not a DBCS string.
v The name is a DBCS string, and you have requested delimited DBCS names.
2. If you use an SQL reserved word as an identifier, edit the DCLGEN output to
add the appropriate SQL delimiters.
3. Make any other necessary edits to the DCLGEN output.
DCLGEN produces output that is intended to meet the needs of most users,
but occasionally, you need to edit the DCLGEN output to work in your specific
case. For example, DCLGEN is unable to determine whether a column that is
defined as NOT NULL also contains the DEFAULT clause, so you must edit the
DCLGEN output to add the DEFAULT clause to the appropriate column
definitions.
Related reference
DCLGEN (DECLARATIONS GENERATOR) (DSN) (DB2 Command Reference)
DSN (TSO) (DB2 Command Reference)
Reserved words (SQL Reference)

Generating table and view declarations by using DCLGEN from

DB2I
DCLGEN generates table and view declarations and the corresponding variable
declarations for C, COBOL, and PL/I programs so that you do not have to code
these statements yourself. The easiest way to start DCLGEN is through DB2I.

To generate table and view declarations by using DCLGEN from DB2I:

1. From the DB2I Primary Option Menu panel, select the DCLGEN option. The
following DCLGEN panel is displayed:

130 Application Programming and SQL Guide

| DSNEDP01 DCLGEN SSID: DSN
| ===>
|
| Enter table name for which declarations are required:
| 1 SOURCE TABLE NAME ===>
|
| 2 TABLE OWNER ..... ===>
|
| 3 AT LOCATION ..... ===> (Optional)
| Enter destination data set: (Can be sequential or partitioned)
| 4 DATA SET NAME ... ===>
| 5 DATA SET PASSWORD ===> (If password protected)
| Enter options as desired:
| 6 ACTION .......... ===> ADD (ADD new or REPLACE old declaration)
| 7 COLUMN LABEL .... ===> NO (Enter YES for column label)
| 8 STRUCTURE NAME .. ===> (Optional)
| 9 FIELD NAME PREFIX ===> (Optional)
| 10 DELIMIT DBCS .... ===> YES (Enter YES to delimit DBCS identifiers)
| 11 COLUMN SUFFIX ... ===> NO (Enter YES to append column name)
| 12 INDICATOR VARS .. ===> NO (Enter YES for indicator variables)
| 13 ADDITIONAL OPTIONS===> YES (Enter YES to change additional options)
|
| PRESS: ENTER to process END to exit HELP for more information

Figure 6. DCLGEN panel

2. Fill in the following fields on the DCLGEN panel:

1 SOURCE TABLE NAME
Is the unqualified name of the table, view, or created temporary table
for which you want DCLGEN to produce SQL data declarations. The
table can be stored at your DB2 location or at another DB2 location. To
specify a table name at another DB2 location, enter the table qualifier in
the TABLE OWNER field and the location name in the AT LOCATION
field. DCLGEN generates a three-part table name from the SOURCE
TABLE NAME, TABLE OWNER, and AT LOCATION fields. You can
also use an alias for a table name.
To specify a table name that contains special characters or blanks,
enclose the name in apostrophes. If the name contains apostrophes, you
must double each one(’ ’). For example, to specify a table named
DON’S TABLE, enter the following text:
'DON''S TABLE'
The underscore is not handled as a special character in DCLGEN. For
example, the table name JUNE_PROFITS does not need to be enclosed
in apostrophes. Because COBOL field names cannot contain
underscores, DCLGEN substitutes hyphens (-) for single-byte
underscores in COBOL field names that are built from the table name.
You do not need to enclose DBCS table names in apostrophes.
If you do not enclose the table name in apostrophes, DB2 converts
lowercase characters to uppercase.
2 TABLE OWNER
| Is the schema qualifier of the source table. If you do not specify this
| value and the table is a local table, DB2 assumes that the table qualifier
| is your TSO logon ID. If the table is at a remote location, you must
| specify this value.
3 AT LOCATION
Is the location of a table or view at another DB2 subsystem. The value
of the AT LOCATION field becomes a prefix for the table name on the
SQL DECLARE statement, as follows: location_name, schema_name,
Chapter 3. Coding SQL statements in application programs: General information 131
table_name For example, if the location name is PLAINS_GA, the
schema name is CARTER, and the table name is CROP_YIELD_89, the
following table name is included in the SQL DECLARE statement:
PLAINS_GA.CARTER.CROP_YIELD_89
The default is the local location name. This field applies to DB2 private
protocol access only. The location must be another DB2 for z/OS
subsystem.
4 DATA SET NAME
Is the name of the data set that you allocated to contain the
declarations that DCLGEN produces. You must supply a name; no
default exists.
The data set must already exist and be accessible to DCLGEN. The data
set can be either sequential or partitioned. If you do not enclose the
data set name in apostrophes, DCLGEN adds a standard TSO prefix
(user ID) and suffix (language). DCLGEN determines the host language
from the DB2I defaults panel.
For example, for library name LIBNAME(MEMBNAME), the name
becomes userid.libname.language(membname) For library name
LIBNAME, the name becomes userid.libname.language.
If this data set is password protected, you must supply the password in
the DATA SET PASSWORD field.
5 DATA SET PASSWORD
Is the password for the data set that is specified in the DATA SET
NAME field, if the data set is password protected. The password is not
displayed on your terminal, and it is not recognized if you issued it
from a previous session.
6 ACTION
Specifies what DCLGEN is to do with the output when it is sent to a
partitioned data set. (The option is ignored if the data set you specify
in the DATA SET NAME field is sequential.) You can specify one of the
following values:
ADD
Indicates that an old version of the output does not exist and
creates a new member with the specified data set name. ADD is the
default.
REPLACE
Replaces an old version, if it already exists. If the member does not
exist, this option creates a new member.
7 COLUMN LABEL
Specifies whether DCLGEN is to include labels that are declared on any
columns of the table or view as comments in the data declarations.
(The SQL LABEL statement creates column labels to use as
supplements to column names.) You can specify one of the following
values:
YES
Include column labels.
NO
Ignore column labels. NO is the default.

132 Application Programming and SQL Guide

8 STRUCTURE NAME
Is the name of the generated data structure. The name can be up to 31
characters. If the name is not a DBCS string, and the first character is
not alphabetic, enclose the name in apostrophes. If you use special
characters, be careful to avoid name conflicts.
If you leave this field blank, DCLGEN generates a name that contains
the table or view name with a prefix of DCL. If the language is COBOL
or PL/I and the table or view name consists of a DBCS string, the
prefix consists of DBCS characters.
For C, lowercase characters that you enter in this field are not
converted to uppercase.
9 FIELD NAME PREFIX
Specifies a prefix that DCLGEN uses to form field names in the output.
For example, if you choose ABCDE, the field names generated are
ABCDE1, ABCDE2, and so on.
You can specify a field name prefix of up to 28 bytes that can include
special and double-byte characters. If you specify a single-byte or
mixed-string prefix and the first character is not alphabetic, enclose the
prefix in apostrophes. If you use special characters, be careful to avoid
name conflicts.
For COBOL and PL/I, if the name is a DBCS string, DCLGEN
generates DBCS equivalents of the suffix numbers.
For C, lowercase characters that you enter in this field do not converted
to uppercase.
If you leave this field blank, the field names are the same as the
column names in the table or view.
10 DELIMIT DBCS
Specifies whether DCLGEN is to delimit DBCS table names and column
names in the table declaration. You can specify one of the following
values:
YES
Specifies that DCLGEN is to enclose the DBCS table and column
names with SQL delimiters.
NO
Specifies that DCLGEN is not to delimit the DBCS table and
column names.
11 COLUMN SUFFIX
Specifies whether DCLGEN is to form field names by attaching the
column name as a suffix to the value that you specify in FIELD NAME
PREFIX. You can specify one of the following values:
YES
Specifies that DCLGEN is to use the column name as a suffix. For
example, if you specify YES, the field name prefix is NEW, and the
column name is EMPNO, the field name is NEWEMPNO.
If you specify YES, you must also enter a value in FIELD NAME
PREFIX. If you do not enter a field name prefix, DCLGEN issues a
warning message and uses the column names as the field names.

Chapter 3. Coding SQL statements in application programs: General information 133

NO
Specifies that DCLGEN is not to use the column name as a suffix.
The default is NO.
12 INDICATOR VARS
Specifies whether DCLGEN is to generate an array of indicator
variables for the host variable structure. You can specify one of the
following values:
YES
Specifies that DCLGEN is to generate an array of indicator
variables for the host variable structure.
If you specify YES, the array name is the table name with a prefix
of I (or DBCS letter <I> if the table name consists solely of
double-byte characters). The form of the data declaration depends
on the language, as shown in the following table. n is the number
of columns in the table.
Table 39. Declarations for indicator variable arrays from DCLGEN
Language Declaration form
C short int Itable-name[n];
COBOL 01 Itable-name PIC S9(4) USAGE COMP
OCCURS n TIMES.
PL/I DCL Itable-name(n) BIN FIXED(15);

For example, suppose that you define the following table:

CREATE TABLE HASNULLS (CHARCOL1 CHAR(1), CHARCOL2 CHAR(1));

If you request an array of indicator variables for a COBOL

program, DCLGEN might generate the following host variable
declaration:
01 DCLHASNULLS.
10 CHARCOL1 PIC X(1).
10 CHARCOL2 PIC X(1).
01 IHASNULLS PIC S9(4) USAGE COMP OCCURS 2 TIMES.
NO
Specifies that DCLGEN is not to generate an array of indicator
variables. The default is NO.
| 13 ADDITIONAL OPTIONS
| Indicates whether to display the panel for additional DCLGEN options,
| including the break point for statement tokens and whether to generate
| DECLARE VARIABLE statements for FOR BIT DATA columns. You can
| specify YES or NO. The default is YES.

If you specified YES in the ADDITIONAL OPTIONS field, the following

ADDITIONAL DCLGEN OPTIONS panel is displayed:

134 Application Programming and SQL Guide

DSNEDP02 ADDITIONAL DCLGEN OPTIONS SSID: DSN
===>

Enter options as desired:

1 RIGHT MARGIN .... ===> 72 (Enter 72 or 80)

2 FOR BIT DATA .... ===> NO (Enter YES to declare SQL variables for
FOR BIT DATA columns)

PRESS: ENTER to process END to exit HELP for more information

Figure 7. ADDITIONAL DCLGEN OPTIONS panel

Otherwise, DCLGEN creates the declarations in the specified data set.

| 3. If the ADDITIONAL DCLGEN OPTIONS panel is displayed, fill in the
| following fields on that panel:
| 1 RIGHT MARGIN
| Specifies the break point for statement tokens that must be wrapped to
| one or more subsequent records. You can specify column 72 or column
| 80.
| The default is 72.
| 2 FOR BIT DATA
| Specifies whether DCLGEN is to generate a DECLARE VARIABLE
| statement for SQL variables for columns that are declared as FOR BIT
| DATA. This statement is required in DB2 applications that meet all of
| the following criteria:
| v are written in COBOL
| v have host variables for FOR BIT DATA columns
| v are prepared with the SQLCCSID option of the DB2 coprocessor.
| You can specify YES or NO. The default is NO.
| If the table or view does not have FOR BIT DATA columns, DCLGEN
| does not generate this statement.

| DCLGEN creates the declarations in the specified data set.

Related reference
“DB2I primary option menu” on page 955
LABEL (SQL Reference)

Data types that DCLGEN uses for variable declarations

DCLGEN produces declarations for tables and views and the corresponding host
variable structures for C, COBOL, and PL/I programs. DCLGEN derives the
variable names and data types for these declarations based on the source tables in
the database.

The following table lists the C, COBOL, and PL/I data types that DCLGEN uses
for variable declarations based on the corresponding SQL data types that are used
in the source tables. var represents a variable name that DCLGEN provides.
Table 40. Type declarations that DCLGEN generates
SQL data type1 C COBOL PL/I
SMALLINT short int PIC S9(4) USAGE COMP BIN FIXED(15)
INTEGER long int PIC S9(9) USAGE COMP BIN FIXED(31)

Chapter 3. Coding SQL statements in application programs: General information 135

Table 40. Type declarations that DCLGEN generates (continued)
SQL data type1 C COBOL PL/I
2
DECIMAL(p,s) or decimal(p,s) PIC S9(p-s)V9(s) USAGE DEC FIXED(p,s)
NUMERIC(p,s) COMP-3
If p>15, the PL/I compiler
must support this precision,
or a warning is generated.
REAL or FLOAT(n) 1 <= n float USAGE COMP-1 BIN FLOAT(n)
<= 21
DOUBLE PRECISION, double USAGE COMP-2 BIN FLOAT(n)
DOUBLE, or FLOAT(n)
CHAR(1) char PIC X(1) CHAR(1)
CHAR(n) char var [n+1] PIC X(n) CHAR(n)
VARCHAR(n) struct 10 var. CHAR(n) VAR
{short int var_len; 49 var_LEN PIC 9(4)
char var_data[n]; USAGE COMP.
} var; 49 var_TEXT PIC X(n).
CLOB(n)3 SQL TYPE IS CLOB_LOCATOR USAGE SQL TYPE IS SQL TYPE IS CLOB_LOCATOR
CLOB-LOCATOR
GRAPHIC(1) sqldbchar PIC G(1) GRAPHIC(1)
GRAPHIC(n) sqldbchar var[n+1]; PIC G(n) USAGE GRAPHIC(n)
DISPLAY-1.4
n>1 or
PIC N(n).4
VARGRAPHIC(n) struct VARGRAPH 10 var. GRAPHIC(n) VAR
{short len; 49 var_LEN PIC 9(4)
sqldbchar data[n]; USAGE COMP.
} var; 49 var_TEXT PIC G(n)
USAGE DISPLAY-1.4
or
10 var.
49 var_LEN PIC 9(4)
USAGE COMP.
49 var_TEXT PIC N(n).4
DBCLOB(n)3 SQL TYPE IS USAGE SQL TYPE IS SQL TYPE IS
DBCLOB_LOCATOR DBCLOB-LOCATOR DBCLOB_LOCATOR
| BINARY(n) SQL TYPE IS BINARY(n) USAGE SQL TYPE IS SQL TYPE IS BINARY(n)
| BINARY(n)
| VARBINARY(n) SQL TYPE IS VARBINARY(n) USAGE SQL TYPE IS SQL TYPE IS VARBINARY(n)
| VARBINARY(n)
BLOB(n)3 SQL TYPE IS BLOB_LOCATOR USAGE SQL TYPE IS SQL TYPE IS BLOB_LOCATOR
BLOB-LOCATOR
DATE char var[11]5 PIC X(10)5 CHAR(10)5
TIME char var[9]6 PIC X(8)6 CHAR(8)6
TIMESTAMP char var[27] PIC X(26) CHAR(26)
ROWID SQL TYPE IS ROWID USAGE SQL TYPE IS ROWID SQL TYPE IS ROWID
| BIGINT long long int PIC S9(18) USAGE COMP FIXED BIN(63)
7
| XML SQL TYPE IS XML AS SQL TYPE IS XML AS SQL TYPE IS XML AS
| CLOB(1M) CLOB(1M) CLOB(1M)

136 Application Programming and SQL Guide

Table 40. Type declarations that DCLGEN generates (continued)
SQL data type1 C COBOL PL/I
| Notes:
| 1. For a distinct type, DCLGEN generates the host language equivalent of the source data type.
| 2. If your C compiler does not support the decimal data type, edit your DCLGEN output and replace the decimal
| data declarations with declarations of type double.
| 3. For a BLOB, CLOB, or DBCLOB data type, DCLGEN generates a LOB locator.
| 4. DCLGEN chooses the format based on the character that you specify as the DBCS symbol on the COBOL Defaults
| panel.
| 5. This declaration is used unless a date installation exit routine exists for formatting dates, in which case the length
| is that specified for the LOCAL DATE LENGTH installation option.
| 6. This declaration is used unless a time installation exit routine exists for formatting times, in which case the length
| is that specified for the LOCAL TIME LENGTH installation option.
| 7. The default setting for XML is 1M; however, you might need to adjust it.

Including declarations from DCLGEN in your program

After you use DCLGEN to produce table, view, and variable declarations for your
C, COBOL, or PL/I program, you should include these declarations in your
program.

Recommendation: To ensure that your program uses a current description of the

table, use DCLGEN to generate the table’s declaration and store it as a member in
a library (usually a partitioned data set) just before you precompile the program.

To include declarations from DCLGEN in your program:

Code the following SQL INCLUDE statement in your program:

EXEC SQL
INCLUDE member-name
END-EXEC.

member-name is the name of the data set member where the DCLGEN output is
stored.

Example: Suppose that you used DCLGEN to generate a table declaration and
corresponding COBOL record description for the table DSN8910.EMP, and those
declarations were stored in the data set member DECEMP. (A COBOL record
description is a two-level host structure that corresponds to the columns of a
table’s row. ) To include those declarations in your program, include the following
statement in your COBOL program:
EXEC SQL
INCLUDE DECEMP
END-EXEC.
Related reference
INCLUDE (SQL Reference)

Example: Adding DCLGEN declarations to a library

You can use DCLGEN to generate table and variable declarations for C, COBOL,
and PL/I programs. If you store these declarations in a library, you can later pull
them into your program with a single SQL INCLUDE statement.

Chapter 3. Coding SQL statements in application programs: General information 137

This example adds a table declaration and a corresponding host-variable structure
to a library. This example is based on the following scenario:
v The library name is prefix.TEMP.COBOL.
v The member is a new member named VPHONE.
v The table is a local table named DSN8910.VPHONE.
v The host-variable structure is for COBOL.
v The structure receives the default name DCLVPHONE.

Throughout this example, information that you must enter on each panel is in
bold-faced type.

In this scenario, to add a table declaration and a corresponding host variable

structure for DSN8910.VPHONE to the library prefix.TEMP.COBOL, complete the
following steps:
1. Specify COBOL as the host language by completing the following actions:
a. On the ISPF/PDF menu, select option D to display the DB2I DEFAULTS
PANEL l panel.
b. Specify IBMCOB as the application language, as shown in the following figure
and press Enter.

DSNEOP01 DB2I DEFAULTS PANEL 1

COMMAND ===>_

Change defaults as desired:

1 DB2 NAME ............. ===> DSN (Subsystem identifier)

2 DB2 CONNECTION RETRIES ===> 0 (How many retries for DB2 connection)
3 APPLICATION LANGUAGE ===> IBMCOB (ASM, C, CPP, IBMCOB, FORTRAN, PLI)
4 LINES/PAGE OF LISTING ===> 80 (A number from 5 to 999)
5 MESSAGE LEVEL ........ ===> I (Information, Warning, Error, Severe)
6 SQL STRING DELIMITER ===> DEFAULT (DEFAULT, ' or ")
7 DECIMAL POINT ........ ===> . (. or ,)
8 STOP IF RETURN CODE >= ===> 8 (Lowest terminating return code)
9 NUMBER OF ROWS ===> 20 (For ISPF Tables)
10 CHANGE HELP BOOK NAMES?===> NO (YES to change HELP data set names)
11 AS USER ===> (Userid to associate with the trusted
connection)

PRESS: ENTER to process END to cancel HELP for more information

Figure 8. DB2I defaults panel—changing the application language

The DB2I DEFAULTS PANEL 2 panel for COBOL is then displayed.

c. Fill in the DB2I DEFAULTS PANEL 2 panel, shown in the following figure,
as needed and press Enter to save the new defaults, if any.

138 Application Programming and SQL Guide

DSNEOP02 DB2I DEFAULTS PANEL 2
COMMAND ===>_

Change defaults as desired:

1 DB2I JOB STATEMENT: (Optional if your site has a SUBMIT exit)

===> //ADMF001A JOB (ACCOUNT),'NAME'
===> //*
===> //*
===> //*

COBOL DEFAULTS: (For IBMCOB)

2 COBOL STRING DELIMITER ===> DEFAULT (DEFAULT, ' or ")
3 DBCS SYMBOL FOR DCLGEN ===> G (G/N - Character in PIC clause)

Figure 9. The COBOL defaults panel. Shown only if the field APPLICATION LANGUAGE on the DB2I DEFAULTS
PANEL l panel is IBMCOB.

The DB2I Primary Option menu is displayed.

2. Generate the table and host structure declarations by completing the following
actions:
a. On the DB2I Primary Option menu, select the DCLGEN option and press
Enter to display the DCLGEN panel.
b. Fill in the fields as shown in the following figure and press Enter.

| DSNEDP01 DCLGEN SSID: DSN

| ===>
|
| Enter table name for which declarations are required:
| 1 SOURCE TABLE NAME ===> DSN8910.VPHONE
|
| 2 TABLE OWNER ..... ===>
|
| 3 AT LOCATION ..... ===> (Optional)
| Enter destination data set: (Can be sequential or partitioned)
| 4 DATA SET NAME ... ===> TEMP(VPHONEC)
| 5 DATA SET PASSWORD ===> (If password protected)
| Enter options as desired:
| 6 ACTION .......... ===> ADD (ADD new or REPLACE old declaration)
| 7 COLUMN LABEL .... ===> NO (Enter YES for column label)
| 8 STRUCTURE NAME .. ===> (Optional)
| 9 FIELD NAME PREFIX ===> (Optional)
| 10 DELIMIT DBCS .... ===> YES (Enter YES to delimit DBCS identifiers)
| 11 COLUMN SUFFIX ... ===> NO (Enter YES to append column name)
| 12 INDICATOR VARS .. ===> NO (Enter YES for indicator variables)
| 13 ADDITIONAL OPTIONS===> NO (Enter YES to change additional options)
|
| PRESS: ENTER to process END to exit HELP for more information

Figure 10. DCLGEN panel—selecting source table and destination data set

A successful completion message, such as the one in the following figure, is

displayed at the top of your screen.

DSNE905I EXECUTION COMPLETE, MEMBER VPHONEC ADDED

***

Figure 11. Successful completion message

DB2 again displays the DCLGEN screen, as shown in the following figure.

Chapter 3. Coding SQL statements in application programs: General information 139

| DSNEDP01 DCLGEN SSID: DSN
| ===>
|
| Enter table name for which declarations are required:
| 1 SOURCE TABLE NAME ===> DSN8910.VPHONE
|
| 2 TABLE OWNER ..... ===>
|
| 3 AT LOCATION ..... ===> (Optional)
| Enter destination data set: (Can be sequential or partitioned)
| 4 DATA SET NAME ... ===> TEMP(VPHONEC)
| 5 DATA SET PASSWORD ===> (If password protected)
| Enter options as desired:
| 6 ACTION .......... ===> ADD (ADD new or REPLACE old declaration)
| 7 COLUMN LABEL .... ===> NO (Enter YES for column label)
| 8 STRUCTURE NAME .. ===> (Optional)
| 9 FIELD NAME PREFIX ===> (Optional)
| 10 DELIMIT DBCS .... ===> YES (Enter YES to delimit DBCS identifiers)
| 11 COLUMN SUFFIX ... ===> NO (Enter YES to append column name)
| 12 INDICATOR VARS .. ===> NO (Enter YES for indicator variables)
| 13 ADDITIONAL OPTIONS===> NO (Enter YES to change additional options)
|
| PRESS: ENTER to process END to exit HELP for more information
|
|
| Figure 12. DCLGEN panel—displaying system and user return codes
|
c. Press Enter to return to the DB2I Primary Option menu.
3. Exit from DB2I.
4. Examine the DCLGEN output by selecting either the browse or the edit option
from the ISPF/PDF menu to view the results in the specified data set member.
For this example, the data set to edit is prefix.TEMP.COBOL(VPHONEC). This
data set member contains the following information.
***** DCLGEN TABLE(DSN8910.VPHONE) ***
***** LIBRARY(SYSADM.TEMP.COBOL(VPHONEC)) ***
***** QUOTE ***
***** ... IS THE DCLGEN COMMAND THAT MADE THE FOLLOWING STATEMENTS ***
EXEC SQL DECLARE DSN8910.VPHONE TABLE
( LASTNAME VARCHAR(15) NOT NULL,
FIRSTNAME VARCHAR(12) NOT NULL,
MIDDLEINITIAL CHAR(1) NOT NULL,
PHONENUMBER VARCHAR(4) NOT NULL,
EMPLOYEENUMBER CHAR(6) NOT NULL,
DEPTNUMBER CHAR(3) NOT NULL,
DEPTNAME VARCHAR(36) NOT NULL
) END-EXEC.
***** COBOL DECLARATION FOR TABLE DSN8910.VPHONE ******
01 DCLVPHONE.
10 LASTNAME.
49 LASTNAME-LEN PIC S9(4) USAGE COMP.
49 LASTNAME-TEXT PIC X(15).
10 FIRSTNAME.
49 FIRSTNAME-LEN PIC S9(4) USAGE COMP.
49 FIRSTNAME-TEXT PIC X(12).
10 MIDDLEINITIAL PIC X(1).
10 PHONENUMBER.
49 PHONENUMBER-LEN PIC S9(4) USAGE COMP.
49 PHONENUMBER-TEXT PIC X(4).
10 EMPLOYEENUMBER PIC X(6).
10 DEPTNUMBER PIC X(3).
10 DEPTNAME.
49 DEPTNAME-LEN PIC S9(4) USAGE COMP.
49 DEPTNAME-TEXT PIC X(36).
***** THE NUMBER OF COLUMNS DESCRIBED BY THIS DECLARATION IS 7 ******
You can now pull these declarations into your program by using an SQL
INCLUDE statement.

140 Application Programming and SQL Guide

Defining the items that your program can use to check whether an
SQL statement executed successfully
If your program contains SQL statements, the program should define some
infrastructure so that it can check whether the statements executed successfully.
You can either include an SQL communications area (SQLCA), which contains
SQLCODE and SQLSTATE variables, or declare individual SQLCODE and
SQLSTATE host variables.

Whether you define the SQLCODE or SQLSTATE variables or an SQLCA in your

program depends on what you specify for the SQL processing option STDSQL.

If your application contains SQL statements and does not include an SQL
communications area (SQLCA), you must declare individual SQLCODE and
SQLSTATE host variables. Your program can use these variables to check whether
an SQL statement executed successfully.
Related tasks
“Accessing the DB2 REXX language support application programming interfaces”
on page 409
“Defining the SQL communications area, SQLSTATE, and SQLCODE in assembler”
on page 229
“Defining the SQL communications area, SQLSTATE, and SQLCODE in C” on page
249
“Defining the SQL communications area, SQLSTATE, and SQLCODE in COBOL”
on page 295
“Defining the SQL communications area, SQLSTATE, and SQLCODE in Fortran”
on page 363
“Defining the SQL communications area, SQLSTATE, and SQLCODE in PL/I” on
page 375
“Defining the SQL communications area, SQLSTATE, and SQLCODE in REXX” on
page 403
Related reference
“Descriptions of SQL processing options” on page 904
Description of SQLCA fields (SQL Reference)
INCLUDE (SQL Reference)
The REXX SQLCA (SQL Reference)

Defining SQL descriptor areas

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

If your program includes any of the following statements, you must include an
SQLDA in your program:
v CALL ... USING DESCRIPTOR descriptor-name
v DESCRIBE statement-name INTO descriptor-name
v DESCRIBE CURSOR host-variable INTO descriptor-name
v DESCRIBE INPUT statement-name INTO descriptor-name
v DESCRIBE PROCEDURE host-variable INTO descriptor-name

Chapter 3. Coding SQL statements in application programs: General information 141

v DESCRIBE TABLE host-variable INTO descriptor-name
v EXECUTE ... USING DESCRIPTOR descriptor-name
| v FETCH ... INTO DESCRIPTOR descriptor-name
v OPEN ... USING DESCRIPTOR descriptor-name
v PREPARE ... INTO descriptor-name

Unlike the SQLCA, a program can have more than one SQLDA, and an SQLDA
can have any valid name.

To define SQL descriptor areas, take the actions that are appropriate for the
programming language that you use.
Related tasks
“Defining SQL descriptor areas in assembler” on page 230
“Defining SQL descriptor areas in C” on page 250
“Defining SQL descriptor areas in COBOL” on page 296
“Defining SQL descriptor areas in Fortran” on page 364
“Defining SQL descriptor areas in PL/I” on page 376
“Defining SQL descriptor areas in REXX” on page 403
Related reference
“Descriptions of SQL processing options” on page 904
Description of SQLCA fields (SQL Reference)
INCLUDE (SQL Reference)
SQL descriptor area (SQLDA) (SQL Reference)
The REXX SQLCA (SQL Reference)

Declaring host variables and indicator variables

You can use host variables and indicator variables in SQL statements in your
program to pass data between DB2 and your application.

To declare host variables, host variable arrays, and host structures, use the
techniques that are appropriate for the programming language that you use.

142 Application Programming and SQL Guide

Related tasks
“Accessing data by using a rowset-positioned cursor” on page 680
“Declaring host variables and indicator variables in assembler” on page 230
“Declaring host variables and indicator variables in C” on page 251
“Declaring host variables and indicator variables in COBOL” on page 297
“Declaring host variables and indicator variables in Fortran” on page 365
“Declaring host variables and indicator variables in PL/I” on page 376
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
Related reference
“Descriptions of SQL processing options” on page 904
“Host structures in C” on page 268
“Host structures in COBOL” on page 314
“Host structures in PL/I” on page 386
“Host variable arrays in C” on page 262
“Host variable arrays in COBOL” on page 307
“Host variable arrays in PL/I” on page 382
“Host variables in assembler” on page 231
“Host variables in C” on page 251
“Host variables in COBOL” on page 298
“Host variables in Fortran” on page 365
“Host variables in PL/I” on page 377

Host variables
Use host variables to pass a single data item between DB2 and your application.

A host variable is a single data item that is declared in the host language to be used
within an SQL statement. You can use host variables in application programs that
are written in the following languages: assembler, C, C++, COBOL, Fortran, and
PL/I to perform the following actions:
v Retrieve data into the host variable for your application program’s use
v Place data into the host variable to insert into a table or to change the contents
of a row
v Use the data in the host variable when evaluating a WHERE or HAVING clause
v Assign the value that is in the host variable to a special register, such as
CURRENT SQLID and CURRENT DEGREE
v Insert null values into columns by using a host indicator variable that contains a
negative value
v Use the data in the host variable in statements that process dynamic SQL, such
as EXECUTE, PREPARE, and OPEN

Chapter 3. Coding SQL statements in application programs: General information 143

Related concepts
“Rules for host variables in an SQL statement” on page 151
Related reference
“Host variables in assembler” on page 231
“Host variables in C” on page 251
“Host variables in COBOL” on page 298
“Host variables in Fortran” on page 365
“Host variables in PL/I” on page 377

Host variable arrays

Use host variable arrays to pass a data array between DB2 and your application.

| A host variable array is a data array that is declared in the host language to be used
| within an SQL statement. You can use host variable arrays to perform the
| following actions:
| v Retrieve data into host variable arrays for your application program’s use
| v Place data into host variable arrays to insert rows into a table
| You typically define host variable arrays for use with multiple-row FETCH,
| INSERT, and MERGE statements.
Related concepts
“Host variable arrays in an SQL statement” on page 159
Related tasks
“Inserting multiple rows of data from host variable arrays” on page 160
“Retrieving multiple rows of data into host variable arrays” on page 160
Related reference
“Host variable arrays in C” on page 262
“Host variable arrays in COBOL” on page 307
“Host variable arrays in PL/I” on page 382

Host structures
Use host structures to pass a group of host variables between DB2 and your
application.

A host structure is a group of host variables that can be referenced with a single
name. You can use host structures in all host languages except REXX. You define
host structures with statements in the host language. You can refer to a host
structure in any context where you want to refer to the list of host variables in the
structure. A host structure reference is equivalent to a reference to each of the host
variables within the structure in the order in which they are defined in the
structure declaration. You can also use indicator variables (or indicator structures)
with host structures.

144 Application Programming and SQL Guide

Related tasks
“Retrieving a single row of data into a host structure” on page 161
Related reference
“Host structures in C” on page 268
“Host structures in COBOL” on page 314
“Host structures in PL/I” on page 386

Indicator variables, arrays, and structures

An indicator variable is associated with a particular host variable. Each indicator
variable contains a small integer value that indicates some information about the
associated host variable. Indicator arrays and structures serve the same purpose for
host variable arrays and structures.

You can use indicator variables to perform the following actions:

v Determine whether the value of an associated output host variable is null or
indicate that the value of an input host variable is null
v Determine the original length of a character string that was truncated when it
was assigned to a host variable
v Determine that a character value could not be converted when it was assigned
to a host variable
v Determine the seconds portion of a time value that was truncated when it was
assigned to a host variable

You can use indicator variable arrays and indicator structures to perform these
same actions for individual items in host data arrays and structures.

If you provide an indicator variable for the variable X, when DB2 retrieves a null
value for X, it puts a negative value in the indicator variable and does not update
X. Your program should check the indicator variable before using X. If the
indicator variable is negative, you know that X is null and any value that you find
in X is irrelevant. When your program uses variable X to assign a null value to a
column, the program should set the indicator variable to a negative number. DB2
then assigns a null value to the column and ignores any value in X.

An indicator variable array contains a series of small integers to help you

determine the associated information for the corresponding item in a host data
array. When you retrieve data into a host variable array, you can check the values
in the associated indicator array to determine how to handle each data item. If a
value in the associated indicator array is negative, you can disregard the contents
of the corresponding element in the host variable array. Values in indicator arrays
have the following meanings:
-1 The corresponding row in the column that is being retrieved is null.
-2 DB2 returns a null value, because an error occurred in numeric conversion
or in an arithmetic expression in the corresponding row.
-3 DB2 returns a null value, because a hole was detected for the
corresponding row during a multiple-row FETCH operation.

An indicator structure is an array of halfword integer variables that supports a

specified host structure. If the column values that your program retrieves into a
host structure can be null, you can attach an indicator structure name to the host
structure name. This name enables DB2 to notify your program about each null
value it returns to a host variable in the host structure.

Chapter 3. Coding SQL statements in application programs: General information 145

Related concepts
“Holes in the result table of a scrollable cursor” on page 688
Related tasks
“Executing SQL statements by using a rowset cursor” on page 681
Related reference
“Indicator variables in assembler” on page 235
“Indicator variables, indicator arrays, and host structure indicator arrays in C” on
page 270
“Indicator variables, indicator arrays, and host structure indicator arrays in
COBOL” on page 319
“Indicator variables in Fortran” on page 368
“Indicator variables in PL/I” on page 388

Setting the CCSID for host variables

All DB2 string data, other than binary data, has an encoding scheme and a coded
character set ID (CCSID) associated with it. You can associate an encoding scheme
and a CCSID with individual host variables. Any data in those host variable is
then associated with that encoding scheme and CCSID.

To set the CCSID for host variables:

Specify the DECLARE VARIABLE statement after the corresponding host variable
declaration and before your first reference to that host variable.
This statement associates an encoding scheme and a CCSID with individual host
variables. You can use this statement in static or dynamic SQL applications.

Restriction: You cannot use the DECLARE VARIABLE statement to control the
CCSID and encoding scheme of data that you retrieve or update by using an
SQLDA.
The DECLARE VARIABLE statement has the following effects on a host variable:
v When you use the host variable to update a table, the local subsystem or the
remote server assumes that the data in the host variable is encoded with the
CCSID and encoding scheme that the DECLARE VARIABLE statement assigns.
v When you retrieve data from a local or remote table into the host variable, the
retrieved data is converted to the CCSID and encoding scheme that are assigned
by the DECLARE VARIABLE statement.

Example

Suppose that you are writing a C program that runs on a DB2 for z/OS subsystem.
The subsystem has an EBCDIC application encoding scheme. The C program
retrieves data from the following columns of a local table that is defined with the
CCSID UNICODE option:
PARTNUM CHAR(10)
JPNNAME GRAPHIC(10)
ENGNAME VARCHAR(30)

Because the application encoding scheme for the subsystem is EBCDIC, the
retrieved data is EBCDIC. To make the retrieved data Unicode, use DECLARE
VARIABLE statements to specify that the data that is retrieved from these columns
is encoded in the default Unicode CCSIDs for the subsystem.

146 Application Programming and SQL Guide

Suppose that you want to retrieve the character data in Unicode CCSID 1208 and
the graphic data in Unicode CCSID 1200. Use the following DECLARE VARIABLE
statements:
EXEC SQL BEGIN DECLARE SECTION;
char hvpartnum[11];
EXEC SQL DECLARE :hvpartnum VARIABLE CCSID 1208;
sqldbchar hvjpnname[11];
EXEC SQL DECLARE :hvjpnname VARIABLE CCSID 1200;
struct {
short len;
char d[30];
} hvengname;
EXEC SQL DECLARE :hvengname VARIABLE CCSID 1208;
EXEC SQL END DECLARE SECTION;
Related reference
DECLARE VARIABLE (SQL Reference)

Determining what caused an error when retrieving data into a

host variable
Errors that occur when DB2 passes data to host variables in an application are
usually caused by a problem in converting from one data type to another. These
errors do not affect the position of the cursor.

For example, suppose that you fetch an integer value of 32768 into a host variable
of type SMALLINT. The conversion might cause an error if you do not provide
sufficient conversion information to DB2.

The variable to which DB2 assigns the data is called the output host variable. If you
provide an indicator variable for the output host variable or if data type
conversion is not required, DB2 returns a positive SQLCODE for the row in most
cases. In other cases where data conversion problems occur, DB2 returns a negative
SQLCODE for that row. Regardless of the SQLCODE for the row, no new values
are assigned to the host variable or to subsequent variables for that row. Any
values that are already assigned to variables remain assigned. Even when a
negative SQLCODE is returned for a row, statement processing continues and DB2
returns a positive SQLCODE for the statement (SQLSTATE 01668, SQLCODE
+354).

To determine what caused an error when retrieving data into a host variable:
1. When DB2 returns SQLCODE = +354, use the GET DIAGNOSTICS statement
with the NUMBER option to determine the number of errors and warnings.

Example: Suppose that no indicator variables are provided for the values that
are returned by the following statement:
FETCH FIRST ROWSET FROM C1 FOR 10 ROWS INTO :hva_col1, :hva_col2;

For each row with an error, DB2 records a negative SQLCODE and continues
processing until the 10 rows are fetched. When SQLCODE = +354 is returned
for the statement, you can use the GET DIAGNOSTICS statement to determine
which errors occurred for which rows. The following statement returns
num_rows = 10 and num_cond = 3:
GET DIAGNOSTICS :num_rows = ROW_COUNT, :num_cond = NUMBER;
2. To investigate the errors and warnings, use additional GET DIAGNOSTIC
statements with the CONDITION option.

Chapter 3. Coding SQL statements in application programs: General information 147

Example: To investigate the three conditions that were reported in the example
in the previous step, use the following statements:
Table 41. GET DIAGNOSTIC statements to investigate conditions
Statement Output
GET DIAGNOSTICS CONDITION 3 :sqlstate sqlstate = 22003
= RETURNED_SQLSTATE, :sqlcode = sqlcode = -304
DB2_RETURNED_SQLCODE, :row_num row_num = 5
= DB2_ROW_NUMBER;
GET DIAGNOSTICS CONDITION 2 :sqlstate sqlstate = 22003
= RETURNED_SQLSTATE, :sqlcode = sqlcode = -802
DB2_RETURNED_SQLCODE, :row_num row_num = 7
= DB2_ROW_NUMBER;
GET DIAGNOSTICS CONDITION 1 :sqlstate sqlstate = 01668
= RETURNED_SQLSTATE, :sqlcode = sqlcode = +354
DB2_RETURNED_SQLCODE, :row_num row_num = 0
= DB2_ROW_NUMBER;

This output shows that the fifth row has a data mapping error (-304) for
column 1 and that the seventh row has a data mapping error (-802) for column
2. These rows do not contain valid data, and they should not be used.
Related concepts
“Indicator variables, arrays, and structures” on page 145
Related reference
GET DIAGNOSTICS (SQL Reference)
Related information
+354 (DB2 Codes)

Compatibility of SQL and language data types

The data types of the host variables that are used in SQL statements must be
compatible with the data types of the columns with which you intend to use them.

When deciding the data types of host variables, consider the following rules and
recommendations:
| v Numeric data types are compatible with each other:
| Assembler: A SMALLINT, INTEGER, BIGINT, DECIMAL, or FLOAT column is
| compatible with a numeric assembler host variable.
| Fortran: An INTEGER column is compatible with any Fortran host variable that
| is defined as INTEGER*2, INTEGER*4, REAL, REAL*4, REAL*8, or DOUBLE
| PRECISION.
| PL/I: A SMALLINT, INTEGER, BIGINT, DECIMAL, or FLOAT column is
| compatible with a PL/I host variable of BIN FIXED(15), BIN FIXED(31),
| DECIMAL(s,p), or BIN FLOAT(n), where n is from 1 to 53, or DEC FLOAT(m)
| where m is from 1 to 16.
v Character data types are compatible with each other:
Assembler: A CHAR, VARCHAR, or CLOB column is compatible with a
fixed-length or varying-length assembler character host variable.
C/C++: A CHAR, VARCHAR, or CLOB column is compatible with a
single-character, NUL-terminated, or VARCHAR structured form of a C
character host variable.
COBOL: A CHAR, VARCHAR, or CLOB column is compatible with a
fixed-length or varying-length COBOL character host variable.

148 Application Programming and SQL Guide

Fortran: A CHAR, VARCHAR, or CLOB column is compatible with Fortran
character host variable.
PL/I: A CHAR, VARCHAR, or CLOB column is compatible with a fixed-length
or varying-length PL/I character host variable.
v Character data types are partially compatible with CLOB locators. You can
perform the following assignments:
– Assign a value in a CLOB locator to a CHAR or VARCHAR column
– Use a SELECT INTO statement to assign a CHAR or VARCHAR column to a
CLOB locator host variable.
– Assign a CHAR or VARCHAR output parameter from a user-defined function
or stored procedure to a CLOB locator host variable.
– Use a SET assignment statement to assign a CHAR or VARCHAR transition
variable to a CLOB locator host variable.
– Use a VALUES INTO statement to assign a CHAR or VARCHAR function
parameter to a CLOB locator host variable.
However, you cannot use a FETCH statement to assign a value in a CHAR or
VARCHAR column to a CLOB locator host variable.
v Graphic data types are compatible with each other:
Assembler: A GRAPHIC, VARGRAPHIC, or DBCLOB column is compatible
with a fixed-length or varying-length assembler graphic character host variable.
C/C++: A GRAPHIC, VARGRAPHIC, or DBCLOB column is compatible with a
single character, NUL-terminated, or VARGRAPHIC structured form of a C
graphic host variable.
COBOL: A GRAPHIC, VARGRAPHIC, or DBCLOB column is compatible with a
fixed-length or varying-length COBOL graphic string host variable.
PL/I: A GRAPHIC, VARGRAPHIC, or DBCLOB column is compatible with a
fixed-length or varying-length PL/I graphic character host variable.
v Graphic data types are partially compatible with DBCLOB locators. You can
perform the following assignments:
– Assign a value in a DBCLOB locator to a GRAPHIC or VARGRAPHIC
column
– Use a SELECT INTO statement to assign a GRAPHIC or VARGRAPHIC
column to a DBCLOB locator host variable.
– Assign a GRAPHIC or VARGRAPHIC output parameter from a user-defined
function or stored procedure to a DBCLOB locator host variable.
– Use a SET assignment statement to assign a GRAPHIC or VARGRAPHIC
transition variable to a DBCLOB locator host variable.
– Use a VALUES INTO statement to assign a GRAPHIC or VARGRAPHIC
function parameter to a DBCLOB locator host variable.
However, you cannot use a FETCH statement to assign a value in a GRAPHIC
or VARGRAPHIC column to a DBCLOB locator host variable.
| v Binary data types are compatible with each other.
| v Binary data types are partially compatible with BLOB locators. You can perform
| the following assignments:
| – Assign a value in a BLOB locator to a BINARY or VARBINARY column.
| – Use a SELECT INTO statement to assign a BINARY or VARBINARY column
| to a BLOB locator host variable.
| – Assign a BINARY or VARBINARY output parameter from a user-defined
| function or stored procedure to a BLOB locator host variable.

Chapter 3. Coding SQL statements in application programs: General information 149

| – Use a SET assignment statement to assign a BINARY or VARBINARY
| transition variable to a BLOB locator host variable.
| – Use a VALUES INTO statement to assign a BINARY or VARBINARY function
| parameter to a BLOB locator host variable.
| However, you cannot use a FETCH statement to assign a value in a BINARY or
| VARBINARY column to a BLOB locator host variable.
| v Fortran: A BINARY, VARBINARY, or BLOB column or BLOB locator is
| compatible only with a BLOB host variable.
v C: For varying-length BIT data, use BINARY. Some C string manipulation
functions process NUL-terminated strings and other functions process strings
that are not NUL-terminated. The C string manipulation functions that process
NUL-terminated strings cannot handle bit data because these functions might
misinterpret a NUL character to be a NUL-terminator.
v Datetime data types are compatible with character host variables.
Assembler: A DATE, TIME, or TIMESTAMP column is compatible with a
fixed-length or varying-length assembler character host variable.
C/C++: A DATE, TIME, or TIMESTAMP column is compatible with a
single-character, NUL-terminated, or VARCHAR structured form of a C
character host variable.
COBOL: A DATE, TIME, or TIMESTAMP column is compatible with a
fixed-length or varying length COBOL character host variable.
Fortran: A DATE, TIME, or TIMESTAMP column is compatible with a Fortran
character host variable.
PL/I: A DATE, TIME, or TIMESTAMP column is compatible with a fixed-length
or varying-length PL/I character host variable.
v The ROWID column is compatible only with a ROWID host variable.
v A host variable is compatible with a distinct type if the host variable type is
compatible with the source type of the distinct type.
| v XML columns are compatible with the XML host variable types, character types,
| and binary string types.

| Recommendation: Use the XML host variable types for data from XML
| columns.
| v Assembler:You can assign LOB data to a file reference variable (BLOB_FILE,
| CLOB_FILE, and DBCLOB_FILE).

When necessary, DB2 automatically converts a fixed-length string to a

varying-length string, or a varying-length string to a fixed-length string.

150 Application Programming and SQL Guide

Related concepts
“Distinct types” on page 477
“Host variable data types for XML data in embedded SQL applications” on page
217
Related reference
“Equivalent SQL and assembler data types” on page 236
“Equivalent SQL and C data types” on page 275
“Equivalent SQL and COBOL data types” on page 322
“Equivalent SQL and Fortran data types” on page 369
“Equivalent SQL and PL/I data types” on page 389
“Equivalent SQL and REXX data types” on page 404

Embedding SQL statements in your application

You can code SQL statements in an assembler, C, C++, COBOL, Fortran, or PL/I
program or REXX procedure wherever you can use executable statements.

To embed SQL statements in your application, take action based on the program
language that you use.
Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405

Delimiting an SQL statement

You must delimit SQL statements in your program so that DB2 knows when a
particular SQL statement ends.

To delimit an SQL statement, take action based on the programming language that
you use.
Related concepts
“Delimiters in SQL statements in assembler programs” on page 246
“Delimiters in SQL statements in C programs” on page 284
“Delimiters in SQL statements in COBOL programs” on page 332
“Delimiters in SQL statements in Fortran programs” on page 374
“Delimiters in SQL statements in PL/I programs” on page 397
“Delimiters in SQL statements in REXX programs” on page 408

Rules for host variables in an SQL statement

Use host variables in embedded SQL statements to represent a single value that the
program does not know until it runs. Host variables are useful for storing retrieved
data or for passing values that are to be assigned or used for comparisons.

When you use host variables, adhere to the following requirements:

v You must declare the name of the host variable in the host program before you
use it. Host variables follow the naming conventions of the host language.

Chapter 3. Coding SQL statements in application programs: General information 151

v You can use a host variable to represent a data value, but you cannot use it to
represent a table, view, or column name. You can specify table, view, or column
names at run time by using dynamic SQL.
v To use a host variable in an SQL statement, you can specify any valid host
variable name that is declared according to the rules of the host language.
v A colon (:) must precede host variables that are used in SQL statements so that
DB2 can distinguish a variable name from a column name. When host variables
are used outside of SQL statements, do not precede them with a colon. PL/I
programs have the following exceptions: If the SQL statement meets any of the
following conditions, do not precede a host variable or host variable array in
that statement with a colon:
– The SQL statement is an EXECUTE IMMEDIATE or PREPARE statement.
– The SQL statement is in a program that also contains a DECLARE VARIABLE
statement.
– The host variable is part of a string expression, but the host variable is not the
only component of the string expression.
v To optimize performance, make sure that the host language declaration maps as
closely as possible to the data type of the associated data in the database.
v For assignments and comparisons between a DB2 column and a host variable of
a different data type or length, expect conversions to occur.
Related concepts
“Dynamic SQL” on page 162
Assignment and comparison (SQL Reference)

Retrieving a single row of data into host variables

If you know that your query returns only one row, you can specify one or more
host variables to contain the column values of the retrieved row.

Restriction: These instructions do not apply if you do not know how many rows
DB2 will return or if you expect DB2 to return more than one row. In these
situations, use a cursor. A cursor enables an application to return a set of rows and
fetch either one row at a time or one rowset at a time from the result table.

To retrieve a single row of data into host variables:

In the SELECT statement specify the INTO clause with the name of one or more
host variables to contain the retrieved values. Specify one variable for each value
that is to be retrieved. The retrieved value can be a column value, a value of a host
variable, the result of an expression, or the result of an aggregate function.

Recommendation: If you want to ensure that only one row is returned, specify the
FETCH FIRST 1 ROW ONLY clause. Consider using the ORDER BY clause to
control which row is returned. If you specify both the ORDER BY clause and the
FETCH FIRST clause, ordering is performed on the entire result set before the first
row is returned.
DB2 assigns the first value in the result row to the first variable in the list, the
second value to the second variable, and so on.
If the SELECT statement returns more than one row, DB2 returns an error, and any
data that is returned is undefined and unpredictable.

152 Application Programming and SQL Guide

Examples

Example of retrieving a single row into a host variable: Suppose that you are
retrieving the LASTNAME and WORKDEPT column values from the
DSN8910.EMP table for a particular employee. You can define a host variable in
your program to hold each column value and then name the host variables in the
INTO clause of the SELECT statement, as shown in the following COBOL example.
MOVE '000110' TO CBLEMPNO.
EXEC SQL
SELECT LASTNAME, WORKDEPT
INTO :CBLNAME, :CBLDEPT
FROM DSN8910.EMP
WHERE EMPNO = :CBLEMPNO
END-EXEC.

In this example, the host variable CBLEMPNO is preceded by a colon (:) in the
SQL statement, but it is not preceded by a colon in the COBOL MOVE statement.

This example also uses a host variable to specify a value in a search condition. The
host variable CBLEMPNO is defined for the employee number, so that you can
retrieve the name and the work department of the employee whose number is the
same as the value of the host variable, CBLEMPNO; in this case, 000110.

In the DATA DIVISION section of a COBOL program, you must declare the host
variables CBLEMPNO, CBLNAME, and CBLDEPT to be compatible with the data
types in the columns EMPNO, LASTNAME, and WORKDEPT of the
DSN8910.EMP table.

Example of ensuring that a query returns only a single row: You can use the
FETCH FIRST 1 ROW ONLY clause in a SELECT statement to ensure that only one
row is returned. This action prevents undefined and unpredictable data from being
returned when you specify the INTO clause of the SELECT statement. The
following example SELECT statement ensures that only one row of the
DSN8910.EMP table is returned.
EXEC SQL
SELECT LASTNAME, WORKDEPT
INTO :CBLNAME, :CBLDEPT
FROM DSN8910.EMP
FETCH FIRST 1 ROW ONLY
END-EXEC.

You can include an ORDER BY clause in the preceding example to control which
row is returned. The following example SELECT statement ensures that the only
row returned is the one with a last name that is first alphabetically.
EXEC SQL
SELECT LASTNAME, WORKDEPT
INTO :CBLNAME, :CBLDEPT
FROM DSN8810.EMP
ORDER BY LASTNAME
FETCH FIRST 1 ROW ONLY
END-EXEC.

Example of retrieving the results of host variable values and expressions into
host variables:

When you specify a list of items in the SELECT clause, that list can include more
than the column names of tables and views. You can request a set of column
values mixed with host variable values and constants. For example, the following

Chapter 3. Coding SQL statements in application programs: General information 153

query requests the values of several columns (EMPNO, LASTNAME, and
SALARY), the value of a host variable (RAISE), and the value of the sum of a
column and a host variable (SALARY and RAISE). For each of these five items in
the SELECT list, a host variable is listed in the INTO clause.
MOVE 4476 TO RAISE.
MOVE '000220' TO PERSON.
EXEC SQL
SELECT EMPNO, LASTNAME, SALARY, :RAISE, SALARY + :RAISE
INTO :EMP-NUM, :PERSON-NAME, :EMP-SAL, :EMP-RAISE, :EMP-TTL
FROM DSN8910.EMP
WHERE EMPNO = :PERSON
END-EXEC.

The preceding SELECT statement returns the following results. The column
headings represent the names of the host variables.
EMP-NUM PERSON-NAME EMP-SAL EMP-RAISE EMP-TTL
======= =========== ======= ========= =======
000220 LUTZ 29840 4476 34316

Example of retrieving the result of an aggregate function into a host variable: A

query can request summary values to be returned from aggregate functions and
store those values in host variables. For example, the following query requests that
the result of the AVG function be stored in the AVG-SALARY host variable.
MOVE 'D11' TO DEPTID.
EXEC SQL
SELECT WORKDEPT, AVG(SALARY)
INTO :WORK-DEPT, :AVG-SALARY
FROM DSN8910.EMP
WHERE WORKDEPT = :DEPTID
END-EXEC.
Related tasks
“Retrieving a set of rows by using a cursor” on page 670
Related reference
SELECT INTO (SQL Reference)

Determining whether a retrieved value in a host variable is

null or truncated
Before your application manipulates the data that was retrieved from DB2 into a
host variable, you might need to know if the value is null or if it was truncated
when assigned to the variable. You can use indicator variables to obtain this
information.

Before you determine whether a retrieved column value is null or truncated, you
must have defined the appropriate indicator variables, arrays, and structures.

An error occurs if you do not use an indicator variable and DB2 retrieves a null
value.

To determine whether a retrieved value in a host variable is null or truncated:

Determine the value of the indicator variable, array, or structure that is associated
with the host variable, array, or structure. Those values have the following
meanings:

154 Application Programming and SQL Guide

Table 42. Meanings of values in indicator variables
Value of indicator variable Meaning
Less than zero The column value is null. The value of the
host variable does not change from its
previous value.

If the indicator variable value is -2, the

column value is null because of a numeric or
character conversion error,
Zero The column value is nonnull. If the column
value is a character string, the retrieved
value is not truncated.
Positive integer The retrieved value is truncated. The integer
is the original length of the string.

Examples

Example of testing an indicator variable: Assume that you have defined the
following indicator variable INDNULL for the host variable CBLPHONE.
EXEC SQL
SELECT PHONENO
INTO :CBLPHONE:INDNULL
FROM DSN8910.EMP
WHERE EMPNO = :EMPID
END-EXEC.

You can then test INDNULL for a negative value. If the value is negative, the
corresponding value of PHONENO is null, and you can disregard the contents of
CBLPHONE.

Example of testing an indicator variable array: Suppose that you declare the
following indicator array INDNULL for the host variable array CBLPHONE.
EXEC SQL
FETCH NEXT ROWSET CURS1
FOR 10 ROWS
INTO :CBLPHONE :INDNULL
END-EXEC.

After the multiple-row FETCH statement, you can test each element of the
INDNULL array for a negative value. If an element is negative, you can disregard
the contents of the corresponding element in the CBLPHONE host variable array.

Example of testing an indicator structure in COBOL: The following example

defines the indicator structure EMP-IND as an array that contains six values and
corresponds to the PEMP-ROW host structure.
01 PEMP-ROW.
10 EMPNO PIC X(6).
10 FIRSTNME.
49 FIRSTNME-LEN PIC S9(4) USAGE COMP.
49 FIRSTNME-TEXT PIC X(12).
10 MIDINIT PIC X(1).
10 LASTNAME.
49 LASTNAME-LEN PIC S9(4) USAGE COMP.
49 LASTNAME-TEXT PIC X(15).
10 WORKDEPT PIC X(3).
10 EMP-BIRTHDATE PIC X(10).
01 INDICATOR-TABLE.
02 EMP-IND PIC S9(4) COMP OCCURS 6 TIMES.

Chapter 3. Coding SQL statements in application programs: General information 155

.
.
.
MOVE
. '000230' TO EMPNO.
.
.
EXEC SQL
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, WORKDEPT, BIRTHDATE
INTO :PEMP-ROW:EMP-IND
FROM DSN8910.EMP
WHERE EMPNO = :EMPNO
END-EXEC.

You can test the indicator structure EMP-IND for negative values. If, for example,
EMP-IND(6) contains a negative value, the corresponding host variable in the host
structure (EMP-BIRTHDATE) contains a null value.
Related concepts
“Arithmetic and conversion errors” on page 216
Related tasks
“Declaring host variables and indicator variables” on page 142

Determining whether a column value is null

Before you retrieve a column value, you might first want to determine if the
column value is null.

To determine whether a column value is null:

Use the IS NULL predicate or the IS DISTINCT FROM predicate.

Restriction: You cannot determine whether a column value is null by comparing it

to a host variable with an indicator variable that is set to -1.

Example

The following code, which uses an indicator variable, does not select the
employees who have no phone number:
MOVE -1 TO PHONE-IND.
EXEC SQL
SELECT LASTNAME
INTO :PGM-LASTNAME
FROM DSN8910.EMP
WHERE PHONENO = :PHONE-HV:PHONE-IND
END-EXEC.

Instead, use the following statement with the IS NULL predicate to select
employees who have no phone number:
EXEC SQL
SELECT LASTNAME
INTO :PGM-LASTNAME
FROM DSN8910.EMP
WHERE PHONENO IS NULL
END-EXEC.

To select employees whose phone numbers are equal to the value of :PHONE-HV
and employees who have no phone number (as in the second example), code two
predicates, one to handle the non-null values and another to handle the null
values, as in the following statement:
EXEC SQL
SELECT LASTNAME
INTO :PGM-LASTNAME

156 Application Programming and SQL Guide

FROM DSN8910.EMP
WHERE (PHONENO = :PHONE-HV AND PHONENO IS NOT NULL AND :PHONE-HV IS NOT NULL)
OR
(PHONENO IS NULL AND :PHONE-HV:PHONE-IND IS NULL)
END-EXEC.

You can simplify the preceding example by coding the following statement with
the NOT form of the IS DISTINCT FROM predicate:
EXEC SQL
SELECT LASTNAME
INTO :PGM-LASTNAME
FROM DSN8910.EMP
WHERE PHONENO IS NOT DISTINCT FROM :PHONE-HV:PHONE-IND
END-EXEC.
Related tasks
“Declaring host variables and indicator variables” on page 142
Related reference
DISTINCT predicate (SQL Reference)
NULL predicate (SQL Reference)

Updating data by using host variables

When you want to update a value in a DB2 table, but you do not know the exact
value until the program runs, use host variables in your SQL statement. DB2 can
change a table value to match the current value of the host variable.

To update data by using host variables:

1. Declare the necessary host variables.
2. Specify an UPDATE statement with the appropriate host variable names in the
SET clause.

Examples

Example of updating a single row by using a host variable: The following

COBOL example changes an employee’s phone number to the value in the
NEWPHONE host variable. The employee ID value is passed through the EMPID
host variable.
MOVE '4246' TO NEWPHONE.
MOVE '000110' TO EMPID.
EXEC SQL
UPDATE DSN8910.EMP
SET PHONENO = :NEWPHONE
WHERE EMPNO = :EMPID
END-EXEC.

Example of updating multiple rows by using a host variable value in the search
condition: The following example gives the employees in a particular department
a salary increase of 10%. The department value is passed through the DEPTID host
variable.
MOVE 'D11' TO DEPTID.
EXEC SQL
UPDATE DSN8910.EMP
SET SALARY = 1.10 * SALARY
WHERE WORKDEPT = :DEPTID
END-EXEC.

Chapter 3. Coding SQL statements in application programs: General information 157

Related reference
UPDATE (SQL Reference)

Inserting a single row by using a host variable

When you want to insert data into a DB2 table, but you do not know at least some
of the values to insert until the program runs, use host variables in your INSERT
statement.

Restriction: These instructions apply only to inserting a single row. If you want to
insert multiple rows, use host variable arrays or the form of the INSERT statement
that selects values from another table or view.

To insert a single row by using host variables:

Specify an INSERT statement with column values in the VALUES clause. Specify
host variables or a combination of host variables and constants as the column
values.
DB2 inserts the first value into the first column in the list, the second value into
the second column, and so on.

Example

The following example uses host variables to insert a single row into the activity
table.
EXEC SQL
INSERT INTO DSN8910.ACT
VALUES (:HV-ACTNO, :HV-ACTKWD, :HV-ACTDESC)
END-EXEC.
Related tasks
“Inserting multiple rows of data from host variable arrays” on page 160
Related reference
INSERT (SQL Reference)

Inserting null values into columns by using indicator variables

or arrays
If you need to insert null values into a column, using an indicator variable or array
is an easy way to do so. An indicator variable or array is associated with a
particular host variable or array.

To insert null values into columns by using indicator variables or arrays:

1. Define an indicator variable or array for a particular host variable or array.
2. Assign a negative value to the indicator variable or array.
| 3. Issue the appropriate INSERT, UPDATE, or MERGE statement with the host
| variable or array and its indicator variable or array.
| When DB2 processes INSERT, UPDATE, and MERGE statements, it checks the
| indicator variable if one exists. If the indicator variable is negative, the column
| value is null. If the indicator variable is greater than -1, the associated host
| variable contains a value for the column.

158 Application Programming and SQL Guide

Examples

Example of setting a column value to null by using an indicator

variable: Suppose your program reads an employee ID and a new phone number
and must update the employee table with the new number. The new number could
be missing if the old number is incorrect, but a new number is not yet available. If
the new value for column PHONENO might be null, you can use an indicator
variable, as shown in the following UPDATE statement.
EXEC SQL
UPDATE DSN8910.EMP
SET PHONENO = :NEWPHONE:PHONEIND
WHERE EMPNO = :EMPID
END-EXEC.

When NEWPHONE contains a non-null value, set the indicator variable

PHONEIND to zero by preceding the UPDATE statement with the following line:
MOVE 0 TO PHONEIND.

When NEWPHONE contains a null value, set PHONEIND to a negative value by

preceding the UPDATE statement with the following line:
MOVE -1 TO PHONEIND.

Example of setting a column value to null by using an indicator variable

array: Assume that host variable arrays hva1 and hva2 have been populated with
values that are to be inserted into the ACTNO and ACTKWD columns. Assume the
ACTDESC column allows nulls. To set the ACTDESC column to null, assign -1 to
the elements in its indicator array, ind3, as shown in the following example:
/* Initialize each indicator array */
for (i=0; i<10; i++) {
ind1[i] = 0;
ind2[i] = 0;
ind3[i] = -1;
}

EXEC SQL
INSERT INTO DSN8910.ACT
(ACTNO, ACTKWD, ACTDESC)
VALUES (:hva1:ind1, :hva2:ind2, :hva3:ind3)
FOR 10 ROWS;

DB2 ignores the values in the hva3 array and assigns the values in the ARTDESC
column to null for the 10 rows that are inserted.
Related tasks
“Declaring host variables and indicator variables” on page 142

Host variable arrays in an SQL statement

Use host variable arrays in embedded SQL statements to represent values that the
program does not know until the query is executed. Host variable arrays are useful
for storing a set of retrieved values or for passing a set of values that are to be
inserted into a table.

To use a host variable array in an SQL statement, specify any valid host variable
array that is declared according to the host language rules. You can specify host
variable arrays in C or C++, COBOL, and PL/I. You must declare the array in the
host program before you use it.

Chapter 3. Coding SQL statements in application programs: General information 159

| Restrictions: Use of host variable arrays in assembler programs is limited in the
| following:
| v The DB2 precompiler does not recognize declarations of host variable arrays for
| assembler, it recognizes these declarations only in C, COBOL, and PL/I.
| v Assembler does not support multiple-row MERGE. You cannot specify MERGE
| statements that reference host variable arrays.
| v Assembler support for multiple-row FETCH is limited to the FETCH statement
| with the INTO DESCRIPTOR clause. For example:
| EXEC SQL FETCH NEXT ROWSET FROM C1 FOR 10 ROWS X
| INTO DESCRIPTOR :SQLDA
| v Assembler support for multiple-row INSERT is limited to the following cases:
| – Static multiple-row INSERT statement with scalar values (scalar host variables
| or scalar expressions) in the VALUES clause. For example:
| EXEC SQL INSERT INTO T1 VALUES (1, CURRENT DATE, 'TEST') X
| FOR 10 ROWS
| – Dynamic multiple-row INSERT executed with the USING DESCRIPTOR
| clause on the EXECUTE statement. For example:
| ATR DS CL20 ATTRIBUTES FOR PREPARE
| S1 DS H,CL30 VARCHAR STATEMENT STRING
| MVC ATR(20),=C'FOR MULTIPLE ROWS '
| MVC S1(2),=H'25'
| MVC S1+2(30),=C'INSERT INTO T1 VALUES (?) '
| EXEC SQL PREPARE STMT ATTRIBUTES :ATR FROM :S1
| EXEC SQL EXECUTE STMT USING DESCRIPTOR :SQLDA FOR 10 ROWS
| where the descriptor is set up correctly in advance according to the
| specifications for dynamic execution of a multiple-row INSERT statement
| with a descriptor
| Related concepts
“Host variable arrays” on page 144
Related tasks
“Embedding SQL statements in your application” on page 151
“Inserting multiple rows of data from host variable arrays”
“Retrieving multiple rows of data into host variable arrays”

Retrieving multiple rows of data into host variable arrays

If you know that your query returns multiple rows, you can specify host variable
arrays to store the retrieved column values.

You can use host variable arrays to specify a program data area to contain multiple
rows of column values. A DB2 rowset cursor enables an application to retrieve and
process a set of rows from the result table of the cursor.
Related concepts
“Host variable arrays” on page 144
“Host variable arrays in an SQL statement” on page 159
Related tasks
“Accessing data by using a rowset-positioned cursor” on page 680
“Inserting multiple rows of data from host variable arrays”

Inserting multiple rows of data from host variable arrays

When you want to insert multiple rows of data into a DB2 table, but you do not
know at least some of the values to insert until the program runs, use host variable
arrays in your INSERT statement.

160 Application Programming and SQL Guide

| You can use a form of the INSERT statement or MERGE statement to insert
| multiple rows from values that are provided in host variable arrays. Each array
| contains values for a column of the target table. The first value in an array
| corresponds to the value for that column for the first inserted row, the second
| value in the array corresponds to the value for the column in the second inserted
| row, and so on. DB2 determines the attributes of the values based on the
| declaration of the array.

Example: You can insert the number of rows that are specified in the host variable
NUM-ROWS by using the following INSERT statement:
EXEC SQL
INSERT INTO DSN8910.ACT
(ACTNO, ACTKWD, ACTDESC)
VALUES (:HVA1, :HVA2, :HVA3)
FOR :NUM-ROWS ROWS
END-EXEC.

Assume that the host variable arrays HVA1, HVA2, and HVA3 have been declared
and populated with the values that are to be inserted into the ACTNO, ACTKWD,
and ACTDESC columns. The NUM-ROWS host variable specifies the number of
rows that are to be inserted, which must be less than or equal to the dimension of
each host variable array.
Related tasks
“Retrieving multiple rows of data into host variable arrays” on page 160

Retrieving a single row of data into a host structure

If you know that your query returns multiple column values for only one row, you
can specify a host structure to contain the column values.

In the following example, assume that your COBOL program includes the
following SQL statement:
EXEC SQL
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, WORKDEPT
INTO :EMPNO, :FIRSTNME, :MIDINIT, :LASTNAME, :WORKDEPT
FROM DSN8910.VEMP
WHERE EMPNO = :EMPID
END-EXEC.

If you want to avoid listing host variables, you can substitute the name of a
structure, say :PEMP, that contains :EMPNO, :FIRSTNME, :MIDINIT, :LASTNAME,
and :WORKDEPT. The example then reads:
EXEC SQL
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, WORKDEPT
INTO :PEMP
FROM DSN8910.VEMP
WHERE EMPNO = :EMPID
END-EXEC.

You can declare a host structure yourself, or you can use DCLGEN to generate a
COBOL record description, PL/I structure declaration, or C structure declaration
that corresponds to the columns of a table.

Chapter 3. Coding SQL statements in application programs: General information 161

Related concepts
“DCLGEN (declarations generator)” on page 129
“Host structures” on page 144
“Example: Adding DCLGEN declarations to a library” on page 137

Including dynamic SQL in your program

Dynamic SQL is prepared and executed while the program is running. Before you
use dynamic SQL, you should consider whether static SQL or dynamic SQL is the
best technique for your application. Also consider the type of dynamic SQL that
you want to use.

Dynamic SQL
Dynamic SQL statements are prepared and executed while the program is running.
Use dynamic SQL when you do not know what SQL statements your application
needs to execute before run time.

Before you decide to use dynamic SQL, you should consider whether using static
SQL or dynamic SQL is the best technique for your application.

For most DB2 users, static SQL, which is embedded in a host language program
and bound before the program runs, provides a straightforward, efficient path to
DB2 data. You can use static SQL when you know before run time what SQL
statements your application needs to execute.

Dynamic SQL prepares and executes the SQL statements within a program, while
the program is running. Four types of dynamic SQL are:
v Interactive SQL
| A user enters SQL statements through SPUFI or the command line processor.
| DB2 prepares and executes those statements as dynamic SQL statements.
v Embedded dynamic SQL
Your application puts the SQL source in host variables and includes PREPARE
and EXECUTE statements that tell DB2 to prepare and run the contents of those
host variables at run time. You must precompile and bind programs that include
embedded dynamic SQL.
v Deferred embedded SQL
Deferred embedded SQL statements are neither fully static nor fully dynamic.
Like static statements, deferred embedded SQL statements are embedded within
applications, but like dynamic statements, they are prepared at run time. DB2
processes deferred embedded SQL statements with bind-time rules. For example,
DB2 uses the authorization ID and qualifier determined at bind time as the plan
or package owner. Deferred embedded SQL statements are used for DB2 private
protocol access to remote data.
v Dynamic SQL executed through ODBC functions
Your application contains ODBC function calls that pass dynamic SQL
statements as arguments. You do not need to precompile and bind programs
that use ODBC function calls.

Differences between static and dynamic SQL:

Static and dynamic SQL are each appropriate for different circumstances. You
should consider the differences between the two when determining whether static
SQL or dynamic SQL is best for your application.

162 Application Programming and SQL Guide

Flexibility of static SQL with host variables

When you use static SQL, you cannot change the form of SQL statements unless
you make changes to the program. However, you can increase the flexibility of
static statements by using host variables.

Example: In the following example, the UPDATE statement can update the salary
of any employee. At bind time, you know that salaries must be updated, but you
do not know until run time whose salaries should be updated, and by how much.
01 IOAREA.
02 EMPID PIC X(06).
. 02 NEW-SALARY PIC S9(7)V9(2) COMP-3.
.
.
(Other declarations)
READ CARDIN RECORD INTO IOAREA
. AT END MOVE 'N' TO INPUT-SWITCH.
.
.
(Other COBOL statements)
EXEC SQL
UPDATE DSN8910.EMP
SET SALARY = :NEW-SALARY
WHERE EMPNO = :EMPID
END-EXEC.

The statement (UPDATE) does not change, nor does its basic structure, but the
input can change the results of the UPDATE statement.

Flexibility of dynamic SQL

What if a program must use different types and structures of SQL statements? If
there are so many types and structures that it cannot contain a model of each one,
your program might need dynamic SQL.

| You can use one of the following programs to execute dynamic SQL:
| DB2 Query Management Facility (DB2 QMF™)
| Provides an alternative interface to DB2 that accepts almost any SQL statement
| SPUFI
| Accepts SQL statements from an input data set, and then processes and
| executes them dynamically
| command line processor
| Accepts SQL statements from a UNIX® System Services environment.

Limitations of dynamic SQL

You cannot use some of the SQL statements dynamically.

Dynamic SQL processing

A program that provides for dynamic SQL accepts as input, or generates, an SQL
statement in the form of a character string. You can simplify the programming if
you can plan the program not to use SELECT statements, or to use only those that
return a known number of values of known types. In the most general case, in
which you do not know in advance about the SQL statements that will execute, the
program typically takes these steps:
1. Translates the input data, including any parameter markers, into an SQL
statement

Chapter 3. Coding SQL statements in application programs: General information 163

2. Prepares the SQL statement to execute and acquires a description of the result
table
3. Obtains, for SELECT statements, enough main storage to contain retrieved data
4. Executes the statement or fetches the rows of data
5. Processes the information returned
6. Handles SQL return codes.

Performance of static and dynamic SQL

To access DB2 data, an SQL statement requires an access path. Two big factors in
the performance of an SQL statement are the amount of time that DB2 uses to
determine the access path at run time and whether the access path is efficient. DB2
determines the access path for a statement at either of these times:
v When you bind the plan or package that contains the SQL statement
v When the SQL statement executes

The time at which DB2 determines the access path depends on these factors:
v Whether the statement is executed statically or dynamically
v Whether the statement contains input host variables

Static SQL statements with no input host variables

For static SQL statements that do not contain input host variables, DB2 determines
the access path when you bind the plan or package. This combination yields the
best performance because the access path is already determined when the program
executes.

Static SQL statements with input host variables

| For static SQL statements that have input host variables, the time at which DB2
| determines the access path depends on which bind option you specify:
| REOPT(NONE), REOPT(ONCE), or REOPT(ALWAYS). REOPT(NONE) is the
| default. Do not specify REOPT(AUTO); this option is applicable only to dynamic
| statements. DB2 ignores REOPT(AUTO) for static SQL statements, because DB2 can
| cache only dynamic statements.

If you specify REOPT(NONE), DB2 determines the access path at bind time, just as
it does when there are no input variables.

DB2 ignores REOPT(ONCE) for static SQL statements because DB2 can cache only
dynamic SQL statements

If you specify REOPT(ALWAYS), DB2 determines the access path at bind time and
again at run time, using the values in these types of input variables:
v Host variables
v Parameter markers
v Special registers

This means that DB2 must spend extra time determining the access path for
statements at run time, but if DB2 determines a significantly better access path
using the variable values, you might see an overall performance improvement. In
general, using REOPT(ALWAYS) can make static SQL statements with input
variables perform like dynamic SQL statements with constants.

164 Application Programming and SQL Guide

Dynamic SQL statements

For dynamic SQL statements, DB2 determines the access path at run time, when
the statement is prepared. This can make the performance worse than that of static
SQL statements. However, if you execute the same SQL statement often, you can
use the dynamic statement cache to decrease the number of times that those
dynamic statements must be prepared.

| Dynamic SQL statements with input host variables: When you bind applications
| that contain dynamic SQL statements with input host variables, use the
| REOPT(ALWAYS) option, the REOPT(ONCE) option, or the REOPT(AUTO) option.

Use REOPT(ALWAYS) when you are not using the dynamic statement cache. DB2
determines the access path for statements at each EXECUTE or OPEN of the
statement. This ensure the best access path for a statement, but using
REOPT(ALWAYS) can increase the cost of frequently used dynamic SQL
statements.

| Use REOPT(ONCE) or REOPT(AUTO) when you are using the dynamic statements
| cache:
| v If you specify REOPT(ONCE), DB2 determines and the access path for
| statements only at the first EXECUTE or OPEN of the statement. It saves that
| access path in the dynamic statement cache and uses it until the statement is
| invalidated or removed from the cache. This reuse of the access path reduces the
| cost of frequently used dynamic SQL statements that contain input host
| variables; however, it does not account for changes to parameter marker values
| for dynamic statements.
| v If you specify REOPT(AUTO), DB2 determines the access path at run time. For
| each execution of a statement with parameter markers, DB2 generates a new
| access path if it determines that a new access path will improve performance.

| You should code your PREPARE statements to minimize overhead. With

| REOPT(AUTO), REOPT(ALWAYS), and REOPT(ONCE), DB2 prepares an SQL
| statement at the same time as it processes OPEN or EXECUTE for the statement.
| That is, DB2 processes the statement as if you specify DEFER(PREPARE). However,
| in the following cases, DB2 prepares the statement twice:
| v If you execute the DESCRIBE statement before the PREPARE statement in your
| program
| v If you use the PREPARE statement with the INTO parameter
| For the first prepare, DB2 determines the access path without using input variable
| values. For the second prepare, DB2 uses the input variable values to determine
| the access path. This extra prepare can decrease performance.

If you specify REOPT(ALWAYS), DB2 prepares the statement twice each time it is
run.

If you specify REOPT(ONCE), DB2 prepares the statement twice only when the
statement has never been saved in the cache. If the statement has been prepared
and saved in the cache, DB2 will use the saved version of the statement to
complete the DESCRIBE statement.

Chapter 3. Coding SQL statements in application programs: General information 165

If you specify REOPT(AUTO), DB2 initially prepares the statement without using
input variable values. If the statement has been saved in the cache, for the
subsequent OPEN or EXECUTE, DB2 determines if a new access path is needed
according to the input variable values.

For a statement that uses a cursor, you can avoid the double prepare by placing
the DESCRIBE statement after the OPEN statement in your program.

If you use predictive governing, and a dynamic SQL statement that is bound with
either REOPT(ALWAYS) or REOPT(ONCE) exceeds a predictive governing warning
threshold, your application does not receive a warning SQLCODE. However, it will
receive an error SQLCODE from the OPEN or EXECUTE statement.

Possible host languages for dynamic SQL applications

Programs that use dynamic SQL are usually written in assembler, C, PL/I, REXX,
and COBOL. All SQL in REXX programs is dynamic SQL.

You can write non-SELECT and fixed-list SELECT statements in any of the DB2
supported languages. A program containing a varying-list SELECT statement is
more difficult to write in Fortran, because the program cannot run without the
help of a subroutine to manage address variables (pointers) and storage allocation.

Most of the examples in this topic are in PL/I. Longer examples in the form of
complete programs are available in the sample applications:
DSNTEP2
Processes both SELECT and non-SELECT statements dynamically. (PL/I).
DSNTIAD
Processes only non-SELECT statements dynamically. (Assembler).
DSNTIAUL
Processes SELECT statements dynamically. (Assembler).

Library prefix.SDSNSAMP contains the sample programs. You can view the
programs online, or you can print them using ISPF, IEBPTPCH, or your own
printing program.

You can use all forms of dynamic SQL in all supported versions of COBOL.
Related concepts
“Sample COBOL dynamic SQL program” on page 333

Including dynamic SQL for non-SELECT statements in your

program
The easiest way to use dynamic SQL is to use non-SELECT statements. Because
you do not need to dynamically allocate any main storage, you can write your
program in any host language, including Fortran.

Your program must take the following steps:

1. Include an SQLCA. The requirements for an SQL communications area
(SQLCA) are the same as for static SQL statements. For REXX, DB2 includes the
SQLCA automatically.
2. Load the input SQL statement into a data area. The procedure for building or
reading the input SQL statement is not discussed here; the statement depends
on your environment and sources of information. You can read in complete
SQL statements, or you can get information to build the statement from data

166 Application Programming and SQL Guide

sets, a user at a terminal, previously set program variables, or tables in the
database. If you attempt to execute an SQL statement dynamically that DB2
does not allow, you get an SQL error.
3. Execute the statement. You can use either of these methods:
v EXECUTE IMMEDIATE
v PREPARE and EXECUTE
4. Handle any errors that might result. The requirements are the same as those for
static SQL statements. The return code from the most recently executed SQL
statement appears in the host variables SQLCODE and SQLSTATE or
corresponding fields of the SQLCA.
Related concepts
“Sample dynamic and static SQL in a C program” on page 285
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related tasks
“Checking the execution of SQL statements” on page 202
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189

Including dynamic SQL for fixed-list SELECT statements in your

program
A fixed-list SELECT statement returns rows that contain a known number of
values of a known type. When you use this type of statement, you know in
advance exactly what kinds of host variables you need to declare to store the
results.

The term “fixed-list” does not imply that you must know in advance how many
rows of data will be returned. However, you must know the number of columns
and the data types of those columns. A fixed-list SELECT statement returns a result
table that can contain any number of rows; your program looks at those rows one
at a time, using the FETCH statement. Each successive fetch returns the same
number of values as the last, and the values have the same data types each time.
Therefore, you can specify host variables as you do for static SQL.

An advantage of the fixed-list SELECT is that you can write it in any of the
programming languages that DB2 supports. Varying-list dynamic SELECT
statements require assembler, C, PL/I, and COBOL.

To execute a fixed-list SELECT statement dynamically, your program must:

1. Include an SQLCA.
2. Load the input SQL statement into a data area. The preceding two steps are
exactly the same including dynamic SQL for non-SELECT statements in your
program.
3. Declare a cursor for the statement name.
4. Prepare the statement.

Chapter 3. Coding SQL statements in application programs: General information 167

5. Open the cursor.
6. Fetch rows from the result table.
7. Close the cursor.
8. Handle any resulting errors. This step is the same as for static SQL, except for
the number and types of errors that can result.

Example: Suppose that your program retrieves last names and phone numbers by
dynamically executing SELECT statements of this form:
SELECT LASTNAME, PHONENO FROM DSN8910.EMP
WHERE ... ;

The program reads the statements from a terminal, and the user determines the
WHERE clause.

As with non-SELECT statements, your program puts the statements into a

varying-length character variable; call it DSTRING. Eventually you prepare a
statement from DSTRING, but first you must declare a cursor for the statement
and give it a name.

Declaring a cursor for the statement name:

Dynamic SELECT statements cannot use INTO. Therefore, you must use a cursor
to put the results into host variables.

Example: When you declare the cursor, use the statement name (call it STMT), and
give the cursor itself a name (for example, C1):
EXEC SQL DECLARE C1 CURSOR FOR STMT;

Preparing the statement:

Prepare a statement (STMT) from DSTRING.

Example: This is one possible PREPARE statement:

EXEC SQL PREPARE STMT FROM :DSTRING ATTRIBUTES :ATTRVAR;

ATTRVAR contains attributes that you want to add to the SELECT statement, such
as FETCH FIRST 10 ROWS ONLY or OPTIMIZE for 1 ROW. In general, if the
SELECT statement has attributes that conflict with the attributes in the PREPARE
statement, the attributes on the SELECT statement take precedence over the
attributes on the PREPARE statement. However, in this example, the SELECT
statement in DSTRING has no attributes specified, so DB2 uses the attributes in
ATTRVAR for the SELECT statement.

As with non-SELECT statements, the fixed-list SELECT could contain parameter

markers. However, this example does not need them.

To execute STMT, your program must open the cursor, fetch rows from the result
table, and close the cursor.

Opening the cursor:

The OPEN statement evaluates the SELECT statement named STMT.

Example: Without parameter markers, use this statement:

EXEC SQL OPEN C1;

168 Application Programming and SQL Guide

If STMT contains parameter markers, you must use the USING clause of OPEN to
provide values for all of the parameter markers in STMT.

Example: If four parameter markers are in STMT, you need the following
statement:
EXEC SQL OPEN C1 USING :PARM1, :PARM2, :PARM3, :PARM4;

Fetching rows from the result table:

Example: Your program could repeatedly execute a statement such as this:

EXEC SQL FETCH C1 INTO :NAME, :PHONE;

The key feature of this statement is the use of a list of host variables to receive the
values returned by FETCH. The list has a known number of items (in this case,
two items, :NAME and :PHONE) of known data types (both are character strings,
of lengths 15 and 4, respectively).

You can use this list in the FETCH statement only because you planned the
program to use only fixed-list SELECTs. Every row that cursor C1 points to must
contain exactly two character values of appropriate length. If the program is to
handle anything else, it must use the techniques for including dynamic SQL for
varying-list SELECT statements in your program.

Closing the cursor:

This step is the same as for static SQL.

Example: A WHENEVER NOT FOUND statement in your program can name a

routine that contains this statement:
EXEC SQL CLOSE C1;
Related concepts
“Sample dynamic and static SQL in a C program” on page 285
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related tasks
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program”

Including dynamic SQL for varying-list SELECT statements in

your program
A varying-list SELECT statement returns rows that contain an unknown number of
values of unknown type. When you use this type of statement, you do not know
in advance exactly what kinds of host variables you need to declare to store the
results.

Because the varying-list SELECT statement requires pointer variables for the SQL
descriptor area, you cannot issue it from a Fortran program. A Fortran program

Chapter 3. Coding SQL statements in application programs: General information 169

can call a subroutine written in a language that supports pointer variables (such as
PL/I or assembler), if you need to use a varying-list SELECT statement.

What your application program must do for varying-list SELECT statements: To

execute a varying-list SELECT statement dynamically, your program must follow
these steps:
1. Include an SQLCA.
DB2 performs this step for a REXX procedure.
2. Load the input SQL statement into a data area.
3. Prepare and execute the statement. This step is more complex than for fixed-list
SELECTs. It involves the following steps:
a. Include an SQLDA (SQL descriptor area).
DB2 performs this step for a REXX procedure.
b. Declare a cursor and prepare the variable statement.
c. Obtain information about the data type of each column of the result table.
d. Determine the main storage needed to hold a row of retrieved data.
You do not perform this step for a REXX procedure.
e. Put storage addresses in the SQLDA to tell where to put each item of
retrieved data.
f. Open the cursor.
g. Fetch a row.
h. Eventually close the cursor and free main storage.
Additional complications exist for statements with parameter markers.
4. Handle any errors that might result.

Preparing a varying-list SELECT statement:

Suppose that your program dynamically executes SQL statements, but this time
without any limits on their form. Your program reads the statements from a
terminal, and you know nothing about them in advance. They might not even be
SELECT statements.

As with non-SELECT statements, your program puts the statements into a

varying-length character variable; call it DSTRING. Your program goes on to
prepare a statement from the variable and then give the statement a name; call it
STMT.

Now, the program must find out whether the statement is a SELECT. If it is, the
program must also find out how many values are in each row, and what their data
types are. The information comes from an SQL descriptor area (SQLDA).

An SQL descriptor area:

The SQLDA is a structure that is used to communicate with your program, and
storage for it is usually allocated dynamically at run time.

To include the SQLDA in a PL/I or C program, use:

EXEC SQL INCLUDE SQLDA;

For assembler, use this in the storage definition area of a CSECT:

EXEC SQL INCLUDE SQLDA

170 Application Programming and SQL Guide

For COBOL, use:
EXEC SQL INCLUDE SQLDA END-EXEC.

You cannot include an SQLDA in a Fortran, or REXX program.

Obtaining information about the SQL statement:

An SQLDA can contain a variable number of occurrences of SQLVAR, each of

which is a set of five fields that describe one column in the result table of a
SELECT statement.

The number of occurrences of SQLVAR depends on the following factors:

v The number of columns in the result table you want to describe.
v Whether you want the PREPARE or DESCRIBE to put both column names and
labels in your SQLDA. This is the option USING BOTH in the PREPARE or
DESCRIBE statement.
v Whether any columns in the result table are LOB types or distinct types.
The following table shows the minimum number of SQLVAR instances you need
for a result table that contains n columns.
Table 43. Minimum number of SQLVARs for a result table with n columns
Type of DESCRIBE and contents of result
table Not USING BOTH USING BOTH
No distinct types or LOBs n 2*n
Distinct types but no LOBs 2*n 3*n
LOBs but no distinct types 2*n 2*n
LOBs and distinct types 2*n 3*n

An SQLDA with n occurrences of SQLVAR is referred to as a single SQLDA, an

SQLDA with 2*n occurrences of SQLVAR a double SQLDA, an SQLDA with 3*n
occurrences of SQLVAR a triple SQLDA.

A program that admits SQL statements of every kind for dynamic execution has
two choices:
v Provide the largest SQLDA that it could ever need. The maximum number of
columns in a result table is 750, so an SQLDA for 750 columns occupies 33 016
bytes for a single SQLDA, 66 016 bytes for a double SQLDA, or 99 016 bytes for
a triple SQLDA. Most SELECT statements do not retrieve 750 columns, so the
program does not usually use most of that space.
v Provide a smaller SQLDA, with fewer occurrences of SQLVAR. From this the
program can find out whether the statement was a SELECT and, if it was, how
many columns are in its result table. If more columns are in the result than the
SQLDA can hold, DB2 returns no descriptions. When this happens, the program
must acquire storage for a second SQLDA that is long enough to hold the
column descriptions, and ask DB2 for the descriptions again. Although this
technique is more complicated to program than the first, it is more general.
How many columns should you allow? You must choose a number that is large
enough for most of your SELECT statements, but not too wasteful of space; 40 is
a good compromise. To illustrate what you must do for statements that return
more columns than allowed, the example in this discussion uses an SQLDA that
is allocated for at least 100 columns.

Chapter 3. Coding SQL statements in application programs: General information 171

Declaring a cursor for the statement:

As before, you need a cursor for the dynamic SELECT. For example, write:
EXEC SQL
DECLARE C1 CURSOR FOR STMT;

Preparing the statement using the minimum SQLDA:

Suppose that your program declares an SQLDA structure with the name
MINSQLDA, having 100 occurrences of SQLVAR and SQLN set to 100. To prepare
a statement from the character string in DSTRING and also enter its description
into MINSQLDA, write this:
EXEC SQL PREPARE STMT FROM :DSTRING;
EXEC SQL DESCRIBE STMT INTO :MINSQLDA;

Equivalently, you can use the INTO clause in the PREPARE statement:
EXEC SQL
PREPARE STMT INTO :MINSQLDA FROM :DSTRING;

Do not use the USING clause in either of these examples. At the moment, only the
minimum SQLDA is in use. The following figure shows the contents of the
minimum SQLDA in use.

Header SQLDAID SQLDABC 100 SQLD

Figure 13. The minimum SQLDA structure

SQLN determines what SQLVAR gets:

The SQLN field, which you must set before using DESCRIBE (or PREPARE INTO),
tells how many occurrences of SQLVAR the SQLDA is allocated for. If DESCRIBE
needs more than that, the results of the DESCRIBE depend on the contents of the
result table. Let n indicate the number of columns in the result table. Then:
v If the result table contains at least one distinct type column but no LOB
columns, you do not specify USING BOTH, and n<=SQLN<2*n, then DB2
returns base SQLVAR information in the first n SQLVAR occurrences, but no
distinct type information. Base SQLVAR information includes:
– Data type code
– Length attribute (except for LOBs)
– Column name or label
– Host variable address
– Indicator variable address
v Otherwise, if SQLN is less than the minimum number of SQLVARs specified in
the table above, then DB2 returns no information in the SQLVARs.

Regardless of whether your SQLDA is big enough, whenever you execute

DESCRIBE, DB2 returns the following values, which you can use to build an
SQLDA of the correct size:
v SQLD is 0 if the SQL statement is not a SELECT. Otherwise, SQLD is the
number of columns in the result table. The number of SQLVAR occurrences you
need for the SELECT depends on the value in the seventh byte of SQLDAID.
v The seventh byte of SQLDAID is 2 if each column in the result table requires
two SQLVAR entries. The seventh byte of SQLDAID is 3 if each column in the
result table requires three SQLVAR entries.

172 Application Programming and SQL Guide

If the statement is not a SELECT:

To find out if the statement is a SELECT, your program can query the SQLD field
in MINSQLDA. If the field contains 0, the statement is not a SELECT, the
statement is already prepared, and your program can execute it. If no parameter
markers are in the statement, you can use:
EXEC SQL EXECUTE STMT;

(If the statement does contain parameter markers, you must use an SQL descriptor
area)

Acquiring storage for a second SQLDA if needed:

Now you can allocate storage for a second, full-size SQLDA; call it FULSQLDA.
The following figure shows its structure.

Figure 14. The full-size SQLDA structure

FULSQLDA has a fixed-length header of 16 bytes in length, followed by a

varying-length section that consists of structures with the SQLVAR format. If the
result table contains LOB columns or distinct type columns, a varying-length
section that consists of structures with the SQLVAR2 format follows the structures
with SQLVAR format. All SQLVAR structures and SQLVAR2 structures are 44 bytes
long. The number of SQLVAR and SQLVAR2 elements you need is in the SQLD
field of MINSQLDA, and the total length you need for FULSQLDA (16 + SQLD *
44) is in the SQLDABC field of MINSQLDA. Allocate that amount of storage.

Describing the SELECT statement again:

After allocating sufficient space for FULSQLDA, your program must take these
steps:

Chapter 3. Coding SQL statements in application programs: General information 173

1. Put the total number of SQLVAR and SQLVAR2 occurrences in FULSQLDA into
the SQLN field of FULSQLDA. This number appears in the SQLD field of
MINSQLDA.
2. Describe the statement again into the new SQLDA:
EXEC SQL DESCRIBE STMT INTO :FULSQLDA;

After the DESCRIBE statement executes, each occurrence of SQLVAR in the

full-size SQLDA (FULSQLDA in our example) contains a description of one
column of the result table in five fields. If an SQLVAR occurrence describes a LOB
column or distinct type column, the corresponding SQLVAR2 occurrence contains
additional information specific to the LOB or distinct type.

The following figure shows an SQLDA that describes two columns that are not
LOB columns or distinct type columns.

SQLDA header SQLDA 8816 200 200

SQLVAR element 1 (44 bytes) 452 3 Undefined 0 8 WORKDEPT

SQLVAR element 2 (44 bytes) 453 4 Undefined 0 7 PHONENO

Figure 15. Contents of FULSQLDA after executing DESCRIBE

Acquiring storage to hold a row:

Before fetching rows of the result table, your program must:

1. Analyze each SQLVAR description to determine how much space you need for
the column value.
2. Derive the address of some storage area of the required size.
3. Put this address in the SQLDATA field.

If the SQLTYPE field indicates that the value can be null, the program must also
put the address of an indicator variable in the SQLIND field. The following figures
show the SQL descriptor area after you take certain actions.

In the previous figure, the DESCRIBE statement inserted all the values except the
first occurrence of the number 200. The program inserted the number 200 before it
executed DESCRIBE to tell how many occurrences of SQLVAR to allow. If the
result table of the SELECT has more columns than this, the SQLVAR fields describe
nothing.

The first SQLVAR pertains to the first column of the result table (the WORKDEPT
column). SQLVAR element 1 contains fixed-length character strings and does not
allow null values (SQLTYPE=452); the length attribute is 3.

The following figure shows the SQLDA after your program acquires storage for the
column values and their indicators, and puts the addresses in the SQLDATA fields
of the SQLDA.

174 Application Programming and SQL Guide

SQLDA header SQLDA 8816 200 200

SQLVAR element 1 (44 bytes) 452 3 Addr FLDA Addr FLDAI 8 WORKDEPT
SQLVAR element 2 (44 bytes) 453 4 Addr FLDB Addr FLDBI 7 PHONENO

Indicator variables
FLDA FLDB (halfword)
CHAR(3) CHAR(4) FLDAI FLDBI

Figure 16. SQL descriptor area after analyzing descriptions and acquiring storage

The following figure shows the SQLDA after your program executes a FETCH
statement.

SQLDA header SQLDA 8816 200 200

SQLVAR element 1 (44 bytes) 452 3 Addr FLDA Addr FLDAI 8 WORKDEPT
SQLVAR element 2 (44 bytes) 453 4 Addr FLDB Addr FLDBI 7 PHONENO

Indicator variables
FLDA FLDB (halfword)
CHAR(3) CHAR(4) FLDAI FLDBI
E11 4502 0 0

Figure 17. SQL descriptor area after executing FETCH

The following table describes the values in the descriptor area.

Table 44. Values inserted in the SQLDA
Value Field Description
SQLDA SQLDAID An “eye-catcher”
8816 SQLDABC The size of the SQLDA in bytes (16 + 44 * 200)
200 SQLN The number of occurrences of SQLVAR, set by the
program
200 SQLD The number of occurrences of SQLVAR actually used
by the DESCRIBE statement
452 SQLTYPE The value of SQLTYPE in the first occurrence of
SQLVAR. It indicates that the first column contains
fixed-length character strings, and does not allow
nulls.
3 SQLLEN The length attribute of the column
Undefined or SQLDATA Bytes 3 and 4 contain the CCSID of a string column.
CCSID value Undefined for other types of columns.
Undefined SQLIND
8 SQLNAME The number of characters in the column name
WORKDEPT SQLNAME+2 The column name of the first column

Putting storage addresses in the SQLDA:

Chapter 3. Coding SQL statements in application programs: General information 175

After analyzing the description of each column, your program must replace the
content of each SQLDATA field with the address of a storage area large enough to
hold values from that column. Similarly, for every column that allows nulls, the
program must replace the content of the SQLIND field. The content must be the
address of a halfword that you can use as an indicator variable for the column.
The program can acquire storage for this purpose, of course, but the storage areas
used do not have to be contiguous.

Figure 16 on page 175 shows the content of the descriptor area before the program
obtains any rows of the result table. Addresses of fields and indicator variables are
already in the SQLVAR.

Changing the CCSID for retrieved data:

All DB2 string data has an encoding scheme and CCSID associated with it. When
you select string data from a table, the selected data generally has the same
encoding scheme and CCSID as the table. If the application uses some method,
such as issuing the DECLARE VARIABLE statement, to change the CCSID of the
selected data, the data is converted from the CCSID of the table to the CCSID that
is specified by the application.

You can set the default application encoding scheme for a plan or package by
specifying the value in the APPLICATION ENCODING field of the panel
DEFAULTS FOR BIND PACKAGE or DEFAULTS FOR BIND PLAN. The default
application encoding scheme for the DB2 subsystem is the value that was specified
in the APPLICATION ENCODING field of installation panel DSNTIPF.

If you want to retrieve the data in an encoding scheme and CCSID other than the
default values, you can use one of the following techniques:
v For dynamic SQL, set the CURRENT APPLICATION ENCODING SCHEME
special register before you execute the SELECT statements. For example, to set
the CCSID and encoding scheme for retrieved data to the default CCSID for
Unicode, execute this SQL statement:
EXEC SQL SET CURRENT APPLICATION ENCODING SCHEME ='UNICODE';

The initial value of this special register is the application encoding scheme that
is determined by the BIND option.
v For static and dynamic SQL statements that use host variables and host variable
arrays, use the DECLARE VARIABLE statement to associate CCSIDs with the
host variables into which you retrieve the data. See “Setting the CCSID for host
variables” on page 146 for information about this technique.
v For static and dynamic SQL statements that use a descriptor, set the CCSID for
the retrieved data in the SQLDA. The following text describes that technique.

To change the encoding scheme for SQL statements that use a descriptor, set up the
SQLDA, and then make these additional changes to the SQLDA:
1. Put the character + in the sixth byte of field SQLDAID.
2. For each SQLVAR entry:
a. Set the length field of SQLNAME to 8.
b. Set the first two bytes of the data field of SQLNAME to X’0000’.
c. Set the third and fourth bytes of the data field of SQLNAME to the CCSID,
in hexadecimal, in which you want the results to display, or to X’0000’.
X’0000’ indicates that DB2 should use the default CCSID If you specify a
nonzero CCSID, it must meet one of the following conditions:

176 Application Programming and SQL Guide

v A row in catalog table SYSSTRINGS has a matching value for
OUTCCSID.
v The Unicode conversion services support conversion to that CCSID. See
z/OS C/C++ Programming Guide for information about the conversions
supported.
If you are modifying the CCSID to retrieve the contents of an ASCII,
EBCDIC, or Unicode table on a DB2 for z/OS system, and you previously
executed a DESCRIBE statement on the SELECT statement that you are
using to retrieve the data, the SQLDATA fields in the SQLDA that you used
for the DESCRIBE contain the ASCII or Unicode CCSID for that table. To set
the data portion of the SQLNAME fields for the SELECT, move the contents
of each SQLDATA field in the SQLDA from the DESCRIBE to each
SQLNAME field in the SQLDA for the SELECT. If you are using the same
SQLDA for the DESCRIBE and the SELECT, be sure to move the contents of
the SQLDATA field to SQLNAME before you modify the SQLDATA field
for the SELECT.
For REXX, you set the CCSID in the stem.n.SQLUSECCSID field instead of
setting the SQLDAID and SQLNAME fields.

For example, suppose that the table that contains WORKDEPT and PHONENO is
defined with CCSID ASCII. To retrieve data for columns WORKDEPT and
PHONENO in ASCII CCSID 437 (X’01B5’), change the SQLDA as shown in the
following figure.

SQLDA header SQLDA+ 8816 200 200

SQLVAR element 1 (44 bytes) 452 3 Addr FLDA Addr FLDAI 8 X 000001B500000000
SQLVAR element 2 (44 bytes) 453 4 Addr FLDB Addr FLDBI 8 X 000001B500000000

Indicator variables
FLDA FLDB (halfword)
CHAR(3) CHAR(4) FLDAI FLDBI

Figure 18. SQL descriptor area for retrieving data in ASCII CCSID 437

Specifying that DESCRIBE use column labels in the SQLNAME field:

By default, DESCRIBE describes each column in the SQLNAME field by the

column name. You can tell it to use column labels instead.

Restriction: You cannot use column labels with set operators (UNION,
INTERSECT, and EXCEPT).

To specify that DESCRIBE use column labels in the SQLNAME field, specify one of
the following options when you issue the DESCRIBE statement:
USING LABELS
Specifies that SQLNAME is to contain labels. If a column has no label,
SQLNAME contains nothing.
USING ANY
Specifies that SQLNAME is to contain labels wherever they exist. If a column
has no label, SQLNAME contains the column name.

Chapter 3. Coding SQL statements in application programs: General information 177

USING BOTH
Specifies that SQLNAME is to contain both labels and column names, when
both exist.
In this case, FULSQLDA must contain a second set of occurrences of SQLVAR.
The first set contains descriptions of all the columns with column names; the
second set contains descriptions with column labels.
If you choose this option, perform the following actions:
v Allocate a longer SQLDA for the second DESCRIBE statement ((16 + SQLD *
88 bytes) instead of (16 + SQLD * 44))
v Put double the number of columns (SLQD * 2) in the SQLN field of the
second SQLDA.
These actions ensure that enough space is available. Otherwise, if not enough
space is available, DESCRIBE does not enter descriptions of any of the
columns.
EXEC SQL
DESCRIBE STMT INTO :FULSQLDA USING LABELS;

| Some columns, such as those derived from functions or expressions, have neither
| name nor label; SQLNAME contains nothing for those columns. For example, if
| you use a UNION to combine two columns that do not have the same name and
| do not use a label, SQLNAME contains a string of length zero.

Describing tables with LOB and distinct type columns:

In general, the steps that you perform when you prepare an SQLDA to select rows
from a table with LOB and distinct type columns are similar to the steps that you
perform if the table has no columns of this type. The only difference is that you
need to analyze some additional fields in the SQLDA for LOB or distinct type
columns.

Example: Suppose that you want to execute this SELECT statement:

SELECT USER, A_DOC FROM DOCUMENTS;

The USER column cannot contain nulls and is of distinct type ID, defined like this:
CREATE DISTINCT TYPE SCHEMA1.ID AS CHAR(20);

The A_DOC column can contain nulls and is of type CLOB(1M).

The result table for this statement has two columns, but you need four SQLVAR
occurrences in your SQLDA because the result table contains a LOB type and a
distinct type. Suppose that you prepare and describe this statement into
FULSQLDA, which is large enough to hold four SQLVAR occurrences. FULSQLDA
looks like the following figure .

178 Application Programming and SQL Guide

SQLDA header SQLDA 2 192 4 4

SQLVAR element 1 (44 bytes) 452 20 Undefined 0 4 USER

SQLVAR element 2 (44 bytes) 409 0 Undefined 0 5 A_DOC
SQLVAR2 element 1 (44 bytes) 7 SCH1.ID
SQLVAR2 element 2 (44 bytes) 1 048 576 11 SYSIBM.CLOB

Figure 19. SQL descriptor area after describing a CLOB and distinct type

The next steps are the same as for result tables without LOBs or distinct types:
1. Analyze each SQLVAR description to determine the maximum amount of space
you need for the column value.
For a LOB type, retrieve the length from the SQLLONGL field instead of the
SQLLEN field.
2. Derive the address of some storage area of the required size.
For a LOB data type, you also need a 4-byte storage area for the length of the
LOB data. You can allocate this 4-byte area at the beginning of the LOB data or
in a different location.
3. Put this address in the SQLDATA field.
For a LOB data type, if you allocated a separate area to hold the length of the
LOB data, put the address of the length field in SQLDATAL. If the length field
is at beginning of the LOB data area, put 0 in SQLDATAL. When you use a file
reference variable for a LOB column, the indicator variable indicates whether
the data in the file is null, not whether the data to which SQLDATA points is
null.
4. If the SQLTYPE field indicates that the value can be null, the program must
also put the address of an indicator variable in the SQLIND field.

The following figure shows the contents of FULSQLDA after you fill in pointers to
the storage locations.

Figure 20. SQL descriptor area after analyzing CLOB and distinct type descriptions and acquiring storage

The following figure shows the contents of FULSQLDA after you execute a FETCH
statement.

Chapter 3. Coding SQL statements in application programs: General information 179

Figure 21. SQL descriptor area after executing FETCH on a table with CLOB and distinct type columns

Setting an XML host variable in an SQLDA:

Instead of specifying host variables to store XML values from a table, you can
create an SQLDA to point to the data areas where DB2 puts the retrieved data. The
SQLDA needs to describe the data type for each data area.

To set an XML host variable in an SQLDA:

1. Allocate an appropriate SQLDA.
2. Issue a DESCRIBE statement for the SQL statement whose result set you want
to store. The DESCRIBE statement populates the SQLDA based on the column
definitions. In the SQLDA, an SQLVAR entry is populated for each column in
the result set. (Multiple SQLVAR entries are populated for LOB columns and
columns with distinct types.) For columns of type XML the associated SQLVAR
entry is populated as follows:
Table 45. SQLVAR field values for XML columns
SQLVAR field Value for an XML column

sqltype 988 for a column that is not nullable

SQLTYPE or 989 for a nullable column
0
sqllen
SQLLEN
0
sqldata
SQLDATA
0
sqlind
SQLIND
The unqualified name or label of the column
sqlname
SQLNAME

3. Check the SQLTYPE field of each SQLVAR entry. If the SQLTYPE field is 988 or
989, the column in the result set is an XML column.

180 Application Programming and SQL Guide

4. For each XML column, make the following changes to the associated SQLVAR
entry:
a. Change the SQLTYPE field to indicate the data type of the host variable to
receive the XML data. You can retrieve the XML data into a host variable of
type XML AS BLOB, XML AS CLOB, or XML AS DBCLOB, or a compatible
string data type.
If the target host variable type is XML AS BLOB, XML AS CLOB, or XML
AS DBCLOB, set the SQLTYPE field to one of the following values:
404
XML AS BLOB
405
nullable XML AS BLOB
408
XML AS CLOB
409
nullable XML AS CLOB
412
XML AS DBCLOB
413
nullable XML AS DBCLOB
If the target host variable type is a string data type, set the SQLTYPE field
to a valid string value.

Restriction: You cannot use the XML type (988/989) as a target host
variable type.
b. If the target host variable type is XML AS BLOB, XML AS CLOB, or XML
AS DBCLOB, change the first two bytes in the SQLNAME field to X’0000’
and the fifth and sixth bytes to X’0100’. These bytes indicate that the value
to be received is an XML value.
5. Populate the extended SQLVAR fields for each XML column as you would for a
LOB column, as indicated in the following table.
Table 46. Fields for an extended SQLVAR entry for an XML host variable
SQLVAR field Value for an XML host variable
length attribute for the XML host variable
len.sqllonglen
SQLLONGL
SQLLONGLEN
* Reserved
pointer to the length of the XML host variable
sqldatalen
SQLDATAL
SQLDATALEN
not used
sqldatatype_name
SQLTNAME
SQLDATATYPENAME

Chapter 3. Coding SQL statements in application programs: General information 181

You can now use the SQLDA to retrieve the XML data into a host variable of type
XML AS BLOB, XML AS CLOB, or XML AS DBCLOB, or a compatible string data
type.

Executing a varying-list SELECT statement dynamically:

You can easily retrieve rows of the result table using a varying-list SELECT
statement. The statements differ only a little from those for the fixed-list example.

Open the cursor: If the SELECT statement contains no parameter marker, this step
is simple enough. For example:
EXEC SQL OPEN C1;

Fetch rows from the result table: This statement differs from the corresponding
one for the case of a fixed-list select. Write:
EXEC SQL
FETCH C1 USING DESCRIPTOR :FULSQLDA;

The key feature of this statement is the clause USING DESCRIPTOR :FULSQLDA.
That clause names an SQL descriptor area in which the occurrences of SQLVAR
point to other areas. Those other areas receive the values that FETCH returns. It is
possible to use that clause only because you previously set up FULSQLDA to look
like Figure 15 on page 174.

Figure 17 on page 175 shows the result of the FETCH. The data areas identified in
the SQLVAR fields receive the values from a single row of the result table.

Successive executions of the same FETCH statement put values from successive
rows of the result table into these same areas.

Close the cursor: This step is the same as for the fixed-list case. When no more
rows need to be processed, execute the following statement:
EXEC SQL CLOSE C1;

When COMMIT ends the unit of work containing OPEN, the statement in STMT
reverts to the unprepared state. Unless you defined the cursor using the WITH
HOLD option, you must prepare the statement again before you can reopen the
cursor.

Executing arbitrary statements with parameter markers:

Consider, as an example, a program that executes dynamic SQL statements of

several kinds, including varying-list SELECT statements, any of which might
contain a variable number of parameter markers. This program might present your
users with lists of choices: choices of operation (update, select, delete); choices of
table names; choices of columns to select or update. The program also enables the
users to enter lists of employee numbers to apply to the chosen operation. From
this, the program constructs SQL statements of several forms, one of which looks
like this:
SELECT .... FROM DSN8910.EMP
WHERE EMPNO IN (?,?,?,...?);

The program then executes these statements dynamically.

When the number and types of parameters are known: In the preceding example,
you do not know in advance the number of parameter markers, and perhaps the

182 Application Programming and SQL Guide

kinds of parameter they represent. You can use techniques described previously if
you know the number and types of parameters, as in the following examples:
v If the SQL statement is not SELECT, name a list of host variables in the
EXECUTE statement:
WRONG: EXEC SQL EXECUTE STMT;

RIGHT: EXEC SQL EXECUTE STMT USING :VAR1, :VAR2, :VAR3;

v If the SQL statement is SELECT, name a list of host variables in the OPEN
statement:
WRONG: EXEC SQL OPEN C1;

RIGHT: EXEC SQL OPEN C1 USING :VAR1, :VAR2, :VAR3;

In both cases, the number and types of host variables named must agree with the
number of parameter markers in STMT and the types of parameter they represent.
The first variable (VAR1 in the examples) must have the type expected for the first
parameter marker in the statement, the second variable must have the type
expected for the second marker, and so on. There must be at least as many
variables as parameter markers.

When the number and types of parameters are not known: When you do not
know the number and types of parameters, you can adapt the SQL descriptor area.
Your program can include an unlimited number of SQLDAs, and you can use them
for different purposes. Suppose that an SQLDA, arbitrarily named DPARM,
describes a set of parameters.

The structure of DPARM is the same as that of any other SQLDA. The number of
occurrences of SQLVAR can vary, as in previous examples. In this case, every
parameter marker must have one SQLVAR. Each occurrence of SQLVAR describes
one host variable that replaces one parameter marker at run time. DB2 replaces the
parameter markers when a non-SELECT statement executes or when a cursor is
opened for a SELECT statement.

You must fill in certain fields in DPARM before using EXECUTE or OPEN; you
can ignore the other fields.
Field Use when describing host variables for parameter markers
SQLDAID
The seventh byte indicates whether more than one SQLVAR entry is used
for each parameter marker. If this byte is not blank, at least one parameter
marker represents a distinct type or LOB value, so the SQLDA has more
than one set of SQLVAR entries.
You do not set this field for a REXX SQLDA.
SQLDABC
The length of the SQLDA, which is equal to SQLN * 44 + 16. You do not
set this field for a REXX SQLDA.
SQLN The number of occurrences of SQLVAR allocated for DPARM. You do not
set this field for a REXX SQLDA.
SQLD The number of occurrences of SQLVAR actually used. This number must
not be less than the number of parameter markers. In each occurrence of
SQLVAR, put information in the following fields: SQLTYPE, SQLLEN,
SQLDATA, SQLIND.

Chapter 3. Coding SQL statements in application programs: General information 183

SQLTYPE
The code for the type of variable, and whether it allows nulls.
SQLLEN
The length of the host variable.
SQLDATA
The address of the host variable.
For REXX, this field contains the value of the host variable.
SQLIND
The address of an indicator variable, if needed.
For REXX, this field contains a negative number if the value in SQLDATA
is null.
SQLNAME
Ignore.

Using the SQLDA with EXECUTE or OPEN: To indicate that the SQLDA called
DPARM describes the host variables substituted for the parameter markers at run
time, use a USING DESCRIPTOR clause with EXECUTE or OPEN.
v For a non-SELECT statement, write:
EXEC SQL EXECUTE STMT USING DESCRIPTOR :DPARM;
v For a SELECT statement, write:
EXEC SQL OPEN C1 USING DESCRIPTOR :DPARM;

How bind options REOPT(ALWAYS), REOPT(AUTO) and REOPT(ONCE) affect

dynamic SQL:

When you specify the bind option REOPT(ALWAYS), DB2 reoptimizes the access
path at run time for SQL statements that contain host variables, parameter
markers, or special registers. The option REOPT(ALWAYS) has the following effects
on dynamic SQL statements:
v When you specify the option REOPT(ALWAYS), DB2 automatically uses
DEFER(PREPARE), which means that DB2 waits to prepare a statement until it
encounters an OPEN or EXECUTE statement.
v When you execute a DESCRIBE statement and then an EXECUTE statement on a
non-SELECT statement, DB2 prepares the statement twice: Once for the
DESCRIBE statement and once for the EXECUTE statement. DB2 uses the values
in the input variables only during the second PREPARE. These multiple
PREPAREs can cause performance to degrade if your program contains many
dynamic non-SELECT statements. To improve performance, consider putting the
code that contains those statements in a separate package and then binding that
package with the option REOPT(NONE).
v If you execute a DESCRIBE statement before you open a cursor for that
statement, DB2 prepares the statement twice. If, however, you execute a
DESCRIBE statement after you open the cursor, DB2 prepares the statement only
once. To improve the performance of a program bound with the option
REOPT(ALWAYS), execute the DESCRIBE statement after you open the cursor.
To prevent an automatic DESCRIBE before a cursor is opened, do not use a
PREPARE statement with the INTO clause.
v If you use predictive governing for applications bound with REOPT(ALWAYS),
DB2 does not return a warning SQLCODE when dynamic SQL statements
exceed the predictive governing warning threshold. DB2 does return an error

184 Application Programming and SQL Guide

SQLCODE when dynamic SQL statements exceed the predictive governing error
threshold. DB2 returns the error SQLCODE for an EXECUTE or OPEN
statement.

| When you specify the bind option REOPT(AUTO), DB2 optimizes the access path
| for SQL statements at the first EXECUTE or OPEN. Each time a statement is
| executed, DB2 determines if a new access path is needed to improve the
| performance of the statement. If a new access path will improve the performance,
| DB2 generates one. The option REOPT(AUTO) has the following effects on
| dynamic SQL statements:
| v When you specify the bind option REOPT(AUTO), DB2 optimizes the access
| path for SQL statements at the first EXECUTE or OPEN. Each time a statement
| is executed, DB2 determines if a new access path is needed to improve the
| performance of the statement. If a new access path will improve the
| performance, DB2 generates one.
| v When you specify the option REOPT(ONCE), DB2 automatically uses
| DEFER(PREPARE), which means that DB2 waits to prepare a statement until it
| encounters an OPEN or EXECUTE statement.
| v When DB2 prepares a statement using REOPT(AUTO), it saves the access path
| in the dynamic statement cache. This access path is used each time the statement
| is run, until DB2 determines that a new access path is needed to improve the
| performance or the statement that is in the cache is invalidated (or removed
| from the cache) and needs to be rebound.
| v The DESCRIBE statement has the following effects on dynamic statements that
| are bound with REOPT(AUTO):
| – When you execute a DESCRIBE statement before an EXECUTE statement on a
| non-SELECT statement, DB2 prepares the statement an extra time if it is not
| already saved in the cache: Once for the DESCRIBE statement and once for
| the EXECUTE statement. DB2 uses the values of the input variables only
| during the second time the statement is prepared. It then saves the statement
| in the cache. If you execute a DESCRIBE statement before an EXECUTE
| statement on a non-SELECT statement that has already been saved in the
| cache, DB2 will always prepare the non-SELECT statement for the DESCRIBE
| statement, and will prepare the statement again on EXECUTE only if DB2
| determines that a new access path different from the one already saved in the
| cache can improve the performance.
| – If you execute DESCRIBE on a statement before you open a cursor for that
| statement, DB2 always prepares the statement on DESCRIBE. However, DB2
| will not prepare the statement again on OPEN if the statement has already
| been saved in the cache and DB2 doesn’t think that a new access path is
| needed at OPEN time. If you execute DESCRIBE on a statement after you
| open a cursor for that statement, DB2 prepared the statement only once if it is
| not already saved in the cache. If the statement is already saved in the cache
| and you execute DESCRIBE after you open a cursor for that statement, DB2
| does not prepare the statement, it used the statement that is saved in the
| cache.
| v If you use predictive governing for applications that are bound with
| REOPT(AUTO), DB2 does not return a warning SQLCODE when dynamic SQL
| statements exceed the predictive governing warning threshold. DB2 does return
| an error SQLCODE when dynamic SQL statements exceed the predictive
| governing error threshold. DB2 returns the error SQLCODE for an EXECUTE or
| OPEN statement.

Chapter 3. Coding SQL statements in application programs: General information 185

When you specify the bind option REOPT(ONCE), DB2 optimizes the access path
only once, at the first EXECUTE or OPEN, for SQL statements that contain host
variables, parameter markers, or special registers. The option REOPT(ONCE) has
the following effects on dynamic SQL statements:
v When you specify the option REOPT(ONCE), DB2 automatically uses
DEFER(PREPARE), which means that DB2 waits to prepare a statement until it
encounters an OPEN or EXECUTE statement.
v When DB2 prepares a statement using REOPT(ONCE), it saves the access path
in the dynamic statement cache. This access path is used each time the statement
is run, until the statement that is in the cache is invalidated (or removed from
the cache) and needs to be rebound.
v The DESCRIBE statement has the following effects on dynamic statements that
are bound with REOPT(ONCE):
– When you execute a DESCRIBE statement before an EXECUTE statement on a
non-SELECT statement, DB2 prepares the statement twice if it is not already
saved in the cache: Once for the DESCRIBE statement and once for the
EXECUTE statement. DB2 uses the values of the input variables only during
the second time the statement is prepared. It then saves the statement in the
cache. If you execute a DESCRIBE statement before an EXECUTE statement
on a non-SELECT statement that has already been saved in the cache, DB2
prepares the non-SELECT statement only for the DESCRIBE statement.
– If you execute DESCRIBE on a statement before you open a cursor for that
statement, DB2 always prepares the statement on DESCRIBE. However, DB2
will not prepare the statement again on OPEN if the statement has already
been saved in the cache. If you execute DESCRIBE on a statement after you
open a cursor for that statement, DB2 prepared the statement only once if it is
not already saved in the cache. If the statement is already saved in the cache
and you execute DESCRIBE after you open a cursor for that statement, DB2
does not prepare the statement, it used the statement that is saved in the
cache.
To improve the performance of a program that is bound with REOPT(ONCE),
execute the DESCRIBE statement after you open a cursor. To prevent an
automatic DESCRIBE before a cursor is opened, do not use a PREPARE
statement with the INTO clause.
v If you use predictive governing for applications that are bound with
REOPT(ONCE), DB2 does not return a warning SQLCODE when dynamic SQL
statements exceed the predictive governing warning threshold. DB2 does return
an error SQLCODE when dynamic SQL statements exceed the predictive
governing error threshold. DB2 returns the error SQLCODE for an EXECUTE or
OPEN statement.

186 Application Programming and SQL Guide

Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related tasks
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
Related reference
DESCRIBE OUTPUT (SQL Reference)
SQL descriptor area (SQLDA) (SQL Reference)
SQLTYPE and SQLLEN (SQL Reference)
The SQLDA Header (SQL Reference)

Dynamically executing an SQL statement by using EXECUTE

IMMEDIATE
In certain situations, you want your program to prepare and dynamically execute a
statement immediately after reading it.

Suppose that you design a program to read SQL DELETE statements, similar to
these, from a terminal:
DELETE FROM DSN8910.EMP WHERE EMPNO = '000190'
DELETE FROM DSN8910.EMP WHERE EMPNO = '000220'

After reading a statement, the program is to run it immediately.

Recall that you must prepare (precompile and bind) static SQL statements before
you can use them. You cannot prepare dynamic SQL statements in advance. The
SQL statement EXECUTE IMMEDIATE causes an SQL statement to prepare and
execute, dynamically, at run time.

Declaring the host variableBefore you prepare and execute an SQL statement, you
can read it into a host variable. If the maximum length of the SQL statement is 32
KB, declare the host variable as a character or graphic host variable according to
the following rules for the host languages:
| v In assembler, PL/I, COBOL and C, you must declare a string host variable as a
| varying-length string.
| v In Fortran, it must be a fixed-length string variable.
If the length is greater than 32 KB, you must declare the host variable as a CLOB
or DBCLOB, and the maximum is 2 MB.

Example: Using a varying-length character host variable: This excerpt is from a C

program that reads a DELETE statement into the host variable dstring and executes
the statement:

Chapter 3. Coding SQL statements in application programs: General information 187

EXEC SQL BEGIN DECLARE SECTION;
...
struct VARCHAR {
short len;
char s[40];
} dstring;
EXEC SQL END DECLARE SECTION;
...
/* Read a DELETE statement into the host variable dstring. */
gets(dstring);
EXEC SQL EXECUTE IMMEDIATE :dstring;
...

EXECUTE IMMEDIATE causes the DELETE statement to be prepared and executed

immediately.

Declaring a CLOB or DBCLOB host variable: You declare CLOB and DBCLOB
host variables according to certain rules.

The precompiler generates a structure that contains two elements, a 4-byte length
field and a data field of the specified length. The names of these fields vary
depending on the host language:
v In PL/I, assembler, and Fortran, the names are variable_LENGTH and
variable_DATA.
v In COBOL, the names are variable–LENGTH and variable–DATA.
v In C, the names are variable.LENGTH and variable.DATA.

Example: Using a CLOB host variable: This excerpt is from a C program that
copies an UPDATE statement into the host variable string1 and executes the
statement:
EXEC SQL BEGIN DECLARE SECTION;
...
SQL TYPE IS CLOB(4k) string1;
EXEC SQL END DECLARE SECTION;
...
/* Copy a statement into the host variable string1. */
strcpy(string1.data, "UPDATE DSN8610.EMP SET SALARY = SALARY * 1.1");
string1.length = 44;
EXEC SQL EXECUTE IMMEDIATE :string1;
...

EXECUTE IMMEDIATE causes the UPDATE statement to be prepared and

executed immediately.

188 Application Programming and SQL Guide

Related concepts
“LOB host variable, LOB locator, and LOB file reference variable declarations” on
page 705
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405

Dynamically executing an SQL statement by using PREPARE and

EXECUTE
As an alternative to executing an SQL statement immediately after it is read, you
can prepare and execute the SQL statement in two steps. This two-step method is
useful when you need to execute an SQL statement multiple times with different
values.

Suppose that you want to execute DELETE statements repeatedly using a list of
employee numbers. Consider how you would do it if you could write the DELETE
statement as a static SQL statement:
< Read a value for EMP from the list. >
DO UNTIL (EMP = 0);
EXEC SQL
DELETE FROM DSN8910.EMP WHERE EMPNO = :EMP ;
< Read a value for EMP from the list. >
END;

The loop repeats until it reads an EMP value of 0.

If you know in advance that you will use only the DELETE statement and only the
table DSN8910.EMP, you can use the more efficient static SQL. Suppose further
that several different tables have rows that are identified by employee numbers,
and that users enter a table name as well as a list of employee numbers to delete.
Although variables can represent the employee numbers, they cannot represent the
table name, so you must construct and execute the entire statement dynamically.
Your program must now do these things differently:
v Use parameter markers instead of host variables
v Use the PREPARE statement
v Use EXECUTE instead of EXECUTE IMMEDIATE

Parameter markers with PREPARE and EXECUTE: Dynamic SQL statements

cannot use host variables. Therefore, you cannot dynamically execute an SQL
statement that contains host variables. Instead, substitute a parameter marker,
indicated by a question mark (?), for each host variable in the statement.

You can indicate to DB2 that a parameter marker represents a host variable of a
certain data type by specifying the parameter marker as the argument of a CAST
specification. When the statement executes, DB2 converts the host variable to the
data type in the CAST specification. A parameter marker that you include in a
CAST specification is called a typed parameter marker. A parameter marker without
a CAST specification is called an untyped parameter marker.

Recommendation: Because DB2 can evaluate an SQL statement with typed

parameter markers more efficiently than a statement with untyped parameter

Chapter 3. Coding SQL statements in application programs: General information 189

markers, use typed parameter markers whenever possible. Under certain
circumstances you must use typed parameter markers.

Example using parameter markers: Suppose that you want to prepare this
statement:
DELETE FROM DSN8910.EMP WHERE EMPNO = :EMP;

You need to prepare a string like this:

DELETE FROM DSN8910.EMP WHERE EMPNO = CAST(? AS CHAR(6))

You associate host variable :EMP with the parameter marker when you execute the
prepared statement. Suppose that S1 is the prepared statement. Then the EXECUTE
statement looks like this:
EXECUTE S1 USING :EMP;

Using the PREPARE statement: Before you prepare an SQL statement, you can
assign it to a host variable. If the length of the statement is greater than 32 KB, you
must declare the host variable as a CLOB or DBCLOB.

You can think of PREPARE and EXECUTE as an EXECUTE IMMEDIATE done in

two steps. The first step, PREPARE, turns a character string into an SQL statement,
and then assigns it a name of your choosing.

Example using the PREPARE statement: Assume that the character host variable
:DSTRING has the value “DELETE FROM DSN8910.EMP WHERE EMPNO = ?”.
To prepare an SQL statement from that string and assign it the name S1, write:
EXEC SQL PREPARE S1 FROM :DSTRING;

The prepared statement still contains a parameter marker, for which you must
supply a value when the statement executes. After the statement is prepared, the
table name is fixed, but the parameter marker enables you to execute the same
statement many times with different values of the employee number.

Using the EXECUTE statement: The EXECUTE statement executes a prepared SQL
statement by naming a list of one or more host variables, one or more host variable
arrays, or a host structure. This list supplies values for all of the parameter
markers.

After you prepare a statement, you can execute it many times within the same unit
of work. In most cases, COMMIT or ROLLBACK destroys statements prepared in a
unit of work. Then, you must prepare them again before you can execute them
again. However, if you declare a cursor for a dynamic statement and use the
option WITH HOLD, a commit operation does not destroy the prepared statement
if the cursor is still open. You can execute the statement in the next unit of work
without preparing it again.

Example using the EXECUTE statement: To execute the prepared statement S1 just
once, using a parameter value contained in the host variable :EMP, write:
EXEC SQL EXECUTE S1 USING :EMP;

Preparing and executing the example DELETE statement: The example in this
topic began with a DO loop that executed a static SQL statement repeatedly:

190 Application Programming and SQL Guide

< Read a value for EMP from the list. >
DO UNTIL (EMP = 0);
EXEC SQL
DELETE FROM DSN8910.EMP WHERE EMPNO = :EMP ;
< Read a value for EMP from the list. >
END;

You can now write an equivalent example for a dynamic SQL statement:
< Read a statement containing parameter markers into DSTRING.>
EXEC SQL PREPARE S1 FROM :DSTRING;
< Read a value for EMP from the list. >
DO UNTIL (EMPNO = 0);
EXEC SQL EXECUTE S1 USING :EMP;
< Read a value for EMP from the list. >
END;

The PREPARE statement prepares the SQL statement and calls it S1. The EXECUTE
statement executes S1 repeatedly, using different values for EMP.

Using more than one parameter marker: The prepared statement (S1 in the
example) can contain more than one parameter marker. If it does, the USING
clause of EXECUTE specifies a list of variables or a host structure. The variables
must contain values that match the number and data types of parameters in S1 in
the proper order. You must know the number and types of parameters in advance
and declare the variables in your program, or you can use an SQLDA (SQL
descriptor area).
Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related tasks
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
Related reference
PREPARE (SQL Reference)

Dynamically executing a data change statement

| Dynamically executing data change statements with host variable arrays is useful if
| you want to enter rows of data into different tables or enter a different number of
| rows. The process is similar for both INSERT and MERGE statements.

For example, suppose that you want to repeatedly execute a multiple-row INSERT
statement with a list of activity IDs, activity keywords, and activity descriptions
that are provided by the user. You can use the following static SQL INSERT
statement to insert multiple rows of data into the activity table:
EXEC SQL
INSERT INTO DSN8910.ACT
VALUES (:hva_actno, :hva_actkwd, :hva_actdesc)
FOR :num_rows ROWS;

However, if you want to enter the rows of data into different tables or enter
different numbers of rows, you can construct the INSERT statement dynamically.

Chapter 3. Coding SQL statements in application programs: General information 191

This topic describes the following methods that you can use to execute a data
change statement dynamically:
v By using host variable arrays that contain the data to be inserted
v By using a descriptor to describe the host variable arrays that contain the data

Dynamically executing a data change statement by using host variable arrays:

To dynamically execute a data change statement by using host variable arrays,

perform the following actions in your program:
1. Assign the appropriate INSERT or MERGE statement to a host variable. If
needed, use the CAST specification to explicitly assign types to parameter
markers that represent host variable arrays.
Example: For the activity table, the following string contains an INSERT
statement that is to be prepared:
INSERT INTO DSN8910.ACT
VALUES (CAST(? AS SMALLINT), CAST(? AS CHAR(6)), CAST(? AS VARCHAR(20)))
2. Assign any attributes for the SQL statement to a host variable.
3. Include a PREPARE statement for the SQL statement.
4. Include an EXECUTE statement with the FOR n ROWS clause.
Each host variable in the USING clause of the EXECUTE statement represents
an array of values for the corresponding column of the target of the SQL
statement. You can vary the number of rows without needing to prepare the
SQL statement again.

Example: The following code prepares and executes an INSERT statement:

/* Copy the INSERT string into the host variable sqlstmt */
strcpy(sqlstmt, "INSERT INTO DSN8910.ACT VALUES (CAST(? AS SMALLINT),");
strcat(sqlstmt, " CAST(? AS CHAR(6)), CAST(? AS VARCHAR(20)))");

/* Copy the INSERT attributes into the host variable attrvar */

strcpy(attrvar, "FOR MULTIPLE ROWS");

/* Prepare and execute my_insert using the host variable arrays */

EXEC SQL PREPARE my_insert ATTRIBUTES :attrvar FROM :sqlstmt;
EXEC SQL EXECUTE my_insert USING :hva1, :hva2, :hva3 FOR :num_rows ROWS;

Dynamically executing a data change statement by using descriptors:

You can use an SQLDA structure to specify data types and other information about
the host variable arrays that contain the values to insert.

To dynamically execute a data change statement by using descriptors, perform the

following actions in your program:
1. Set the following fields in the SQLDA structure for your INSERT statement.
v SQLN
v SQLABC
v SQLD
v SQLVAR
v SQLNAME
Example: Assume that your program includes the standard SQLDA structure
declaration and declarations for the program variables that point to the SQLDA
structure. For C application programs, the following example code sets the
SQLDA fields:

192 Application Programming and SQL Guide

| strcpy(sqldaptr->sqldaid,"SQLDA");
| sqldaptr->sqldabc = 192; /* number of bytes of storage allocated for the SQLDA */
| sqldaptr->sqln = 4; /* number of SQLVAR occurrences */
| sqldaptr->sqld = 4;
| varptr = (struct sqlvar *) (&(sqldaptr->sqlvar[0])); /* Point to first SQLVAR */
| varptr->sqltype = 500; /* data type SMALLINT */
| varptr->sqllen = 2;
| varptr->sqldata = (char *) hva1;
| varptr->sqlname.length = 8;
| memcpy(varptr->sqlname.data, "\x00\x00\x00\x00\x00\x01\x00\x14",varptr->sqlname.length);
| varptr = (struct sqlvar *) (&(sqldaptr->sqlvar[0]) + 1); /* Point to next SQLVAR */
| varptr->sqltype = 452; /* data type CHAR(6) */
| varptr->sqllen = 6;
| varptr->sqldata = (char *) hva2;
| varptr->sqlname.length = 8;
| memcpy(varptr->sqlname.data, "\x00\x00\x00\x00\x00\x01\x00\x14",varptr->sqlname.length);
| varptr = (struct sqlvar *) (&(sqldaptr->sqlvar[0]) + 2); /* Point to next SQLVAR */
| varptr->sqltype = 448; /* data type VARCHAR(20) */
| varptr->sqllen = 20;
| varptr->sqldata = (char *) hva3;
| varptr->sqlname.length = 8;
| memcpy(varptr->sqlname.data, "\x00\x00\x00\x00\x00\x01\x00\x14",varptr->sqlname.length);

The SQLDA structure has the following fields:

v SQLDABC indicates the number of bytes of storage that are allocated for the
SQLDA. The storage includes a 16-byte header and 44 bytes for each
SQLVAR field. The value is SQLN x 44 + 16, or 192 for this example.
v SQLN is the number of SQLVAR occurrences, plus one for use by DB2 for
the host variable that contains the number n in the FOR n ROWS clause.
v SQLD is the number of variables in the SQLDA that are used by DB2 when
processing the INSERT statement.
v An SQLVAR occurrence specifies the attributes of an element of a host
variable array that corresponds to a value provided for a target column of
the INSERT. Within each SQLVAR:
– SQLTYPE indicates the data type of the elements of the host variable
array.
– SQLLEN indicates the length of a single element of the host variable array.
– SQLDATA points to the corresponding host variable array. Assume that
your program allocates the dynamic variable arrays hva1, hva2, and hva3.
| – SQLNAME has two parts: the LENGTH and the DATA. The LENGTH is
| 8. The first two bytes of the DATA field is X’0000’. Bytes 5 and 6 of the
| DATA field are a flag indicating whether the variable is an array or a FOR
| n ROWS value. Bytes 7 and 8 are a two-byte binary integer representation
| of the dimension of the array.
2. Assign the appropriate INSERT or MERGE statement to a host variable.
Example: The following string contains an INSERT statement that is to be
prepared:
INSERT INTO DSN8910.ACT VALUES (?, ?, ?)
3. Assign any attributes for the SQL statement to a host variable.
4. Include a PREPARE statement for the SQL statement.
5. Include an EXECUTE statement with the FOR n ROWS clause. The host
variable in the USING clause of the EXECUTE statement names the SQLDA
that describes the parameter markers in the INSERT statement.

Example: The following code prepares and executes an INSERT statement:

Chapter 3. Coding SQL statements in application programs: General information 193

/* Copy the INSERT string into the host variable sqlstmt */
strcpy(sqlstmt, "INSERT INTO DSN8910.ACT VALUES (?, ?, ?)");

/* Copy the INSERT attributes into the host variable attrvar */

strcpy(attrvar, "FOR MULTIPLE ROWS");

/* Prepare and execute my_insert using the descriptor */

EXEC SQL PREPARE my_insert ATTRIBUTES :attrvar FROM :sqlstmt;
EXEC SQL EXECUTE my_insert USING DESCRIPTOR :*sqldaptr FOR :num_rows ROWS;
Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
Related tasks
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
Related reference
SQLTYPE and SQLLEN (SQL Reference)

Dynamically executing a statement with parameter markers by

using the SQLDA
Your program can get data type information about parameter markers by asking
DB2 to set the fields in the SQLDA.

Before you dynamically execute a statement with parameter markers, allocate an

SQLDA with enough instances of SQLVAR to represent all parameter markers in
the SQL statement.

To dynamically execute a statement with parameter markers by using the SQLDA:

1. Include in your program a DESCRIBE INPUT statement that specifies the
prepared SQL statement and the name of an appropriate SQLDA.
DB2 puts the requested parameter marker information in the SQLDA.
2. Code the application in the same way as any other application in which you
execute a prepared statement by using an SQLDA. First, obtain the addresses of
the input host variables and their indicator variables and insert those addresses
into the SQLDATA and SQLIND fields. Then, execute the prepared SQL
statement.

Example

Suppose that you want to execute the following statement dynamically:

DELETE FROM DSN8910.EMP WHERE EMPNO = ?

You can use the following code to set up an SQLDA, obtain parameter information
by using the DESCRIBE INPUT statement, and execute the statement:
SQLDAPTR=ADDR(INSQLDA); /* Get pointer to SQLDA */
SQLDAID='SQLDA'; /* Fill in SQLDA eye-catcher */
SQLDABC=LENGTH(INSQLDA); /* Fill in SQLDA length */
SQLN=1; /* Fill in number of SQLVARs */
SQLD=0; /* Initialize # of SQLVARs used */
DO IX=1 TO SQLN; /* Initialize the SQLVAR */
SQLTYPE(IX)=0;
SQLLEN(IX)=0;

194 Application Programming and SQL Guide

SQLNAME(IX)='';
END;
SQLSTMT='DELETE FROM DSN8910.EMP WHERE EMPNO = ?';
EXEC SQL PREPARE SQLOBJ FROM SQLSTMT;
EXEC SQL DESCRIBE INPUT SQLOBJ INTO :INSQLDA;
SQLDATA(1)=ADDR(HVEMP); /* Get input data address */
SQLIND(1)=ADDR(HVEMPIND); /* Get indicator address */
EXEC SQL EXECUTE SQLOBJ USING DESCRIPTOR :INSQLDA;
Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related tasks
“Defining SQL descriptor areas” on page 141
Related reference
DESCRIBE INPUT (SQL Reference)

Enabling the dynamic statement cache

The dynamic statement cache is a pool in which DB2 saves prepared SQL
statements that can be shared among different threads, plans, and packages. By
sharing these statements, applications can avoid unnecessary preparation processes
and thus improve performance. You must enable the dynamic statement cache
before it can be used.

To enable the dynamic statement cache to save prepared statements, specify YES
on the CACHE DYNAMIC SQL field of installation panel DSNTIP8.
Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related reference
Performance and optimization panel: DSNTIP8 (DB2 Installation and
Migration)

Dynamic SQL statements that DB2 can cache:

The dynamic statement cache is a pool in which DB2 saves prepared SQL
statements that can be shared among different threads, plans, and packages to
improve performance. Only certain dynamic SQL statements can be saved in this
cache.

As the DB2 ability to optimize SQL has improved, the cost of preparing a dynamic
SQL statement has grown. Applications that use dynamic SQL might be forced to
pay this cost more than once. When an application performs a commit operation, it
must issue another PREPARE statement if that SQL statement is to be executed
again. For a SELECT statement, the ability to declare a cursor WITH HOLD

Chapter 3. Coding SQL statements in application programs: General information 195

provides some relief but requires that the cursor be open at the commit point.
WITH HOLD also causes some locks to be held for any objects that the prepared
statement is dependent on. Also, WITH HOLD offers no relief for SQL statements
that are not SELECT statements.

DB2 can save prepared dynamic statements in a cache. The cache is a dynamic
statement cache pool that all application processes can use to save and retrieve
prepared dynamic statements. After an SQL statement has been prepared and is
automatically saved in the cache, subsequent prepare requests for that same SQL
statement can avoid the costly preparation process by using the statement that is in
the cache. Statements that are saved in the cache can be shared among different
threads, plans, or packages.

Example: Assume that your application program contains a dynamic SQL

statement, STMT1, which is prepared and executed multiple times. If you are using
the dynamic statement cache when STMT1 is prepared for the first time, it is
placed in the cache. When your application program encounters the identical
PREPARE statement for STMT1, DB2 uses the already prepared STMT1 that is
saved in the dynamic statement cache. The following example shows the identical
STMT1 that might appear in your application program:
PREPARE STMT1 FROM ... Statement is prepared and the prepared
EXECUTE STMT1 statement is put in the cache.
COMMIT
.
.
.
PREPARE STMT1 FROM ... Identical statement. DB2 uses the prepared
EXECUTE STMT1 statement from the cache.
COMMIT
.
.
.

Eligible statements: The following SQL statements can be saved in the cache:
SELECT
UPDATE
INSERT
DELETE
| MERGE

Distributed and local SQL statements are eligible to be saved. Prepared, dynamic
statements that use DB2 private protocol access are also eligible to be saved.

Restriction: Even though static statements that use DB2 private protocol access are
dynamic at the remote site, those statements can not be saved in the cache.

| Statements in plans or packages that are bound with REOPT(ALWAYS) can not be
| saved in the cache. Statements in plans and packages that are bound with
| REOPT(ONCE) or REOPT(AUTO) can be saved in the cache.

Prepared statements cannot be shared among data sharing members. Because each
member has its own EDM pool, a cached statement on one member is not
available to an application that runs on another member.
Related tasks
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169

Conditions for statement sharing:

196 Application Programming and SQL Guide

If a prepared version of an identical SQL statement already exists in the dynamic
statement cache, certain conditions must still be met before DB2 can reuse that
prepared statement.

Suppose that S1 and S2 are source statements, and P1 is the prepared version of
S1. P1 is in the dynamic statement cache.

The following conditions must be met before DB2 can use statement P1 instead of
preparing statement S2:
v S1 and S2 must be identical. The statements must pass a character by character
comparison and must be the same length. If the PREPARE statement for either
statement contains an ATTRIBUTES clause, DB2 concatenates the values in the
ATTRIBUTES clause to the statement string before comparing the strings. That
is, if A1 is the set of attributes for S1 and A2 is the set of attributes for S2, DB2
compares S1||A1 to S2||A2.
If the statement strings are not identical, DB2 cannot use the statement in the
cache.
For example, assume that S1 and S2 are specified as follows:
'UPDATE EMP SET SALARY=SALARY+50'

In this case, DB2 can use P1 instead of preparing S2.

However, assume that S1 is specified as follows:
'UPDATE EMP SET SALARY=SALARY+50'

Assume also that S2 is specified as follows:

'UPDATE EMP SET SALARY=SALARY+50 '

In this case, DB2 cannot use P1 for S2. DB2 prepares S2 and saves the prepared
version of S2 in the cache.
| v The authorization ID or role that was used to prepare S1 must be used to
| prepare S2:
| – When a plan or package has run behavior, the authorization ID is the current
| SQLID value.
| For secondary authorization IDs:
| - The application process that searches the cache must have the same
| secondary authorization ID list as the process that inserted the entry into
| the cache or must have a superset of that list.
| - If the process that originally prepared the statement and inserted it into the
| cache used one of the privileges held by the primary authorization ID to
| accomplish the prepare, that ID must either be part of the secondary
| authorization ID list of the process searching the cache, or it must be the
| primary authorization ID of that process.
| – When a plan or package has bind behavior, the authorization ID is the plan
| owner’s ID. For a DDF server thread, the authorization ID is the package
| owner’s ID.
| – When a package has define behavior, then the authorization ID is the
| user-defined function or stored procedure owner.
| – When a package has invoke behavior, then the authorization ID is the
| authorization ID under which the statement that invoked the user-defined
| function or stored procedure executed.
| – If the application process has a role associated with it, DB2 uses the role to
| search the cache instead of the authorization IDs. If the trusted context that

Chapter 3. Coding SQL statements in application programs: General information 197

| associated the role with the application process is defined with the WITH
| ROLE AS OBJECT OWNER clause, the role value is used as the default for
| the CURRENT SCHEMA special register and the SQL path.
v When the plan or package that contains S2 is bound, the values of these bind
options must be the same as when the plan or package that contains S1 was
bound:
CURRENTDATA
DYNAMICRULES
ISOLATION
SQLRULES
QUALIFIER
v When S2 is prepared, the values of the following special registers must be the
same as when S1 was prepared:
| CURRENT DECFLOAT ROUNDING MODE
CURRENT DEGREE
CURRENT RULES
CURRENT PRECISION
CURRENT REFRESH AGE
CURRENT MAINTAINED TABLE TYPES FOR OPTIMIZATION
| CURRENT LOCALE LC_CTYPE

Exception: If you set the CACHEDYN_FREELOCAL subsystem parameter to 1

and a storage shortage occurs, DB2 frees the cached dynamic statements. In this
case, DB2 cannot use P1 instead of preparing statement S2, because P1 no longer
exists in the statement cache.
Related concepts
“DYNAMICRULES bind option” on page 932

Finding information about statements in the statement cache:

As part of an online monitoring strategy, you can examine all statements in the
dynamic statement cache and concentrate on improving specific statements for
specific performance characteristics.

The EXPLAIN STATEMENT CACHE ALL statement puts statement cache

information into the DSN_STATEMENT_CACHE_TABLE table for all queries in
the cache that qualify based on the user’s SQLID. If the SQLID has SYSADM
authority, all statements are put into the table.

EXPLAIN STATEMENT CACHE ALL provides

DSN_STATEMENT_CACHE_TABLE with a snapshot of the cache.

Example: If you are concerned about CPU time, you can select from the
STAT_CPU column in the DSN_STATEMENT_CACHE_TABLE table to identify the
queries that consume the most CPU time. Then you can work to improve the
performance of those specific queries.
Related reference
EXPLAIN (SQL Reference)

Keeping prepared statements after commit points

If your program issues the same dynamic SQL statement in different commit
scopes, consider specifying that DB2 keep the prepared versions of these
statements after the commit points. This behavior can improve performance. By
default, DB2 does not keep these statements after commit points.

198 Application Programming and SQL Guide

The bind option KEEPDYNAMIC(YES) lets you hold dynamic statements past a
commit point for an application process. An application can issue a PREPARE for a
statement once and omit subsequent PREPAREs for that statement. The following
example illustrates an application that is written to use KEEPDYNAMIC(YES).
PREPARE STMT1 FROM ... Statement is prepared.
EXECUTE STMT1
COMMIT
.
.
.
EXECUTE STMT1 Application does not issue PREPARE.
COMMIT
.
.
.
EXECUTE STMT1 Again, no PREPARE needed.
COMMIT

To understand how the KEEPDYNAMIC bind option works, you need to

differentiate between the executable form of a dynamic SQL statement, which is
the prepared statement, and the character string form of the statement, which is
the statement string.

Relationship between KEEPDYNAMIC(YES) and statement caching: When the

dynamic statement cache is not active, and you run an application bound with
KEEPDYNAMIC(YES), DB2 saves only the statement string for a prepared
statement after a commit operation. On a subsequent OPEN, EXECUTE, or
DESCRIBE, DB2 must prepare the statement again before performing the requested
operation. The following example illustrates this concept.
PREPARE STMT1 FROM ... Statement is prepared and put in memory.
EXECUTE STMT1
COMMIT
.
.
.
EXECUTE STMT1 Application does not issue PREPARE.
COMMIT
. DB2 prepares the statement again.
.
.
EXECUTE STMT1 Again, no PREPARE needed.
COMMIT

When the dynamic statement cache is active, and you run an application bound
with KEEPDYNAMIC(YES), DB2 retains a copy of both the prepared statement
and the statement string. The prepared statement is cached locally for the
application process. In general, the statement is globally cached in the EDM pool,
to benefit other application processes. If the application issues an OPEN,
EXECUTE, or DESCRIBE after a commit operation, the application process uses its
local copy of the prepared statement to avoid a prepare and a search of the cache.
The following example illustrates this process.
| PREPARE STMT1 FROM ... Statement is prepared and put in memory.
| EXECUTE STMT1
|| COMMIT
.
|| .
.
| EXECUTE STMT1 Application does not issue PREPARE.
|| COMMIT
. DB2 uses the prepared statement in memory.
|| .
.
| EXECUTE STMT1 Again, no PREPARE needed.
|| COMMIT
. DB2 uses the prepared statement in memory.
|| .
.
| PREPARE STMT1 FROM ... Again, no PREPARE needed.
| COMMIT DB2 uses the prepared statement in memory.

The local instance of the prepared SQL statement is kept in ssnmDBM1 storage
until one of the following occurs:
v The application process ends.
Chapter 3. Coding SQL statements in application programs: General information 199
v A rollback operation occurs.
v The application issues an explicit PREPARE statement with the same statement
name.
If the application does issue a PREPARE for the same SQL statement name that
has a kept dynamic statement associated with it, the kept statement is discarded
and DB2 prepares the new statement.
v The statement is removed from memory because the statement has not been
used recently, and the number of kept dynamic SQL statements reaches the
subsystem default as set during installation.

Handling implicit prepare errors: If a statement is needed during the lifetime of an

application process, and the statement has been removed from the local cache, DB2
might be able to retrieve it from the global cache. If the statement is not in the
global cache, DB2 must implicitly prepare the statement again. The application
does not need to issue a PREPARE statement. However, if the application issues an
OPEN, EXECUTE, or DESCRIBE for the statement, the application must be able to
handle the possibility that DB2 is doing the prepare implicitly. Any error that
occurs during this prepare is returned on the OPEN, EXECUTE, or DESCRIBE.

How KEEPDYNAMIC affects applications that use distributed data: If a requester

does not issue a PREPARE after a COMMIT, the package at the DB2 for z/OS
server must be bound with KEEPDYNAMIC(YES). If both requester and server are
DB2 for z/OS subsystems, the DB2 requester assumes that the KEEPDYNAMIC
value for the package at the server is the same as the value for the plan at the
requester.

The KEEPDYNAMIC option has performance implications for DRDA clients that
specify WITH HOLD on their cursors:
v If KEEPDYNAMIC(NO) is specified, a separate network message is required
when the DRDA client issues the SQL CLOSE for the cursor.
v If KEEPDYNAMIC(YES) is specified, the DB2 for z/OS server automatically
closes the cursor when SQLCODE +100 is detected, which means that the client
does not have to send a separate message to close the held cursor. This reduces
network traffic for DRDA applications that use held cursors. It also reduces the
duration of locks that are associated with the held cursor.

Considerations for data sharing: If one member of a data sharing group has
enabled the cache but another has not, and an application is bound with
KEEPDYNAMIC(YES), DB2 must implicitly prepare the statement again if the
statement is assigned to a member without the cache. This can mean a slight
reduction in performance.

Limiting CPU time for dynamic SQL statements by using the

resource limit facility
The resource limit facility (or governor) limits the amount of CPU time an SQL
statement can take, which prevents SQL statements from making excessive
requests.

The predictive governing function of the resource limit facility provides an

estimate of the processing cost of SQL statements before they run. To predict the
cost of an SQL statement, you execute EXPLAIN to put information about the
statement cost in DSN_STATEMNT_TABLE.

200 Application Programming and SQL Guide

The governor controls only the dynamic SQL manipulative statements SELECT,
UPDATE, DELETE, and INSERT. Each dynamic SQL statement used in a program
is subject to the same limits. The limit can be a reactive governing limit or a
predictive governing limit. If the statement exceeds a reactive governing limit, the
statement receives an error SQL code. If the statement exceeds a predictive
governing limit, it receives a warning or error SQL code.

Your system administrator can establish the limits for individual plans or packages,
for individual users, or for all users who do not have personal limits.

Follow the procedures defined by your location for adding, dropping, or

modifying entries in the resource limit specification table.
Related concepts
“Predictive governing”
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405
Related tasks
Managing resource limit tables (DB2 Performance)

Reactive governing
The reactive governing function of the resource limit facility stops any dynamic
SQL statements that overuse system resources. When a statement exceeds a
reactive governing threshold, the application program receives SQLCODE -905. The
application must then determine what to do next.

If the failed statement involves an SQL cursor, the cursor’s position remains
unchanged. The application can then close that cursor. All other operations with
the cursor do not run and the same SQL error code occurs.

If the failed SQL statement does not involve a cursor, then all changes that the
statement made are undone before the error code returns to the application. The
application can either issue another SQL statement or commit all work done so far.

Predictive governing
The predictive governing function of the resource limit facility provides an
estimate of the processing cost of SQL statements before they run.

If your installation uses predictive governing, you need to modify your

applications to check for the +495 and -495 SQLCODEs that predictive governing
can generate after a PREPARE statement executes. The +495 SQLCODE in
combination with deferred prepare requires that DB2 do some special processing to
ensure that existing applications are not affected by this new warning SQLCODE.

For information about setting up the resource limit facility for predictive
governing, see the topic “The resource limit facility (governor)” in DB2 Performance
Monitoring and Tuning Guide.

Handling the +495 SQLCODEIf your requester uses deferred prepare, the
presence of parameter markers determines when the application receives the +495

Chapter 3. Coding SQL statements in application programs: General information 201

SQLCODE. When parameter markers are present, DB2 cannot do PREPARE,
OPEN, and FETCH processing in one message. If SQLCODE +495 is returned, no
OPEN or FETCH processing occurs until your application requests it.
v If there are parameter markers, the +495 is returned on the OPEN (not the
PREPARE).
v If there are no parameter markers, the +495 is returned on the PREPARE.

Normally with deferred prepare, the PREPARE, OPEN, and first FETCH of the
data are returned to the requester. For a predictive governor warning of +495, you
would ideally like to have the option to choose beforehand whether you want the
OPEN and FETCH of the data to occur. For down-level requesters, you do not
have this option.

Using predictive governing and down-level DRDA requesters

If SQLCODE +495 is returned to the requester, OPEN processing continues but the
first block of data is not returned with the OPEN. Thus, if your application does
not continue with the query, you have already incurred the performance cost of
OPEN processing.

Using predictive governing and enabled requesters

If your application does not defer the prepare, SQLCODE +495 is returned to the
requester and OPEN processing does not occur.

If your application does defer prepare processing, the application receives the +495
at its usual time (OPEN or PREPARE). If you have parameter markers with
deferred prepare, you receive the +495 at OPEN time as you normally do.
However, an additional message is exchanged.

Recommendation: Do not use deferred prepare for applications that use parameter
markers and that are predictively governed at the server side.

Checking the execution of SQL statements

After executing an SQL statement, your program should check for any errors codes
before you commit the data and handle the errors that they represent.

You can check the execution of SQL statements in one of the following ways:
v By displaying specific fields in the SQLCA.
v By testing SQLCODE or SQLSTATE for specific values.
v By using the WHENEVER statement in your application program.
v By testing indicator variables to detect numeric errors.
v By using the GET DIAGNOSTICS statement in your application program to
return all the condition information that results from the execution of an SQL
statement.
v By calling DSNTIAR to display the contents of the SQLCA.

202 Application Programming and SQL Guide

Related concepts
“Arithmetic and conversion errors” on page 216
Related tasks
“Defining the SQL communications area, SQLSTATE, and SQLCODE in assembler”
on page 229
“Defining the SQL communications area, SQLSTATE, and SQLCODE in C” on page
249
“Defining the SQL communications area, SQLSTATE, and SQLCODE in COBOL”
on page 295
“Defining the SQL communications area, SQLSTATE, and SQLCODE in Fortran”
on page 363
“Defining the SQL communications area, SQLSTATE, and SQLCODE in PL/I” on
page 375
“Defining the SQL communications area, SQLSTATE, and SQLCODE in REXX” on
page 403
“Displaying SQLCA fields by calling DSNTIAR” on page 204

Checking the execution of SQL statements by using the

SQLCA
One way to check whether an SQL statement executed successfully is to use the
SQL communication area (SQLCA). This area is set apart for communication with
DB2.

If you use the SQLCA, include the necessary instructions to display information
that is contained in the SQLCA in your application program. Alternatively, you can
use the GET DIAGNOSTICS statement, which is an SQL standard, to diagnose
problems.
v When DB2 processes an SQL statement, it places return codes that indicate the
success or failure of the statement execution in SQLCODE and SQLSTATE.
v When DB2 processes a FETCH statement, and the FETCH is successful, the
contents of SQLERRD(3) in the SQLCA is set to the number of returned rows.
v When DB2 processes a multiple-row FETCH statement, the contents of
SQLCODE is set to +100 if the last row in the table has been returned with the
set of rows.
v When DB2 processes an UPDATE, INSERT, or DELETE statement, and the
statement execution is successful, the contents of SQLERRD(3) in the SQLCA is
set to the number of rows that are updated, inserted, or deleted.
| v When DB2 processes a TRUNCATE statement and the statement execution is
| successful, SQLERRD(3) in the SQLCA is set to -1. The number of rows that are
| deleted is not returned.
v If SQLWARN0 contains W, DB2 has set at least one of the SQL warning flags
(SQLWARN1 through SQLWARNA):
– SQLWARN1 contains N for non-scrollable cursors and S for scrollable cursors
after an OPEN CURSOR or ALLOCATE CURSOR statement.
– SQLWARN4 contains I for insensitive scrollable cursors, S for sensitive static
scrollable cursors, and D for sensitive dynamic scrollable cursors, after an
OPEN CURSOR or ALLOCATE CURSOR statement, or blank if the cursor is
not scrollable.
– SQLWARN5 contains a character value of 1 (read only), 2 (read and delete),
or 4 (read, delete, and update) to indicate the operation that is allowed on the
result table of the cursor.

Chapter 3. Coding SQL statements in application programs: General information 203

Related tasks
“Accessing data by using a rowset-positioned cursor” on page 680
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the SQL communications area, SQLSTATE, and SQLCODE in assembler”
on page 229
“Defining the SQL communications area, SQLSTATE, and SQLCODE in C” on page
249
“Defining the SQL communications area, SQLSTATE, and SQLCODE in COBOL”
on page 295
“Defining the SQL communications area, SQLSTATE, and SQLCODE in Fortran”
on page 363
“Defining the SQL communications area, SQLSTATE, and SQLCODE in PL/I” on
page 375
“Defining the SQL communications area, SQLSTATE, and SQLCODE in REXX” on
page 403
Related reference
Description of SQLCA fields (SQL Reference)

Displaying SQLCA fields by calling DSNTIAR

If you choose to use the SQLCA as a way of checking whether an SQL statement
executed successfully, your program needs to read the data in the appropriate
SQLCA fields. One easy way to read these fields is to use the assembler subroutine
DSNTIAR.

You should check for errors codes before you commit data, and handle the errors
that they represent. The assembler subroutine DSNTIAR helps you to obtain a
formatted form of the SQLCA and a text message based on the SQLCODE field of
the SQLCA. You can retrieve this same message text by using the MESSAGE_TEXT
condition item field of the GET DIAGNOSTICS statement. Programs that require
long token message support should code the GET DIAGNOSTICS statement
instead of DSNTIAR.

DSNTIAR takes data from the SQLCA, formats it into a message, and places the
result in a message output area that you provide in your application program.
Each time you use DSNTIAR, it overwrites any previous messages in the message
output area. You should move or print the messages before using DSNTIAR again,
and before the contents of the SQLCA change, to get an accurate view of the
SQLCA.

DSNTIAR expects the SQLCA to be in a certain format. If your application

modifies the SQLCA format before you call DSNTIAR, the results are
unpredictable.

DSNTIAR:

The assembler subroutine DSNTIAR helps you to obtain a formatted form of the
SQLCA and a text message based on the SQLCODE field of the SQLCA.

DSNTIAR can run either above or below the 16-MB line of virtual storage. The
DSNTIAR object module that comes with DB2 has the attributes AMODE(31) and
RMODE(ANY). At install time, DSNTIAR links as AMODE(31) and RMODE(ANY).
DSNTIAR runs in 31-bit mode if any of the following conditions is true:

204 Application Programming and SQL Guide

v DSNTIAR is linked with other modules that also have the attributes AMODE(31)
and RMODE(ANY).
v DSNTIAR is linked into an application that specifies the attributes AMODE(31)
and RMODE(ANY) in its link-edit JCL.
v An application loads DSNTIAR.

When loading DSNTIAR from another program, be careful how you branch to
DSNTIAR. For example, if the calling program is in 24-bit addressing mode and
DSNTIAR is loaded above the 16-MB line, you cannot use the assembler BALR
instruction or CALL macro to call DSNTIAR, because they assume that DSNTIAR
is in 24-bit mode. Instead, you must use an instruction that is capable of branching
into 31-bit mode, such as BASSM.

You can dynamically link (load) and call DSNTIAR directly from a language that
does not handle 31-bit addressing. To do this, link a second version of DSNTIAR
with the attributes AMODE(24) and RMODE(24) into another load module library.
Alternatively, you can write an intermediate assembler language program that calls
DSNTIAR in 31-bit mode and then call that intermediate program in 24-bit mode
from your application.

For more information on the allowed and default AMODE and RMODE settings
for a particular language, see the application programming guide for that
language. For details on how the attributes AMODE and RMODE of an application
are determined, see the linkage editor and loader user’s guide for the language in
which you have written the application.

Defining a message output area:

If a program calls DSNTIAR, the program must allocate enough storage in the
message output area to hold all of the message text.

You will probably need no more than 10 lines, 80-bytes each, for your message
output area. An application program can have only one message output area.

You must define the message output area in VARCHAR format. In this varying
character format, a 2-byte length field precedes the data. The length field indicates
to DSNTIAR how many total bytes are in the output message area; the minimum
length of the output area is 240-bytes.

The following figure shows the format of the message output area, where length is
the 2-byte total length field, and the length of each line matches the logical record
length (lrecl) you specify to DSNTIAR.

Chapter 3. Coding SQL statements in application programs: General information 205

Line:
1

.
.
.
n-1

Field sizes (in bytes):

2 Logical record length

Figure 22. Format of the message output area

When you call DSNTIAR, you must name an SQLCA and an output message area
in the DSNTIAR parameters. You must also provide the logical record length (lrecl)
as a value between 72 and 240 bytes. DSNTIAR assumes the message area contains
fixed-length records of length lrecl.

DSNTIAR places up to 10 lines in the message area. If the text of a message is

longer than the record length you specify on DSNTIAR, the output message splits
into several records, on word boundaries if possible. The split records are indented.
All records begin with a blank character for carriage control. If you have more
lines than the message output area can contain, DSNTIAR issues a return code of
4. A completely blank record marks the end of the message output area.

Possible return codes from DSNTIAR:

The assembler subroutine DSNTIAR helps your program read the information in
the SQLCA. The subroutine also returns its own return code.
Code Meaning
0 Successful execution.
4 More data available than could fit into the provided message area.
8 Logical record length not between 72 and 240, inclusive.
12 Message area not large enough. The message length was 240 or greater.
16 Error in TSO message routine.
20 Module DSNTIA1 could not be loaded.
24 SQLCA data error.

A scenario for using DSNTIAR:

You can use the assembler subroutine DSNTIAR to generate the error message text
in the SQLCA.

Suppose you want your DB2 COBOL application to check for deadlocks and
timeouts, and you want to make sure your cursors are closed before continuing.
You use the statement WHENEVER SQLERROR to transfer control to an error
routine when your application receives a negative SQLCODE.

206 Application Programming and SQL Guide

In your error routine, you write a section that checks for SQLCODE -911 or -913.
You can receive either of these SQLCODEs when a deadlock or timeout occurs.
When one of these errors occurs, the error routine closes your cursors by issuing
the statement:
EXEC SQL CLOSE cursor-name

An SQLCODE of 0 or -501 resulting from that statement indicates that the close
was successful.

To use DSNTIAR to generate the error message text, first follow these steps:
1. Choose a logical record length (lrecl) of the output lines. For this example,
assume lrecl is 72 (to fit on a terminal screen) and is stored in the variable
named ERROR-TEXT-LEN.
2. Define a message area in your COBOL application. Assuming you want an area
for up to 10 lines of length 72, you should define an area of 720 bytes, plus a
2-byte area that specifies the total length of the message output area.
01 ERROR-MESSAGE.
02 ERROR-LEN PIC S9(4) COMP VALUE +720.
02 ERROR-TEXT PIC X(72) OCCURS 10 TIMES
INDEXED BY ERROR-INDEX.
77 ERROR-TEXT-LEN PIC S9(9) COMP VALUE +72.

For this example, the name of the message area is ERROR-MESSAGE.

3. Make sure you have an SQLCA. For this example, assume the name of the
SQLCA is SQLCA.

To display the contents of the SQLCA when SQLCODE is 0 or -501, call DSNTIAR
after the SQL statement that produces SQLCODE 0 or -501:
CALL 'DSNTIAR' USING SQLCA ERROR-MESSAGE ERROR-TEXT-LEN.

You can then print the message output area just as you would any other variable.
Your message might look like this:
DSNT408I SQLCODE = -501, ERROR: THE CURSOR IDENTIFIED IN A FETCH OR
CLOSE STATEMENT IS NOT OPEN
DSNT418I SQLSTATE = 24501 SQLSTATE RETURN CODE
DSNT415I SQLERRP = DSNXERT SQL PROCEDURE DETECTING ERROR
DSNT416I SQLERRD = -315 0 0 -1 0 0 SQL DIAGNOSTIC INFORMATION
DSNT416I SQLERRD = X'FFFFFEC5' X'00000000' X'00000000'
X'FFFFFFFF' X'00000000' X'00000000' SQL DIAGNOSTIC
INFORMATION

Checking the execution of SQL statements by using

SQLCODE and SQLSTATE
Whenever an SQL statement executes, the SQLCODE and SQLSTATE fields of the
SQLCA receive a return code. Portable applications should use SQLSTATE instead
of SQLCODE, although SQLCODE values can provide additional DB2-specific
information about an SQL error or warning.

SQLCODE: DB2 returns the following codes in SQLCODE:

v If SQLCODE = 0, execution was successful.
v If SQLCODE > 0, execution was successful with a warning.
v If SQLCODE < 0, execution was not successful.

SQLCODE 100 indicates that no data was found.

Chapter 3. Coding SQL statements in application programs: General information 207

The meaning of SQLCODEs other than 0 and 100 varies with the particular
product implementing SQL.

SQLSTATE: SQLSTATE enables an application program to check for errors in the

same way for different IBM database management systems.

Using SQLCODE and SQLSTATE: An advantage to using the SQLCODE field is

that it can provide more specific information than the SQLSTATE. Many of the
SQLCODEs have associated tokens in the SQLCA that indicate, for example, which
object incurred an SQL error. However, an SQL standard application uses only
SQLSTATE.

You can declare SQLCODE and SQLSTATE (SQLCOD and SQLSTA in Fortran) as
stand-alone host variables. If you specify the STDSQL(YES) precompiler option,
these host variables receive the return codes, and you should not include an
SQLCA in your program.
Related tasks
“Defining the SQL communications area, SQLSTATE, and SQLCODE in assembler”
on page 229
“Defining the SQL communications area, SQLSTATE, and SQLCODE in C” on page
249
“Defining the SQL communications area, SQLSTATE, and SQLCODE in COBOL”
on page 295
“Defining the SQL communications area, SQLSTATE, and SQLCODE in Fortran”
on page 363
“Defining the SQL communications area, SQLSTATE, and SQLCODE in PL/I” on
page 375
“Defining the SQL communications area, SQLSTATE, and SQLCODE in REXX” on
page 403
Related reference
SQLSTATE values and common error codes (DB2 Codes)

Checking the execution of SQL statements by using the

WHENEVER statement
The WHENEVER statement causes DB2 to check the SQLCA and continue
processing your program, or branch to another area in your program if an error,
exception, or warning occurs. The condition handling area of your program can
then examine SQLCODE or SQLSTATE to react specifically to the error or
exception.

The WHENEVER statement is not supported for REXX.

The WHENEVER statement enables you to specify what to do if a general

condition is true. You can specify more than one WHENEVER statement in your
program. When you do this, the first WHENEVER statement applies to all
subsequent SQL statements in the source program until the next WHENEVER
statement.

The WHENEVER statement looks like this:

EXEC SQL
WHENEVER condition action
END-EXEC

208 Application Programming and SQL Guide

The condition of the WHENEVER statement is one of these three values:
SQLWARNING
Indicates what to do when SQLWARN0 = W or SQLCODE contains a
positive value other than 100. DB2 can set SQLWARN0 for several
reasons—for example, if a column value is truncated when moved into a
host variable. Your program might not regard this as an error.
SQLERROR
Indicates what to do when DB2 returns an error code as the result of an
SQL statement (SQLCODE < 0).
NOT FOUND
Indicates what to do when DB2 cannot find a row to satisfy your SQL
statement or when there are no more rows to fetch (SQLCODE = 100).

The action of the WHENEVER statement is one of these two values:

CONTINUE
Specifies the next sequential statement of the source program.
GOTO or GO TO host-label
Specifies the statement identified by host-label. For host-label, substitute a
single token, preceded by an optional colon. The form of the token
depends on the host language. In COBOL, for example, it can be
section-name or an unqualified paragraph-name.

The WHENEVER statement must precede the first SQL statement it is to affect.
However, if your program checks SQLCODE directly, you must check SQLCODE
after each SQL statement.
Related concepts
Chapter 9, “Coding SQL statements in REXX application programs,” on page 403
Related reference
WHENEVER (SQL Reference)

Checking the execution of SQL statements by using the GET

DIAGNOSTICS statement
One way to check whether an SQL statement executed successfully is to ask DB2
to return the diagnostic information about the last SQL statement that was
executed.

You can use the GET DIAGNOSTICS statement to return diagnostic information
about the last SQL statement that was executed. You can request individual items
of diagnostic information from the following groups of items:
v Statement items, which contain information about the SQL statement as a whole
v Condition items, which contain information about each error or warning that
occurred during the execution of the SQL statement
v Connection items, which contain information about the SQL statement if it was a
CONNECT statement

In addition to requesting individual items, you can request that GET

DIAGNOSTICS return ALL diagnostic items that are set during the execution of
the last SQL statement as a single string.

| In SQL procedures, you can also retrieve diagnostic information by using handlers.
| Handlers tell the procedure what to do if a particular error occurs.
Chapter 3. Coding SQL statements in application programs: General information 209
| Use the GET DIAGNOSTICS statement to handle multiple SQL errors that might
| result from the execution of a single SQL statement. First, check SQLSTATE (or
| SQLCODE) to determine whether diagnostic information should be retrieved by
| using GET DIAGNOSTICS. This method is especially useful for diagnosing
| problems that result from a multiple-row INSERT that is specified as NOT
| ATOMIC CONTINUE ON SQLEXCEPTIONand multiple row MERGE statements.

Even if you use only the GET DIAGNOSTICS statement in your application
program to check for conditions, you must either include the instructions required
to use the SQLCA or you must declare SQLSTATE (or SQLCODE) separately in
your program.

Restriction: If you issue a GET DIAGNOSTICS statement immediately following

an SQL statement that uses private protocol access, DB2 returns an error.

When you use the GET DIAGNOSTICS statement, you assign the requested
diagnostic information to host variables. Declare each target host variable with a
data type that is compatible with the data type of the requested item.

To retrieve condition information, you must first retrieve the number of condition
items (that is, the number of errors and warnings that DB2 detected during the
execution of the last SQL statement). The number of condition items is at least one.
If the last SQL statement returned SQLSTATE ’00000’ (or SQLCODE 0), the number
of condition items is one.

Example: Using GET DIAGNOSTICS with multiple-row INSERT: You want to

display diagnostic information for each condition that might occur during the
execution of a multiple-row INSERT statement in your application program. You
specify the INSERT statement as NOT ATOMIC CONTINUE ON SQLEXCEPTION,
which means that execution continues regardless of the failure of any single-row
insertion. DB2 does not insert the row that was processed at the time of the error.

In the following example, the first GET DIAGNOSTICS statement returns the
number of rows inserted and the number of conditions returned. The second GET
DIAGNOSTICS statement returns the following items for each condition:
SQLCODE, SQLSTATE, and the number of the row (in the rowset that was being
inserted) for which the condition occurred.
EXEC SQL BEGIN DECLARE SECTION;
long row_count, num_condns, i;
long ret_sqlcode, row_num;
char ret_sqlstate[6];
...
EXEC SQL END DECLARE SECTION;
...
EXEC SQL
INSERT INTO DSN8910.ACT
(ACTNO, ACTKWD, ACTDESC)
VALUES (:hva1, :hva2, :hva3)
FOR 10 ROWS
NOT ATOMIC CONTINUE ON SQLEXCEPTION;

EXEC SQL GET DIAGNOSTICS

:row_count = ROW_COUNT, :num_condns = NUMBER;
printf("Number of rows inserted = %d\n", row_count);

for (i=1; i<=num_condns; i++) {

EXEC SQL GET DIAGNOSTICS CONDITION :i
:ret_sqlcode = DB2_RETURNED_SQLCODE,
:ret_sqlstate = RETURNED_SQLSTATE,

210 Application Programming and SQL Guide

:row_num = DB2_ROW_NUMBER;
printf("SQLCODE = %d, SQLSTATE = %s, ROW NUMBER = %d\n",
ret_sqlcode, ret_sqlstate, row_num);
}

In the activity table, the ACTNO column is defined as SMALLINT. Suppose that
you declare the host variable array hva1 as an array with data type long, and you
populate the array so that the value for the fourth element is 32768.

If you check the SQLCA values after the INSERT statement, the value of
SQLCODE is equal to 0, the value of SQLSTATE is ’00000’, and the value of
SQLERRD(3) is 9 for the number of rows that were inserted. However, the INSERT
statement specified that 10 rows were to be inserted.

The GET DIAGNOSTICS statement provides you with the information that you
need to correct the data for the row that was not inserted. The printed output from
your program looks like this:
Number of rows inserted = 9
SQLCODE = -302, SQLSTATE = 22003, ROW NUMBER = 4

The value 32768 for the input variable is too large for the target column ACTNO.
You can print the MESSAGE_TEXT condition item.

Retrieving statement and condition items:

When you use the GET DIAGNOSTICS statement, you assign the requested
diagnostic information to host variables. Declare each target host variable with a
data type that is compatible with the data type of the requested item.

To retrieve condition information, you must first retrieve the number of condition
items (that is, the number of errors and warnings that DB2 detected during the
execution of the last SQL statement). The number of condition items is at least one.
If the last SQL statement returned SQLSTATE ’00000’ (or SQLCODE 0), the number
of condition items is one.

Example: Using GET DIAGNOSTICS with multiple-row INSERT: You want to

display diagnostic information for each condition that might occur during the
execution of a multiple-row INSERT statement in your application program. You
specify the INSERT statement as NOT ATOMIC CONTINUE ON SQLEXCEPTION,
which means that execution continues regardless of the failure of any single-row
insertion. DB2 does not insert the row that was processed at the time of the error.

In the following example code, the first GET DIAGNOSTICS statement returns the
number of rows inserted and the number of conditions returned. The second GET
DIAGNOSTICS statement returns the following items for each condition:
SQLCODE, SQLSTATE, and the number of the row (in the rowset that was being
inserted) for which the condition occurred
EXEC SQL BEGIN DECLARE SECTION;
long row_count, num_condns, i;
long ret_sqlcode, row_num;
char ret_sqlstate[6];
...
EXEC SQL END DECLARE SECTION;
...
EXEC SQL
INSERT INTO DSN8810.ACT
(ACTNO, ACTKWD, ACTDESC)
VALUES (:hva1, :hva2, :hva3)

Chapter 3. Coding SQL statements in application programs: General information 211

FOR 10 ROWS
NOT ATOMIC CONTINUE ON SQLEXCEPTION;

EXEC SQL GET DIAGNOSTICS

:row_count = ROW_COUNT, :num_condns = NUMBER;
printf("Number of rows inserted = %d\n", row_count);

for (i=1; i<=num_condns; i++) {

EXEC SQL GET DIAGNOSTICS CONDITION :i
:ret_sqlcode = DB2_RETURNED_SQLCODE,
:ret_sqlstate = RETURNED_SQLSTATE,
:row_num = DB2_ROW_NUMBER;
printf("SQLCODE = %d, SQLSTATE = %s, ROW NUMBER = %d\n",
ret_sqlcode, ret_sqlstate, row_num);
}

In the activity table, the ACTNO column is defined as SMALLINT. Suppose that
you declare the host variable array hva1 as an array with data type long, and you
populate the array so that the value for the fourth element is 32768.

If you check the SQLCA values after the INSERT statement, the value of
SQLCODE is equal to 0, the value of SQLSTATE is ’00000’, and the value if
SQLERRD(3) is 9 for the number of rows that were inserted. However, the INSERT
statement specified that 10 rows were to be inserted.

The GET DIAGNOSTICS statement provides you with the information that you
need to correct the data for the row that was not inserted. The printed output from
your program looks like this:
Number of rows inserted = 9
SQLCODE = -302, SQLSTATE = 22003, ROW NUMBER = 4

The value 32768 for the input variable is too large for the target column ACTNO.
You can print the MESSAGE_TEXT condition item.
Related concepts
“Handlers in an SQL procedure” on page 540
Related reference
“Data types for GET DIAGNOSTICS items”
GET DIAGNOSTICS (SQL Reference)
Related information
-302 (DB2 Codes)

Data types for GET DIAGNOSTICS items

You can use the GET DIAGNOSTICS statement to request statement, condition,
and connection information about the last SQL statement that was executed. You
must declare each target host variable with a data type that is compatible with the
data type of the requested item.

The following tables specify the data types for the statement, condition, and
connection information items that you can request by using the GET
DIAGNOSTICS statement.

212 Application Programming and SQL Guide

Table 47. Data types for GET DIAGNOSTICS items that return statement information
Item Description Data type
DB2_GET_DIAGNOSTICS_DIAGNOSTICS After a GET DIAGNOSTICS statement, VARCHAR(32672)
if any error or warning occurred, this
item contains all of the diagnostics as a
single string.
DB2_LAST_ROW After a multiple-row FETCH statement, INTEGER
this item contains a value of +100 if the
last row in the table is in the rowset
that was returned.
DB2_NUMBER_PARAMETER_MARKERS After a PREPARE statement, this item INTEGER
contains the number of parameter
markers in the prepared statement.
DB2_NUMBER_RESULT_SETS After a CALL statement that invokes a INTEGER
stored procedure, this item contains the
number of result sets that are returned
by the procedure.
DB2_NUMBER_ROWS After an OPEN or FETCH statement DECIMAL(31,0)
for which the size of the result table is
known, this item contains the number
of rows in the result table. After a
PREPARE statement, this item contains
the estimated number of rows in the
result table for the prepared statement.
For SENSITIVE DYNAMIC cursors,
this item contains the approximate
number of rows. Otherwise, or if the
server only returns an SQLCA, the
value zero is returned.
DB2_RETURN_STATUS After a CALL statement that invokes INTEGER
an SQL procedure, this item contains
the return status if the procedure
contains a RETURN statement.
DB2_SQL_ATTR_CURSOR_HOLD After an ALLOCATE or OPEN CHAR(1)
statement, this item indicates whether
the cursor can be held open across
multiple units of work (Y or N).
DB2_SQL_ATTR_CURSOR_ROWSET After an ALLOCATE or OPEN CHAR(1)
statement, this item indicates whether
the cursor can use rowset positioning
(Y or N).
DB2_SQL_ATTR_CURSOR_SCROLLABLE After an ALLOCATE or OPEN CHAR(1)
statement, this item indicates whether
the cursor is scrollable (Y or N).
| DB2_SQL_ATTR_CURSOR_SENSITIVITY After an ALLOCATE or OPEN CHAR(1)
| statement, this item indicates whether
| the cursor shows updates made by
| other processes (sensitivity I or S).
| DB2_SQL_ATTR_CURSOR_TYPE After an ALLOCATE or OPEN CHAR(1)
| statement, this item indicates whether
| the cursor is forward (F), declared
| static (S for INSENSITIVE or
| SENSITIVE STATIC, or dynamic (D for
| SENSITIVE DYNAMIC).

Chapter 3. Coding SQL statements in application programs: General information 213

Table 47. Data types for GET DIAGNOSTICS items that return statement information (continued)
Item Description Data type
MORE After any SQL statement, this item CHAR(1)
indicates whether some conditions
items were discarded because of
insufficient storage (Y or N).
NUMBER After any SQL statement, this item INTEGER
contains the number of condition
items. If no warning or error occurred,
or if no previous SQL statement has
been executed, the number that is
returned is 1.
ROW_COUNT After an insert, update, delete, or fetch, DECIMAL(31,0)
this item contains the number of rows
that are deleted, inserted, updated, or
fetched. After PREPARE, this item
contains the estimated number of
result rows in the prepared statement.
| After TRUNCATE, it contains -1.

Table 48. Data types for GET DIAGNOSTICS items that return condition information
Item Description Data type
CATALOG_NAME This item contains the server name of the VARCHAR(128)
table that owns a constraint that caused an
error, or that caused an access rule or check
violation.
CONDITION_NUMBER This item contains the number of the INTEGER
condition.
CURSOR_NAME This item contains the name of a cursor in VARCHAR(128)
an invalid cursor state.
DB2_ERROR_CODE1 This item contains an internal error code. INTEGER
DB2_ERROR_CODE2 This item contains an internal error code. INTEGER
DB2_ERROR_CODE3 This item contains an internal error code. INTEGER
DB2_ERROR_CODE4 This item contains an internal error code. INTEGER
DB2_INTERNAL_ERROR_POINTER For some errors, this item contains a INTEGER
negative value that is an internal error
pointer.
DB2_MESSAGE_ID This item contains the message ID that CHAR(10)
corresponds to the message that is contained
in the MESSAGE_TEXT diagnostic item.
DB2_MODULE_DETECTING_ERROR After any SQL statement, this item indicates CHAR(8)
which module detected the error.
DB2_ORDINAL_TOKEN_n After any SQL statement, this item contains VARCHAR(515)
the nth token, where n is a value from 1 to
100.
DB2_REASON_CODE After any SQL statement, this item contains INTEGER
the reason code for errors that have a reason
code token in the message text.
DB2_RETURNED_SQLCODE After any SQL statement, this item contains INTEGER
the SQLCODE for the condition.

214 Application Programming and SQL Guide

Table 48. Data types for GET DIAGNOSTICS items that return condition information (continued)
Item Description Data type
DB2_ROW_NUMBER After any SQL statement that involves DECIMAL(31,0)
multiple rows, this item contains the row
number on which DB2 detected the
condition.
DB2_TOKEN_COUNT After any SQL statement, this item contains INTEGER
the number of tokens available for the
condition.
MESSAGE_TEXT After any SQL statement, this item contains VARCHAR(32672)
the message text associated with the
SQLCODE.
RETURNED_SQLSTATE After any SQL statement, this item contains CHAR(5)
the SQLSTATE for the condition.
SERVER_NAME After a CONNECT, DISCONNECT, or SET VARCHAR(128)
CONNECTION statement, this item contains
the name of the server specified in the
statement.

Table 49. Data types for GET DIAGNOSTICS items that return connection information
Item Description Data type
DB2_AUTHENTICATION_TYPE This item contains the authentication type (S, CHAR(1)
C, D, E, or blank).
DB2_AUTHORIZATION_ID This item contains the authorization ID that VARCHAR(128)
is used by the connected server.
DB2_CONNECTION_STATE This item indicates whether the connection is INTEGER
unconnected (-1), local (0), or remote (1).
DB2_CONNECTION_STATUS This item indicates whether updates can be INTEGER
committed for the current unit of work (1 for
Yes, 2 for No).
DB2_ENCRYPTION_TYPE This item contains one of the following CHAR(1)
values that indicates the level of encryption
for the connection:
A Only the authentication tokens
(authid and password) are
encrypted
D All of the data for the connection is
encrypted
DB2_SERVER_CLASS_NAME After a CONNECT or SET CONNECTION VARCHAR(128)
statement, this item contains the DB2 server
class name.
DB2_PRODUCT_ID This item contains the DB2 product VARCHAR(8)
signature.

Related reference
GET DIAGNOSTICS (SQL Reference)

Handling SQL error codes

You can use the subroutine DSNTIAR or the GET DIAGNOSTICS statement to
convert an SQL return code into a text message.

Chapter 3. Coding SQL statements in application programs: General information 215

To handle SQL error codes, take action based on the programming language that
you use.
Related concepts
“SQL statements in assembler programs” on page 241
“SQL statements in C programs” on page 280
“SQL statements in COBOL programs” on page 326
“SQL statements in Fortran programs” on page 371
“SQL statements in PL/I programs” on page 393
“SQL statements in REXX programs” on page 405

Arithmetic and conversion errors

You can track arithmetic and conversion errors by using indicator variables. An
indicator variable contains a small integer value that indicates some information
about the associated host variable.

Numeric or character conversion errors or arithmetic expression errors can set an

indicator variable to -2. For example, division by zero and arithmetic overflow do
not necessarily halt the execution of a SELECT statement. If you use indicator
variables and an error occurs in the SELECT list, the statement can continue to
execute and return good data for rows in which the error does not occur.

For rows in which a conversion or arithmetic expression error does occur, the
indicator variable indicates that one or more selected items have no meaningful
value. The indicator variable flags this error with a -2 for the affected host variable
and an SQLCODE of +802 (SQLSTATE ’01519’) in the SQLCA.

Writing applications that enable users to create and modify tables

You can write a DB2 application that enables users to create new tables, add
columns to them, increase the length of character columns, rearrange the columns,
and delete columns.

To write an SQL application that allows you to create new tables, add columns to
them, increase the length of character columns, rearrange the columns, and delete
columns:

Use the CREATE TABLE and ALTER TABLE statements to create new tables, add
columns to existing table, or change the data types of existing columns. Added
columns initially contain either the null value or a default value. Both statements,
like any data definition statement, are relatively expensive to execute; consider the
effects of locks.
You cannot rearrange or delete columns in a table without dropping the entire
table. You can, however, create a view on the table, which includes only the
columns you want, in the order you want. This has the same effect as redefining
the table.
Related concepts
“Dynamic SQL” on page 162

Saving SQL statements that are translated from end user requests
If your program translates requests from end users into SQL statements and allows
users to save their requests, your program can improve performance by saving
those translated statements.

216 Application Programming and SQL Guide

A program translates requests from end users into SQL statements before executing
them, and users can save a request.

To save the corresponding SQL statement:

Save the corresponding SQL statements in a table with a column having a data
type of VARCHAR(n), where n is the maximum length of any SQL statement. You
must save the source SQL statements, not the prepared versions. That means that
you must retrieve and then prepare each statement before executing the version
stored in the table. In essence, your program prepares an SQL statement from a
character string and executes it dynamically.
Related concepts
“Dynamic SQL” on page 162

XML data in embedded SQL applications

Embedded SQL applications that are written in assembler language, C, C++,
COBOL, or PL/I can update and retrieve data in XML columns.

In embedded SQL applications, you can:

v Store an entire XML document in an XML column using INSERT or UPDATE
statements.
v Retrieve an entire XML document from an XML column using SELECT
statements.
v Retrieve a sequence from a document in an XML column by using the SQL
XMLQUERY function within a SELECT or FETCH statement, to retrieve the
sequence into a textual XML string in the database, and then retrieve the data
into an application variable.

Recommendation: Follow these guidelines when you write embedded SQL

applications:
v Avoid using the XMLPARSE and XMLSERIALIZE functions.
Let DB2 do the conversions between the external and internal XML formats
implicitly.
v Use XML host variables for input and output.
Doing so allows DB2 to process values as XML data instead of character or
binary string data. If the application cannot use XML host variables, it should
use binary string host variables to minimize character conversion issues.
v Avoid character conversion by using UTF-8 host variables for input and output
of XML values whenever possible.

Host variable data types for XML data in embedded SQL

applications
DB2 provides XML host variable types for assembler, C, C++, COBOL, and PL/I.

Those types are:

v XML AS BLOB
v XML AS CLOB
v XML AS DBCLOB
v XML AS BLOB_FILE
v XML AS CLOB_FILE
v XML AS DBCLOB_FILE

Chapter 3. Coding SQL statements in application programs: General information 217

The XML host variable types are compatible only with the XML column data type.

You can use BLOB, CLOB, DBCLOB, CHAR, VARCHAR, GRAPHIC,

VARGRAPHIC, BINARY, or VARBINARY host variables to update XML columns.
You can convert the host variable data types to the XML type using the
XMLPARSE function, or you can let the DB2 database server perform the
conversion implicitly.

You can use BLOB, CLOB, DBCLOB, CHAR, VARCHAR, GRAPHIC,

VARGRAPHIC, BINARY, or VARBINARY host variables to retrieve data from XML
columns. You can convert the XML data to the host variable type using the
XMLSERIALIZE function, or you can let the DB2 database server perform the
conversion implicitly.

The following examples show you how to declare XML host variables in each
supported language. In each table, the left column contains the declaration that
you code in your application program. The right column contains the declaration
that DB2 generates.

Declarations of XML host variables in assembler

The following table shows assembler language declarations for some typical XML
types.
Table 50. Example of assembler XML variable declarations
You declare this variable DB2 generates this variable
BLOB_XML SQL TYPE IS XML AS BLOB 1M BLOB_XML DS 0FL4
BLOB_XML_LENGTH DS FL4
BLOB_XML_DATA DS CL655351
ORG *+(983041)
CLOB_XML SQL TYPE IS XML AS CLOB 40000K CLOB_XML DS 0FL4
CLOB_XML_LENGTH DS FL4
CLOB_XML_DATA DS CL655351
ORG *+(40894465)
DBCLOB_XML SQL TYPE IS XML AS DBCLOB 4000K DBCLOB_XML DS 0FL4
DBCLOB_XML_LENGTH DS FL4
DBCLOB_XML_DATA DS GL655342
ORG *+(4030466)
|| BLOB_XML_FILE SQL TYPE IS XML AS BLOB_FILE BLOB_XML_FILE DS 0FL4
| BLOB_XML_FILE_NAME_LENGTH DS FL4
| BLOB_XML_FILE_DATA_LENGTH DS FL4
| BLOB_XML_FILE_FILE_OPTIONS DS FL4
| BLOB_XML_FILE_NAME DS CL255
|| CLOB_XML_FILE SQL TYPE IS XML AS CLOB_FILE CLOB_XML_FILE DS 0FL4
| CLOB_XML_FILE_NAME_LENGTH DS FL4
| CLOB_XML_FILE_DATA_LENGTH DS FL4
| CLOB_XML_FILE_FILE_OPTIONS DS FL4
| CLOB_XML_FILE_NAME DS CL255
|| DBCLOB_XML_FILE SQL TYPE IS XML AS DBCLOB_FILE DBCLOB_XML_FILE DS 0FL4
| DBCLOB_XML_FILE_NAME_LENGTH DS FL4
| DBCLOB_XML_FILE_DATA_LENGTH DS FL4
| DBCLOB_XML_FILE_FILE_OPTIONS DS FL4
| DBCLOB_XML_FILE_NAME DS CL255

218 Application Programming and SQL Guide

Table 50. Example of assembler XML variable declarations (continued)
You declare this variable DB2 generates this variable
Notes:
1. Because assembler language allows character declarations of no more than 65535 bytes, DB2 separates the host
language declarations for XML AS BLOB and XML AS CLOB host variables that are longer than 65535 bytes into
two parts.
2. Because assembler language allows graphic declarations of no more than 65534 bytes, DB2 separates the host
language declarations for XML AS DBCLOB host variables that are longer than 65534 bytes into two parts.

Declarations of XML host variables in C

The following table shows C and C++ language declarations that are generated by
the DB2 precompiler for some typical XML types. The declarations that the DB2
coprocessor generates might be different.
Table 51. Examples of C language variable declarations
You declare this variable DB2 generates this variable
SQL TYPE IS XML AS BLOB (1M) blob_xml; struct
{ unsigned long length;
char data??(1048576??);
} blob_xml;
SQL TYPE IS XML AS CLOB(40000K) clob_xml; struct
{ unsigned long length;
char data??(40960000??);
} clob_xml;
SQL TYPE IS XML AS DBCLOB (4000K) dbclob_xml; struct
{ unsigned long length;
unsigned short data??(4096000??);
} dbclob_xml;
|| SQL TYPE IS XML AS BLOB_FILE blob_xml_file; struct {
| unsigned long name_length;
| unsigned long data_length;
| unsigned long file_options;
| char name??(255??);
| } blob_xml_file;
|| SQL TYPE IS XML AS CLOB_FILE clob_xml_file; struct {
| unsigned long name_length;
| unsigned long data_length;
| unsigned long file_options;
| char name??(255??);
| } clob_xml_file;
|| SQL TYPE IS XML AS DBCLOB_FILE dbclob_xml_file; struct {
| unsigned long name_length;
| unsigned long data_length;
| unsigned long file_options;
| char name??(255??);
| } dbclob_xml_file;

Declarations of XML host variables in COBOL

The declarations that are generated for COBOL differ, depending on whether you
use the DB2 precompiler or the DB2 coprocessor.

Chapter 3. Coding SQL statements in application programs: General information 219

The following table shows COBOL declarations that the DB2 precompiler generates
for some typical XML types.
Table 52. Examples of COBOL variable declarations by the DB2 precompiler
You declare this variable DB2 precompiler generates this variable

01 BLOB-XML USAGE IS 01 BLOB-XML.

SQL TYPE IS XML AS BLOB(1M). 02BLOB-XML-LENGTH
PIC 9(9) COMP.
02 BLOB-XML-DATA.
49 FILLER PIC X(32767).1
49 FILLER PIC X(32767).
.. Repeat 30 times
.
49 FILLER
PIC X(1048576-32*32767).

01 CLOB-XML USAGE IS 01 CLOB-XML.

SQL TYPE IS XML AS CLOB(40000K). 02CLOB-XML-LENGTH
PIC 9(9) COMP.
02 CLOB-XML-DATA.
49 FILLER PIC X(32767).1
49 FILLER PIC X(32767).
.. Repeat 1248 times
.
49 FILLER
PIC X(40960000-1250*32767).

01 DBCLOB-XML USAGE IS 01 DBCLOB-XML.

SQL TYPE IS XML AS DBCLOB(4000K). 02DBCLOB-XML-LENGTH
PIC 9(9) COMP.
02 DBCLOB-XML-DATA.
49 FILLER PIC G(32767)
USAGE DISPLAY-1.2
49 FILLER PIC G(32767)
USAGE DISPLAY-1.
.. Repeat 123 times
.
49 FILLER
PIC G(4096000-125*32767)
USAGE DISPLAY-1.

| 01 BLOB-XML-FILE USAGE IS SQL 01 BLOB-XML-FILE.

| TYPE IS XML AS BLOB-FILE. 49 BLOB-XML-FILE-NAME-LENGTH PIC S9(9) COMP-5 SYNC.
| 49 BLOB-XML-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 BLOB-XML-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 BLOB-XML-FILE-NAME PIC X(255).

| 01 CLOB-XML-FILE USAGE IS SQL 01 CLOB-XML-FILE.

| TYPE IS XML AS CLOB-FILE. 49 CLOB-XML-FILE-NAME-LENGTH PIC S9(9) COMP-5 SYNC.
| 49 CLOB-XML-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 CLOB-XML-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 CLOB-XML-FILE-NAME PIC X(255).

| 01 DBCLOB-XML-FILE USAGE IS SQL 01 DBCLOB-XML-FILE.

| TYPE IS XML AS DBCLOB-FILE. 49 DBCLOB-XML-FILE-NAME-LENGTH PIC S9(9) COMP-5 SYNC.
| 49 DBCLOB-XML-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 DBCLOB-XML-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 DBCLOB-XML-FILE-NAME PIC X(255).
Notes:
1. For XML AS BLOB or XML AS CLOB host variables that are greater than 32767 bytes in length, DB2 creates
multiple host language declarations of 32767 or fewer bytes.
2. For XML AS DBCLOB host variables that are greater than 32767 double-byte characters in length, DB2 creates
multiple host language declarations of 32767 or fewer double-byte characters.

220 Application Programming and SQL Guide

Declarations of XML host variables in PL/I

The declarations that are generated for PL/I differ, depending on whether you use
the DB2 precompiler or the DB2 coprocessor.

The following table shows PL/I declarations that the DB2 precompiler generates
for some typical XML types.
Table 53. Examples of PL/I variable declarations
You declare this variable DB2 precompiler generates this variable

DCL BLOB_XML DCL

SQL TYPE IS XML AS BLOB (1M); 1 BLOB_XML,
2 BLOB_XML_LENGTH BIN FIXED(31),
2 BLOB_XML_DATA,1
3 BLOB_XML_DATA1 (32) CHAR(32767),
3 BLOB_XML_DATA2 CHAR(32);

DCL CLOB_XML DCL

SQL TYPE IS XML AS CLOB (40000K); 1 CLOB_XML,
2 CLOB_XML_LENGTH BIN FIXED(31),
2 CLOB_XML_DATA,1
3 CLOB_XML_DATA1 (1250) CHAR(32767),
3 CLOB_XML_DATA2 CHAR(1250);

DCL DBCLOB_XML DCL

SQL TYPE IS XML AS DBCLOB (4000K); 1 DBCLOB_XML,
2 DBCLOB_XML_LENGTH BIN FIXED(31),
2 DBCLOB_XML_DATA,2
3 DBCLOB_XML_DATA1 (250 ) GRAPHIC(16383),
3 DBCLOB_XML_DATA2 GRAPHIC(250);

| DCL BLOB_XML_FILE DCL

| SQL TYPE IS XML AS BLOB_FILE; 1 BLOB_XML_FILE,
| 2 BLOB_XML_FILE_NAME_LENGTH BIN FIXED(31) ALIGNED,
| 2 BLOB_XML_FILE_DATA_LENGTH BIN FIXED(31),
| 2 BLOB_XML_FILE_FILE_OPTIONS BIN FIXED(31),
| 2 BLOB_XML_FILE_NAME CHAR(255);

| DCL CLOB_XML_FILE DCL

| SQL TYPE IS XML AS CLOB_FILE; 1 CLOB_XML_FILE,
| 2 CLOB_XML_FILE_NAME_LENGTH BIN FIXED(31) ALIGNED,
| 2 CLOB_XML_FILE_DATA_LENGTH BIN FIXED(31),
| 2 CLOB_XML_FILE_FILE_OPTIONS BIN FIXED(31),
| 2 CLOB_XML_FILE_NAME CHAR(255);

| DCL DBCLOB_XML_FILE SQL TYPE IS XML AS DCL

| DBCLOB_FILE; 1 DBCLOB_XML_FILE,
| 2 DBCLOB_XML_FILE_NAME_LENGTH BIN FIXED(31) ALIGNED,
| 2 DBCLOB_XML_FILE_DATA_LENGTH BIN FIXED(31),
| 2 DBCLOB_XML_FILE_FILE_OPTIONS BIN FIXED(31),
| 2 DBCLOB_XML_FILE_NAME CHAR(255);

Chapter 3. Coding SQL statements in application programs: General information 221

Table 53. Examples of PL/I variable declarations (continued)
You declare this variable DB2 precompiler generates this variable
Notes:
| 1. For XML AS BLOB or XML AS CLOB host variables that are greater than 32767 bytes in length, DB2 creates host
| language declarations in the following way:
| v If the length of the XML is greater than 32767 bytes and evenly divisible by 32767, DB2 creates an array of
| 32767-byte strings. The dimension of the array is length/32767.
| v If the length of the XML is greater than 32767 bytes but not evenly divisible by 32767, DB2 creates two
| declarations: The first is an array of 32767 byte strings, where the dimension of the array, n, is length/32767.
| The second is a character string of length length-n*32767.
| 2. For XML AS DBCLOB host variables that are greater than 16383 double-byte characters in length, DB2 creates
| host language declarations in the following way:
| v If the length of the XML is greater than 16383 characters and evenly divisible by 16383, DB2 creates an array of
| 16383-character strings. The dimension of the array is length/16383.
| v If the length of the XML is greater than 16383 characters but not evenly divisible by 16383, DB2 creates two
| declarations: The first is an array of 16383 byte strings, where the dimension of the array, m, is length/16383.
| The second is a character string of length length-m*16383.

XML column updates in embedded SQL applications

When you update or insert data into XML columns of a DB2 table, the input data
must be in the textual XML format.

The encoding of XML data can be derived from the data itself, which is known as
internally encoded data, or from external sources, which is known as externally
encoded data. XML data that is sent to the database server as binary data is treated
as internally encoded data. XML data that is sent to the database server as
character data is treated as externally encoded data.

Externally encoded data can have internal encoding. That is, the data might be sent
to the database server as character data, but the data contains encoding
information. DB2 does not enforce consistency of the internal and external
encoding. When the internal and external encoding information differs, the
external encoding takes precedence. However, if there is a difference between the
external and internal encoding, intervening character conversion might have
occurred on the data, and there might be data loss.

Character data in XML columns is stored in UTF-8 encoding. The database server
handles conversion of the data from its internal or external encoding to UTF-8.

The following examples demonstrate how to update XML columns in assembler, C,

COBOL, and PL/I applications. The examples use a table named MYCUSTOMER,
which is a copy of the sample CUSTOMER table.

Example: The following example shows an assembler program that inserts data
from XML AS BLOB, XML AS CLOB, and CLOB host variables into an XML
column. The XML AS BLOB data is inserted as binary data, so the database server
honors the internal encoding. The XML AS CLOB and CLOB data is inserted as
character data, so the database server honors the external encoding.
**********************************************************************
* UPDATE AN XML COLUMN WITH DATA IN AN XML AS CLOB HOST VARIABLE *
**********************************************************************
EXEC SQL +
UPDATE MYCUSTOMER +
SET INFO = :XMLBUF +

222 Application Programming and SQL Guide

WHERE CID = 1000
**********************************************************************
* UPDATE AN XML COLUMN WITH DATA IN AN XML AS BLOB HOST VARIABLE *
**********************************************************************
EXEC SQL +
UPDATE MYCUSTOMER +
SET INFO = :XMLBLOB +
WHERE CID = 1000
**********************************************************************
* UPDATE AN XML COLUMN WITH DATA IN A CLOB HOST VARIABLE. USE *
* THE XMLPARSE FUNCTION TO CONVERT THE DATA TO THE XML TYPE. *
**********************************************************************
EXEC SQL +
UPDATE MYCUSTOMER +
SET INFO = XMLPARSE(DOCUMENT :CLOBBUF) +
WHERE CID = 1000
...
LTORG
******************************
* HOST VARIABLE DECLARATIONS *
******************************
XMLBUF SQL TYPE IS XML AS CLOB 10K
XMLBLOB SQL TYPE IS XML AS BLOB 10K
CLOBBUF SQL TYPE IS CLOB 10K

Example: The following example shows a C language program that inserts data
from XML AS BLOB, XML AS CLOB, and CLOB host variables into an XML
column. The XML AS BLOB data is inserted as binary data, so the database server
honors the internal encoding. The XML AS CLOB and CLOB data is inserted as
character data, so the database server honors the external encoding.
/******************************/
/* Host variable declarations */
/******************************/
EXEC SQL BEGIN DECLARE SECTION;
SQL TYPE IS XML AS CLOB( 10K ) xmlBuf;
SQL TYPE IS XML AS BLOB( 10K ) xmlblob;
SQL TYPE IS CLOB( 10K ) clobBuf;
EXEC SQL END DECLARE SECTION;
/******************************************************************/
/* Update an XML column with data in an XML AS CLOB host variable */
/******************************************************************/
EXEC SQL UPDATE MYCUSTOMER SET INFO = :xmlBuf where CID = 1000;
/******************************************************************/
/* Update an XML column with data in an XML AS BLOB host variable */
/******************************************************************/
EXEC SQL UPDATE MYCUSTOMER SET INFO = :xmlblob where CID = 1000;
/******************************************************************/
/* Update an XML column with data in a CLOB host variable. Use */
/* the XMLPARSE function to convert the data to the XML type. */
/******************************************************************/
EXEC SQL UPDATE MYCUSTOMER SET INFO = XMLPARSE(DOCUMENT :clobBuf) where CID = 1000;

Example: The following example shows a COBOL program that inserts data from
XML AS BLOB, XML AS CLOB, and CLOB host variables into an XML column.
The XML AS BLOB data is inserted as binary data, so the database server honors
the internal encoding. The XML AS CLOB and CLOB data is inserted as character
data, so the database server honors the external encoding.
******************************
* Host variable declarations *
******************************
01 XMLBUF USAGE IS SQL TYPE IS XML as CLOB(10K).
01 XMLBLOB USAGE IS SQL TYPE IS XML AS BLOB(10K).
01 CLOBBUF USAGE IS SQL TYPE IS CLOB(10K).
*******************************************************************

Chapter 3. Coding SQL statements in application programs: General information 223

* Update an XML column with data in an XML AS CLOB host variable *
*******************************************************************
EXEC SQL UPDATE MYCUSTOMER SET INFO = :XMLBUF where CID = 1000.
*******************************************************************
* Update an XML column with data in an XML AS BLOB host variable *
*******************************************************************
EXEC SQL UPDATE MYCUSTOMER SET INFO = :XMLBLOB where CID = 1000.
*******************************************************************
* Update an XML column with data in a CLOB host variable. Use *
* the XMLPARSE function to convert the data to the XML type. *
*******************************************************************
EXEC SQL UPDATE MYCUSTOMER SET INFO = XMLPARSE(DOCUMENT :CLOBBUF) where CID = 1000.

Example: The following example shows a PL/I program that inserts data from
XML AS BLOB, XML AS CLOB, and CLOB host variables into an XML column.
The XML AS BLOB data is inserted as binary data, so the database server honors
the internal encoding. The XML AS CLOB and CLOB data is inserted as character
data, so the database server honors the external encoding.
/******************************/
/* Host variable declarations */
/******************************/
DCL
XMLBUF SQL TYPE IS XML AS CLOB(10K),
XMLBLOB SQL TYPE IS XML AS BLOB(10K),
CLOBBUF SQL TYPE IS CLOB(10K);
/*******************************************************************/
/* Update an XML column with data in an XML AS CLOB host variable */
/*******************************************************************/
EXEC SQL UPDATE MYCUSTOMER SET INFO = :XMLBUF where CID = 1000;
/*******************************************************************/
/* Update an XML column with data in an XML AS BLOB host variable */
/*******************************************************************/
EXEC SQL UPDATE MYCUSTOMER SET INFO = :XMLBLOB where CID = 1000;
/*******************************************************************/
/* Update an XML column with data in a CLOB host variable. Use */
/* the XMLPARSE function to convert the data to the XML type. */
/*******************************************************************/
EXEC SQL UPDATE MYCUSTOMER SET INFO = XMLPARSE(DOCUMENT :CLOBBUF) where CID = 1000;

XML data retrieval in embedded SQL applications

In an embedded SQL application, if you retrieve the data into a character host
variable, DB2 converts the data from the UTF-8 encoding scheme to the application
encoding scheme. If you retrieve the data into binary host variable, DB2 does not
convert the data to another encoding scheme.

The output data is in the textual XML format.

DB2 might add an XML encoding specification to the retrieved data, depending on
whether you call the XMLSERIALIZE function when you retrieve the data. If you
do not call the XMLSERIALIZE function, DB2 adds the correct XML encoding
specification to the retrieved data. If you call the XMLSERIALIZE function, DB2
adds an internal XML encoding declaration for UTF-8 encoding if you specify
INCLUDING XMLDECLARATION in the function call. When you use
INCLUDING XMLDECLARATION, you need to ensure that the retrieved data is
not converted from UTF-8 encoding to another encoding.

The following examples demonstrate how to retrieve data from XML columns in
assembler, C, COBOL, and PL/I applications. The examples use a table named
MYCUSTOMER, which is a copy of the sample CUSTOMER table.

224 Application Programming and SQL Guide

Example: The following example shows an assembler program that retrieves data
from an XML column into XML AS BLOB, XML AS CLOB, and CLOB host
variables. The data that is retrieved into an XML AS BLOB host variable is
retrieved as binary data, so the database server generates an XML declaration with
UTF-8 encoding. The data that is retrieved into an XML AS CLOB host variable is
retrieved as character data, so the database server generates an XML declaration
with an internal encoding declaration that is consistent with the external encoding.
The data that is retrieved into a CLOB host variable is retrieved as character data,
so the database server generates an XML declaration with an internal encoding
declaration. That declaration might not be consistent with the external encoding.
**********************************************************************
* RETRIEVE XML COLUMN DATA INTO AN XML AS CLOB HOST VARIABLE *
**********************************************************************
EXEC SQL +
SELECT INFO +
INTO :XMLBUF +
FROM MYCUSTOMER +
WHERE CID = 1000
**********************************************************************
* RETRIEVE XML COLUMN DATA INTO AN XML AS BLOB HOST VARIABLE *
**********************************************************************
EXEC SQL +
SELECT INFO +
INTO :XMLBLOB +
FROM MYCUSTOMER +
WHERE CID = 1000
**********************************************************************
* RETRIEVE DATA FROM AN XML COLUMN INTO A CLOB HOST VARIABLE. *
* BEFORE SENDING THE DATA TO THE APPLICATION, INVOKE THE *
* XMLSERIALIZE FUNCTION TO CONVERT THE DATA FROM THE XML *
* TYPE TO THE CLOB TYPE. *
**********************************************************************
EXEC SQL +
SELECT XMLSERIALIZE(INFO AS CLOB(10K)) +
INTO :CLOBBUF +
FROM MYCUSTOMER +
WHERE CID = 1000
...
LTORG
******************************
* HOST VARIABLE DECLARATIONS *
******************************
XMLBUF SQL TYPE IS XML AS CLOB 10K
XMLBLOB SQL TYPE IS XML AS BLOB 10K
CLOBBUF SQL TYPE IS CLOB 10K

Example: The following example shows a C language program that retrieves data
from an XML column into XML AS BLOB, XML AS CLOB, and CLOB host
variables. The data that is retrieved into an XML AS BLOB host variable is
retrieved as binary data, so the database server generates an XML declaration with
UTF-8 encoding. The data that is retrieved into an XML AS CLOB host variable is
retrieved as character data, so the database server generates an XML declaration
with an internal encoding declaration that is consistent with the external encoding.
The data that is retrieved into a CLOB host variable is retrieved as character data,
so the database server generates an XML declaration with an internal encoding
declaration. That declaration might not be consistent with the external encoding.
/******************************/
/* Host variable declarations */
/******************************/
EXEC SQL BEGIN DECLARE SECTION;
SQL TYPE IS XML AS CLOB( 10K ) xmlBuf;
SQL TYPE IS XML AS BLOB( 10K ) xmlBlob;

Chapter 3. Coding SQL statements in application programs: General information 225

SQL TYPE IS CLOB( 10K ) clobBuf;
EXEC SQL END DECLARE SECTION;
/**********************************************************************/
/* Retrieve data from an XML column into an XML AS CLOB host variable */
/**********************************************************************/
EXEC SQL SELECT INFO INTO :xmlBuf from myTable where CID = 1000;
/**********************************************************************/
/* Retrieve data from an XML column into an XML AS BLOB host variable */
/**********************************************************************/
EXEC SQL SELECT INFO INTO :xmlBlob from myTable where CID = 1000;
/**********************************************************************/
/* RETRIEVE DATA FROM AN XML COLUMN INTO A CLOB HOST VARIABLE. */
/* BEFORE SENDING THE DATA TO THE APPLICATION, INVOKE THE */
/* XMLSERIALIZE FUNCTION TO CONVERT THE DATA FROM THE XML */
/* TYPE TO THE CLOB TYPE. */
/**********************************************************************/
EXEC SQL SELECT XMLSERIALIZE(INFO AS CLOB(10K))
INTO :clobBuf from myTable where CID = 1000;

Example: The following example shows a COBOL program that retrieves data
from an XML column into XML AS BLOB, XML AS CLOB, and CLOB host
variables. The data that is retrieved into an XML AS BLOB host variable is
retrieved as binary data, so the database server generates an XML declaration with
UTF-8 encoding. The data that is retrieved into an XML AS CLOB host variable is
retrieved as character data, so the database server generates an XML declaration
with an internal encoding declaration that is consistent with the external encoding.
The data that is retrieved into a CLOB host variable is retrieved as character data,
so the database server generates an XML declaration with an internal encoding
declaration. That declaration might not be consistent with the external encoding.
| ******************************
| * Host variable declarations *
| ******************************
| 01 XMLBUF USAGE IS SQL TYPE IS XML AS CLOB(10K).
| 01 XMLBLOB USAGE IS SQL TYPE IS XML AS BLOB(10K).
| 01 CLOBBUF USAGE IS SQL TYPE IS CLOB(10K).
| **********************************************************************
| * Retrieve data from an XML column into an XML AS CLOB host variable *
| **********************************************************************
| EXEC SQL SELECT INFO
| INTO :XMLBUF
| FROM MYTABLE
| WHERE CID = 1000
| END-EXEC.
| **********************************************************************
| * Retrieve data from an XML column into an XML AS BLOB host variable *
| **********************************************************************
| EXEC SQL SELECT INFO
| INTO :XMLBLOB
| FROM MYTABLE
| WHERE CID = 1000
| END-EXEC.
| **********************************************************************
| * RETRIEVE DATA FROM AN XML COLUMN INTO A CLOB HOST VARIABLE. *
| * BEFORE SENDING THE DATA TO THE APPLICATION, INVOKE THE *
| * XMLSERIALIZE FUNCTION TO CONVERT THE DATA FROM THE XML *
| * TYPE TO THE CLOB TYPE. *
| **********************************************************************
| EXEC SQL SELECT XMLSERIALIZE(INFO AS CLOB(10K))
| INTO :CLOBBUF
| FROM MYTABLE
| WHERE CID = 1000
| END-EXEC.

226 Application Programming and SQL Guide

Example: The following example shows a PL/I program that retrieves data from
an XML column into XML AS BLOB, XML AS CLOB, and CLOB host variables.
The data that is retrieved into an XML AS BLOB host variable is retrieved as
binary data, so the database server generates an XML declaration with UTF-8
encoding. The data that is retrieved into an XML AS CLOB host variable is
retrieved as character data, so the database server generates an XML declaration
with an internal encoding declaration that is consistent with the external encoding.
The data that is retrieved into a CLOB host variable is retrieved as character data,
so the database server generates an XML declaration with an internal encoding
declaration. That declaration might not be consistent with the external encoding.
/******************************/
/* Host variable declarations */
/******************************/
DCL
XMLBUF SQL TYPE IS XML AS CLOB(10K),
XMLBLOB SQL TYPE IS XML AS BLOB(10K),
CLOBBUF SQL TYPE IS CLOB(10K);
/**********************************************************************/
/* Retrieve data from an XML column into an XML AS CLOB host variable */
/**********************************************************************/
EXEC SQL SELECT INFO INTO :XMLBUF FROM MYTABLE WHERE CID = 1000;
/**********************************************************************/
/* Retrieve data from an XML column into an XML AS BLOB host variable */
/**********************************************************************/
EXEC SQL SELECT INFO INTO :XMLBLOB FROM MYTABLE WHERE CID = 1000;
/**********************************************************************/
/* RETRIEVE DATA FROM AN XML COLUMN INTO A CLOB HOST VARIABLE. */
/* BEFORE SENDING THE DATA TO THE APPLICATION, INVOKE THE */
/* XMLSERIALIZE FUNCTION TO CONVERT THE DATA FROM THE XML */
/* TYPE TO THE CLOB TYPE. */
/**********************************************************************/
EXEC SQL SELECT XMLSERIALIZE(INFO AS CLOB(10K))
INTO :CLOBBUF FROM MYTABLE WHERE CID = 1000;

Programming examples
You can write DB2 programs in assembler language, C, C++, COBOL, Fortran,
PL/I or REXX. These programs can access a local or remote DB2 subsystem and
can execute static or dynamic SQL statements. This information contains several
such programming examples.

You can write DB2 programs in assembler language, C, C++, COBOL, Fortran,
PL/I or REXX. These programs can access a local or remote DB2 subsystem and
can execute static or dynamic SQL statements. This information contains several
such programming examples.

To prepare and run these applications, use the JCL in DSN910.SDSNSAMP as a

model for your JCL.

Conventions used in examples of coding SQL statements

The examples in this information use certain conventions and assumptions. Some
of the examples vary from these conventions. Exceptions are noted where they
occur.

The SQL statements in this information use the following conventions:

v The SQL statement is part of a C or COBOL application program. Each SQL
example is displayed on several lines, with each clause of the statement on a
separate line.

Chapter 3. Coding SQL statements in application programs: General information 227

v The use of the precompiler options APOST and APOSTSQL are assumed
(although they are not the defaults). Therefore, apostrophes (’) are used to
delimit character string literals within SQL and host language statements.
v The SQL statements access data in the sample tables provided with DB2. The
tables contain data that a manufacturing company might keep about its
employees and its current projects.
v An SQL example does not necessarily show the complete syntax of an SQL
statement.
v Examples do not take referential constraints into account.
Related concepts
“DB2 sample applications” on page 1069
“Programming examples in assembler” on page 247
“Programming examples in C” on page 284
“Programming examples in COBOL” on page 333
“Delimiters in SQL statements in Fortran programs” on page 374
“Programming examples in PL/I” on page 397
“Programming examples in REXX” on page 414
C and C++ language options to use with the installation verification
procedures (DB2 Installation and Migration)
COBOL options to use with the installation verification procedures (DB2
Installation and Migration)
PL/I options to use with the installation verification procedures (DB2
Installation and Migration)
Related reference
DB2 sample tables (Introduction to DB2 for z/OS)
Statements (SQL Reference)

Examples of programs that call stored procedures

These examples can be used as models when you write applications that call
stored procedures. In addition to these example programs, DSN910.SDSNSAMP
contains sample jobs DSNTEJ6P and DSNTEJ6S and programs DSN8EP1 and
DSN8EP2, which you can run.

228 Application Programming and SQL Guide

Chapter 4. Coding SQL statements in assembler application
programs
When you code SQL statements in assembler application programs, you should
follow certain guidelines.

Defining the SQL communications area, SQLSTATE, and SQLCODE in

assembler
Assembler programs that contain SQL statements can include an SQL
communications area (SQLCA) to check whether an SQL statement executed
successfully. Alternatively, these programs can declare individual SQLCODE and
SQLSTATE host variables.

If you specify the SQL processing option STDSQL(YES), do not define an SQLCA.
If you do, DB2 ignores your SQLCA, and your SQLCA definition causes
compile-time errors. If you specify the SQL processing option STDSQL(NO),
include an SQLCA explicitly.

If your application contains SQL statements and does not include an SQL
communications area (SQLCA), you must declare individual SQLCODE and
SQLSTATE host variables. Your program can use these variables to check whether
an SQL statement executed successfully.

To define the SQL communications area, SQLSTATE, and SQLCODE:

Option Description
To define the SQL communications area: 1. Code the SQLCA directly in the program
or use the following SQL INCLUDE
statement to request a standard SQLCA
declaration:
EXEC SQL INCLUDE SQLCA

If your program is reentrant, you must

include the SQLCA within a unique data
area that is acquired for your task (a
DSECT). For example, at the beginning
of your program, specify the following
code:
PROGAREA DSECT
EXEC SQL INCLUDE SQLCA

As an alternative, you can create a

separate storage area for the SQLCA and
provide addressability to that area.
DB2 sets the SQLCODE and SQLSTATE
values in the SQLCA after each SQL
statement executes. Your application should
check these values to determine whether the
last SQL statement was successful.

© Copyright IBM Corp. 1983, 2009 229

Option Description
To declare SQLCODE and SQLSTATE host 1. Declare the SQLCODE variable within a
variables: BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as a fullword integer.
2. Declare the SQLSTATE variable within a
BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as a character string of length 5 (CL5).
Restriction: Do not declare an SQLSTATE
variable as an element of a structure.
Requirement: After you declare the
SQLCODE and SQLSTATE variables, ensure
that all SQL statements in the program are
within the scope of the declaration of these
variables.

Related tasks
“Checking the execution of SQL statements” on page 202
“Checking the execution of SQL statements by using the SQLCA” on page 203
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the items that your program can use to check whether an SQL statement
executed successfully” on page 141

Defining SQL descriptor areas in assembler

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

To define SQL descriptor areas:

Code the SQLDA directly in the program, or use the following SQL INCLUDE
statement to request a standard SQLDA declaration:
EXEC SQL INCLUDE SQLDA

Restriction: You must place SQLDA declarations before the first SQL statement
that references the data descriptor, unless you use the TWOPASS SQL processing
option.
Related tasks
“Defining SQL descriptor areas” on page 141

Declaring host variables and indicator variables in assembler

You can use host variables, host variable arrays, and host structures in SQL
statements in your program to pass data between DB2 and your application.

To declare host variables, host variable arrays, and host structures:

1. Declare the variables according to the following rules and guidelines:

230 Application Programming and SQL Guide

v You can declare host variables in normal assembler style (DC or DS),
depending on the data type and the limitations on that data type. You can
specify a value on DC or DS declarations (for example, DC H'5'). The DB2
precompiler examines only packed decimal declarations.
v If you specify the ONEPASS SQL processing option, you must explicitly
declare each host variable and each host variable array before using them in
an SQL statement. If you specify the TWOPASS precompiler option, you
must declare each host variable before using it in the DECLARE CURSOR
statement.
v If you specify the STDSQL(YES) SQL processing option, you must precede
the host language statements that define the host variables and host variable
arrays with the BEGIN DECLARE SECTION statement and follow the host
language statements with the END DECLARE SECTION statement.
Otherwise, these statements are optional.
v Ensure that any SQL statement that uses a host variable or host variable
array is within the scope of the statement that declares that variable or array.
| v If you are using the DB2 precompiler, ensure that the names of host variables
| and host variable arrays are unique within the program, even if the variables
| and variable arrays are in different blocks, classes, procedures, functions, or
| subroutines. You can qualify the names with a structure name to make them
| unique.
2. Optional: Define any associated indicator variables, arrays, and structures.
Related tasks
“Declaring host variables and indicator variables” on page 142

Host variables in assembler

In assembler programs, you can specify numeric, character, graphic, binary, LOB,
XML, and ROWID host variables. You can also specify result set, table, and LOB
locators and LOB and XML file reference variables.

Restrictions:
v Only some of the valid assembler declarations are valid host variable
declarations. If the declaration for a host variable is not valid, any SQL
statement that references the variable might result in the message
UNDECLARED HOST VARIABLE.
v The locator data types are assembler language data types and SQL data types.
You cannot use locators as column types.

Recommendations:
v Be careful of overflow. For example, suppose that you retrieve an INTEGER
column value into a DS H host variable, and the column value is larger than
32767. You get an overflow warning or an error, depending on whether you
provide an indicator variable.
v Be careful of truncation. For example, if you retrieve an 80-character CHAR
column value into a host variable that is declared as DS CL70, the rightmost ten
characters of the retrieved string are truncated. If you retrieve a floating-point or
decimal column value into a host variable declared as DS F, any fractional part
of the value is removed.

Chapter 4. Coding SQL statements in assembler application programs 231

Numeric host variables

The following diagram shows the syntax for declaring numeric host variables.

|

variable-name DC H

DS 1 L2
F
L4
FD
L8
(1)
P ’value ’
Ln
E
L4
EH
L4
EB
L4
ED
L4
D
L8
DH
L8
DB
L8
DD
L8
LD
L16

Notes:
1 value is a numeric value that specifies the scale of the packed decimal
variable. If value does not include a decimal point, the scale is 0.

For floating-point data types (E, EH, EB, D, DH, and DB), use the FLOAT SQL
processing option to specify whether the host variable is in IEEE binary
floating-point or z/Architecture® hexadecimal floating-point format. If you specify
FLOAT(S390), you need to define your floating-point host variables as E, EH, D, or
DH. If you specify FLOAT(IEEE), you need to define your floating-point host
variables as EB or DB. DB2 does not check if the host variable declarations or
format of the host variable contents match the format that you specified with the
FLOAT SQL processing option. Therefore, you need to ensure that your
floating-point host variable types and contents match the format that you specified
with the FLOAT SQL processing option. DB2 converts all floating-point input data
to z/Architecture hexadecimal floating-point format before storing it.

| Restriction: The FLOAT SQL processing options do not apply to the decimal
| floating-point host variable types ED, DD, or LD.

For the decimal floating-point host variable types ED, DD, and LD, you can specify
the following special values: MIN, MAX, NAN, SNAN, and INFINITY.

232 Application Programming and SQL Guide

Character host variables

You can specify the following forms of character host variables:

v Fixed-length strings
v Varying-length strings
v CLOBs

The following diagrams show the syntax for forms other than CLOBs.

The following diagram shows the syntax for declaring fixed-length character
strings.

variable-name DC C

DS 1 (1)
Ln

Notes:
1 If you declare a character string host variable without a length (for example,
DC C 'ABCD') DB2 interprets the length as 1. To get the correct length, specify
a length attribute (for example, DC CL 4 'ABCD').

The following diagram shows the syntax for declaring varying-length character
strings.

variable-name DC H , CLn

DS 1 L2 1

Graphic host variables

You can specify the following forms of graphic host variables:

v Fixed-length strings
v Varying-length strings
v DBCLOBs

The following diagrams show the syntax for forms other than DBCLOBs. In the
syntax diagrams, value denotes one or more DBCS characters, and the symbols <
and > represent the shift-out and shift-in characters.

The following diagram shows the syntax for declaring fixed-length graphic strings.

variable-name DC G

DS Ln
’<value>’
Ln’<value>’

The following diagram shows the syntax for declaring varying-length graphic
strings.

variable-name DS H , GLn

DC L2 ’m’ ’<value>’

Chapter 4. Coding SQL statements in assembler application programs 233

Binary host variables

The following diagram shows the syntax for declaring binary host variables.

(1)


variable-name DS X Ln


Notes:
1 1 ≤ n ≤ 255

Varbinary host variables

The following diagram shows the syntax for declaring varbinary host variables.

(1)


variable-name DS H L2 , X Ln


Notes:
1 1 ≤ n ≤ 32704

Result set locators

The following diagram shows the syntax for declaring result set locators.

variable-name DC F

DS 1 L4

Table Locators

The following diagram shows the syntax for declaring of table locators.

variable-name SQL TYPE IS TABLE LIKE table-name AS LOCATOR


LOB variables, locators, and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variables, locators, and file reference variables.

|

variable-name SQL TYPE IS BINARY LARGE OBJECT length


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_LOCATOR
CLOB_LOCATOR
DBCLOB_LOCATOR
BLOB_FILE
CLOB_FILE
DBCLOB_FILE
|

234 Application Programming and SQL Guide

XML data host and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variables and file reference variables for XML data types.

| (1)


variable-name SQL TYPE IS XML AS BINARY LARGE OBJECT length

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_FILE
CLOB_FILE
DBCLOB_FILE
|
Notes:
1 If you specify the length of the LOB in terms of KB, MB, or GB, do not leave
spaces between the length and K, M, or G.

ROWIDs

The following diagram shows the syntax for declaring ROWID host variables.

variable-name SQL TYPE IS ROWID


Related concepts
“Host variables” on page 143
“Rules for host variables in an SQL statement” on page 151
“Large objects (LOBs)” on page 430
Related tasks
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157
Related reference
“Descriptions of SQL processing options” on page 904
Related information
High Level Assembler (HLASM) and Toolkit Feature library
z/OS Internet Library

Indicator variables in assembler

An indicator variable is a 2-byte integer (DS HL2). You declare indicator variables
in the same way as host variables. You can mix the declarations of the two types of
variables.

The following diagram shows the syntax for declaring an indicator variable in
assembler.

Chapter 4. Coding SQL statements in assembler application programs 235

variable-name DC H

DS 1 L2

Example

The following example shows a FETCH statement with the declarations of the host
variables that are needed for the FETCH statement and their associated indicator
variables.
EXEC SQL FETCH CLS_CURSOR INTO :CLSCD, X
:DAY :DAYIND, X
:BGN :BGNIND, X
:END :ENDIND

You can declare these variables as follows:

CLSCD DS CL7
DAY DS HL2
BGN DS CL8
END DS CL8
DAYIND DS HL2 INDICATOR VARIABLE FOR DAY
BGNIND DS HL2 INDICATOR VARIABLE FOR BGN
ENDIND DS HL2 INDICATOR VARIABLE FOR END
Related concepts
“Indicator variables, arrays, and structures” on page 145
Related tasks
“Inserting null values into columns by using indicator variables or arrays” on page
158

Equivalent SQL and assembler data types

When you declare host variables in your assembler programs, the precompiler uses
equivalent SQL data types. When you retrieve data of a particular SQL data type
into a host variable, you need to ensure that the host variable is of an equivalent
data type.

The following table describes the SQL data type and the base SQLTYPE and
SQLLEN values that the precompiler uses for host variables in SQL statements.
Table 54. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in
assembler programs
SQLTYPE of host SQLLEN of
Assembler host variable data type variable1 host variable SQL data type

DS HL2 500 2 SMALLINT

DS FL4 496 4 INTEGER

DS P'value' 484 p in byte 1, s in DECIMAL(p,s)

DS PLn'value' or byte 2
DS PLn
1<=n<=16
|| short decimal FLOAT: 996 4 DECFLOAT
| SDFP DC ED
| SDFP DC EDL4
| SDFP DC EDL4'11.11'

236 Application Programming and SQL Guide

Table 54. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in
assembler programs (continued)
SQLTYPE of host SQLLEN of
Assembler host variable data type variable1 host variable SQL data type
|| long decimal FLOAT: 996 8 DECFLOAT
| LDFP DC DD
| LDFP DC DDL8
| LDFP DC DDL8'22.22'
|| extended decimal FLOAT: 996 16 DECFLOAT
| EDFP DC LD
| EDFP DC LDL16
| EDFP DC LDL16'33.33'

DS EL4 480 4 REAL or FLOAT (n)

DS EHL4 1<=n<=21
DS EBL4

DS DL8 480 8 DOUBLE PRECISION,

DS DHL8 or FLOAT (n)
DS DBL8 22<=n<=53
|| DS FDL8 492 8 BIGINT
| DS FD
|| SQL TYPE IS BINARY(n) 912 n BINARY(n)
| 1<=n<=255
|| SQL TYPE IS VARBINARY(n) or 908 n VARBINARY(n)
| SQL TYPE IS BINARY(n) VARYING
| 1<=n<=32704

DS CLn 452 n CHAR(n)

1<=n<=255

DS HL2,CLn 448 n VARCHAR(n)

1<=n<=255

DS HL2,CLn 456 n VARCHAR(n)

n>255

DS GLm 468 n GRAPHIC(n)

2<=m<=254
3
2

DS HL2,GLm 464 n VARGRAPHIC(n)

2<=m<=254
3
2

DS HL2,GLm 472 n VARGRAPHIC(n)

m>254
3
2

DS FL4 972 4 Result set locator4

SQL TYPE IS 976 4 Table locator4

TABLE LIKE
table-name
AS LOCATOR

SQL TYPE IS 960 4 BLOB locator4

BLOB_LOCATOR

Chapter 4. Coding SQL statements in assembler application programs 237

Table 54. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in
assembler programs (continued)
SQLTYPE of host SQLLEN of
Assembler host variable data type variable1 host variable SQL data type

SQL TYPE IS 964 4 CLOB locator4

CLOB_LOCATOR

SQL TYPE IS 968 4 DBCLOB locator4

DBCLOB_LOCATOR

SQL TYPE IS 404 n BLOB(n)

BLOB(n)
1≤n≤2147483647

SQL TYPE IS 408 n CLOB(n)

CLOB(n)
1≤n≤2147483647

SQL TYPE IS 412 n DBCLOB(n)

DBCLOB(n)
1≤n≤1073741823 3

| SQL TYPE IS XML AS BLOB(n) 404 0 XML

| SQL TYPE IS XML AS CLOB(n) 408 0 XML

| SQL TYPE IS XML AS DBCLOB(n) 412 0 XML

|| SQL TYPE IS BLOB_FILE 916/917 267 BLOB file reference 4

|| SQL TYPE IS CLOB_FILE 920/921 267 CLOB file reference 4

|| SQL TYPE IS DBCLOB_FILE 924/925 267 DBCLOB file reference 4

SQL TYPE IS XML AS BLOB_FILE 916/917 267 XML BLOB file reference 4

SQL TYPE IS XML AS CLOB_FILE 920/921 267 XML CLOB file reference 4

SQL TYPE IS XML AS DBCLOB_FILE 924/925 267 XML DBCLOB file reference 4

SQL TYPE IS ROWID 904 40 ROWID

Notes:
1. If a host variable includes an indicator variable, the SQLTYPE value is the base SQLTYPE value plus 1.
2. m is the number of bytes.
3. n is the number of double-byte characters.
4. This data type cannot be used as a column type.

The following table shows equivalent assembler host variables for each SQL data
type. Use this table to determine the assembler data type for host variables that
you define to receive output from the database. For example, if you retrieve
TIMESTAMP data, you can define variable DS CLn.

This table shows direct conversions between SQL data types and assembler data
types. However, a number of SQL data types are compatible. When you do
assignments or comparisons of data that have compatible data types, DB2 converts
those compatible data types.

238 Application Programming and SQL Guide

Table 55. Assembler host variable equivalents that you can use when retrieving data of a
particular SQL data type
Assembler host variable
SQL data type equivalent Notes
SMALLINT DS HL2
INTEGER DS F
| BIGINT DS FD OR DS FDL8 DS FDL8 requires High Level Assembler
| (HLASM), Release 4 or later.
DECIMAL(p,s) or DS P’value’ DS PLn’value’ p is precision; s is scale. 1<=p<=31 and
NUMERIC(p,s) DS PLn 0<=s<=p. 1<=n<=16. value is a literal value
that includes a decimal point. You must
use Ln, value, or both. Using only value is
recommended.

Precision: If you use Ln, it is 2n-1;

otherwise, it is the number of digits in
value. Scale: If you use value, it is the
number of digits to the right of the
decimal point; otherwise, it is 0.

For efficient use of indexes: Use value. If

p is even, do not use Ln and be sure the
precision of value is p and the scale of
value is s. If p is odd, you can use Ln
(although it is not advised), but you must
choose n so that 2n-1=p, and value so that
the scale is s. Include a decimal point in
value, even when the scale of value is 0.
REAL or FLOAT(n) DS EL4 DS EHL4 DS 1<=n<=21
EBL41
DOUBLE DS DL8 DS DHL8 DS 22<=n<=53
PRECISION, DBL81
DOUBLE, or
FLOAT(n)
| DECFLOAT DC EDL4 DC DDL8 DC
| LDL16
CHAR(n) DS CLn 1<=n<=255
VARCHAR(n) DS HL2,CLn
GRAPHIC(n) DS GLm m is expressed in bytes. n is the number
of double-byte characters. 1<=n<=127
VARGRAPHIC(n) DS HL2,GLx DS x and m are expressed in bytes. n is the
HL2’m’,GLx’<value>’ number of double-byte characters. < and
> represent shift-out and shift-in
characters.
| BINARY(n) 1<=n<=255
| Format 1:
| variable-name--
| DS--X--Ln
| Format 2:
| SQL TYPE IS
| BINARY(n)

Chapter 4. Coding SQL statements in assembler application programs 239

Table 55. Assembler host variable equivalents that you can use when retrieving data of a
particular SQL data type (continued)
Assembler host variable
SQL data type equivalent Notes
| VARBINARY(n) 1<=n<=32704
| Format 1:
| variable-name--
| DS--H--L2--,--
| X--Ln
| Format 2:
| SQL TYPE IS
| VARBINARY(n)
| or SQL TYPE IS
| BINARY(n)
| VARYING
DATE DS CLn If you are using a date exit routine, n is
determined by that routine; otherwise, n
must be at least 10.
TIME DS CLn If you are using a time exit routine, n is
determined by that routine. Otherwise, n
must be at least 6; to include seconds, n
must be at least 8.
TIMESTAMP DS CLn n must be at least 19. To include
microseconds, n must be 26; if n is less
than 26, truncation occurs on the
microseconds part.
Result set locator DS F Use this data type only to receive result
sets. Do not use this data type as a
column type.
Table locator SQL TYPE IS TABLE Use this data type only in a user-defined
LIKE table-name AS function or stored procedure to receive
LOCATOR rows of a transition table. Do not use this
data type as a column type.
BLOB locator SQL TYPE IS Use this data type only to manipulate
BLOB_LOCATOR data in BLOB columns. Do not use this
data type as a column type.
CLOB locator SQL TYPE IS Use this data type only to manipulate
CLOB_LOCATOR data in CLOB columns. Do not use this
data type as a column type.
DBCLOB locator SQL TYPE IS Use this data type only to manipulate
DBCLOB_LOCATOR data in DBCLOB columns. Do not use this
data type as a column type.
BLOB(n) SQL TYPE IS BLOB(n) 1≤n≤2147483647
CLOB(n) SQL TYPE IS CLOB(n) 1≤n≤2147483647
DBCLOB(n) SQL TYPE IS DBCLOB(n) n is the number of double-byte characters.
1≤n≤1073741823
| XML SQL TYPE IS XML AS 1≤n≤2147483647
| BLOB(n)
| XML SQL TYPE IS XML AS 1≤n≤2147483647
| CLOB(n)
| XML SQL TYPE IS XML AS n is the number of double-byte characters.
| DBCLOB(n) 1≤n≤1073741823

240 Application Programming and SQL Guide

Table 55. Assembler host variable equivalents that you can use when retrieving data of a
particular SQL data type (continued)
Assembler host variable
SQL data type equivalent Notes
| BLOB file reference SQL TYPE IS BLOB_FILE Use this data type only to manipulate
| data in BLOB columns. Do not use this
| data type as a column type.
| CLOB file reference SQL TYPE IS CLOB_FILE Use this data type only to manipulate
| data in CLOB columns. Do not use this
| data type as a column type.
| DBCLOB file SQL TYPE IS Use this data type only to manipulate
| reference DBCLOB_FILE data in DBCLOB columns. Do not use this
| data type as a column type.
| XML BLOB file SQL TYPE IS XML AS Use this data type only to manipulate
| reference BLOB_FILE XML data as BLOB files. Do not use this
| data type as a column type.
| XML CLOB file SQL TYPE IS XML AS Use this data type only to manipulate
| reference CLOB_FILE XML data as CLOB files. Do not use this
| data type as a column type.
| XML DBCLOB file SQL TYPE IS XML AS Use this data type only to manipulate
| reference DBCLOB_FILE XML data as DBCLOB files. Do not use
| this data type as a column type.
ROWID SQL TYPE IS ROWID
Notes:
| 1. Although stored procedures and user-defined functions can use IEEE floating-point host
| variables, you cannot declare a user-defined function or stored procedure parameter as
| IEEE.

Related concepts
“Compatibility of SQL and language data types” on page 148
“LOB host variable, LOB locator, and LOB file reference variable declarations” on
page 705
“Host variable data types for XML data in embedded SQL applications” on page
217

SQL statements in assembler programs

You can code SQL statements in a assembler program wherever you can use
executable statements.

Each SQL statement in an assembler program must begin with EXEC SQL. The
EXEC and SQL keywords must appear on one line, but the remainder of the
statement can appear on subsequent lines.

You might code an UPDATE statement in an assembler program as follows:

EXEC SQL UPDATE DSN8910.DEPT X
SET MGRNO = :MGRNUM X
WHERE DEPTNO = :INTDEPT

Comments: You cannot include assembler comments in SQL statements. However,

you can include SQL comments in any embedded SQL statement.

Chapter 4. Coding SQL statements in assembler application programs 241

Continuation for SQL statements: The line continuation rules for SQL statements
are the same as those for assembler statements, except that you must specify EXEC
SQL within one line. Any part of the statement that does not fit on one line can
appear on subsequent lines, beginning at the continuation margin (column 16, the
default). Every line of the statement, except the last, must have a continuation
character (a non-blank character) immediately after the right margin in column 72.

Declaring tables and views: Your assembler program should include a DECLARE
statement to describe each table and view the program accesses.

Including code: To include SQL statements or assembler host variable declaration

statements from a member of a partitioned data set, place the following SQL
statement in the source code where you want to include the statements:
EXEC SQL INCLUDE member-name

You cannot nest SQL INCLUDE statements.

Margins: Use the precompiler option MARGINS to set a left margin, a right
margin, and a continuation margin. The default values for these margins are
columns 1, 71, and 16, respectively. If EXEC SQL starts before the specified left
margin, the DB2 precompiler does not recognize the SQL statement. If you use the
default margins, you can place an SQL statement anywhere between columns 2
and 71.

Multiple-row FETCH statements: You can use only the FETCH ... USING
DESCRIPTOR form of the multiple-row FETCH statement in an assembler
program. The DB2 precompiler does not recognize declarations of host variable
arrays for an assembler program.

Names: You can use any valid assembler name for a host variable. However, do
not use external entry names or access plan names that begin with ’DSN’ or host
variable names that begin with ’SQL’. These names are reserved for DB2.

The first character of a host variable that is used in embedded SQL cannot be an
underscore. However, you can use an underscore as the first character in a symbol
that is not used in embedded SQL.

Statement labels: You can prefix an SQL statement with a label. The first line of an
SQL statement can use a label beginning in the left margin (column 1). If you do
not use a label, leave column 1 blank.

WHENEVER statement: The target for the GOTO clause in an SQL WHENEVER
statement must be a label in the assembler source code and must be within the
scope of the SQL statements that WHENEVER affects.

Special assembler considerations: The following considerations apply to programs

written in assembler:
| v To allow for reentrant programs, the precompiler puts all the variables and
| structures it generates within a DSECT called SQLDSECT, and it generates an
| assembler symbol called SQLDLEN. SQLDLEN contains the length of the
| DSECT. Your program must allocate an area of the size indicated by SQLDLEN,
| initialize it, and provide addressability to it as the DSECT SQLDSECT. The
| precompiler does not generate code to allocate the storage for SQLDSECT; the
| application program must allocate the storage.

242 Application Programming and SQL Guide

| CICS: An example of code to support reentrant programs, running under CICS,
| follows:
| DFHEISTG DSECT
| DFHEISTG
| EXEC SQL INCLUDE SQLCA
| *
| DS 0F
| SQDWSREG EQU R7
| SQDWSTOR DS (SQLDLEN)C RESERVE STORAGE TO BE USED FOR SQLDSECT
|| .
|| .
.
|
| XXPROGRM DFHEIENT CODEREG=R12,EIBREG=R11,DATAREG=R13
| *
| *
| * SQL WORKING STORAGE
| LA SQDWSREG,SQDWSTOR GET ADDRESS OF SQLDSECT
| USING SQLDSECT,SQDWSREG AND TELL ASSEMBLER ABOUT IT
| *

| In this example, the actual storage allocation is done by the DFHEIENT macro.
| TSO: The sample program in prefix.SDSNSAMP(DSNTIAD) contains an example
| of how to acquire storage for the SQLDSECT in a program that runs in a TSO
| environment. The following example code contains pieces from
| prefix.SDSNSAMP(DSNTIAD) with explanations in the comments.
| DSNTIAD CSECT CONTROL SECTION NAME
| SAVE (14,12) ANY SAVE SEQUENCE
| LR R12,R15 CODE ADDRESSABILITY
| USING DSNTIAD,R12 TELL THE ASSEMBLER
| LR R7,R1 SAVE THE PARM POINTER
| *
| * Allocate storage of size PRGSIZ1+SQLDSIZ, where:
| * - PRGSIZ1 is the size of the DSNTIAD program area
| * - SQLDSIZ is the size of the SQLDSECT, and declared
| * when the DB2 precompiler includes the SQLDSECT
| *
| L R6,PRGSIZ1 GET SPACE FOR USER PROGRAM
| A R6,SQLDSIZ GET SPACE FOR SQLDSECT
| GETMAIN R,LV=(6) GET STORAGE FOR PROGRAM VARIABLES
| LR R10,R1 POINT TO IT
| *
| * Initialize the storage
| *
| LR R2,R10 POINT TO THE FIELD
| LR R3,R6 GET ITS LENGTH
| SR R4,R4 CLEAR THE INPUT ADDRESS
| SR R5,R5 CLEAR THE INPUT LENGTH
| MVCL R2,R4 CLEAR OUT THE FIELD
| *
| * Map the storage for DSNTIAD program area
| *
| ST R13,FOUR(R10) CHAIN THE SAVEAREA PTRS
| ST R10,EIGHT(R13) CHAIN SAVEAREA FORWARD
| LR R13,R10 POINT TO THE SAVEAREA
| USING PRGAREA1,R13 SET ADDRESSABILITY
| *
| * Map the storage for the SQLDSECT
| *
| LR R9,R13 POINT TO THE PROGAREA
| A R9,PRGSIZ1 THEN PAST TO THE SQLDSECT
| USING SQLDSECT,R9 SET ADDRESSABILITY
| ...
| LTORG
| **********************************************************************

Chapter 4. Coding SQL statements in assembler application programs 243

| * *
| * DECLARE VARIABLES, WORK AREAS *
| * *
| **********************************************************************
| PRGAREA1 DSECT WORKING STORAGE FOR THE PROGRAM
| ...
| DS 0D
| PRGSIZE1 EQU *-PRGAREA1 DYNAMIC WORKAREA SIZE
| ...
| DSNTIAD CSECT RETURN TO CSECT FOR CONSTANT
| PRGSIZ1 DC A(PRGSIZE1) SIZE OF PROGRAM WORKING STORAGE
| CA DSECT
| EXEC SQL INCLUDE SQLCA
| ...
v DB2 does not process set symbols in SQL statements.
v Generated code can include more than two continuations per comment.
v Generated code uses literal constants (for example, =F’-84’), so an LTORG
statement might be necessary.
v Generated code uses registers 0, 1, 14, and 15. Register 13 points to a save area
that the called program uses. Register 15 does not contain a return code after a
call that is generated by an SQL statement.
CICS: A CICS application program uses the DFHEIENT macro to generate the
entry point code. When using this macro, consider the following:
– If you use the default DATAREG in the DFHEIENT macro, register 13 points
to the save area.
– If you use any other DATAREG in the DFHEIENT macro, you must provide
addressability to a save area.
For example, to use SAVED, you can code instructions to save, load, and
restore register 13 around each SQL statement as in the following example.
ST 13,SAVER13 SAVE REGISTER 13
LA 13,SAVED POINT TO SAVE AREA
EXEC SQL . . .
L 13,SAVER13 RESTORE REGISTER 13
v If you have an addressability error in precompiler-generated code because of
input or output host variables in an SQL statement, check to make sure that you
have enough base registers.
v Do not put CICS translator options in the assembly source code. Instead, pass
the options to the translator by using the PARM field.

Handling SQL error return codes in assembler

You can use the subroutine DSNTIAR to convert an SQL return code into a text
message. DSNTIAR takes data from the SQLCA, formats it into a message, and
places the result in a message output area that you provide in your application
program. For concepts and more information about the behavior of DSNTIAR, see
“Displaying SQLCA fields by calling DSNTIAR” on page 204.

You can also use the MESSAGE_TEXT condition item field of the GET
DIAGNOSTICS statement to convert an SQL return code into a text message.
Programs that require long token message support should code the GET
DIAGNOSTICS statement instead of DSNTIAR. For more information about GET
DIAGNOSTICS, see “Checking the execution of SQL statements by using the GET
DIAGNOSTICS statement” on page 209.

DSNTIAR syntax:

244 Application Programming and SQL Guide

CALL DSNTIAR,(sqlca, message, lrecl),MF=(E,PARM)

The DSNTIAR parameters have the following meanings:

sqlca
An SQL communication area.
message
An output area, defined as a varying-length string, in which DSNTIAR places
the message text. The first halfword contains the length of the remaining area;
its minimum value is 240.
The output lines of text, each line being the length specified in lrecl, are put
into this area. For example, you could specify the format of the output area as:
LINES EQU 10
LRECL EQU 132
.
.
.
MSGLRECL DC AL4(LRECL)
MESSAGE DS H,CL(LINES*LRECL)
ORG MESSAGE
MESSAGEL DC AL2(LINES*LRECL)
MESSAGE1 DS CL(LRECL) text line 1
MESSAGE2 DS CL(LRECL) text line 2
.
.
.
MESSAGEn DS CL(LRECL) text line n
.
.
.
CALL DSNTIAR,(SQLCA,MESSAGE,MSGLRECL),MF=(E,PARM)

where MESSAGE is the name of the message output area, LINES is the
number of lines in the message output area, and LRECL is the length of each
line.
lrecl
A fullword containing the logical record length of output messages, between 72
and 240.

The expression MF=(E,PARM) is an z/OS macro parameter that indicates dynamic

execution. PARM is the name of a data area that contains a list of pointers to the
call parameters of DSNTIAR.

See “DB2 sample applications” on page 1069 for instructions on how to access and
print the source code for the sample program.

CICS: If your CICS application requires CICS storage handling, you must use the
subroutine DSNTIAC instead of DSNTIAR. DSNTIAC has the following syntax:
CALL DSNTIAC,(eib,commarea,sqlca,msg,lrecl),MF=(E,PARM)

DSNTIAC has extra parameters, which you must use for calls to routines that use
CICS commands.
eib EXEC interface block
commarea
communication area

Chapter 4. Coding SQL statements in assembler application programs 245

For more information on these parameters, see the appropriate application
programming guide for CICS. The remaining parameter descriptions are the same
as those for DSNTIAR. Both DSNTIAC and DSNTIAR format the SQLCA in the
same way.

You must define DSNTIA1 in the CSD. If you load DSNTIAR or DSNTIAC, you
must also define them in the CSD. For an example of CSD entry generation
statements for use with DSNTIAC, see member DSN8FRDO in the data set
prefix.SDSNSAMP.

The assembler source code for DSNTIAC and job DSNTEJ5A, which assembles and
link-edits DSNTIAC, are also in the data set prefix.SDSNSAMP.
Related concepts
“Dynamic SQL” on page 162
“Rules for host variables in an SQL statement” on page 151
“Possible host languages for dynamic SQL applications” on page 166
Related tasks
“Determining whether a column value is null” on page 156
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Dynamically executing a data change statement” on page 191
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189
“Enabling the dynamic statement cache” on page 195
“Handling SQL error codes” on page 215
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Limiting CPU time for dynamic SQL statements by using the resource limit
facility” on page 200
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Delimiters in SQL statements in assembler programs

You must delimit SQL statements in your assembler program so that DB2 knows
when a particular SQL statement ends.

Delimit an SQL statement in your assembler program with the beginning keyword
EXEC SQL and an end of line or end of last continued line.

Macros for assembler applications

Data set DSN910.SDSNMACS contains all DB2 macros that are available for use.

246 Application Programming and SQL Guide

Programming examples in assembler
You can write DB2 programs in assembler. These programs can access a local or
remote DB2 subsystem and can execute static or dynamic SQL statements. This
information contains several such programming examples.

To prepare and run these applications, use the JCL in DSN910.SDSNSAMP as a

model for your JCL.
Related reference
“Programming examples” on page 227

Chapter 4. Coding SQL statements in assembler application programs 247

248 Application Programming and SQL Guide
Chapter 5. Coding SQL statements in C application programs
When you code SQL statements in C or C++ application programs, you should
follow certain guidelines.

Defining the SQL communications area, SQLSTATE, and SQLCODE in

C
C and C++ programs that contain SQL statements can include an SQL
communications area (SQLCA) to check whether an SQL statement executed
successfully. Alternatively, these programs can declare individual SQLCODE and
SQLSTATE host variables.

If you specify the SQL processing option STDSQL(YES), do not define an SQLCA.
If you do, DB2 ignores your SQLCA, and your SQLCA definition causes
compile-time errors. If you specify the SQL processing option STDSQL(NO),
include an SQLCA explicitly.

If your application contains SQL statements and does not include an SQL
communications area (SQLCA), you must declare individual SQLCODE and
SQLSTATE host variables. Your program can use these variables to check whether
an SQL statement executed successfully.

To define the SQL communications area, SQLSTATE, and SQLCODE:

Option Description
To define the SQL communications area: 1. Code the SQLCA directly in the program
or use the following SQL INCLUDE
statement to request a standard SQLCA
declaration:
EXEC SQL INCLUDE SQLCA

The standard declaration includes both a

structure definition and a static data area
named ’sqlca’.
DB2 sets the SQLCODE and SQLSTATE
values in the SQLCA after each SQL
statement executes. Your application should
check these values to determine whether the
last SQL statement was successful.

© Copyright IBM Corp. 1983, 2009 249

Option Description
To declare SQLCODE and SQLSTATE host 1. Declare the SQLCODE variable within a
variables: BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as a long integer:
long SQLCODE;
2. Declare the SQLSTATE variable within a
BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as a character array of length 6:
char SQLSTATE[6];
Restriction: Do not declare an SQLSTATE
variable as an element of a structure.
Requirement: After you declare the
SQLCODE and SQLSTATE variables, ensure
that all SQL statements in the program are
within the scope of the declaration of these
variables.

Related tasks
“Checking the execution of SQL statements” on page 202
“Checking the execution of SQL statements by using the SQLCA” on page 203
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the items that your program can use to check whether an SQL statement
executed successfully” on page 141

Defining SQL descriptor areas in C

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

To define SQL descriptor areas:

Code the SQLDA directly in the program, or use the following SQL INCLUDE
statement to request a standard SQLDA declaration:
EXEC SQL INCLUDE SQLDA

You can place an SQLDA declaration wherever C allows a structure definition.

Normal C scoping rules apply. The standard declaration includes only a structure
definition with the name sqlda.

Restriction: You must place SQLDA declarations before the first SQL statement
that references the data descriptor, unless you use the TWOPASS SQL processing
option.

250 Application Programming and SQL Guide

Related tasks
“Defining SQL descriptor areas” on page 141

Declaring host variables and indicator variables in C

You can use host variables, host variable arrays, and host structures in SQL
statements in your program to pass data between DB2 and your application.

To declare host variables, host variable arrays, and host structures:

1. Declare the variables according to the following rules and guidelines:
v You can have more than one host variable declaration section in your
program.
v You can use class members as host variables. Class members that are used as
host variables are accessible to any SQL statement within the class. However,
you cannot use class objects as host variables.
v If you specify the ONEPASS SQL processing option, you must explicitly
declare each host variable and each host variable array before using them in
an SQL statement. If you specify the TWOPASS precompiler option, you
must declare each host variable before using it in the DECLARE CURSOR
statement.

Restriction: The DB2 coprocessor for C/C++ supports only the ONEPASS
option.
v If you specify the STDSQL(YES) SQL processing option, you must precede
the host language statements that define the host variables and host variable
arrays with the BEGIN DECLARE SECTION statement and follow the host
language statements with the END DECLARE SECTION statement.
Otherwise, these statements are optional.
v Ensure that any SQL statement that uses a host variable or host variable
array is within the scope of the statement that declares that variable or array.
| v If you are using the DB2 precompiler, ensure that the names of host variables
| and host variable arrays are unique within the program, even if the variables
| and variable arrays are in different blocks, classes, procedures, functions, or
| subroutines. You can qualify the names with a structure name to make them
| unique.
2. Optional: Define any associated indicator variables, arrays, and structures.
Related tasks
“Declaring host variables and indicator variables” on page 142

Host variables in C
In C and C++ programs, you can specify numeric, character, graphic, binary, LOB,
XML, and ROWID host variables. You can also specify result set, table, and LOB
locators and LOB and XML file reference variables.

Restrictions:
v Only some of the valid C declarations are valid host variable declarations. If the
declaration for a variable is not valid, any SQL statement that references the
variable might result in the message UNDECLARED HOST VARIABLE.
v C supports some data types and storage classes with no SQL equivalents, such
as register storage class, typedef, and long long.
| v The following locator data types are special SQL data types that do not have C
| equivalents:

Chapter 5. Coding SQL statements in C application programs 251

| – Result set locator
| – Table locator
| – LOB locators
| You cannot use them to define column types.
v Although DB2 allows you to use properly formed L-literals in C application
programs, DB2 does not check for all the restrictions that the C compiler
imposes on the L-literal. \
v Do not use L-literals in SQL statements. Use DB2 graphic string constants in
SQL statements to work with the L-literal.

Recommendations:
v Be careful of overflow. For example, suppose that you retrieve an INTEGER
column value into a short integer host variable, and the column value is larger
than 32767. You get an overflow warning or an error, depending on whether you
provide an indicator variable.
v Be careful of truncation. Ensure that the host variable that you declare can
contain the data and a NUL terminator, if needed. Retrieving a floating-point or
decimal column value into a long integer host variable removes any fractional
part of the value.

Numeric host variables

The following diagram shows the syntax for declaring numeric host variables.

|

float

auto const double
extern volatile int
static short
sqlint32
int
long
int
long long
decimal ( precision )
, scale
_Decimal32
_Decimal64
_Decimal128

 variable-name ;

(1) =expression
*pointer-name

Notes:
1 If you use the pointer notation of the host variable, you must use the DB2
coprocessor.

Restrictions:

252 Application Programming and SQL Guide

v If your C compiler does not have a decimal data type, no exact equivalent exists
for the SQL data type DECIMAL. In this case, you can use one of the following
variables or techniques to handle decimal values:
– An integer or floating-point variable, which converts the value. If you use an
integer variable, you lose the fractional part of the number. If the decimal
number can exceed the maximum value for an integer or if you want to
preserve a fractional value, use floating-point variables. Floating-point
numbers are approximations of real numbers. Therefore, when you assign a
decimal number to a floating-point variable, the result might be different from
the original number.
– A character-string host variable. Use the CHAR function to get a string
representation of a decimal number.
– The DECIMAL function to explicitly convert a value to a decimal data type,
as shown in the following example:
long duration=10100; /* 1 year and 1 month */
char result_dt[11];

EXEC SQL SELECT START_DATE + DECIMAL(:duration,8,0)

INTO :result_dt FROM TABLE1;
| v z/OS 1.10 or above (z/OS V1R10 XL C/C++ ) is required to use the decimal
| floating-point host data types.
| v The special C only ’complex floating-point’ host data type is not a supported
| type for host variable.
| v The FLOAT precompiler option does not apply to the decimal floating-point host
| variable types.
| v To use decimal floating-point host variable, you must use the DB2 coprocessor.

For floating-point data types, use the FLOAT SQL processing option to specify
whether the host variable is in IEEE binary floating-point or z/Architecture
hexadecimal floating-point format. DB2 does not check if the format of the host
variable contents match the format that you specified with the FLOAT SQL
processing option. Therefore, you need to ensure that your floating-point host
variable contents match the format that you specified with the FLOAT SQL
processing option. DB2 converts all floating-point input data to z/Architecture
hexadecimal floating-point format before storing it.

Character host variables

You can specify the following forms of character host variables:

v Single-character form
v NUL-terminated character form
v VARCHAR structured form
v CLOBs

The following diagrams show the syntax for forms other than CLOBs.

The following diagram shows the syntax for declaring single-character host
variables.

char  variable-name ;

auto const unsigned (1) =expression
extern volatile *pointer-name
static

Chapter 5. Coding SQL statements in C application programs 253

Notes:
1 If you use the pointer notation of the host variable, you must use the DB2
coprocessor.

The following diagram shows the syntax for declaring NUL-terminated character
host variables.

char

auto const unsigned
extern volatile
static

,
(2) (3)

 variable-name [ length ] ;

(1) =expression
*pointer-name

Notes:
1 If you use the pointer notation of the host variable, you must use the DB2
coprocessor.
2 Any string that is assigned to this variable must be NUL-terminated. Any
string that is retrieved from this variable is NUL-terminated.
3 A NUL-terminated character host variable maps to a varying-length character
string (except for the NUL).

The following diagram shows the syntax for declaring varying-length character
host variables that use the VARCHAR structured form.

auto const
extern volatile
static

(1) int (2)

struct { short var-1 ;

tag

(2)

char var-2 [ length ] ; }

unsigned

 variable-name ;

(3) ={expression, expression}
*pointer-name

254 Application Programming and SQL Guide

Notes:
1 You can use the struct tag to define other variables, but you cannot use them
as host variables in SQL.
2 You cannot use var-1 and var-2 as host variables in an SQL statement.
3 If you use the pointer notation of the host variable, you must use the DB2
coprocessor.

Example: The following example code shows valid and invalid declarations of the
VARCHAR structured form:
EXEC SQL BEGIN DECLARE SECTION;

/* valid declaration of host variable VARCHAR vstring */

struct VARCHAR {
short len;
char s[10];
} vstring;

/* invalid declaration of host variable VARCHAR wstring */

struct VARCHAR wstring;

For NUL-terminated string host variables, use the SQL processing options
PADNTSTR and NOPADNTSTR to specify whether the variable should be padded
with blanks. The option that you specify determines where the NUL-terminator is
placed.

If you assign a string of length n to a NUL-terminated string host variable, the

variable has one of the values that is shown in the following table.
Table 56. Value of a NUL-terminated string host variable that is assigned a string of length n
Length of the NUL-terminated string host
variable Value of the variable
Less than or equal to n The source string up to a length of n-1 and a
NUL at the end of the string. 1

DB2 sets SQLWARN[1] to W and any

indicator variable that you provide to the
original length of the source string.
Equal to n+1 The source string and a NUL at the end of
the string. 1
Greater than n+1 and the source is a
If PADNTSTR is in effect
fixed-length string
The source string, blanks to pad the
value, and a NUL at the end of the
string.
If NOPADNTSTR is in effect
The source string and a NUL at the end
of the string.
Greater than n+1 and the source is a The source string and a NUL at the end of
varying-length string the string. 1
Note:
1. In these cases, whether NOPADNTSTR or PADNTSTR is in effect is irrelevant.

Restriction: If you use the DB2 precompiler, you cannot use a host variable that is
of the NUL-terminated form in either a PREPARE or DESCRIBE statement.

Chapter 5. Coding SQL statements in C application programs 255

However, if you use the DB2 coprocessor, you can use host variables of the
NUL-terminated form in PREPARE, DESCRIBE, and EXECUTE IMMEDIATE
statements.

Graphic host variables

You can specify the following forms of graphic host variables:

v Single-graphic form
v NUL-terminated graphic form
v VARGRAPHIC structured form.
v DBCLOBs

| Recommendation: Instead of using the C data type wchar_t to define graphic and
| vargraphic host variables, use one of the following techniques:
| v Define the sqldbchar data type by using the following typedef statement:
| typedef unsigned short sqldbchar;
| v Use the sqldbchar data type that is defined in the typedef statement in one of
| the following files or libraries:
| – SQL library, sql.h
| – DB2 CLI library, sqlcli.h
| – SQLUDF file in data set DSN910.SDSNC.H
| v Use the C data type unsigned short.

| Using sqldbchar or unsigned short enables you to manipulate DBCS and Unicode
| UTF-16 data in the same format in which it is stored in DB2. Using sqldbchar also
| makes applications easier to port to other platforms.

The following diagrams show the syntax for forms other than DBCLOBs.

The following diagram shows the syntax for declaring single-graphic host
variables.

,
(1) (2)


sqldbchar  variable-name ;

auto const *pointer-name =expression
extern volatile
static

Notes:
1 You cannot use array notation in variable-name.
2 The single-graphic form declares a fixed-length graphic string of length 1.

The following diagram shows the syntax for declaring NUL-terminated graphic
host variables.

,
(2) (3) (4)


sqldbchar  variable-name [ length ] ;

auto const (1) =expression
extern volatile *pointer-name
static

Notes:
1 If you use the pointer notation of the host variable, you must use the DB2
coprocessor.

256 Application Programming and SQL Guide

2 length must be a decimal integer constant greater than 1 and not greater than
16352.
3 Any string that is assigned to this variable must be NUL-terminated. Any
string that is retrieved from this variable is NUL-terminated.
4 The NUL-terminated graphic form does not accept single-byte characters for
the variable.

The following diagram shows the syntax for declaring graphic host variables that
use the VARGRAPHIC structured form.

auto const
extern volatile
static

(1) int (2) (3)

struct { short var-1 ;

tag

(3) (4)

sqldbchar var-2 [ length ] ; }

 variable-name ;

(5) ={ expression, expression}
*pointer-name

Notes:
1 You can use the struct tag to define other variables, but you cannot use them
as host variables in SQL.
2 var-1 must be less than or equal to length.
3 You cannot use var-1 or var-2 as host variables in an SQL statement.
4 length must be a decimal integer constant greater than 1 and not greater than
16352.
5 If you use the pointer notation of the host variable, you must use the DB2
coprocessor.

Example: The following example shows valid and invalid declarations of graphic
host variables that use the VARGRAPHIC structured form:
EXEC SQL BEGIN DECLARE SECTION;

/* valid declaration of host variable structured vgraph */

struct VARGRAPH {
short len;
sqldbchar d[10];
} vgraph;

/* invalid declaration of host variable structured wgraph */

struct VARGRAPH wgraph;

Chapter 5. Coding SQL statements in C application programs 257

| Binary host variables

| You can specify the following forms of binary host variables:

| v Fixed-length strings
| v Varying-length strings
| v BLOBs

| The following diagrams show the syntax for forms other than BLOBs.

| The following diagram shows the syntax for declaring binary host variables.

| ,
(1)


SQL TYPE IS BINARY ( length )  variable-name ;

auto const
extern volatile
static
|
| Notes:
| 1 The length must be a value from 1 to 255.

| The following diagram shows the syntax for declaring VARBINARY host variables.

| (1)
|

SQL TYPE IS VARBINARY ( length )

auto const BINARY VARYING
extern volatile
static

| ,
|

 variable-name ;

= { init-len , ″ init-data ″ }
|
| Notes:
| 1 For VARBINARY host variables, the length must be in the range from 1 to
| 32 704.

| The C language does not have variables that correspond to the SQL binary data
| types BINARY and VARBINARY. To create host variables that can be used with
| these data types, use the SQL TYPE IS clause. The SQL precompiler replaces this
| declaration with the C language structure in the output source member.

| When you reference a BINARY or VARBINARY host variable in an SQL statement,

| you must use the variable that you specify in the SQL TYPE declaration. When
| you reference the host variable in a host language statement, you must use the
| variable that DB2 generates.

| Examples of binary variable declarations: The following table shows examples of

| variables that DB2 generates when you declare binary host variables.
| Table 57. Examples of BINARY and VARBINARY variable declarations for C
| Variable declaration that you include in Corresponding variable that DB2 generates
| your C program in the output source member
| SQL TYPE IS BINARY(10) bin_var; char bin_var[10]

258 Application Programming and SQL Guide

| Table 57. Examples of BINARY and VARBINARY variable declarations for C (continued)
| Variable declaration that you include in Corresponding variable that DB2 generates
| your C program in the output source member
| SQL TYPE IS VARBINARY(10) vbin_var; struct {
| short length;
| char data[10];
| } vbin_var;
|

| Recommendation: Be careful when you use binary host variables with C and C++.
| The SQL TYPE declaration for BINARY and VARBINARY does not account for the
| NUL-terminator that C expects, because binary strings are not NUL-terminated
| strings. Also, the binary host variable might contain zeroes at any point in the
| string.

Result set locators

The following diagram shows the syntax for declaring result set locators.

SQL TYPE IS RESULT_SET_LOCATOR VARYING

auto const
extern volatile
static
register

 variable-name ;

*pointer-name = init-value

Table locators

The following diagram shows the syntax for declaring table locators.

auto const
extern volatile
static
register

SQL TYPE IS TABLE LIKE table-name AS LOCATOR

 variable-name ;

*pointer-name =init-value

Chapter 5. Coding SQL statements in C application programs 259

LOB variables, locators, and file reference variables

The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
host variables, locators, and file reference variables.

SQL TYPE IS

auto const
extern volatile
static
register

|
BINARY LARGE OBJECT ( length )

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_LOCATOR
CLOB_LOCATOR
DBCLOB_LOCATOR
BLOB_FILE
CLOB_FILE
DBCLOB_FILE

 variable-name ;

*pointer-name (1)
=init-value

Notes:
| 1 Specify the initial value as a series of expressions. For example, specify
| ={expression, expression}. For BLOB_FILE, CLOB_FILE, and
| DBCLOB_FILE, specify ={name_length, data_length, file_option_map,
| file_name}.

| XML data host and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variables and file reference variables for XML data types.

|

SQL TYPE IS XML AS BLOB

| auto const XML AS CLOB
extern volatile XML AS DBCLOB
static XML AS BLOB_FILE
register XML AS CLOB_FILE
XML AS DBCLOB_FILE

260 Application Programming and SQL Guide

| ,
(1)

 variable-name ;

*pointer-name =init-value
|
| Notes:
| 1 Specify the initial value as a series of expressions. For example, specify
| ={expression, expression}. For BLOB_FILE, CLOB_FILE, and
| DBCLOB_FILE, specify ={name_length, data_length, file_option_map,
| file_name}.

| ROWID host variables

The following diagram shows the syntax for declaring ROWID host variables.

variable-name SQL TYPE IS ROWID ;


auto const *pointer-name
extern volatile
static
register

Constants

The syntax for constants in C and C++ programs differs from the syntax for
constants in SQL statements in the following ways:
| v C/C++ uses various forms for numeric literals (possible suffixes are: ll, LL, u, U,
| f,F,l,L,df,DF, dd, DD, dl, DL,d, D). For example, in C/C++:
| 4850976 is a decimal literal
| 0x4bD is a hexadecimal integer literal
| 03245 is an octal integer literal
| 3.2E+4 is a double floating-point literal
| 3.2E+4f is a float floating-point literal
| 3.2E+4l is a long double floating-point literal
| 0x4bDP+4 is a double hexadecimal floating-point literal
| 22.2df is a _Decimal32 decimal floating-point literal
| 0.00D is a fixed-point decimal literal (z/OS only when
| LANGLVL(EXTENDED) is specified)
| v Use C/C++ literal form only outside of SQL statements. Within SQL statements,
| use numeric constants.
v In C, character constants and string constants can use escape sequences. You
cannot use the escape sequences in SQL statements.
v Apostrophes and quotation marks have different meanings in C and SQL. In C,
you can use double quotation marks to delimit string constants, and apostrophes
to delimit character constants.

Example of the use of quotation marks in C:

printf( "%d lines read. \n", num_lines);

Example of the use of apostrophes in C:

#define NUL '\0'

Chapter 5. Coding SQL statements in C application programs 261

In SQL, you can use double quotation marks to delimit identifiers and
apostrophes to delimit string constants.

Example of the use of quotation marks in SQL:

SELECT "COL#1" FROM TBL1;

Example of the use of apostrophes in SQL:

SELECT COL1 FROM TBL1 WHERE COL2 = 'BELL';
v Character data in SQL is distinct from integer data. Character data in C is a
subtype of integer data.
Related concepts
“Host variables” on page 143
“Rules for host variables in an SQL statement” on page 151
“Large objects (LOBs)” on page 430
Related tasks
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Retrieving a single row of data into a host structure” on page 161
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157
Related reference
“Descriptions of SQL processing options” on page 904

Host variable arrays in C

In C and C++ programs, you can specify numeric, character, graphic, binary, LOB,
XML, and ROWID host variable arrays. You can also specify LOB locators and
LOB and XML file reference variables.

Restrictions:
v Only some of the valid C declarations are valid host variable array declarations.
If the declaration for a variable array is not valid, any SQL statement that
references the variable array might result in the message UNDECLARED HOST
VARIABLE ARRAY.
| v For both C and C++, you cannot specify the _packed attribute on the structure
| declarations for the following arrays that are used in multiple-row INSERT,
| FETCH, and MERGE statements:
| – varying-length character arrays
| – varying-length graphic arrays
| – LOB arrays
| In addition, the #pragma pack(1) directive cannot be in effect if you plan to use
| these arrays in multiple-row statements.

Numeric host variable arrays

The following diagram shows the syntax for declaring numeric host variable
arrays.

262 Application Programming and SQL Guide

auto const unsigned
extern volatile
static

|
float

double
int
long
short
int
long long
decimal ( precision )
, scale
_Decimal32
_Decimal64
_Decimal128

,
(1)

 variable-name [ dimension ] ;

,

= {  expression }

Notes:
1 dimension must be an integer constant between 1 and 32767.

Example: The following example shows a declaration of a numeric host variable

array:
EXEC SQL BEGIN DECLARE SECTION;
/* declaration of numeric host variable array */
long serial_num[10];
...
EXEC SQL END DECLARE SECTION;

Character host variable arrays

You can specify the following forms of character host variable arrays:
v NUL-terminated character form
v VARCHAR structured form
v CLOBs

The following diagrams show the syntax for forms other than CLOBs.

The following diagram shows the syntax for declaring NUL-terminated character
host variable arrays.

char

auto const unsigned
extern volatile
static

Chapter 5. Coding SQL statements in C application programs 263

,
(1) (2) (3)

 variable-name [ dimension ] [ length ] ;

,

= {  expression }

Notes:
1 dimension must be an integer constant between 1 and 32767.
2 Any string that is assigned to this variable must be NUL-terminated. Any
string that is retrieved from this variable is NUL-terminated.
3 The strings in a NUL-terminated character host variable array map to
varying-length character strings (except for the NUL).

The following diagram shows the syntax for declaring varying-length character
host variable arrays that use the VARCHAR structured form.

auto const
extern volatile
static

(1) int (2)

struct { short var-1 ;

(3)

char var-2 [ length ] ; }

unsigned

,
(4)

 variable-name [ dimension ] ;

,

= {  expression }

Notes:
1 You can use the struct tag to define other variables, but you cannot use them
as host variable arrays in SQL.
| 2 var-1 must be a scalar numeric variable.
| 3 var-2 must be a scalar CHAR array variable.
4 dimension must be an integer constant between 1 and 32767.

Example: The following example shows valid and invalid declarations of

VARCHAR host variable arrays.
EXEC SQL BEGIN DECLARE SECTION;
/* valid declaration of VARCHAR host variable array */
struct VARCHAR {
short len;
char s[18];
} name[10];

/* invalid declaration of VARCHAR host variable array */

struct VARCHAR name[10];

264 Application Programming and SQL Guide

| Binary host variable arrays

| The following diagram shows the syntax for declaring binary host variable arrays.

|

SQL TYPE IS BINARY (length)

| auto const VARBINARY
extern volatile
static
register

| ,
| (1)

 variable-name [ dimension ] ;

|
| Notes:
| 1 dimension must be an integer constant between 1 and 32767.

| Graphic host variable arrays

You can specify the following forms of graphic host variable arrays:
v NUL-terminated graphic form
v VARGRAPHIC structured form.

Recommendation: Instead of using the C data type wchar_t to define graphic and
vargraphic host variable arrays, use one of the following techniques:
v Define the sqldbchar data type by using the following typedef statement:
typedef unsigned short sqldbchar;
v Use the sqldbchar data type that is defined in the typedef statement in the
header files that are supplied by DB2.
v Use the C data type unsigned short.

The following diagram shows the syntax for declaring NUL-terminated graphic
host variable arrays.

sqldbchar

auto const unsigned
extern volatile
static

,
(1) (2) (3) (4)

 variable-name [ dimension ] [ length ] ;

,

= {  expression }

Notes:
1 dimension must be an integer constant between 1 and 32767.
2 length must be a decimal integer constant greater than 1 and not greater than
16352.
3 Any string that is assigned to this variable must be NUL-terminated. Any
string that is retrieved from this variable is NUL-terminated.

Chapter 5. Coding SQL statements in C application programs 265

4 Do not assign single-byte characters into a NUL-terminated graphic host
variable array

The following diagram shows the syntax for declaring graphic host variable arrays
that use the VARGRAPHIC structured form.

auto const
extern volatile
static

(1) int (2)

struct { short var-1 ;

(3) (4)

sqldbchar var-2 [ length ] ; }

unsigned

,
(5)

 variable-name [ dimension ] ;

,

= {  expression }

Notes:
1 You can use the struct tag to define other variables, but you cannot use them
as host variable arrays in SQL.
2 var-1 must be a scalar numeric variable.
3 var-2 must be a scalar char array variable.
4 length must be a decimal integer constant greater than 1 and not greater than
16352.
5 dimension must be an integer constant between 1 and 32767.

Example: The following example shows valid and invalid declarations of graphic
host variable arrays that use the VARGRAPHIC structured form.
EXEC SQL BEGIN DECLARE SECTION;
/* valid declaration of host variable array vgraph */
struct VARGRAPH {
short len;
sqldbchar d[10];
} vgraph[20];

/* invalid declaration of host variable array vgraph */

struct VARGRAPH vgraph[20];

LOB, locator, and file reference variable arrays

The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
host variable arrays, locators, and file reference variables.

266 Application Programming and SQL Guide

SQL TYPE IS

auto const
extern volatile
static
register

|
BINARY LARGE OBJECT ( length )

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_LOCATOR
CLOB_LOCATOR
DBCLOB_LOCATOR
BLOB_FILE
CLOB_FILE
DBCLOB_FILE

,
(1)

 variable-name [ dimension ] ;

,

= {  expression }

Notes:
1 dimension must be an integer constant between 1 and 32767.

| XML host and file reference variable arrays

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variable arrays and file reference variable arrays for XML data types.

|

SQL TYPE IS XML AS

| auto const
extern volatile
static
register

|
BINARY LARGE OBJECT ( length )

| BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_FILE
CLOB_FILE
DBCLOB_FILE

Chapter 5. Coding SQL statements in C application programs 267

| ,
(1)

 variable-name [ dimension ] ;

,

= {  expression }
|
| Notes:
| 1 dimension must be an integer constant between 1 and 32767.

| ROWID variable arrays

The following diagram shows the syntax for declaring ROWID variable arrays.

,
(1)


SQL TYPE IS ROWID  variable-name [ dimension ] ;

auto const
extern volatile
static
register

Notes:
1 dimension must be an integer constant between 1 and 32767.
Related concepts
“Host variable arrays” on page 144
“Host variable arrays in an SQL statement” on page 159
“Large objects (LOBs)” on page 430
Related tasks
“Inserting multiple rows of data from host variable arrays” on page 160
“Retrieving multiple rows of data into host variable arrays” on page 160

Host structures in C
A C host structure contains an ordered group of data fields.

Host structures

The following diagram shows the syntax for declaring host structures.

struct {

auto const packed tag
extern volatile
static

268 Application Programming and SQL Guide

|

 float var-1 ; }

double
int
short
sqlint32
int
long
int
long long
decimal ( precision
, scale )
_Decimal32
_Decimal64
_Decimal128
varchar structure
binary structure
vargraphic structure
SQL TYPE IS ROWID
LOB data type
char var-2 ;
unsigned [ length ]
sqldbchar var-5 ;
[ length ]

variable-name ;

=expression

VARCHAR structures

The following diagram shows the syntax for VARCHAR structures that are used
within declarations of host structures.

int


struct { short var-3 ;

tag signed

char var-4 [ length ] ; }


unsigned

VARGRAPHIC structures

The following diagram shows the syntax for VARGRAPHIC structures that are
used within declarations of host structures.

int


struct { short var-6 ; sqldbchar var-7 [ length ] ; }

tag signed

| Binary structures

| The following diagram shows the syntax for binary structures that are used within
| declarations of host structures.

Chapter 5. Coding SQL statements in C application programs 269

|

SQL TYPE IS BINARY (length)

VARBINARY
BINARY VARYING
|

| LOB data types

The following diagram shows the syntax for LOB data types that are used within
declarations of host structures.

SQL TYPE IS BINARY LARGE OBJECT ( length )


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_LOCATOR
CLOB_LOCATOR
DBCLOB_LOCATOR

| LOB data types for XML data

| The following diagram shows the syntax for LOB data types that are used within
| declarations of host structures for XML data.

|

SQL TYPE IS XML AS BINARY LARGE OBJECT ( length )


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_FILE
CLOB_FILE
DBCLOB_FILE
|

| Example

In the following example, the host structure is named target, and it contains the
fields c1, c2, and c3. c1 and c3 are character arrays, and c2 is a host variable that is
equivalent to the SQL VARCHAR data type. The target host structure can be part
of another host structure but must be the deepest level of the nested structure.
struct {char c1[3];
struct {short len;
char data[5];
}c2;
char c3[2];
}target;
Related concepts
“Host structures” on page 144

Indicator variables, indicator arrays, and host structure

indicator arrays in C
An indicator variable is a 2-byte integer (short int). An indicator variable array is
an array of 2-byte integers (short int). You declare indicator variables in the same
way as host variables. You can mix the declarations of the two types of variables.

270 Application Programming and SQL Guide

The following diagram shows the syntax for declaring an indicator variable in C
and C++.

int


short

auto const signed
extern volatile
static

 variable-name ;

= expression

The following diagram shows the syntax for declaring an indicator array or a host
structure indicator array in C and C++.

int


short

auto const signed
extern volatile
static

,
(1)

 variable-name [ dimension ] ;

= expression

Notes:
1 dimension must be an integer constant between 1 and 32767.

Example

The following example shows a FETCH statement with the declarations of the host
variables that are needed for the FETCH statement and their associated indicator
variables.
EXEC SQL FETCH CLS_CURSOR INTO :ClsCd,
:Day :DayInd,
:Bgn :BgnInd,
:End :EndInd;

You can declare these variables as follows:

EXEC SQL BEGIN DECLARE SECTION;
char ClsCd[8];
char Bgn[9];
char End[9];
short Day, DayInd, BgnInd, EndInd;
EXEC SQL END DECLARE SECTION;

Chapter 5. Coding SQL statements in C application programs 271

Related concepts
“Indicator variables, arrays, and structures” on page 145
Related tasks
“Inserting null values into columns by using indicator variables or arrays” on page
158

Referencing pointer host variables in C programs

If you use the DB2 coprocessor, you can reference any declared pointer host
variables in your SQL statements.

To reference pointer host variables in C and C++ programs:

Specify the pointer host variable exactly as it was declared. The only exception is
when you reference pointers to nul-terminated character arrays. In this case, you
do not have to include the parentheses that were part of the declaration.

Examples of scalar pointer host variable references:

Table 58. Example references to scalar pointer host variables
Declaration Description Reference

short *hvshortp; hvshortp is a pointer host EXEC SQL set:*hvshortp=123;

variable that points to two
bytes of storage.

double *hvdoubp; hvdoubp is a pointer host EXEC SQL set:*hvdoubp=456;

variable that points to eight
bytes of storage.

char (*hvcharpn) [20]; hvcharpn is a pointer host EXEC SQL set:

variable that points to a *hvcharpn='nul_terminated';
nul-terminated character
array of up to 20 bytes.

Example of a bounded character pointer host variable reference: Suppose that

your program declares the following bounded character pointer host variable:
struct {
unsigned long len;
char * data;
} hvbcharp;

The following example references this bounded character pointer host variable:
hvcharp.len = dynlen;
a
hvcharp.data = (char 8) malloc (hvcharp.len);
b
EXEC SQL set :hvcharp = 'data buffer with length';
c

Note:
1. dynlen can be either a compile time constant or a variable with a value that is
assigned at run time.
2. Storage is dynamically allocated for hvcharp.data.
3. The SQL statement references the name of the structure, not an element within
the structure.

Examples of array pointer host variable references:

272 Application Programming and SQL Guide

Table 59. Example references to array pointer host variables
Declaration Description Reference

short * hvarrpl[6] hvarrp1 is an array of 6 pointers that EXEC SQL set:*hvarrpl[n]=123;

point to two bytes of storage each.

double * hvarrp2[3] hvarrp2 is an array of 3 pointers that EXEC SQL set:*hvarrp2[n]=456;

point to 8 bytes of storage each.

struct { hvbarrp3 is an array of 5 bounded EXEC SQL set :hvarrp3[n] =

unsigned long len; character pointers. 'data buffer with length'
char * data; }
hvbarrp3[5];

Example of a structure array host variable reference: Suppose that your program
declares the following pointer to the structure tbl_struct:
struct tbl_struct *ptr_tbl_struct =
(struct tbl_struct *) malloc (sizeof (struct tbl_struct) * n);

To reference this data is SQL statements, use the pointer as shown in the following
example. Assume that tbl_sel_cur is a declared cursor.
for (L_col_cnt = 0; L_col_cnt < n; L_con_cnt++)
{ ...
EXEC SQL FETCH tbl_sel_cur INTO :ptr_tbl_struct [L_col_cnt]
...
}
Related tasks
“Declaring pointer host variables in C programs”

Declaring pointer host variables in C programs

If you use the DB2 coprocessor, you can use pointer host variables with statically
or dynamically allocated storage. These pointer host variables can point to numeric
data, non-numeric data, or a structure.

You can declare the following types of pointer host variables:

scalar pointer host variable
A host variable that points to numeric or non-numeric scalar data.
array pointer host variable
A host variable that is an array of pointers.
structure array host variable
A host variable that points to a structure.

To declare pointer host variables in C and C++ programs:

Include an asterisk (*) in each variable declaration to indicate that the variable is a
pointer.

Restrictions:
v You cannot use pointer host variables that point to character data of an
unknown length. For example, do not specify the following declaration: char *
hvcharpu. Instead, specify the length of the data by using a bounded character
pointer host variable. A bounded character pointer host variable is a host variable
that is declared as a structure with the following elements:
– A 4-byte field that contains the length of the storage area.

Chapter 5. Coding SQL statements in C application programs 273

– A pointer to the non-numeric dynamic storage area.
v You cannot use untyped pointers. For example, do not specify the following
declaration: void * untypedprt .

Examples of scalar pointer host variable declarations:

Table 60. Example declarations of scalar pointer host variables
Declaration Description

short *hvshortp; hvshortp is a pointer host variable that

points to two bytes of storage.

double *hvdoubp; hvdoubp is a pointer host variable that

points to eight bytes of storage.

char (*hvcharpn) [20]; hvcharpn is a pointer host variable that

points to a nul-terminated character array of
up to 20 bytes.

Example of a bounded character pointer host variable declaration: The following

example code declares a bounded character pointer host variable called hvbcharp
with two elements: len and data.
struct {
unsigned long len;
char * data;
} hvbcharp;

Examples of array pointer host variable declarations:

Table 61. Example declarations of array pointer host variables
Declaration Description

short * hvarrpl[6] hvarrp1 is an array of 6 pointers that point to

two bytes of storage each.

double * hvarrp2[3] hvarrp2 is an array of 3 pointers that point to

8 bytes of storage each.

struct { hvbarrp3 is an array of 5 bounded character

unsigned long len; pointers.
char * data; }
hvbarrp3[5];

Example of a structure array host variable declaration: The following example

code declares a table structure called tbl_struct.
struct tbl_struct
{
char colname[20];
small int colno;
small int coltype;
small int collen;
};

The following example code declares a pointer to the structure tbl_struct. Storage is
allocated dynamically for up to n rows.
struct tbl_struct *ptr_tbl_struct =
(struct tbl_struct *) malloc (sizeof (struct tbl_struct) * n);

274 Application Programming and SQL Guide

Related tasks
“Referencing pointer host variables in C programs” on page 272

Equivalent SQL and C data types

When you declare host variables in your C programs, the precompiler uses
equivalent SQL data types. When you retrieve data of a particular SQL data type
into a host variable, you need to ensure that the host variable is of an equivalent
data type.

The following table describes the SQL data type and the base SQLTYPE and
SQLLEN values that the precompiler uses for host variables in SQL statements.
Table 62. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses
for host variables in C programs
SQLTYPE of host SQLLEN of host
C host variable data type variable1 variable SQL data type
short int 500 2 SMALLINT
long int 496 4 INTEGER
| long long 492 8 BIGINT5
| long long int
| sqlint64
decimal(p,s)2 484 p in byte 1, s in DECIMAL(p,s)2
byte 2

|| v _Decimal32 996/997 4 DECFLOAT(16)7, 8

|| v _Decimal64 996/997 8 DECFLOAT(16)8

|| v _Decimal128 996/997 16 DECFLOAT(34)8

float 480 4 FLOAT (single

precision)
double 480 8 FLOAT (double
precision)
| v 912 n BINARY(n)
| SQL TYPE IS
| BINARY(n),
| 1<=n<=255
|
| v 908 n VARBINARY(n)
| SQL TYPE IS
| VARBINARY(n),
| 1<=n<=32704
|
Single-character form 452 1 CHAR(1)
NUL-terminated 460 n VARCHAR (n-1)
character form
VARCHAR structured 448 n VARCHAR(n)
form 1<=n<=255
VARCHAR structured 456 n VARCHAR(n)
form
n>255
Single-graphic form 468 1 GRAPHIC(1)

Chapter 5. Coding SQL statements in C application programs 275

Table 62. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses
for host variables in C programs (continued)
SQLTYPE of host SQLLEN of host
C host variable data type variable1 variable SQL data type
NUL-terminated 400 n VARGRAPHIC (n-1)
graphic form
VARGRAPHIC 464 n VARGRAPHIC(n)
structured form
1<=n<128
VARGRAPHIC 472 n VARGRAPHIC(n)
structured form
n>127
v 972 4 Result set locator3
SQL TYPE IS
RESULT_SET
_LOCATOR

SQL TYPE IS 976 4 Table locator3

TABLE LIKE
table-name
AS LOCATOR
SQL TYPE IS 960 4 BLOB locator3
BLOB_LOCATOR
SQL TYPE IS 964 4 CLOB locator3
CLOB_LOCATOR
SQL TYPE IS 968 4 DBCLOB locator3
DBCLOB_LOCATOR
SQL TYPE IS 404 n BLOB(n)
BLOB(n)
1≤n≤2147483647
SQL TYPE IS 408 n CLOB(n)
CLOB(n)
1≤n≤2147483647
SQL TYPE IS 412 n DBCLOB(n)4
DBCLOB(n)
1≤n≤1073741823
| SQL TYPE IS XML AS 404 0 XML
| BLOB(n)
| SQL TYPE IS XML AS 408 0 XML
| CLOB(n)
| SQL TYPE IS XML AS 412 0 XML
| DBCLOB(n)
3
| SQL TYPE IS BLOB_FILE 916/917 267 BLOB file reference
3
| SQL TYPE IS CLOB_FILE 920/921 267 CLOB file reference
| SQL TYPE IS 924/925 267 DBCLOB file reference
3
| DBCLOB_FILE
| SQL TYPE IS XML AS 916/917 267 XML BLOB file
| BLOB_FILE reference 3
| SQL TYPE IS XML AS 920/921 267 XML CLOB file
| CLOB_FILE reference 3

276 Application Programming and SQL Guide

Table 62. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses
for host variables in C programs (continued)
SQLTYPE of host SQLLEN of host
C host variable data type variable1 variable SQL data type
| SQL TYPE IS XML AS 924/925 267 XML DBCLOB file
| DBCLOB_FILE reference 3
SQL TYPE IS ROWID 904 40 ROWID
Notes:
1. If a host variable includes an indicator variable, the SQLTYPE value is the base
SQLTYPE value plus 1.
2. p is the precision; in SQL terminology, this the total number of digits. In C, this is called
the size.
s is the scale; in SQL terminology, this is the number of digits to the right of the decimal
point. In C, this is called the precision.
C++ does not support the decimal data type.
3. Do not use this data type as a column type.
4. n is the number of double-byte characters.
5. No exact equivalent. Use DECIMAL(19,0).
| 6. Starting in Version 9, the C data type long long no longer maps to the SQL data type
| DEC (19,0). Instead, the C data type long long maps to the SQL data type BIGINT. This
| new mapping applies if the application is precompiled again.
| 7. DFP host variable with a length of 4 is supported while DFP column can be defined only
| with length 8(DECFLOAT(16)) or 16(DECFLOAT(34)).
| 8. To use the decimal floating-point host data type, you must do the following:
| v Use z/OS 1.10 or above (z/OS V1R10 XL C/C++ ).
| v Compile with the C/C++ compiler option, DFP.
| v Specify the SQL compiler option to enable the DB2 coprocessor.
| v Specify C/C++ compiler option, ARCH(7). It is required by the DFP compiler option if
| the DFP type is used in the source.
| v Specify ’DEFINE(__STDC_WANT_DEC_FP__)’ compiler option because DFP is not
| officially part of the C/C++ Language Standard.

The following table shows equivalent C host variables for each SQL data type. Use
this table to determine the C data type for host variables that you define to receive
output from the database. For example, if you retrieve TIMESTAMP data, you can
define a variable of NUL-terminated character form or VARCHAR structured form

This table shows direct conversions between SQL data types and C data types.
However, a number of SQL data types are compatible. When you do assignments
or comparisons of data that have compatible data types, DB2 converts those
compatible data types.
Table 63. C host variable equivalents that you can use when retrieving data of a particular SQL data type
SQL data type C host variable equivalent Notes
SMALLINT short int
INTEGER long int
DECIMAL(p,s) or decimal You can use the double data type if your
NUMERIC(p,s) C compiler does not have a decimal data
type; however, double is not an exact
equivalent.
REAL or FLOAT(n) float 1<=n<=21

Chapter 5. Coding SQL statements in C application programs 277

Table 63. C host variable equivalents that you can use when retrieving data of a particular SQL data type (continued)
SQL data type C host variable equivalent Notes
DOUBLE PRECISION or double 22<=n<=53
FLOAT(n)
| DECFLOAT(16) _Decminal32
| DECFLOAT(34) _Decimal128
| BIGINT long long, long long int, and sqlint64
| BINARY(n) SQL TYPE IS BINARY(n) 1<=n<=255

| If data can contain character NULs (\0),

| certain C and C++ library functions might
| not handle the data correctly. Ensure that
| your application handles the data
| properly.
| VARBINARY(n) SQL TYPE IS VARBINARY(n) 1<=n<=32 704
CHAR(1) single-character form
CHAR(n) no exact equivalent If n>1, use NUL-terminated character form
VARCHAR(n) NUL-terminated character form If data can contain character NULs (\0),
use VARCHAR structured form. Allow at
least n+1 to accommodate the
NUL-terminator.
VARCHAR structured form
GRAPHIC(1) single-graphic form
GRAPHIC(n) no exact equivalent If n>1, use NUL-terminated graphic form.
n is the number of double-byte characters.
VARGRAPHIC(n) NUL-terminated graphic form If data can contain graphic NUL values
(\0\0), use VARGRAPHIC structured
form. Allow at least n+1 to accommodate
the NUL-terminator. n is the number of
double-byte characters.
VARGRAPHIC structured form n is the number of double-byte characters.
DATE NUL-terminated character form If you are using a date exit routine, that
routine determines the length. Otherwise,
allow at least 11 characters to
accommodate the NUL-terminator.
VARCHAR structured form If you are using a date exit routine, that
routine determines the length. Otherwise,
allow at least 10 characters.
TIME NUL-terminated character form If you are using a time exit routine, the
length is determined by that routine.
Otherwise, the length must be at least 7;
to include seconds, the length must be at
least 9 to accommodate the
NUL-terminator.
VARCHAR structured form If you are using a time exit routine, the
length is determined by that routine.
Otherwise, the length must be at least 6;
to include seconds, the length must be at
least 8.

278 Application Programming and SQL Guide

Table 63. C host variable equivalents that you can use when retrieving data of a particular SQL data type (continued)
SQL data type C host variable equivalent Notes
TIMESTAMP NUL-terminated character form The length must be at least 20. To include
microseconds, the length must be 27. If the
length is less than 27, truncation occurs on
the microseconds part.
VARCHAR structured form The length must be at least 19. To include
microseconds, the length must be 26. If the
length is less than 26, truncation occurs on
the microseconds part.
Result set locator SQL TYPE IS RESULT_SET_LOCATOR Use this data type only for receiving result
sets. Do not use this data type as a
column type.
Table locator SQL TYPE IS TABLE LIKE table-name AS Use this data type only in a user-defined
LOCATOR function or stored procedure to receive
rows of a transition table. Do not use this
data type as a column type.
BLOB locator SQL TYPE IS BLOB_LOCATOR Use this data type only to manipulate data
in BLOB columns. Do not use this data
type as a column type.
CLOB locator SQL TYPE IS CLOB_LOCATOR Use this data type only to manipulate data
in CLOB columns. Do not use this data
type as a column type.
DBCLOB locator SQL TYPE IS DBCLOB_LOCATOR Use this data type only to manipulate data
in DBCLOB columns. Do not use this data
type as a column type.
BLOB(n) SQL TYPE IS BLOB(n) 1≤n≤2147483647
CLOB(n) SQL TYPE IS CLOB(n) 1≤n≤2147483647
DBCLOB(n) SQL TYPE IS DBCLOB(n) n is the number of double-byte characters.
1≤n≤1073741823
| XML SQL TYPE IS XML AS BLOB(n) 1≤n≤2147483647
| XML SQL TYPE IS XML AS CLOB(n) 1≤n≤2147483647
| XML SQL TYPE IS XML AS DBCLOB(n) n is the number of double-byte characters.
| 1≤n≤1073741823
| BLOB file reference SQL TYPE IS BLOB_FILE Use this data type only to manipulate data
| in BLOB columns. Do not use this data
| type as a column type.
| CLOB file reference SQL TYPE IS CLOB_FILE Use this data type only to manipulate data
| in CLOB columns. Do not use this data
| type as a column type.
| DBCLOB file reference SQL TYPE IS DBCLOB_FILE Use this data type only to manipulate data
| in DBCLOB columns. Do not use this data
| type as a column type.
| XML BLOB file reference SQL TYPE IS XML AS BLOB_FILE Use this data type only to manipulate
| XML data as BLOB files. Do not use this
| data type as a column type.
| XML CLOB file reference SQL TYPE IS XML AS CLOB_FILE Use this data type only to manipulate
| XML data as CLOB files. Do not use this
| data type as a column type.

Chapter 5. Coding SQL statements in C application programs 279

Table 63. C host variable equivalents that you can use when retrieving data of a particular SQL data type (continued)
SQL data type C host variable equivalent Notes
| XML DBCLOB file reference SQL TYPE IS XML AS DBCLOB_FILE Use this data type only to manipulate
| XML data as DBCLOB files. Do not use
| this data type as a column type.
ROWID SQL TYPE IS ROWID

Related concepts
“Compatibility of SQL and language data types” on page 148
“LOB host variable, LOB locator, and LOB file reference variable declarations” on
page 705
“Host variable data types for XML data in embedded SQL applications” on page
217

SQL statements in C programs

You can code SQL statements in a C program wherever you can use executable
statements.

Each SQL statement in a C program must begin with EXEC SQL and end with a
semicolon (;). The EXEC and SQL keywords must appear on one line, but the
remainder of the statement can appear on subsequent lines.

In general, because C is case sensitive, use uppercase letters to enter all SQL
keywords. However, if you use the FOLD precompiler suboption, DB2 folds
lowercase letters in SBCS SQL ordinary identifiers to uppercase. For information
about host language precompiler options, see Table 150 on page 904.

You must keep the case of host variable names consistent throughout the program.
For example, if a host variable name is lowercase in its declaration, it must be
lowercase in all SQL statements. You might code an UPDATE statement in a C
program as follows:
EXEC SQL
UPDATE DSN8910.DEPT
SET MGRNO = :mgr_num
WHERE DEPTNO = :int_dept;

| Comments: You can include C comments (/* ... */) within SQL statements
| wherever you can use a blank, except between the keywords EXEC and SQL. You
| can use single-line comments (starting with //) in C language statements, but not
| in embedded SQL. You can use SQL comments within embedded SQL statements.
| You can nest comments.

To include EBCDIC DBCS characters in comments, you must delimit the characters
by a shift-out and shift-in control character; the first shift-in character in the DBCS
string signals the end of the DBCS string.

Continuation for SQL statements: You can use a backslash to continue a

character-string constant or delimited identifier on the following line. However,
EBCDIC DBCS string constants cannot be continued on a second line.

Declaring tables and views: Your C program should use the DECLARE TABLE
statement to describe each table and view the program accesses. You can use the

280 Application Programming and SQL Guide

DB2 declarations generator (DCLGEN) to generate the DECLARE TABLE
statements. For more information, see “DCLGEN (declarations generator)” on page
129.

| Including SQL statements and variable declarations in source code that is to be

| processed by the DB2 precompiler: To include SQL statements or C host variable
declarations from a member of a partitioned data set, add the following SQL
statement to the source code where you want to include the statements:
EXEC SQL INCLUDE member-name;

You cannot nest SQL INCLUDE statements. Do not use C #include statements to
include SQL statements or C host variable declarations.

| Margins: Code SQL statements in columns 1 through 72, unless you specify other
| margins to the DB2 precompiler. If EXEC SQL is not within the specified margins,
| the DB2 precompiler does not recognize the SQL statement. The margin rules do
| not apply to the DB2 coprocessor. The DB2 coprocessor allows variable length
| source input.

Names:You can use any valid C name for a host variable, subject to the following
restrictions:
v Do not use DBCS characters.
| v Do not use external entry names or access plan names that begin with ’DSN’,
| and do not use host variable names or macro names that begin with ’SQL’ (in
| any combination of uppercase or lowercase letters). These names are reserved
| for DB2.

Nulls and NULs: C and SQL differ in the way they use the word null. The C
language has a null character (NUL), a null pointer (NULL), and a null statement
(just a semicolon). The C NUL is a single character that compares equal to 0. The C
NULL is a special reserved pointer value that does not point to any valid data
object. The SQL null value is a special value that is distinct from all non-null
values and denotes the absence of a (nonnull) value. NUL (or NUL-terminator) is
the null character in C and C++, and NULL is the SQL null value.

Sequence numbers: The DB2 precompiler generates statements without sequence

| numbers. (The DB2 coprocessor does not perform this action, because the source is
| read and modified by the compiler. )

Statement labels: You can precede SQL statements with a label.

Trigraph characters: Some characters from the C character set are not available on
all keyboards. You can enter these characters into a C source program using a
sequence of three characters called a trigraph. The trigraph characters that DB2
supports are the same as those that the C compiler supports.

WHENEVER statement: The target for the GOTO clause in an SQL WHENEVER
statement must be within the scope of any SQL statements that the statement
WHENEVER affects.

Special C/C++ considerations:

v Using the C/370™ multi-tasking facility, in which multiple tasks execute SQL
statements, causes unpredictable results.
| v Except for the DB2 coprocessor, you must run the DB2 precompiler before
| running the C preprocessor.

Chapter 5. Coding SQL statements in C application programs 281

| v Except for the DB2 coprocessor, DB2 precompiler does not support C
| preprocessor directives.
v If you use conditional compiler directives that contain C code, either place them
after the first C token in your application program, or include them in the C
program using the #include preprocessor directive.

Refer to the appropriate C documentation for more information about C

preprocessor directives.

| To use the decimal floating-point host data type, you must do the following:
| v Use z/OS 1.10 or above (z/OS V1R10 XL C/C++ ).
| v Compile with the C/C++ compiler option, DFP.
| v Specify the SQL compiler option to enable the DB2 coprocessor.
| v Specify C/C++ compiler option, ARCH(7). It is required by the DFP compiler
| option if the DFP type is used in the source.
| v Specify ’DEFINE(__STDC_WANT_DEC_FP__)’ compiler option.

Handling SQL error return codes in C or C++

You can use the subroutine DSNTIAR to convert an SQL return code into a text
message. DSNTIAR takes data from the SQLCA, formats it into a message, and
places the result in a message output area that you provide in your application
program. For concepts and more information about the behavior of DSNTIAR, see
“Displaying SQLCA fields by calling DSNTIAR” on page 204.

You can also use the MESSAGE_TEXT condition item field of the GET
DIAGNOSTICS statement to convert an SQL return code into a text message.
Programs that require long token message support should code the GET
DIAGNOSTICS statement instead of DSNTIAR. For more information about GET
DIAGNOSTICS, see “Checking the execution of SQL statements by using the GET
DIAGNOSTICS statement” on page 209.

DSNTIAR syntax:

rc = dsntiar(&sqlca, &message, &lrecl);

The DSNTIAR parameters have the following meanings:

&sqlca
An SQL communication area.
&message
An output area, in VARCHAR format, in which DSNTIAR places the message
text. The first halfword contains the length of the remaining area; its minimum
value is 240.
The output lines of text, each line being the length specified in &lrecl, are put
into this area. For example, you could specify the format of the output area as:
#define data_len 132
#define data_dim 10
struct error_struct {
short int error_len;
char error_text[data_dim][data_len];
. } error_message = {data_dim * data_len};
.
.
rc = dsntiar(&sqlca, &error_message, &data_len);

282 Application Programming and SQL Guide

where error_message is the name of the message output area, data_dim is the
number of lines in the message output area, and data_len is the length of each
line.
&lrecl
A fullword containing the logical record length of output messages, between 72
and 240.

To inform your compiler that DSNTIAR is an assembler language program, include

one of the following statements in your application.

For C, include:
#pragma linkage (dsntiar,OS)

For C++, include a statement similar to this:

extern "OS" short int dsntiar(struct sqlca *sqlca,
struct error_struct *error_message,
int *data_len);

Examples of calling DSNTIAR from an application appear in the DB2 sample C

program DSN8BD3 and in the sample C++ program DSN8BE3. Both are in the
library DSN8910.SDSNSAMP. See “DB2 sample applications” on page 1069 for
instructions on how to access and print the source code for the sample programs.

CICS: If your CICS application requires CICS storage handling, you must use the
subroutine DSNTIAC instead of DSNTIAR. DSNTIAC has the following syntax:
rc = DSNTIAC(&eib, &commarea, &sqlca, &message, &lrecl);

DSNTIAC has extra parameters, which you must use for calls to routines that use
CICS commands.
&eib EXEC interface block
&commarea
communication area

For more information on these parameters, see the appropriate application

programming guide for CICS. The remaining parameter descriptions are the same
as those for DSNTIAR. Both DSNTIAC and DSNTIAR format the SQLCA in the
same way.

You must define DSNTIA1 in the CSD. If you load DSNTIAR or DSNTIAC, you
must also define them in the CSD. For an example of CSD entry generation
statements for use with DSNTIAC, see job DSNTEJ5A.

The assembler source code for DSNTIAC and job DSNTEJ5A, which assembles and
link-edits DSNTIAC, are in the data set prefix.SDSNSAMP.

Chapter 5. Coding SQL statements in C application programs 283

Related concepts
“Dynamic SQL” on page 162
“Host variable arrays in an SQL statement” on page 159
“Rules for host variables in an SQL statement” on page 151
“Possible host languages for dynamic SQL applications” on page 166
Related tasks
“Determining whether a column value is null” on page 156
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Dynamically executing a data change statement” on page 191
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189
“Enabling the dynamic statement cache” on page 195
“Handling SQL error codes” on page 215
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
“Inserting a single row by using a host variable” on page 158
“Inserting multiple rows of data from host variable arrays” on page 160
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Limiting CPU time for dynamic SQL statements by using the resource limit
facility” on page 200
“Retrieving multiple rows of data into host variable arrays” on page 160
“Retrieving a single row of data into a host structure” on page 161
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Delimiters in SQL statements in C programs

You must delimit SQL statements in your C program so that DB2 knows when a
particular SQL statement ends.

Delimit an SQL statement in your C program with the beginning keyword EXEC
SQL and a Semicolon (;).

Programming examples in C
You can write DB2 programs in C and C++. These programs can access a local or
remote DB2 subsystem and can execute static or dynamic SQL statements. This
information contains several such programming examples.

To prepare and run these applications, use the JCL in DSN910.SDSNSAMP as a

model for your JCL.

284 Application Programming and SQL Guide

Related reference
“Programming examples” on page 227

Sample dynamic and static SQL in a C program

Programs that access DB2 can contain static SQL, dynamic SQL, or both. This
example shows a C program that contains both static and dynamic SQL.

The following figure illustrates dynamic SQL and static SQL embedded in a C
program. Each section of the program is identified with a comment. Section 1 of
the program shows static SQL; sections 2, 3, and 4 show dynamic SQL. The
function of each section is explained in detail in the prologue to the program.
/**********************************************************************/
/* Descriptive name = Dynamic SQL sample using C language */
/* */
/* Function = To show examples of the use of dynamic and static */
/* SQL. */
/* */
/* Notes = This example assumes that the EMP and DEPT tables are */
/* defined. They need not be the same as the DB2 Sample */
/* tables. */
/* */
/* Module type = C program */
/* Processor = DB2 precompiler, C compiler */
/* Module size = see link edit */
/* Attributes = not reentrant or reusable */
/* */
/* Input = */
/* */
/* symbolic label/name = DEPT */
/* description = arbitrary table */
/* symbolic label/name = EMP */
/* description = arbitrary table */
/* */
/* Output = */
/* */
/* symbolic label/name = SYSPRINT */
/* description = print results via printf */
/* */
/* Exit-normal = return code 0 normal completion */
/* */
/* Exit-error = */
/* */
/* Return code = SQLCA */
/* */
/* Abend codes = none */
/* */
/* External references = none */
/* */
/* Control-blocks = */
/* SQLCA - sql communication area */
/* */
/* Logic specification: */
/* */
/* There are four SQL sections. */
/* */
/* 1) STATIC SQL 1: using static cursor with a SELECT statement. */
/* Two output host variables. */
/* 2) Dynamic SQL 2: Fixed-list SELECT, using same SELECT statement */
/* used in SQL 1 to show the difference. The prepared string */
/* :iptstr can be assigned with other dynamic-able SQL statements. */
/* 3) Dynamic SQL 3: Insert with parameter markers. */
/* Using four parameter markers which represent four input host */
/* variables within a host structure. */
/* 4) Dynamic SQL 4: EXECUTE IMMEDIATE */

Chapter 5. Coding SQL statements in C application programs 285

/* A GRANT statement is executed immediately by passing it to DB2 */
/* via a varying string host variable. The example shows how to */
/* set up the host variable before passing it. */
/* */
/**********************************************************************/

#include "stdio.h"
#include "stdefs.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL INCLUDE SQLDA;
EXEC SQL BEGIN DECLARE SECTION;
short edlevel;
struct { short len;
char x1[56];
} stmtbf1, stmtbf2, inpstr;
struct { short len;
char x1[15];
} lname;
short hv1;
struct { char deptno[4];
struct { short len;
char x[36];
} deptname;
char mgrno[7];
char admrdept[4];
} hv2;
short ind[4];
EXEC SQL END DECLARE SECTION;
EXEC SQL DECLARE EMP TABLE
(EMPNO CHAR(6) ,
FIRSTNAME VARCHAR(12) ,
MIDINIT CHAR(1) ,
LASTNAME VARCHAR(15) ,
WORKDEPT CHAR(3) ,
PHONENO CHAR(4) ,
HIREDATE DECIMAL(6) ,
JOBCODE DECIMAL(3) ,
EDLEVEL SMALLINT ,
SEX CHAR(1) ,
BIRTHDATE DECIMAL(6) ,
SALARY DECIMAL(8,2) ,
FORFNAME VARGRAPHIC(12) ,
FORMNAME GRAPHIC(1) ,
FORLNAME VARGRAPHIC(15) ,
FORADDR VARGRAPHIC(256) ) ;
EXEC SQL DECLARE DEPT TABLE
(
DEPTNO CHAR(3) ,
DEPTNAME VARCHAR(36) ,
MGRNO CHAR(6) ,
ADMRDEPT CHAR(3) );
main ()
{
printf("??/n*** begin of program ***");
EXEC SQL WHENEVER SQLERROR GO TO HANDLERR;
EXEC SQL WHENEVER SQLWARNING GO TO HANDWARN;
EXEC SQL WHENEVER NOT FOUND GO TO NOTFOUND;
/******************************************************************/
/* Assign values to host variables which will be input to DB2 */
/******************************************************************/
strcpy(hv2.deptno,"M92");
strcpy(hv2.deptname.x,"DDL");
hv2.deptname.len = strlen(hv2.deptname.x);
strcpy(hv2.mgrno,"123456");
strcpy(hv2.admrdept,"abc");
/******************************************************************/
/* Static SQL 1: DECLARE CURSOR, OPEN, FETCH, CLOSE */

286 Application Programming and SQL Guide

/* Select into :edlevel, :lname */
/******************************************************************/
printf("??/n*** begin declare ***");
EXEC SQL DECLARE C1 CURSOR FOR SELECT EDLEVEL, LASTNAME FROM EMP
WHERE EMPNO = '000010';
printf("??/n*** begin open ***");
EXEC SQL OPEN C1;

printf("??/n*** begin fetch ***");

EXEC SQL FETCH C1 INTO :edlevel, :lname;
printf("??/n*** returned values ***");
printf("??/n??/nedlevel =
printf("??/nlname =

printf("??/n*** begin close ***");

EXEC SQL CLOSE C1;
/******************************************************************/
/* Dynamic SQL 2: PREPARE, DECLARE CURSOR, OPEN, FETCH, CLOSE */
/* Select into :edlevel, :lname */
/******************************************************************/
sprintf (inpstr.x1,
"SELECT EDLEVEL, LASTNAME FROM EMP WHERE EMPNO = '000010'");
inpstr.len = strlen(inpstr.x1);
printf("??/n*** begin prepare ***");
EXEC SQL PREPARE STAT1 FROM :inpstr;
printf("??/n*** begin declare ***");
EXEC SQL DECLARE C2 CURSOR FOR STAT1;
printf("??/n*** begin open ***");
EXEC SQL OPEN C2;

printf("??/n*** begin fetch ***");

EXEC SQL FETCH C2 INTO :edlevel, :lname;
printf("??/n*** returned values ***");
printf("??/n??/nedlevel =
printf("??/nlname =

printf("??/n*** begin close ***");

EXEC SQL CLOSE C2;
/******************************************************************/
/* Dynamic SQL 3: PREPARE with parameter markers */
/* Insert into with four values. */
/******************************************************************/
sprintf (stmtbf1.x1,
"INSERT INTO DEPT VALUES (?,?,?,?)");
stmtbf1.len = strlen(stmtbf1.x1);
printf("??/n*** begin prepare ***");
EXEC SQL PREPARE s1 FROM :stmtbf1;
printf("??/n*** begin execute ***");
EXEC SQL EXECUTE s1 USING :hv2:ind;
printf("??/n*** following are expected insert results ***");
printf("??/n hv2.deptno =
printf("??/n hv2.deptname.len =
printf("??/n hv2.deptname.x =
printf("??/n hv2.mgrno =
printf("??/n hv2.admrdept =
EXEC SQL COMMIT;
/******************************************************************/
/* Dynamic SQL 4: EXECUTE IMMEDIATE */
/* Grant select */
/******************************************************************/
sprintf (stmtbf2.x1,
"GRANT SELECT ON EMP TO USERX");
stmtbf2.len = strlen(stmtbf2.x1);
printf("??/n*** begin execute immediate ***");
EXEC SQL EXECUTE IMMEDIATE :stmtbf2;
printf("??/n*** end of program ***");
goto progend;

Chapter 5. Coding SQL statements in C application programs 287

HANDWARN: HANDLERR: NOTFOUND: ;
printf("??/n SQLCODE =
printf("??/n SQLWARN0 =
printf("??/n SQLWARN1 =
printf("??/n SQLWARN2 =
printf("??/n SQLWARN3 =
printf("??/n SQLWARN4 =
printf("??/n SQLWARN5 =
printf("??/n SQLWARN6 =
printf("??/n SQLWARN7 =
progend: ;
}

Example C program that calls a stored procedure

This example shows how to call the C language version of the GETPRML stored
procedure that uses the GENERAL WITH NULLS linkage convention. Because the
stored procedure returns result sets, this program checks for result sets and
retrieves the contents of the result sets.

The following figure contains the example C program that calls the GETPRML
stored procedure.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
main()
{
/************************************************************/
/* Include the SQLCA and SQLDA */
/************************************************************/
EXEC SQL INCLUDE SQLCA;
EXEC SQL INCLUDE SQLDA;
/************************************************************/
/* Declare variables that are not SQL-related. */
/************************************************************/
short int i; /* Loop counter */
/************************************************************/
/* Declare the following: */
/* - Parameters used to call stored procedure GETPRML */
/* - An SQLDA for DESCRIBE PROCEDURE */
/* - An SQLDA for DESCRIBE CURSOR */
/* - Result set variable locators for up to three result */
/* sets */
/************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
char procnm[19]; /* INPUT parm -- PROCEDURE name */
char schema[9]; /* INPUT parm -- User's schema */
long int out_code; /* OUTPUT -- SQLCODE from the */
/* SELECT operation. */
struct {
short int parmlen;
char parmtxt[254];
} parmlst; /* OUTPUT -- RUNOPTS values */
/* for the matching row in */
/* catalog table SYSROUTINES */
struct indicators {
short int procnm_ind;
short int schema_ind;
short int out_code_ind;
short int parmlst_ind;
} parmind;
/* Indicator variable structure */

struct sqlda *proc_da;

/* SQLDA for DESCRIBE PROCEDURE */
struct sqlda *res_da;

288 Application Programming and SQL Guide

/* SQLDA for DESCRIBE CURSOR */
static volatile
SQL TYPE IS RESULT_SET_LOCATOR *loc1, *loc2, *loc3;
/* Locator variables */
EXEC SQL END DECLARE SECTION;

/*************************************************************/
/* Allocate the SQLDAs to be used for DESCRIBE */
/* PROCEDURE and DESCRIBE CURSOR. Assume that at most */
/* three cursors are returned and that each result set */
/* has no more than five columns. */
/*************************************************************/
proc_da = (struct sqlda *)malloc(SQLDASIZE(3));
res_da = (struct sqlda *)malloc(SQLDASIZE(5));

/************************************************************/
/* Call the GETPRML stored procedure to retrieve the */
/* RUNOPTS values for the stored procedure. In this */
/* example, we request the PARMLIST definition for the */
/* stored procedure named DSN8EP2. */
/* */
/* The call should complete with SQLCODE +466 because */
/* GETPRML returns result sets. */
/************************************************************/
strcpy(procnm,"dsn8ep2 ");
/* Input parameter -- PROCEDURE to be found */
strcpy(schema," ");
/* Input parameter -- Schema name for proc */
parmind.procnm_ind=0;
parmind.schema_ind=0;
parmind.out_code_ind=0;
/* Indicate that none of the input parameters */
/* have null values */
parmind.parmlst_ind=-1;
/* The parmlst parameter is an output parm. */
/* Mark PARMLST parameter as null, so the DB2 */
/* requester doesn't have to send the entire */
/* PARMLST variable to the server. This */
/* helps reduce network I/O time, because */
/* PARMLST is fairly large. */
EXEC SQL
CALL GETPRML(:procnm INDICATOR :parmind.procnm_ind,
:schema INDICATOR :parmind.schema_ind,
:out_code INDICATOR :parmind.out_code_ind,
:parmlst INDICATOR :parmind.parmlst_ind);
if(SQLCODE!=+466) /* If SQL CALL failed, */
{
/* print the SQLCODE and any */
/* message tokens */
printf("SQL CALL failed due to SQLCODE =
printf("sqlca.sqlerrmc = ");
for(i=0;i<sqlca.sqlerrml;i++)
printf("i]);
printf("\n");
}
else /* If the CALL worked, */
if(out_code!=0) /* Did GETPRML hit an error? */
printf("GETPRML failed due to RC =
/**********************************************************/
/* If everything worked, do the following: */
/* - Print out the parameters returned. */
/* - Retrieve the result sets returned. */
/**********************************************************/
else
{
printf("RUNOPTS =

Chapter 5. Coding SQL statements in C application programs 289

/* Print out the runopts list */

/********************************************************/
/* Use the statement DESCRIBE PROCEDURE to */
/* return information about the result sets in the */
/* SQLDA pointed to by proc_da: */
/* - SQLD contains the number of result sets that were */
/* returned by the stored procedure. */
/* - Each SQLVAR entry has the following information */
/* about a result set: */
/* - SQLNAME contains the name of the cursor that */
/* the stored procedure uses to return the result */
/* set. */
/* - SQLIND contains an estimate of the number of */
/* rows in the result set. */
/* - SQLDATA contains the result locator value for */
/* the result set. */
/********************************************************/
EXEC SQL DESCRIBE PROCEDURE INTO :*proc_da;
/********************************************************/
/* Assume that you have examined SQLD and determined */
/* that there is one result set. Use the statement */
/* ASSOCIATE LOCATORS to establish a result set locator */
/* for the result set. */
/********************************************************/
EXEC SQL ASSOCIATE LOCATORS (:loc1) WITH PROCEDURE GETPRML;

/********************************************************/
/* Use the statement ALLOCATE CURSOR to associate a */
/* cursor for the result set. */
/********************************************************/
EXEC SQL ALLOCATE C1 CURSOR FOR RESULT SET :loc1;
/********************************************************/
/* Use the statement DESCRIBE CURSOR to determine the */
/* columns in the result set. */
/********************************************************/
EXEC SQL DESCRIBE CURSOR C1 INTO :*res_da;

/********************************************************/
/* Call a routine (not shown here) to do the following: */
/* - Allocate a buffer for data and indicator values */
/* fetched from the result table. */
/* - Update the SQLDATA and SQLIND fields in each */
/* SQLVAR of *res_da with the addresses at which to */
/* to put the fetched data and values of indicator */
/* variables. */
/********************************************************/
alloc_outbuff(res_da);

/********************************************************/
/* Fetch the data from the result table. */
/********************************************************/
while(SQLCODE==0)
EXEC SQL FETCH C1 USING DESCRIPTOR :*res_da;
}
return;
}

Example C stored procedure with a GENERAL linkage

convention
This example shows how to call a stored procedure that uses the GENERAL
linkage convention from a C program.

This example stored procedure does the following:

290 Application Programming and SQL Guide

v Searches the DB2 catalog table SYSROUTINES for a row that matches the input
parameters from the client program. The two input parameters contain values
for NAME and SCHEMA.
v Searches the DB2 catalog table SYSTABLES for all tables in which the value of
CREATOR matches the value of input parameter SCHEMA. The stored
procedure uses a cursor to return the table names.

The linkage convention used for this stored procedure is GENERAL.

The output parameters from this stored procedure contain the SQLCODE from the
SELECT statement and the value of the RUNOPTS column from SYSROUTINES.

The CREATE PROCEDURE statement for this stored procedure might look like
this:
CREATE PROCEDURE GETPRML(PROCNM CHAR(18) IN, SCHEMA CHAR(8) IN,
OUTCODE INTEGER OUT, PARMLST VARCHAR(254) OUT)
LANGUAGE C
DETERMINISTIC
READS SQL DATA
EXTERNAL NAME "GETPRML"
COLLID GETPRML
ASUTIME NO LIMIT
PARAMETER STYLE GENERAL
STAY RESIDENT NO
RUN OPTIONS "MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)"
WLM ENVIRONMENT SAMPPROG
PROGRAM TYPE MAIN
SECURITY DB2
RESULT SETS 2
COMMIT ON RETURN NO;

The following example is a C stored procedure with linkage convention GENERAL

#pragma runopts(plist(os))
#include <stdlib.h>

EXEC SQL INCLUDE SQLCA;

/***************************************************************/
/* Declare C variables for SQL operations on the parameters. */
/* These are local variables to the C program, which you must */
/* copy to and from the parameter list provided to the stored */
/* procedure. */
/***************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
char PROCNM[19];
char SCHEMA[9];
char PARMLST[255];
EXEC SQL END DECLARE SECTION;

/***************************************************************/
/* Declare cursors for returning result sets to the caller. */
/***************************************************************/
EXEC SQL DECLARE C1 CURSOR WITH RETURN FOR
SELECT NAME
FROM SYSIBM.SYSTABLES
WHERE CREATOR=:SCHEMA;

main(argc,argv)
int argc;
char *argv[];
{
/********************************************************/
/* Copy the input parameters into the area reserved in */

Chapter 5. Coding SQL statements in C application programs 291

/* the program for SQL processing. */
/********************************************************/
strcpy(PROCNM, argv[1]);
strcpy(SCHEMA, argv[2]);

/********************************************************/
/* Issue the SQL SELECT against the SYSROUTINES */
/* DB2 catalog table. */
/********************************************************/
strcpy(PARMLST, ""); /* Clear PARMLST */
EXEC SQL
SELECT RUNOPTS INTO :PARMLST
FROM SYSIBM.ROUTINES
WHERE NAME=:PROCNM AND
SCHEMA=:SCHEMA;
/********************************************************/
/* Copy SQLCODE to the output parameter list. */
/********************************************************/
*(int *) argv[3] = SQLCODE;

/********************************************************/
/* Copy the PARMLST value returned by the SELECT back to*/
/* the parameter list provided to this stored procedure.*/
/********************************************************/
strcpy(argv[4], PARMLST);

/********************************************************/
/* Open cursor C1 to cause DB2 to return a result set */
/* to the caller. */
/********************************************************/
EXEC SQL OPEN C1;
}

Example C stored procedure with a GENERAL WITH NULLS

linkage convention
This example shows how to call a stored procedure that uses the GENERAL WITH
NULLS linkage convention from a C program.

This example stored procedure does the following:

v Searches the DB2 catalog table SYSROUTINES for a row that matches the input
parameters from the client program. The two input parameters contain values
for NAME and SCHEMA.
v Searches the DB2 catalog table SYSTABLES for all tables in which the value of
CREATOR matches the value of input parameter SCHEMA. The stored
procedure uses a cursor to return the table names.

The linkage convention for this stored procedure is GENERAL WITH NULLS.

The output parameters from this stored procedure contain the SQLCODE from the
SELECT operation, and the value of the RUNOPTS column retrieved from the
SYSROUTINES table.

The CREATE PROCEDURE statement for this stored procedure might look like
this:
CREATE PROCEDURE GETPRML(PROCNM CHAR(18) IN, SCHEMA CHAR(8) IN,
OUTCODE INTEGER OUT, PARMLST VARCHAR(254) OUT)
LANGUAGE C
DETERMINISTIC
READS SQL DATA
EXTERNAL NAME "GETPRML"
COLLID GETPRML

292 Application Programming and SQL Guide

ASUTIME NO LIMIT
PARAMETER STYLE GENERAL WITH NULLS
STAY RESIDENT NO
RUN OPTIONS "MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)"
WLM ENVIRONMENT SAMPPROG
PROGRAM TYPE MAIN
SECURITY DB2
RESULT SETS 2
COMMIT ON RETURN NO;

The following example is a C stored procedure with linkage convention GENERAL

WITH NULLS.
#pragma runopts(plist(os))
#include <stdlib.h>

EXEC SQL INCLUDE SQLCA;

/***************************************************************/
/* Declare C variables used for SQL operations on the */
/* parameters. These are local variables to the C program, */
/* which you must copy to and from the parameter list provided */
/* to the stored procedure. */
/***************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
char PROCNM[19];
char SCHEMA[9];
char PARMLST[255];
struct INDICATORS {
short int PROCNM_IND;
short int SCHEMA_IND;
short int OUT_CODE_IND;
short int PARMLST_IND;
} PARM_IND;
EXEC SQL END DECLARE SECTION;

/***************************************************************/
/* Declare cursors for returning result sets to the caller. */
/***************************************************************/
EXEC SQL DECLARE C1 CURSOR WITH RETURN FOR
SELECT NAME
FROM SYSIBM.SYSTABLES
WHERE CREATOR=:SCHEMA;

main(argc,argv)
int argc;
char *argv[];
{

/********************************************************/
/* Copy the input parameters into the area reserved in */
/* the local program for SQL processing. */
/********************************************************/
strcpy(PROCNM, argv[1]);
strcpy(SCHEMA, argv[2]);

/********************************************************/
/* Copy null indicator values for the parameter list. */
/********************************************************/
memcpy(&PARM_IND,(struct INDICATORS *) argv[5],
sizeof(PARM_IND));
/********************************************************/
/* If any input parameter is NULL, return an error */
/* return code and assign a NULL value to PARMLST. */
/********************************************************/
if (PARM_IND.PROCNM_IND<0 ||
PARM_IND.SCHEMA_IND<0 || {

Chapter 5. Coding SQL statements in C application programs 293

*(int *) argv[3] = 9999; /* set output return code */
PARM_IND.OUT_CODE_IND = 0; /* value is not NULL */
PARM_IND.PARMLST_IND = -1; /* PARMLST is NULL */
}

else {
/********************************************************/
/* If the input parameters are not NULL, issue the SQL */
/* SELECT against the SYSIBM.SYSROUTINES catalog */
/* table. */
/********************************************************/
strcpy(PARMLST, ""); /* Clear PARMLST */
EXEC SQL
SELECT RUNOPTS INTO :PARMLST
FROM SYSIBM.SYSROUTINES
WHERE NAME=:PROCNM AND
SCHEMA=:SCHEMA;
/********************************************************/
/* Copy SQLCODE to the output parameter list. */
/********************************************************/
*(int *) argv[3] = SQLCODE;
PARM_IND.OUT_CODE_IND = 0; /* OUT_CODE is not NULL */
}

/********************************************************/
/* Copy the RUNOPTS value back to the output parameter */
/* area. */
/********************************************************/
strcpy(argv[4], PARMLST);

/********************************************************/
/* Copy the null indicators back to the output parameter*/
/* area. */
/********************************************************/
memcpy((struct INDICATORS *) argv[5],&PARM_IND,
sizeof(PARM_IND));

/********************************************************/
/* Open cursor C1 to cause DB2 to return a result set */
/* to the caller. */
/********************************************************/
EXEC SQL OPEN C1;
}

294 Application Programming and SQL Guide

Chapter 6. Coding SQL statements in COBOL application
programs
When you code SQL statements in COBOL application programs, you should
follow certain guidelines.

Defining the SQL communications area, SQLSTATE, and SQLCODE in

COBOL
COBOL programs that contain SQL statements can include an SQL
communications area (SQLCA) to check whether an SQL statement executed
successfully. Alternatively, these programs can declare individual SQLCODE and
SQLSTATE host variables.

If you specify the SQL processing option STDSQL(YES), do not define an SQLCA.
If you do, DB2 ignores your SQLCA, and your SQLCA definition causes
compile-time errors. If you specify the SQL processing option STDSQL(NO),
include an SQLCA explicitly.

For COBOL programs, when you specify STDSQL(YES), you must declare an
SQLCODE variable. DB2 declares an SQLCA area for you in the
WORKING-STORAGE SECTION. DB2 controls the structure and location of the
SQLCA.

If your application contains SQL statements and does not include an SQL
communications area (SQLCA), you must declare individual SQLCODE and
SQLSTATE host variables. Your program can use these variables to check whether
an SQL statement executed successfully.

To define the SQL communications area, SQLSTATE, and SQLCODE:

Option Description
To define the SQL communications area: 1. Code the SQLCA directly in the program
or use the following SQL INCLUDE
statement to request a standard SQLCA
declaration:
EXEC SQL INCLUDE SQLCA

You can specify INCLUDE SQLCA or a

declaration for SQLCODE wherever you
can specify a 77 level or a record
description entry in the
WORKING-STORAGE SECTION.
DB2 sets the SQLCODE and SQLSTATE
values in the SQLCA after each SQL
statement executes. Your application should
check these values to determine whether the
last SQL statement was successful.

© Copyright IBM Corp. 1983, 2009 295

Option Description
To declare SQLCODE and SQLSTATE host 1. Declare the SQLCODE variable within a
variables: BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as PIC S9(9) BINARY, PIC S9(9) COMP-4,
PIC S9(9) COMP-5, or PICTURE S9(9)
COMP.
When you use the DB2 precompiler, you
can declare a stand-alone SQLCODE
variable in either the
WORKING-STORAGE SECTION or
LINKAGE SECTION. When you use the
DB2 coprocessor, you can declare a
stand-alone SQLCODE variable in the
WORKING-STORAGE SECTION,
LINKAGE SECTION or
LOCAL-STORAGE SECTION.
2. Declare the SQLSTATE variable within a
BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as PICTURE X(5).
Restriction: Do not declare an SQLSTATE
variable as an element of a structure.
Requirement: After you declare the
SQLCODE and SQLSTATE variables, ensure
that all SQL statements in the program are
within the scope of the declaration of these
variables.

Related tasks
“Checking the execution of SQL statements” on page 202
“Checking the execution of SQL statements by using the SQLCA” on page 203
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the items that your program can use to check whether an SQL statement
executed successfully” on page 141

Defining SQL descriptor areas in COBOL

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

To define SQL descriptor areas:

Perform one of the following actions:

v Code the SQLDA declarations directly in your program. When you use the DB2
precompiler, you must place SQLDA declarations in the WORKING-STORAGE
SECTION or LINKAGE SECTION of your program, wherever you can specify a
record description entry in that section. When you use the DB2 coprocessor, you
must place SQLDA declarations in the WORKING-STORAGE SECTION,

296 Application Programming and SQL Guide

LINKAGE SECTION or LOCAL-STORAGE SECTION of your program,
wherever you can specify a record description entry in that section.
v Call a subroutine that is written in C, PL/I, or assembler language and that uses
the INCLUDE SQLDA statement to define the SQLDA. The subroutine can also
include SQL statements for any dynamic SQL functions that you need.

Restrictions:
v You must place SQLDA declarations before the first SQL statement that
references the data descriptor, unless you use the TWOPASS SQL processing
option.
v You cannot use the SQL INCLUDE statement for the SQLDA, because it is not
supported in COBOL.
Related tasks
“Defining SQL descriptor areas” on page 141

Declaring host variables and indicator variables in COBOL

You can use host variables, host variable arrays, and host structures in SQL
statements in your program to pass data between DB2 and your application.

To declare host variables, host variable arrays, and host structures:

1. Declare the variables according to the following rules and guidelines:
v You must explicitly declare all host variables and host variable arrays that
are used in SQL statements in the WORKING-STORAGE SECTION or
LINKAGE SECTION of your program’s DATA DIVISION.
v You must explicitly declare each host variable and host variable array before
using them in an SQL statement.
v You can specify OCCURS when defining an indicator structure, a host
variable array, or an indicator variable array. You cannot specify OCCURS for
any other type of host variable.
v You cannot implicitly declare any host variables through default typing or by
using the IMPLICIT statement.
v If you specify the ONEPASS SQL processing option, you must explicitly
declare each host variable and each host variable array before using them in
an SQL statement. If you specify the TWOPASS precompiler option, you
must declare each host variable before using it in the DECLARE CURSOR
statement.
v If you specify the STDSQL(YES) SQL processing option, you must precede
the host language statements that define the host variables and host variable
arrays with the BEGIN DECLARE SECTION statement and follow the host
language statements with the END DECLARE SECTION statement.
Otherwise, these statements are optional.
v Ensure that any SQL statement that uses a host variable or host variable
array is within the scope of the statement that declares that variable or array.
| v If you are using the DB2 precompiler, ensure that the names of host variables
| and host variable arrays are unique within the program, even if the variables
| and variable arrays are in different blocks, classes, procedures, functions, or
| subroutines. You can qualify the names with a structure name to make them
| unique.
2. Optional: Define any associated indicator variables, arrays, and structures.

Chapter 6. Coding SQL statements in COBOL application programs 297

Related tasks
“Declaring host variables and indicator variables” on page 142

Host variables in COBOL

In COBOL programs, you can specify numeric, character, graphic, binary, LOB,
XML, and ROWID host variables. You can also specify result set and table locators
and LOB and XML file reference variables.

Restrictions:
v Only some of the valid COBOL declarations are valid host variable declarations.
If the declaration for a variable is not valid, any SQL statement that references
the variable might result in the message UNDECLARED HOST VARIABLE.
v You can not use locators as column types.
The following locator data types are COBOL data types and SQL data types:
– Result set locator
– Table locator
– LOB locators
– LOB file reference variables
v One or more REDEFINES entries can follow any level 77 data description entry.
However, you cannot use the names in these entries in SQL statements. Entries
with the name FILLER are ignored.

Recommendations:
v Be careful of overflow. For example, suppose that you retrieve an INTEGER
column value into a PICTURE S9(4) host variable and the column value is larger
than 32767 or smaller than -32768. You get an overflow warning or an error,
depending on whether you specify an indicator variable.
v Be careful of truncation. For example, if you retrieve an 80-character CHAR
column value into a PICTURE X(70) host variable, the rightmost 10 characters of
the retrieved string are truncated. Retrieving a double precision floating-point or
decimal column value into a PIC S9(8) COMP host variable removes any
fractional part of the value. Similarly, retrieving a column value with DECIMAL
data type into a COBOL decimal variable with a lower precision might truncate
the value.
v If your varying-length string host variables receive values whose length is
greater than 9999 bytes, compile the applications in which you use those host
variables with the option TRUNC(BIN). TRUNC(BIN) lets the length field for the
string receive a value of up to 32767 bytes.

Numeric host variables

You can specify the following forms of numeric host variables:

v Floating-point numbers
v Integers and small integers
v Decimal numbers

The following diagram shows the syntax for declaring floating-point or real host
variables.

298 Application Programming and SQL Guide

01 variable-name

77 IS
(1) USAGE
level-1

(2)

COMPUTATIONAL-1 .

COMP-1 IS
(3) VALUE numeric-constant
COMPUTATIONAL-2
COMP-2

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 COMPUTATIONAL-1 and COMP-1 are equivalent.
3 COMPUTATIONAL-2 and COMP-2 are equivalent.

The following diagram shows the syntax for declaring integer and small integer
host variables.

| IS


01 variable-name PICTURE S9(4)

77 PIC S9999
(1) S9(9)
level-1 S999999999
S9(18)

(2)

BINARY

IS COMPUTATIONAL-4
USAGE COMP-4
(3)
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

(4)

.

IS
VALUE numeric-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 The COBOL binary integer data types BINARY, COMPUTATIONAL, COMP,
COMPUTATIONAL-4, and COMP-4 are equivalent.
3 COMPUTATIONAL-5 (and COMP-5) are equivalent to the other COBOL
binary integer data types if you compile the other data types with
TRUNC(BIN).
4 Any specification for scale is ignored.

The following diagram shows the syntax for declaring decimal host variables.

Chapter 6. Coding SQL statements in COBOL application programs 299

IS (2)


01 variable-name PICTURE picture-string

77 PIC
(1)
level-1

IS
USAGE

(3)

PACKED-DECIMAL

COMPUTATIONAL-3
COMP-3
IS CHARACTER
DISPLAY SIGN LEADING SEPARATE
NATIONAL

.

IS
VALUE numeric-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 The picture-string that is associated with SIGN LEADING SEPARATE must
have the form S9(i)V9(d) (or S9...9V9...9, with i and d instances of 9 or S9...9V
with i instances of 9).
3 PACKED-DECIMAL, COMPUTATIONAL-3, and COMP-3 are equivalent. The
picture-string that is that is associated with these types must have the form
S9(i)V9(d) (or S9...9V9...9, with i and d instances of 9) or S9(i)V.

In COBOL, you declare the SMALLINT and INTEGER data types as a number of
decimal digits. DB2 uses the full size of the integers (in a way that is similar to
processing with the TRUNC(BIN) compiler option) and can place larger values in
the host variable than would be allowed in the specified number of digits in the
COBOL declaration. If you compile with TRUNC(OPT) or TRUNC(STD), ensure
that the size of numbers in your application is within the declared number of
digits.

For small integers that can exceed 9999, use S9(4) COMP-5 or compile with
TRUNC(BIN). For large integers that can exceed 999 999 999, use S9(10) COMP-3
to obtain the decimal data type. If you use COBOL for integers that exceed the
COBOL PICTURE, specify the column as decimal to ensure that the data types
match and perform well.

If you are using a COBOL compiler that does not support decimal numbers of
more than 18 digits, use one of the following data types to hold values of greater
than 18 digits:
v A decimal variable with a precision less than or equal to 18, if the actual data
values fit. If you retrieve a decimal value into a decimal variable with a scale
that is less than the source column in the database, the fractional part of the
value might be truncated.

300 Application Programming and SQL Guide

v An integer or a floating-point variable, which converts the value. If you use an
integer variable, you lose the fractional part of the number. If the decimal
number might exceed the maximum value for an integer or if you want to
preserve a fractional value, use a floating-point variable. Floating-point numbers
are approximations of real numbers. Therefore, when you assign a decimal
number to a floating-point variable, the result might be different from the
original number.
v A character-string host variable. Use the CHAR function to retrieve a decimal
value into it.

Restriction: The SQL data type DECFLOAT has no equivalent in COBOL.

Character host variables

You can specify the following forms of character host variables:

v Fixed-length strings
v Varying-length strings
v CLOBs

The following diagrams show the syntax for forms other than CLOBs.

The following diagram shows the syntax for declaring fixed-length character host
variables.

IS (2)


01 variable-name PICTURE picture-string

77 PIC
(1)
level-1

.

DISPLAY IS
IS VALUE character-constant
USAGE

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 The picture-string that is associated with these forms must be X(m) (or XX...X,
with m instances of X), where m is up to COBOL’s limitation. However, the
maximum length of the CHAR data type (fixed-length character string) in
DB2 is 255 bytes.

The following diagrams show the syntax for declaring varying-length character
host variables.

01 variable-name .

(1)
level-1

Notes:
1 level-1 indicates a COBOL level between 2 and 48.

Chapter 6. Coding SQL statements in COBOL application programs 301

(1) (2) IS (3)


49 var-1 PICTURE S9(4)

PIC S9999 IS
USAGE

BINARY .

COMPUTATIONAL-4 IS
COMP-4 VALUE numeric-constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

Notes:
1 You cannot use an intervening REDEFINE at level 49.
2 You cannot directly reference var-1 as a host variable.
3 DB2 uses the full length of the S9(4) BINARY variable even though COBOL
with TRUNC(STD) recognizes values up to only 9999. This behavior can
cause data truncation errors when COBOL statements execute and might
effectively limit the maximum length of variable-length character strings to
9999. Consider using the TRUNC(BIN) compiler option or USAGE COMP-5
to avoid data truncation.

(1) (2) IS (3)

49 var-2 PICTURE picture-string

PIC

.

DISPLAY IS
IS VALUE character-constant
USAGE

Notes:
1 You cannot use an intervening REDEFINE at level 49.
2 You cannot directly reference var-2 as a host variable.
3 For fixed-length strings, the picture-string must be X(m) (or XX, with m
instances of X), where mis up to COBOL’s limitation. However, the maximum
length of the VARCHAR data type in DB2 varies depending on the data page
size.

Graphic character host variables

You can specify the following forms of graphic host variables:

v Fixed-length strings
v Varying-length strings
v DBCLOBs

The following diagrams show the syntax for forms other than DBCLOBs.

The following diagram shows the syntax for declaring fixed-length graphic host
variables.

302 Application Programming and SQL Guide

IS (2)


01 variable-name PICTURE picture-string

77 PIC
(1)
level-1

DISPLAY-1 .

IS (3) IS
USAGE NATIONAL VALUE graphic-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 For fixed-length strings, the picture-string is G(m) or N(m) (or, m instances of
GG...G or NN...N), where m is up to COBOL’s limitation. However, the
maximum length of the GRAPHIC data type (fixed-length graphic string) in
DB2 is 127 double-bytes.
3 Use USAGE NATIONAL only for Unicode UTF-16 data. In the picture-string
for USAGE NATIONAL, you must use N in place of G. USAGE NATIONAL
is supported only by the DB2 coprocessor.

The following diagrams show the syntax for declaring varying-length graphic host
variables.

01 variable-name .

(1)
level-1

Notes:
1 level-1 indicates a COBOL level between 2 and 48.

(1) IS (2)


49 var-1 PICTURE S9(4)

PIC S9999 IS
USAGE

BINARY .

COMPUTATIONAL-4 IS
COMP-4 VALUE numeric-constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

Notes:
1 You cannot directly reference var-1 as a host variable.
2 DB2 uses the full length of the S9(4) BINARY variable even though COBOL
with TRUNC(STD) recognizes values up to only 9999. This behavior can
cause data truncation errors when COBOL statements execute and might
effectively limit the maximum length of variable-length character strings to
9999. Consider using the TRUNC(BIN) compiler option or USAGE COMP-5
to avoid data truncation.

Chapter 6. Coding SQL statements in COBOL application programs 303

(1) IS (2)


49 var-2 PICTURE picture-string

PIC IS
USAGE

DISPLAY-1 .

(3) IS
NATIONAL VALUE graphic-constant

Notes:
1 You cannot directly reference var-2 as a host variable.
2 For fixed-length strings, the picture-string is G(m) or N(m) (or, m instances of
GG...G or NN...N), where m is up to COBOL’s limitation. However, the
maximum length of the VARGRAPHIC data type in DB2 varies depending on
the data page size.
3 Use USAGE NATIONAL only for Unicode UTF-16 data. In the picture-string
for USAGE NATIONAL, you must use N in place of G. USAGE NATIONAL
is supported only by the DB2 coprocessor.

| Binary host variables

| You can specify the following forms of binary host variables:

| v Fixed-length strings
| v Varying-length strings
| v BLOBs

| The following diagram shows the syntax for declaring BINARY and VARBINARY
| host variables.

| IS
| USAGE


01 variable-name SQL TYPE IS BINARY

VARBINARY
BINARY VARYING

| (1)
|
( length ) .


|
| Notes:
| 1 For BINARY host variables, the length must be in the range from 1 to 255.
| For VARBINARY host variables, the length must be in the range from 1 to
| 32 704.

| COBOL does not have variables that correspond to the SQL binary types BINARY
| and VARBINARY. To create host variables that can be used with these data types,
| use the SQL TYPE IS clause. The SQL precompiler replaces this declaration with a
| COBOL language structure in the output source member.

| When you reference a BINARY or VARBINARY host variable in an SQL statement,

| you must use the variable that you specify in the SQL TYPE declaration. When
| you reference the host variable in a host language statement, you must use the
| variable that DB2 generates.

304 Application Programming and SQL Guide

| Examples of binary variable declarations: The following table shows examples of
| variables that DB2 generates when you declare binary host variables.
| Table 64. Examples of BINARY and VARBINARY variable declarations for COBOL
| Variable declaration that you include in your COBOL Corresponding variable that DB2 generates in the
| program output source member
| 01 BIN-VAR USAGE IS SQL TYPE IS BINARY(10). 01 BIN-VAR PIC X(10).
| 01 VBIN-VAR USAGE IS SQL TYPE IS VARBINARY(10). 01 VBIN-VAR.
| 49 VBIN-VAR-LEN PIC S9(4) USAGE BINARY.
| 49 VBIN-VAR-TEXT PIC X(10).
|

| Result set locators

The following diagram shows the syntax for declaring result set locators.

01 variable-name SQL TYPE IS RESULT-SET-LOCATOR VARYING .


IS
USAGE

Table Locators

The following diagram shows the syntax for declaring table locators.

01 variable-name SQL TYPE IS TABLE LIKE table-name AS LOCATOR .


(1) IS
level-1 USAGE

Notes:
1 level-1 indicates a COBOL level between 2 and 48.

LOB variables and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| variables and file reference variables.

01 variable-name SQL TYPE IS

level-1 IS
USAGE

BINARY LARGE OBJECT ( length ) .


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB-LOCATOR
CLOB-LOCATOR
DBCLOB-LOCATOR
BLOB-FILE
CLOB-FILE
DBCLOB-FILE

Chapter 6. Coding SQL statements in COBOL application programs 305

XML data host and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variables and file reference variables for XML data types.

01 variable-name SQL TYPE IS XML AS

(1) IS
level-1 USAGE

BINARY LARGE OBJECT ( length ) .


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB-FILE
CLOB-FILE
DBCLOB-FILE

Notes:
1 level-1 indicates a COBOL level between 2 and 48.

ROWID host variables

The following diagram shows the syntax for declaring ROWID host variables.

01 variable-name SQL TYPE IS ROWID .


(1) IS
level-1 USAGE

Notes:
1 level-1 indicates a COBOL level between 2 and 48.

306 Application Programming and SQL Guide

Related concepts
“Host variables” on page 143
“Rules for host variables in an SQL statement” on page 151
“Large objects (LOBs)” on page 430
Related tasks
“Controlling the CCSID for COBOL host variables” on page 320
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Retrieving a single row of data into a host structure” on page 161
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157
Related reference
Limits in (SQL Reference)

Host variable arrays in COBOL

In COBOL programs, you can specify numeric, character, graphic, LOB, XML, and
ROWID host variable arrays. You can also specify LOB locators and LOB and XML
file reference variables.

Restriction: Only some of the valid COBOL declarations are valid host variable
array declarations. If the declaration for a variable array is not valid, any SQL
statement that references the variable array might result in the message
UNDECLARED HOST VARIABLE ARRAY.

Numeric host variable arrays

You can specify the following forms of numeric host variable arrays:
v Floating-point numbers
v Integers and small integers
v Decimal numbers

The following diagram shows the syntax for declaring floating-point host variable
arrays.

(1)


level-1 variable-name COMPUTATIONAL-1

IS (2)
USAGE COMP-1
COMPUTATIONAL-2
(3)
COMP-2

(4)

OCCURS dimension .

TIMES IS
VALUE numeric-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.

Chapter 6. Coding SQL statements in COBOL application programs 307

2 COMPUTATIONAL-1 and COMP-1 are equivalent.
3 COMPUTATIONAL-2 and COMP-2 are equivalent.
4 dimension must be an integer constant between 1 and 32767.

The following diagram shows the syntax for declaring integer and small integer
host variable arrays.

(1) IS


level-1 variable-name PICTURE S9(4)

PIC S9999
S9(9)
S999999999

(2) (4)

BINARY OCCURS dimension

IS COMPUTATIONAL-4 TIMES
USAGE COMP-4
COMPUTATIONAL-5
(3)
COMP-5
COMPUTATIONAL
COMP

(5)

.

IS
VALUE numeric-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 The COBOL binary integer data types BINARY, COMPUTATIONAL, COMP,
COMPUTATIONAL-4, and COMP-4 are equivalent.
3 COMPUTATIONAL-5 (and COMP-5) are equivalent to the other COBOL
binary integer data types if you compile the other data types with
TRUNC(BIN).
4 dimension must be an integer constant between 1 and 32767.
5 Any specification for scale is ignored.

The following diagram shows the syntax for declaring decimal host variable
arrays.

(1) IS


level-1 variable-name PICTURE picture-string

PIC

IS
USAGE

308 Application Programming and SQL Guide

(2)

PACKED-DECIMAL

COMPUTATIONAL-3
COMP-3
IS (3) CHARACTER
DISPLAY SIGN LEADING SEPARATE
NATIONAL

(4)

OCCURS dimension .

TIMES IS
VALUE numeric-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 PACKED-DECIMAL, COMPUTATIONAL-3, and COMP-3 are equivalent. The
picture-string that is associated with these types must have the form S9(i)V9(d)
(or S9...9V9...9, with i and d instances of 9) or S9(i)V.
3 The picture-string that is associated with SIGN LEADING SEPARATE must
have the form S9(i)V9(d) (or S9...9V9...9, with i and d instances of 9 or S9...9V
with i instances of 9).
4 dimension must be an integer constant between 1 and 32767.

Character host variable arrays

You can specify the following forms of character host variable arrays:
v Fixed-length character strings
v Varying-length character strings
v CLOBs

The following diagrams show the syntax for forms other than CLOBs.

The following diagram shows the syntax for declaring fixed-length character string
arrays.

(1) IS (2)


level-1 variable-name PICTURE picture-string

PIC

(3)

OCCURS dimension

DISPLAY TIMES
IS
USAGE

.

IS
VALUE character-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 The picture-string must be in the form X(m) (or XX...X, with m instances of X),

Chapter 6. Coding SQL statements in COBOL application programs 309

where 1 <= m <= 32767 for fixed-length strings. However, the maximum
length of the CHAR data type (fixed-length character string) in DB2 is 255
bytes.
3 dimension must be an integer constant between 1 and 32767.

The following diagrams show the syntax for declaring varying-length character
string arrays.

(1) (2)


level-1 variable-name OCCURS dimension .

TIMES

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 dimension must be an integer constant between 1 and 32767.

(1) IS (2)


49 var-1 PICTURE S9(4)

PIC S9999 IS
USAGE

BINARY SYNCHRONIZED

COMPUTATIONAL-4 SYNC IS
COMP-4 VALUE numeric-constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

.


Notes:
1 You cannot directly reference var-1 as a host variable array.
2 DB2 uses the full length of the S9(4) BINARY variable even though COBOL
with TRUNC(STD) recognizes values up to only 9999. This behavior can
cause data truncation errors when COBOL statements execute and might
effectively limit the maximum length of variable-length character strings to
9999. Consider using the TRUNC(BIN) compiler option or USAGE COMP-5
to avoid data truncation.

(1) IS (2)


49 var-2 PICTURE picture-string

PIC

DISPLAY IS
IS VALUE character-constant
USAGE

310 Application Programming and SQL Guide

(3)

.


Notes:
1 You cannot directly reference var-2 as a host variable array.
2 The picture-string must be in the form X(m) (or XX...X, with m instances of X),
where 1 <= m <= 32767 for fixed-length strings; for other strings, m cannot be
greater than the maximum size of a varying-length character string.
3 You cannot use an intervening REDEFINE at level 49.

Example: The following example shows declarations of a fixed-length character

array and a varying-length character array.
01 OUTPUT-VARS.
05 NAME OCCURS 10 TIMES.
49 NAME-LEN PIC S9(4) COMP-4 SYNC.
49 NAME-DATA PIC X(40).
05 SERIAL-NUMBER PIC S9(9) COMP-4 OCCURS 10 TIMES.

Graphic character host variable arrays

You can specify the following forms of graphic host variable arrays:
v Fixed-length strings
v Varying-length strings
v DBCLOBs

The following diagrams show the syntax for forms other than DBCLOBs.

The following diagram shows the syntax for declaring fixed-length graphic string
arrays.

(1) IS (2)


level-1 variable-name PICTURE picture-string

PIC

IS (5)

USAGE DISPLAY-1 OCCURS dimension

(3) (4) TIMES
NATIONAL

.

IS
VALUE graphic-constant

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 For fixed-length strings, the format for picture-string is G(m) or N(m) (or, m
instances of GG...G or NN...N), where 1 <= m <= 127; for other strings, m
cannot be greater than the maximum size of a varying-length graphic string.
3 Use USAGE NATIONAL only for Unicode UTF-16 data. In the picture-string
for USAGE NATIONAL, you must use N in place of G.
4 You can use USAGE NATIONAL only if you are using the DB2 coprocessor.

Chapter 6. Coding SQL statements in COBOL application programs 311

5 dimension must be an integer constant between 1 and 32767.

The following diagrams show the syntax for declaring varying-length graphic
string arrays.

(1) (2)


level-1 variable-name OCCURS dimension .

TIMES

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 dimension must be an integer constant between 1 and 32767.

(1) IS (2)


49 var-1 PICTURE S9(4)

PIC S9999 IS
USAGE

BINARY SYNCHRONIZED

COMPUTATIONAL-4 SYNC IS
COMP-4 VALUE numeric-constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

.


Notes:
1 You cannot directly reference var-1 as a host variable array.
2 DB2 uses the full length of the S9(4) BINARY variable even though COBOL
with TRUNC(STD) recognizes values up to only 9999. This behavior can
cause data truncation errors when COBOL statements execute and might
effectively limit the maximum length of variable-length character strings to
9999. Consider using the TRUNC(BIN) compiler option or USAGE COMP-5
to avoid data truncation.

(1)


49 var-2 PICTURE

PIC

IS (2) IS

picture-string USAGE DISPLAY-1

(3) (4)
NATIONAL

.

IS
VALUE graphic-constant

312 Application Programming and SQL Guide

Notes:
1 You cannot directly reference var-2 as a host variable array.
2 For fixed-length strings, the format for picture-string is G(m) or N(m) (or, m
instances of GG...G or NN...N), where 1 <= m <= 127; for other strings, m
cannot be greater than the maximum size of a varying-length graphic string.
3 Use USAGE NATIONAL only for Unicode UTF-16 data. In the picture-string
for USAGE NATIONAL, you must use N in place of G.
4 You can use USAGE NATIONAL only if you are using the DB2 coprocessor.

LOB, locator, and file reference variable arrays

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variable, locator, and file reference arrays.

(1)


level-1 variable-name SQL TYPE IS

IS
USAGE

|
BINARY LARGE OBJECT ( length )

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB-LOCATOR
CLOB-LOCATOR
DBCLOB-LOCATOR
BLOB-FILE
CLOB-FILE
DBCLOB-FILE

(2)

OCCURS dimension .

TIMES

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 dimension must be an integer constant between 1 and 32767.

| XML host and file reference variable arrays

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variable and file reference arrays for XML data types.

| (1)
|

level-1 variable-name SQL TYPE IS XML AS

IS
USAGE

Chapter 6. Coding SQL statements in COBOL application programs 313

|
BINARY LARGE OBJECT ( length )

| BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB-FILE
CLOB-FILE
DBCLOB-FILE

| (2)
|
OCCURS dimension .

TIMES
|
| Notes:
| 1 level-1 indicates a COBOL level between 2 and 48.
| 2 dimension must be an integer constant between 1 and 32767.

| ROWID variable arrays

The following diagram shows the syntax for declaring ROWID variable arrays.

(1) (2)


level-1 variable-name SQL TYPE IS ROWID OCCURS dimension .

IS TIMES
USAGE

Notes:
1 level-1 indicates a COBOL level between 2 and 48.
2 dimension must be an integer constant between 1 and 32767.
Related concepts
“Host variable arrays” on page 144
“Host variable arrays in an SQL statement” on page 159
“Large objects (LOBs)” on page 430
Related tasks
“Inserting multiple rows of data from host variable arrays” on page 160
“Retrieving multiple rows of data into host variable arrays” on page 160

Host structures in COBOL

A COBOL host structure is a named set of host variables that are defined in your
program’s WORKING-STORAGE SECTION or LINKAGE SECTION.

Requirements: Host structure declarations in COBOL must satisfy the following

requirements:
v COBOL host structures can have a maximum of two levels, even though the
host structure might occur within a structure with multiple levels. However, you
can declare a varying-length character string, which must be level 49.
v A host structure name can be a group name whose subordinate levels name
elementary data items.
v If you are using the DB2 precompiler, do not declare host variables or host
structures on any subordinate levels after one of the following items:
– A COBOL item that begins in area A
314 Application Programming and SQL Guide
– Any SQL statement (except SQL INCLUDE)
– Any SQL statement within an included member
When the DB2 precompiler encounters one of the preceding items in a host
structure, it considers the structure to be complete.

When you write an SQL statement that contains a qualified host variable name
(perhaps to identify a field within a structure), use the name of the structure
followed by a period and the name of the field. For example, for structure B that
contains field C1, specify B.C1 rather than C1 OF B or C1 IN B.

Host structures

The following diagram shows the syntax for declaring host structures.

(1)


level-1 variable-name .

(2) (3) (4)

 level-2 var-1 numeric-usage .

IS
PICTURE integer-decimal-usage .
PIC picture-string
char-inner-variable .
varchar-inner-variables
vargraphic-inner-variables
SQL TYPE IS ROWID .
IS
USAGE
SQL TYPE IS TABLE LIKE table-name AS LOCATOR .
IS
USAGE
LOB data type .
IS
USAGE

Notes:
1 level-1 indicates a COBOL level between 1 and 47.
2 level-2 indicates a COBOL level between 2 and 48.
3 For elements within a structure, use any level 02 through 48 (rather than 01
or 77), up to a maximum of two levels.
4 Using a FILLER or optional FILLER item within a host structure declaration
can invalidate the whole structure.

Numeric usage items

The following diagram shows the syntax for numeric-usage items that are used
within declarations of host structures.

COMPUTATIONAL-1

IS COMP-1 IS
USAGE COMPUTATIONAL-2 VALUE constant
COMP-2

Integer and decimal usage items

The following diagram shows the syntax for integer and decimal usage items that
are used within declarations of host structures.

Chapter 6. Coding SQL statements in COBOL application programs 315

IS
USAGE

BINARY

COMPUTATIONAL-4
COMP-4
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP
PACKED-DECIMAL
COMPUTATIONAL-3
COMP-3
IS
DISPLAY SIGN LEADING SEPARATE
NATIONAL CHARACTER


IS
VALUE constant

CHAR inner variables

The following diagram shows the syntax for CHAR inner variables that are used
within declarations of host structures.

IS


PICTURE picture-string

PIC DISPLAY
IS
USAGE


IS
VALUE constant

VARCHAR inner variables

The following diagrams show the syntax for VARCHAR inner variables that are
used within declarations of host structures.

(1) IS


49 var-2 PICTURE S9(4)

PIC S9999 IS
USAGE

316 Application Programming and SQL Guide

BINARY .

COMPUTATIONAL-4 IS
COMP-4 VALUE numeric-constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

Notes:
| 1 The number 49 has a special meaning to DB2. Do not specify another number.

IS


49 var-3 PICTURE picture-string

PIC

.

DISPLAY IS
IS VALUE character-constant
USAGE

VARGRAPHIC inner variables

The following diagrams show the syntax for VARGRAPHIC inner variables that
are used within declarations of host structures.

IS


49 var-4 PICTURE S9(4)

PIC S9999 IS
USAGE

BINARY .

COMPUTATIONAL-4 IS
COMP-4 VALUE numeric-constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

IS (1)


49 var-5 PICTURE picture-string

PIC IS
USAGE

(2) (3)

DISPLAY-1 .

NATIONAL IS
VALUE graphic-constant

Notes:
1 For fixed-length strings, the format of picture-string is G(m) or N(m) (or, m
instances of GG...G or NN...N), where 1 <= m <= 127; for other strings, m
cannot be greater than the maximum size of a varying-length graphic string.

Chapter 6. Coding SQL statements in COBOL application programs 317

2 Use USAGE NATIONAL for only Unicode UTF-16 data. In the picture-string
for USAGE NATIONAL, you must use N in place of G.
3 You can use USAGE NATIONAL only if you are using the DB2 coprocessor.

LOB variables, locators, and file reference variables

The following diagram shows the syntax for LOB variables, locators, and file
reference variables that are used within declarations of host structures.

|

SQL TYPE IS BINARY LARGE OBJECT ( length )


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB-LOCATOR
CLOB-LOCATOR
DBCLOB-LOCATOR
BLOB-FILE
CLOB-FILE
DBCLOB-FILE

| LOB variables and file reference variables for XML data

| The following diagram shows the syntax for LOB variables and file reference
| variables that are used within declarations of host structures for XML.

|

SQL TYPE IS XML AS BINARY LARGE OBJECT ( length )


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB-FILE
CLOB-FILE
DBCLOB-FILE
|

| Example

In the following example, B is the name of a host structure that contains the
elementary items C1 and C2.
01 A
02 B
03 C1 PICTURE ...
03 C2 PICTURE ...

To reference the C1 field in an SQL statement, specify B.C1.

318 Application Programming and SQL Guide

Related concepts
“Host structures” on page 144

Indicator variables, indicator arrays, and host structure

indicator arrays in COBOL
An indicator variable is a 2-byte integer (PIC S9(4) USAGE BINARY). An indicator
variable array is an array of 2-byte integers (PIC S9(4) USAGE BINARY). You
declare indicator variables in the same way as host variables. You can mix the
declarations of the two types of variables.

You can define indicator variables as scalar variables or as array elements in a

structure form or as an array variable by using a single level OCCURS clause.

The following diagram shows the syntax for declaring an indicator variable in
COBOL.

IS


01 variable-name PICTURE S9(4)

77 PIC S9999 IS
USAGE

BINARY .

COMPUTATIONAL-4 IS
COMP-4 VALUE constant
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

The following diagram shows the syntax for declaring an indicator array in
COBOL.

(1) IS


level-1 variable-name PICTURE S9(4)

PIC S9999

(2)

BINARY OCCURS dimension

IS COMPUTATIONAL-4 TIMES
USAGE COMP-4
COMPUTATIONAL-5
COMP-5
COMPUTATIONAL
COMP

.

IS
VALUE constant

Notes:
1 level-1 must be an integer between 2 and 48.
2 dimension must be an integer constant between 1 and 32767.

Chapter 6. Coding SQL statements in COBOL application programs 319

Example

The following example shows a FETCH statement with the declarations of the host
variables that are needed for the FETCH statement and their associated indicator
variables.
EXEC SQL FETCH CLS_CURSOR INTO :CLS-CD,
:DAY :DAY-IND,
:BGN :BGN-IND,
:END :END-IND
END-EXEC.

You can declare these variables as follows:

77 CLS-CD PIC X(7).
77 DAY PIC S9(4) BINARY.
77 BGN PIC X(8).
77 END PIC X(8).
77 DAY-IND PIC S9(4) BINARY.
77 BGN-IND PIC S9(4) BINARY.
77 END-IND PIC S9(4) BINARY.
Related concepts
“Indicator variables, arrays, and structures” on page 145
Related tasks
“Inserting null values into columns by using indicator variables or arrays” on page
158

Controlling the CCSID for COBOL host variables

Setting the CCSID for COBOL host variables is slightly different than the process
for other host languages. In COBOL, several other settings affect the CCSID.

This task applies to programs that use IBM Enterprise COBOL for z/OS and the
DB2 coprocessor.

To control the CCSID for COBOL host variables:

Use one or more of the following items:

The NATIONAL data type
Use this data type to declare Unicode values in the UTF-16 format (CCSID
1200).
If you declare a host variable HV1 as USAGE NATIONAL, DB2 always
handles HV1 as if you had used the following DECLARE VARIABLE
statement:
DECLARE :HV1 VARIABLE CCSID 1200
The COBOL CODEPAGE compiler option
Use this option to specify the default EBCDIC CCSID of character data
items.
The SQLCCSID compiler option
Use this option to control whether the CODEPAGE compiler option
influences the processing of SQL host variables in your COBOL programs
(available in Enterprise COBOL V3R4 or later).
When you specify the SQLCCSID compiler option, the COBOL DB2
coprocessor uses the CCSID that is specified in the CODEPAGE compiler

320 Application Programming and SQL Guide

option. All host variables of character data type, other than NATIONAL,
are specified with that CCSID unless they are explicitly overridden by a
DECLARE VARIABLE statement.
When you specify the NOSQLCCSID compiler option, the CCSID that is
specified in the CODEPAGE compiler option is used for processing only
COBOL statements within the COBOL program. That CCSID is not used
for the processing of host variables in SQL statements. DB2 uses the
CCSIDs that are specified through DB2 mechanisms and defaults as host
variable data value encodings.
The DECLARE VARIABLE statement.
This statement explicitly sets the CCSID for individual host variables.

Example

Assume that the COBOL SQLCCSID compiler option is specified and that the
COBOL CODEPAGE compiler option is specified as CODEPAGE(1141). The
following code shows how you can control the CCSID:
DATA DIVISION.
01 HV1 PIC N(10) USAGE NATIONAL.
01 HV2 PIC X(20) USAGE DISPLAY.
01 HV3 PIC X(30) USAGE DISPLAY.
...
EXEC SQL
DECLARE :HV3 VARIABLE CCSID 1047
END-EXEC.
...
PROCEDURE DIVISION.
...
EXEC SQL
SELECT C1, C2, C3 INTO :HV1, :HV2, :HV3 FROM T1
END-EXEC.

Each of the host variables have the following CCSIDs:

HV1 1200
HV2 1141
HV3 1047

Assume that the COBOL NOSQLCCSID compiler option is specified, the COBOL
CODEPAGE compiler option is specified as CODEPAGE(1141), and the DB2 default
single byte CCSID is set to 37. In this case, each of the host variables in this
example have the following CCSIDs:
HV1 1200
HV2 37
HV3 1047

Chapter 6. Coding SQL statements in COBOL application programs 321

Related reference
“Host variables in COBOL” on page 298
Related information
IBM System z Enterprise Development Tools & Compilers information center

Equivalent SQL and COBOL data types

When you declare host variables in your COBOL programs, the precompiler uses
equivalent SQL data types. When you retrieve data of a particular SQL data type
into a host variable, you need to ensure that the host variable is of an equivalent
data type.

The following table describes the SQL data type and the base SQLTYPE and
SQLLEN values that the precompiler uses for host variables in SQL statements.
Table 65. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in
COBOL programs
SQLTYPE of host
COBOL host variable data type variable1 SQLLEN of host variable SQL data type
COMP-1 480 4 REAL or FLOAT(n) 1<=n<=21
COMP-2 480 8 DOUBLE PRECISION, or
FLOAT(n) 22<=n<=53
S9(i)V9(d) COMP-3 or S9(i)V9(d) 484 i+d in byte 1, d in byte 2 DECIMAL(i+d,d) or
PACKED-DECIMAL NUMERIC(i+d,d)
S9(i)V9(d) DISPLAY SIGN 504 i+d in byte 1, d in byte 2 No exact equivalent. Use
LEADING SEPARATE DECIMAL(i+d,d) or
NUMERIC(i+d,d)
S9(i)V9(d) NATIONAL SIGN 504 i+d in byte 1, d in byte 2 No exact equivalent. Use
LEADING SEPARATE DECIMAL(i+d,d) or
NUMERIC(i+d,d)
S9(4) COMP-4, S9(4) COMP-5, 500 2 SMALLINT
S9(4) COMP, or S9(4) BINARY
S9(9) COMP-4, S9(9) COMP-5, 496 4 INTEGER
S9(9) COMP, or S9(9) BINARY
| S9(18) COMP-4, S9(18) COMP-5, 492 8 BIGINT
| S9(18) COMP, or S9(18) BINARY
Fixed-length character data 452 n CHAR(n)
Varying-length character data 448 n VARCHAR(n)
1<=n<=255
Varying-length character data 456 m VARCHAR(m)
m>255
Fixed-length graphic data 468 m GRAPHIC(m)
Varying-length graphic data 464 m VARGRAPHIC(m)
1<=m<=127
Varying-length graphic data 472 m VARGRAPHIC(m)
m>127
| SQL TYPE is BINARY(n), 912 n BINARY(n)
| 1<=n<=255
| SQL TYPE is VARBINARY(n), 908 n VARBINARY(n)
| 1<=n<=32 704

322 Application Programming and SQL Guide

Table 65. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in
COBOL programs (continued)
SQLTYPE of host
COBOL host variable data type variable1 SQLLEN of host variable SQL data type
SQL TYPE IS 972 4 Result set locator2
RESULT-SET-LOCATOR
SQL TYPE IS TABLE LIKE 976 4 Table locator2
table-name AS LOCATOR
SQL TYPE IS BLOB-LOCATOR 960 4 BLOB locator2
SQL TYPE IS CLOB-LOCATOR 964 4 CLOB locator2
SQL TYPE IS 968 4 DBCLOB locator2
DBCLOB-LOCATOR
USAGE IS SQL TYPE IS 404 n BLOB(n)
BLOB(n) 1≤n≤2147483647
USAGE IS SQL TYPE IS 408 n CLOB(n)
CLOB(n) 1≤n≤2147483647
USAGE IS SQL TYPE IS 412 n DBCLOB(m)3
DBCLOB(m) 1≤m≤10737418233
| SQL TYPE IS XML AS BLOB(n) 404 0 XML
| SQL TYPE IS XML AS CLOB(n) 408 0 XML
| SQL TYPE IS XML AS 412 0 XML
| DBCLOB(n)
| SQL TYPE IS BLOB-FILE 916/917 267 BLOB file reference2
| SQL TYPE IS CLOB-FILE 920/921 267 CLOB file reference2
| SQL TYPE IS DBCLOB-FILE 924/925 267 DBCLOB file reference2
| SQL TYPE IS XML AS 916/917 267 XML BLOB file reference2
| BLOB-FILE
| SQL TYPE IS XML AS 920/921 267 XML CLOB file reference2
| CLOB-FILE
| SQL TYPE IS XML AS 924/925 267 XML DBCLOB file reference2
| DBCLOB-FILE
SQL TYPE IS ROWID 904 40 ROWID
Notes:
1. If a host variable includes an indicator variable, the SQLTYPE value is the base SQLTYPE value plus 1.
2. Do not use this data type as a column type.
3. m is the number of double-byte characters.

The following table shows equivalent COBOL host variables for each SQL data
type. Use this table to determine the COBOL data type for host variables that you
define to receive output from the database. For example, if you retrieve
TIMESTAMP data, you can define a fixed-length character string variable of length
n

This table shows direct conversions between SQL data types and COBOL data
types. However, a number of SQL data types are compatible. When you do
assignments or comparisons of data that have compatible data types, DB2 converts
those compatible data types.

Chapter 6. Coding SQL statements in COBOL application programs 323

Table 66. COBOL host variable equivalents that you can use when retrieving data of a particular SQL data type
SQL data type COBOL host variable equivalent Notes
SMALLINT S9(4) COMP-4,
S9(4) COMP-5,
S9(4) COMP,
or S9(4) BINARY
INTEGER S9(9) COMP-4,
S9(9) COMP-5,
S9(9) COMP,
or S9(9) BINARY
DECIMAL(p,s) or S9(p-s)V9(s) COMP-3 or p is precision; s is scale. 0<=s<=p<=31. If
NUMERIC(p,s) S9(p-s)V9(s) s=0, use S9(p)V or S9(p). If s=p, use SV9(s).
PACKED-DECIMAL If the COBOL compiler does not support
DISPLAY SIGN 31–digit decimal numbers, no exact
LEADING SEPARATE equivalent exists. Use COMP-2.
NATIONAL SIGN
LEADING SEPARATE
REAL or FLOAT (n) COMP-1 1<=n<=21

DOUBLE PRECISION, COMP-2 22<=n<=53

DOUBLE or FLOAT (n)
| BIGINT S9(18) COMP-4, S9(18) COMP-5, S9(18)
| COMP, or S9(18) BINARY
CHAR(n) Fixed-length character string. For example, 1<=n<=255
01 VAR-NAME PIC X(n).
VARCHAR(n) Varying-length character string. For The inner variables must have a level of
example, 49.
01 VAR-NAME.
49 VAR-LEN PIC S9(4)
USAGE BINARY.
49 VAR-TEXT PIC X(n).
GRAPHIC(n) Fixed-length graphic string. For example, n refers to the number of double-byte
01 VAR-NAME PIC G(n) characters, not to the number of bytes.
USAGE IS DISPLAY-1. 1<=n<=127

VARGRAPHIC(n) Varying-length graphic string. For n refers to the number of double-byte

example, characters, not to the number of bytes.
01 VAR-NAME.
49 VAR-LEN PIC S9(4) The inner variables must have a level of
USAGE BINARY. 49.
49 VAR-TEXT PIC G(n)
USAGE IS DISPLAY-1.
| BINARY(n) SQL TYPE IS BINARY(n) 1<=n<=255
| VARBINARY(n) SQL TYPE IS VARBINARY(n) 1<=n<=32 704
DATE Fixed-length character string of length n. If you are using a date exit routine, n is
For example, determined by that routine. Otherwise, n
01 VAR-NAME PIC X(n). must be at least 10.

TIME Fixed-length character string of length n. If you are using a time exit routine, n is
For example, determined by that routine. Otherwise, n
01 VAR-NAME PIC X(n). must be at least 6; to include seconds, n
must be at least 8.
TIMESTAMP Fixed-length character string of length n. n must be at least 19. To include
For example, microseconds, n must be 26; if n is less
01 VAR-NAME PIC X(n). than 26, truncation occurs on the
microseconds part.

324 Application Programming and SQL Guide

Table 66. COBOL host variable equivalents that you can use when retrieving data of a particular SQL data
type (continued)
SQL data type COBOL host variable equivalent Notes
Result set locator SQL TYPE IS Use this data type only for receiving result
RESULT-SET-LOCATOR sets. Do not use this data type as a
column type.
Table locator SQL TYPE IS Use this data type only in a user-defined
TABLE LIKE function or stored procedure to receive
table-name rows of a transition table. Do not use this
AS LOCATOR data type as a column type.
BLOB locator USAGE IS SQL TYPE IS Use this data type only to manipulate data
BLOB-LOCATOR in BLOB columns. Do not use this data
type as a column type.
CLOB locator USAGE IS SQL TYPE IS Use this data type only to manipulate data
CLOB-LOCATOR in CLOB columns. Do not use this data
type as a column type.
DBCLOB locator USAGE IS SQL TYPE IS Use this data type only to manipulate data
DBCLOB-LOCATOR in DBCLOB columns. Do not use this data
type as a column type.
BLOB(n) USAGE IS SQL TYPE IS 1≤n≤2147483647
BLOB(n)
CLOB(n) USAGE IS SQL TYPE IS 1≤n≤2147483647
CLOB(n)
DBCLOB(n) USAGE IS SQL TYPE IS n is the number of double-byte characters.
DBCLOB(n) 1≤n≤1073741823

| XML SQL TYPE IS XML AS BLOB(n) 1≤n≤2147483647

| XML SQL TYPE IS XML AS CLOB(n) 1≤n≤2147483647
| XML SQL TYPE IS XML AS DBCLOB(n) n is the number of double-byte characters.
| 1≤n≤1073741823
|| BLOB file reference USAGE IS SQL TYPE IS Use this data type only to manipulate data
|| BLOB-FILE in BLOB columns. Do not use this data
| type as a column type.
|| CLOB file reference USAGE IS SQL TYPE IS Use this data type only to manipulate data
|| CLOB-FILE in CLOB columns. Do not use this data
| type as a column type.
|| DBCLOB file reference USAGE IS SQL TYPE IS Use this data type only to manipulate data
|| DBCLOB-FILE in DBCLOB columns. Do not use this data
| type as a column type.
| XML BLOB file reference SQL TYPE IS XML AS BLOB-FILE Use this data type only to manipulate
| XML data as BLOB files. Do not use this
| data type as a column type.
| XML CLOB file reference SQL TYPE IS XML AS CLOB-FILE Use this data type only to manipulate
| XML data as CLOB files. Do not use this
| data type as a column type.
| XML DBCLOB file reference SQL TYPE IS XML AS DBCLOB-FILE Use this data type only to manipulate
| XML data as DBCLOB files. Do not use
| this data type as a column type.
ROWID SQL TYPE IS ROWID

Chapter 6. Coding SQL statements in COBOL application programs 325

Related concepts
“Compatibility of SQL and language data types” on page 148
“LOB host variable, LOB locator, and LOB file reference variable declarations” on
page 705
“Host variable data types for XML data in embedded SQL applications” on page
217

SQL statements in COBOL programs

You can code SQL statements in certain COBOL program sections.

The allowable sections are shown in the following table.

Table 67. Allowable SQL statements for COBOL program sections
SQL statement Program section
BEGIN DECLARE SECTION WORKING-STORAGE SECTION1 or LINKAGE
END DECLARE SECTION SECTION
INCLUDE SQLCA WORKING-STORAGE SECTION1 or LINKAGE
SECTION
INCLUDE text-file-name PROCEDURE DIVISION or DATA DIVISION2
DECLARE TABLE DATA DIVISION or PROCEDURE DIVISION
DECLARE CURSOR
| DECLARE VARIABLE WORKING-STORAGE SECTION1
Other PROCEDURE DIVISION
Notes:
| 1. If you use the DB2 coprocessor, you can use the LOCAL-STORAGE SECTION wherever
| WORKING-STORAGE SECTION is listed in the table.
2. When including host variable declarations, the INCLUDE statement must be in the
WORKING-STORAGE SECTION or the LINKAGE SECTION.

You cannot put SQL statements in the DECLARATIVES section of a COBOL

program.

| Each SQL statement in a COBOL program must begin with EXEC SQL and end
| with END-EXEC. If you are using the DB2 precompiler, the EXEC and SQL
| keywords must appear on one line, but the remainder of the statement can appear
| on subsequent lines. If you are using the DB2 coprocessor, the EXEC and SQL
| keywords can be on different lines. Do not include any tokens between the two
| keywords EXEC and SQL except for COBOL comments, including debugging lines.
| Do not include SQL comments between the keywords EXEC and SQL.

If the SQL statement appears between two COBOL statements, the period after
END-EXEC is optional and might not be appropriate. If the statement appears in
an IF...THEN set of COBOL statements, omit the ending period to avoid
inadvertently ending the IF statement.

You might code an UPDATE statement in a COBOL program as follows:

EXEC SQL
UPDATE DSN8910.DEPT
SET MGRNO = :MGR-NUM
WHERE DEPTNO = :INT-DEPT
END-EXEC.

326 Application Programming and SQL Guide

| Comments: You can include COBOL comment lines (* in column 7) in SQL
| statements wherever you can use a blank. If you are using the DB2 precompiler,
| you cannot include COBOL comment lines between the keywords EXEC and SQL.
| The precompiler treats COBOL debugging lines and page-eject lines (/ in column
| 7) as comment lines. The DB2 coprocessor treats the debugging lines based on the
| COBOL rules, which depend on the WITH DEBUGGING mode setting.

| For an SQL INCLUDE statement, the DB2 precompiler treats any text that follows
| the period after END-EXEC, and on the same line as END-EXEC, as a comment.
| The DB2 coprocessor treats this text as part of the COBOL program syntax.

In addition, you can include SQL comments (’--’) in any embedded SQL statement.

| Debugging lines: The DB2 precompiler ignores the ’D’ in column 7 on debugging
| lines and treats it as a blank. The DB2 coprocessor follows the COBOL language
| rules regarding debugging lines.

Continuation for SQL statements: The rules for continuing a character string
constant from one line to the next in an SQL statement embedded in a COBOL
program are the same as those for continuing a non-numeric literal in COBOL.
However, you can use either a quote or an apostrophe as the first nonblank
character in area B of the continuation line. The same rule applies for the
continuation of delimited identifiers and does not depend on the string delimiter
option.

To conform with SQL standard, delimit a character string constant with an

apostrophe, and use a quote as the first nonblank character in area B of the
continuation line for a character string constant.

Continued lines of an SQL statement can be in columns 8 through 72 when using

the DB2 precompiler and columns 12 through 72 when using the DB2 coprocessor.

| COPY: If you use the DB2 precompiler, do not use a COBOL COPY statement
| within host variable declarations. If you use the DB2 coprocessor, you can use
| COBOL COPY.

REPLACE: If you use the DB2 precompiler, the REPLACE statement has no effect
on SQL statements. It affects only the COBOL statements that the precompiler
generates.

If you use the DB2 coprocessor, the REPLACE statement replaces text strings in
SQL statements as well as in generated COBOL statements.

Declaring tables and views: Your COBOL program should include the statement
DECLARE TABLE to describe each table and view the program accesses. You can
use the DB2 declarations generator (DCLGEN) to generate the DECLARE TABLE
statements. You should include the DCLGEN members in the DATA DIVISION.
For more information, see “DCLGEN (declarations generator)” on page 129.

Dynamic SQL in a COBOL program: In general, COBOL programs can easily

handle dynamic SQL statements. COBOL programs can handle SELECT statements
if the data types and the number of fields returned are fixed. If you want to use
variable-list SELECT statements, use an SQLDA. See “Defining SQL descriptor
areas” on page 141 for more information on SQLDA.

Chapter 6. Coding SQL statements in COBOL application programs 327

Including code: To include SQL statements or COBOL host variable declarations
from a member of a partitioned data set, use the following SQL statement in the
source code where you want to include the statements:
EXEC SQL INCLUDE member-name END-EXEC.

If you are using the DB2 precompiler, you cannot nest SQL INCLUDE statements.
In this case, do not use COBOL verbs to include SQL statements or host variable
declarations, and do not use the SQL INCLUDE statement to include CICS
preprocessor related code. In general, if you are using the DB2 precompiler, use the
SQL INCLUDE statement only for SQL-related coding. If you are using the COBOL
DB2 coprocessor, none of these restrictions apply.

Margins: You must code SQL statements that begin with EXEC SQL in columns 12
through 72. Otherwise the DB2 precompiler does not recognize the SQL statement.

Names: You can use any valid COBOL name for a host variable. Do not use
external entry names or access plan names that begin with ’DSN’, and do not use
host variable names that begin with ’SQL’. These names are reserved for DB2.

Sequence numbers: The source statements that the DB2 precompiler generates do
not include sequence numbers.

Statement labels: You can precede executable SQL statements in the PROCEDURE
DIVISION with a paragraph name, if you wish.

WHENEVER statement: The target for the GOTO clause in an SQL statement
WHENEVER must be a section name or unqualified paragraph name in the
PROCEDURE DIVISION.

Special COBOL considerations: The following considerations apply to programs

written in COBOL:
v In a COBOL program that uses elements in a multi-level structure as host
variable names, the DB2 precompiler generates the lowest two-level names.
v Using the COBOL compiler options DYNAM and NODYNAM depends on the
operating environment.
TSO and IMSYou can specify the option DYNAM when compiling a COBOL
program if you use the following guidelines. IMS and DB2 share a common alias
name, DSNHLI, for the language interface module. You must do the following
when you concatenate your libraries:
– If you use IMS with the COBOL option DYNAM, be sure to concatenate the
IMS library first.
– If you run your application program only under DB2, be sure to concatenate
the DB2 library first.
| CICS, CAF, and RRSAFYou must specify the NODYNAM option when you
| compile a COBOL program that either includes CICS statements or is translated
| by a separate CICS translator or the integrated CICS translator. In these cases,
| you cannot specify the DYNAM option. If your CICS program has a subroutine
| that is not translated by a separate CICS translator or the integrated CICS
| translator but contains SQL statements, you can specify the DYNAM option.
| However, in this case, you must concatenate the CICS libraries before the DB2
| libraries.

328 Application Programming and SQL Guide

You can compile COBOL stored procedures with either the DYNAM option or
the NODYNAM option. If you use DYNAM, ensure that the correct DB2
language interface module is loaded dynamically by performing one of the
following actions:
– Use the ATTACH(RRSAF) precompiler option.
– Copy the DSNRLI module into a load library that is concatenated in front of
the DB2 libraries. Use the member name DSNHLI.
v To avoid truncating numeric values, use either of the following methods:
– Use the COMP-5 data type for binary integer host variables.
– Specify the COBOL compiler option:
- TRUNC(OPT) if you are certain that the data being moved to each binary
variable by the application does not have a larger precision than is defined
in the PICTURE clause of the binary variable.
- TRUNC(BIN) if the precision of data being moved to each binary variable
might exceed the value in the PICTURE clause.
DB2 assigns values to binary integer host variables as if you had specified the
COBOL compiler option TRUNC(BIN) or used the COMP-5 data type.
v If you are using the DB2 precompiler and your COBOL program contains
several entry points or is called several times, the USING clause of the entry
statement that executes before the first SQL statement executes must contain the
SQLCA and all linkage section entries that any SQL statement uses as host
variables.
v If you use the DB2 precompiler, no compiler directives should appear between
the PROCEDURE DIVISION and the DECLARATIVES statement.
v Do not use COBOL figurative constants (such as ZERO and SPACE), symbolic
characters, reference modification, and subscripts within SQL statements.
v Observe the rules for naming SQL identifiers. For information about those rules,
see the topic “SQL identifiers” in DB2 SQL Reference. However, for COBOL only,
the names of SQL identifiers can follow the rules for naming COBOL words, if
the names do not exceed the allowable length for the DB2 object. For example,
the name 1ST-TIME is a valid cursor name because it is a valid COBOL word,
but the name 1ST_TIME is not valid because it is not a valid SQL identifier or a
valid COBOL word.
v Observe these rules for hyphens:
– Surround hyphens used as subtraction operators with spaces. DB2 usually
interprets a hyphen with no spaces around it as part of a host variable name.
v If you include an SQL statement in a COBOL PERFORM ... THRU paragraph and
also specify the SQL statement WHENEVER ... GO, the COBOL compiler returns
the warning message IGYOP3094. That message might indicate a problem. This
usage is not recommended.
v If you are using the DB2 precompiler, all SQL statements and any host variables
they reference must be within the first program when using nested programs or
batch compilation.
v If you are using the DB2 precompiler, your COBOL programs must have a
DATA DIVISION and a PROCEDURE DIVISION. Both divisions and the
WORKING-STORAGE section must be present in programs that contain SQL
statements.

PSPI If your program uses the DB2 precompiler and uses parameters that are
defined in LINKAGE SECTION as host variables to DB2 and the address of the
input parameter might change on subsequent invocations of your program, your

Chapter 6. Coding SQL statements in COBOL application programs 329

program must reset the variable SQL-INIT-FLAG. This flag is generated by the
DB2 precompiler. Resetting this flag indicates that the storage must initialize when
the next SQL statement executes. To reset the flag, insert the statement MOVE
ZERO TO SQL-INIT-FLAG in the called program’s PROCEDURE DIVISION, ahead
of any executable SQL statements that use the host variables. If you use the
COBOL DB2 coprocessor, the called program does not need to reset
SQL-INIT-FLAG. PSPI

You can use the MESSAGE_TEXT condition item field of the GET DIAGNOSTICS
statement to convert an SQL return code into a text message. Programs that require
long token message support should code the GET DIAGNOSTICS statement
instead of DSNTIAR. For more information about GET DIAGNOSTICS, see
“Checking the execution of SQL statements by using the GET DIAGNOSTICS
statement” on page 209.

You can use the subroutine DSNTIAR to convert an SQL return code into a text
message. DSNTIAR takes data from the SQLCA, formats it into a message, and
places the result in a message output area that you provide in your application
program. For concepts and more information on the behavior of DSNTIAR, see
“Displaying SQLCA fields by calling DSNTIAR” on page 204.

DSNTIAR syntax:

CALL ’DSNTIAR’ USING sqlca message lrecl.

The DSNTIAR parameters have the following meanings:

sqlca
An SQL communication area.
message
An output area, in VARCHAR format, in which DSNTIAR places the message
text. The first halfword contains the length of the remaining area; its minimum
value is 240.
The output lines of text, each line being the length specified in lrecl, are put
into this area. For example, you could specify the format of the output area as:
01 ERROR-MESSAGE.
02 ERROR-LEN PIC S9(4) COMP VALUE +1320.
02 ERROR-TEXT PIC X(132) OCCURS 10 TIMES
INDEXED BY ERROR-INDEX.
77
. ERROR-TEXT-LEN PIC S9(9) COMP VALUE +132.
.
.
CALL 'DSNTIAR' USING SQLCA ERROR-MESSAGE ERROR-TEXT-LEN.

where ERROR-MESSAGE is the name of the message output area containing

10 lines of length 132 each, and ERROR-TEXT-LEN is the length of each line.
lrecl
A fullword containing the logical record length of output messages, between 72
and 240.

An example of calling DSNTIAR from an application appears in the DB2 sample

assembler program DSN8BC3, which is contained in the library
DSN8910.SDSNSAMP. See “DB2 sample applications” on page 1069 for instructions
on how to access and print the source code for the sample program.

330 Application Programming and SQL Guide

CICSIf you call DSNTIAR dynamically from a CICS COBOL application program,
be sure you do the following:
v Compile the COBOL application with the NODYNAM option.
v Define DSNTIAR in the CSD.

If your CICS application requires CICS storage handling, you must use the
subroutine DSNTIAC instead of DSNTIAR. DSNTIAC has the following syntax:
CALL 'DSNTIAC' USING eib commarea sqlca msg lrecl.

DSNTIAC has extra parameters, which you must use for calls to routines that use
CICS commands.
eib EXEC interface block
commarea
communication area

For more information on these parameters, see the appropriate application

programming guide for CICS. The remaining parameter descriptions are the same
as those for DSNTIAR. Both DSNTIAC and DSNTIAR format the SQLCA in the
same way.

You must define DSNTIA1 in the CSD. If you load DSNTIAR or DSNTIAC, you
must also define them in the CSD. For an example of CSD entry generation
statements for use with DSNTIAC, see job DSNTEJ5A.

The assembler source code for DSNTIAC and job DSNTEJ5A, which assembles and
link-edits DSNTIAC, are in the data set prefix.SDSNSAMP.

Chapter 6. Coding SQL statements in COBOL application programs 331

Related concepts
“Dynamic SQL” on page 162
“Host variable arrays in an SQL statement” on page 159
“Rules for host variables in an SQL statement” on page 151
“Possible host languages for dynamic SQL applications” on page 166
Related tasks
“Determining whether a column value is null” on page 156
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Dynamically executing a data change statement” on page 191
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189
“Enabling the dynamic statement cache” on page 195
“Handling SQL error codes” on page 215
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
“Inserting a single row by using a host variable” on page 158
“Inserting multiple rows of data from host variable arrays” on page 160
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Limiting CPU time for dynamic SQL statements by using the resource limit
facility” on page 200
“Retrieving multiple rows of data into host variable arrays” on page 160
“Retrieving a single row of data into a host structure” on page 161
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Delimiters in SQL statements in COBOL programs

You must delimit SQL statements in your COBOL program so that DB2 knows
when a particular SQL statement ends.

Delimit an SQL statement in your COBOL program with the beginning keyword
EXEC SQL and an END-EXEC.

Example

Use EXEC SQL and END-EXEC. to delimit an SQL statement in a COBOL program:
EXEC SQL
an SQL statement
END-EXEC.

332 Application Programming and SQL Guide

Object-oriented extensions in COBOL
When you use object-oriented extensions in a COBOL application, you need to
consider where to place SQL statements, the SQLCA, the SQLDA, and host
variable declarations, and the rules for host variables.

Where to place SQL statements in your application: A COBOL source data set or
member can contain the following elements:
v Multiple programs
v Multiple class definitions, each of which contains multiple methods
You can put SQL statements in only the first program or class in the source data
set or member. However, you can put SQL statements in multiple methods within
a class. If an application consists of multiple data sets or members, each of the data
sets or members can contain SQL statements.

Where to place the SQLCA, SQLDA, and host variable declarations: You can put
the SQLCA, SQLDA, and SQL host variable declarations in the
WORKING-STORAGE SECTION of a program, class, or method. An SQLCA or
SQLDA in a class WORKING-STORAGE SECTION is global for all the methods of
the class. An SQLCA or SQLDA in a method WORKING-STORAGE SECTION is
local to that method only.

If a class and a method within the class both contain an SQLCA or SQLDA, the
method uses the SQLCA or SQLDA that is local.

Rules for host variables: You can declare COBOL variables that are used as host
variables in the WORKING-STORAGE SECTION or LINKAGE-SECTION of a
program, class, or method. You can also declare host variables in the
LOCAL-STORAGE SECTION of a method. The scope of a host variable is the
method, class, or program within which it is defined.

Programming examples in COBOL

You can write DB2 programs in COBOL. These programs can access a local or
remote DB2 subsystem and can execute static or dynamic SQL statements. This
information contains several such programming examples.

To prepare and run these applications, use the JCL in DSN910.SDSNSAMP as a

model for your JCL.
Related reference
“Programming examples” on page 227

Sample COBOL dynamic SQL program

This example shows how to code dynamic varying-list SELECT statements in a
COBOL program. Varying-List SELECT statements are statements for which you do
not know the number of columns returned and their data types when you write
the program.

“Dynamic SQL” on page 162 describes three variations of dynamic SQL statements:
v Non-SELECT statements
v Fixed-List SELECT statements
In this case, you know the number of columns returned and their data types
when you write the program.
v Varying-List SELECT statements.

Chapter 6. Coding SQL statements in COBOL application programs 333

In this case, you do not know the number of columns returned and their data
types when you write the program.

This section documents a technique of coding varying list SELECT statements in

COBOL. For a list of the supported versions of COBOL, see DB2 Program Directory
.

This example program does not support BLOB, CLOB, or DBCLOB data types.

Pointers and based variables in the sample COBOL program

COBOL has a POINTER type and a SET statement that provide pointers and based
variables.

The SET statement sets a pointer from the address of an area in the linkage section
or another pointer; the statement can also set the address of an area in the linkage
section. DSN8BCU2 in “Example of the sample COBOL program” provides these
uses of the SET statement. The SET statement does not permit the use of an
address in the WORKING-STORAGE section.

Storage allocation for the sample COBOL program

COBOL does not provide a means to allocate main storage within a program. You
can achieve the same end by having an initial program which allocates the storage,
and then calls a second program that manipulates the pointer. (COBOL does not
permit you to directly manipulate the pointer because errors and abends are likely
to occur.)

The initial program is extremely simple. It includes a working storage section that
allocates the maximum amount of storage needed. This program then calls the
second program, passing the area or areas on the CALL statement. The second
program defines the area in the linkage section and can then use pointers within
the area.

If you need to allocate parts of storage, the best method is to use indexes or
subscripts. You can use subscripts for arithmetic and comparison operations.

Example of the sample COBOL program

The following example shows an example of the initial program DSN8BCU1 that
allocates the storage and calls the second program DSN8BCU2. DSN8BCU2 then
defines the passed storage areas in its linkage section and includes the USING
clause on its PROCEDURE DIVISION statement.

Defining the pointers, then redefining them as numeric, permits some

manipulation of the pointers that you cannot perform directly. For example, you
cannot add the column length to the record pointer, but you can add the column
length to the numeric value that redefines the pointer.

The following example is the initial program that allocates storage.

**** DSN8BCU1- DB2 SAMPLE BATCH COBOL UNLOAD PROGRAM ***********
* *
* MODULE NAME = DSN8BCU1 *
* *
* DESCRIPTIVE NAME = DB2 SAMPLE APPLICATION *
* UNLOAD PROGRAM *
* BATCH *

334 Application Programming and SQL Guide

* ENTERPRISE COBOL FOR Z/OS *
* *
* FUNCTION = THIS MODULE PROVIDES THE STORAGE NEEDED BY *
* DSN8BCU2 AND CALLS THAT PROGRAM. *
* *
* NOTES = *
* DEPENDENCIES = NONE. *
* *
* RESTRICTIONS = *
* THE MAXIMUM NUMBER OF COLUMNS IS 750, *
* WHICH IS THE SQL LIMIT. *
* *
* DATA RECORDS ARE LIMITED TO 32700 BYTES, *
* INCLUDING DATA, LENGTHS FOR VARCHAR DATA, *
* AND SPACE FOR NULL INDICATORS. *
* *
* MODULE TYPE = COBOL PROGRAM *
* PROCESSOR = ENTERPRISE COBOL FOR Z/OS *
* *
* MODULE SIZE = SEE LINK EDIT *
* ATTRIBUTES = REENTRANT *
* *
* ENTRY POINT = DSN8BCU1 *
* PURPOSE = SEE FUNCTION *
* LINKAGE = INVOKED FROM DSN RUN *
* INPUT = NONE *
* OUTPUT = NONE *
* *
* EXIT-NORMAL = RETURN CODE 0 NORMAL COMPLETION *
* *
* EXIT-ERROR = *
* RETURN CODE = NONE *
* ABEND CODES = NONE *
* ERROR-MESSAGES = NONE *
* *
* EXTERNAL REFERENCES = *
* ROUTINES/SERVICES = *
* DSN8BCU2 - ACTUAL UNLOAD PROGRAM *
* *
* DATA-AREAS = NONE *
* CONTROL-BLOCKS = NONE *
* *
* TABLES = NONE *
* CHANGE-ACTIVITY = NONE *
* *
* *PSEUDOCODE* *
* *
* PROCEDURE *
* CALL DSN8BCU2. *
* END. *
*---------------------------------------------------------------*
/
IDENTIFICATION DIVISION.
*-----------------------
PROGRAM-ID. DSN8BCU1
*
ENVIRONMENT DIVISION.
*
CONFIGURATION SECTION.
DATA DIVISION.
*
WORKING-STORAGE SECTION.
*
01 WORKAREA-IND.
02 WORKIND PIC S9(4) COMP OCCURS 750 TIMES.
01 RECWORK.
02 RECWORK-LEN PIC S9(8) COMP VALUE 32700.

Chapter 6. Coding SQL statements in COBOL application programs 335

02 RECWORK-CHAR PIC X(1) OCCURS 32700 TIMES.
*
PROCEDURE DIVISION.
*
CALL 'DSN8BCU2' USING WORKAREA-IND RECWORK.
GOBACK.

The following example is the called program that does pointer manipulation.
**** DSN8BCU2- DB2 SAMPLE BATCH COBOL UNLOAD PROGRAM ***********
* *
* MODULE NAME = DSN8BCU2 *
* *
* DESCRIPTIVE NAME = DB2 SAMPLE APPLICATION *
* UNLOAD PROGRAM *
* BATCH *
* ENTERPRISE COBOL FOR Z/OS *
* *
* *
* FUNCTION = THIS MODULE ACCEPTS A TABLE NAME OR VIEW NAME *
* AND UNLOADS THE DATA IN THAT TABLE OR VIEW. *
* READ IN A TABLE NAME FROM SYSIN. *
* PUT DATA FROM THE TABLE INTO DD SYSREC01. *
* WRITE RESULTS TO SYSPRINT. *
* *
* NOTES = *
* DEPENDENCIES = NONE. *
* *
* RESTRICTIONS = *
* THE SQLDA IS LIMITED TO 33016 BYTES. *
* THIS SIZE ALLOWS FOR THE DB2 MAXIMUM *
* OF 750 COLUMNS. *
* *
* DATA RECORDS ARE LIMITED TO 32700 BYTES, *
* INCLUDING DATA, LENGTHS FOR VARCHAR DATA, *
* AND SPACE FOR NULL INDICATORS. *
* *
* TABLE OR VIEW NAMES ARE ACCEPTED, AND ONLY *
* ONE NAME IS ALLOWED PER RUN. *
* *
* MODULE TYPE = COBOL PROGRAM *
* PROCESSOR = DB2 PRECOMPILER *
* *
* *
* MODULE SIZE = SEE LINK EDIT *
* ATTRIBUTES = REENTRANT *
* *
* ENTRY POINT = DSN8BCU2 *
* PURPOSE = SEE FUNCTION *
* LINKAGE = *
* CALL 'DSN8BCU2' USING WORKAREA-IND RECWORK. *
* *
* INPUT = SYMBOLIC LABEL/NAME = WORKAREA-IND *
* DESCRIPTION = INDICATOR VARIABLE ARRAY *
* 01 WORKAREA-IND. *
* 02 WORKIND PIC S9(4) COMP OCCURS 750 TIMES. *
* *
* SYMBOLIC LABEL/NAME = RECWORK *
* DESCRIPTION = WORK AREA FOR OUTPUT RECORD *
* 01 RECWORK. *
* 02 RECWORK-LEN PIC S9(8) COMP. *
* *
* SYMBOLIC LABEL/NAME = SYSIN *
* DESCRIPTION = INPUT REQUESTS - TABLE OR VIEW *
* *

336 Application Programming and SQL Guide

* OUTPUT = SYMBOLIC LABEL/NAME = SYSPRINT *
* DESCRIPTION = PRINTED RESULTS *
* *
* SYMBOLIC LABEL/NAME = SYSREC01 *
* DESCRIPTION = UNLOADED TABLE DATA *
* *
* EXIT-NORMAL = RETURN CODE 0 NORMAL COMPLETION *
* EXIT-ERROR = *
* RETURN CODE = NONE *
* ABEND CODES = NONE *
* ERROR-MESSAGES = *
* DSNT490I SAMPLE COBOL DATA UNLOAD PROGRAM RELEASE 3.0*
* - THIS IS THE HEADER, INDICATING A NORMAL *
* - START FOR THIS PROGRAM. *
* DSNT493I SQL ERROR, SQLCODE = NNNNNNNN *
* - AN SQL ERROR OR WARNING WAS ENCOUNTERED *
* - ADDITIONAL INFORMATION FROM DSNTIAR *
* - FOLLOWS THIS MESSAGE. *
* DSNT495I SUCCESSFUL UNLOAD XXXXXXXX ROWS OF *
* TABLE TTTTTTTT *
* - THE UNLOAD WAS SUCCESSFUL. XXXXXXXX IS *
* - THE NUMBER OF ROWS UNLOADED. TTTTTTTT *
* - IS THE NAME OF THE TABLE OR VIEW FROM *
* - WHICH IT WAS UNLOADED. *
* DSNT496I UNRECOGNIZED DATA TYPE CODE OF NNNNN *
* - THE PREPARE RETURNED AN INVALID DATA *
* - TYPE CODE. NNNNN IS THE CODE, PRINTED *
* - IN DECIMAL. USUALLY AN ERROR IN *
* - THIS ROUTINE OR A NEW DATA TYPE. *
* DSNT497I RETURN CODE FROM MESSAGE ROUTINE DSNTIAR *
* - THE MESSAGE FORMATTING ROUTINE DETECTED *
* - AN ERROR. SEE THAT ROUTINE FOR RETURN *
* - CODE INFORMATION. USUALLY AN ERROR IN *
* - THIS ROUTINE. *
* DSNT498I ERROR, NO VALID COLUMNS FOUND *
* - THE PREPARE RETURNED DATA WHICH DID NOT *
* - PRODUCE A VALID OUTPUT RECORD. *
* - USUALLY AN ERROR IN THIS ROUTINE. *
* DSNT499I NO ROWS FOUND IN TABLE OR VIEW *
* - THE CHOSEN TABLE OR VIEWS DID NOT *
* - RETURN ANY ROWS. *
* ERROR MESSAGES FROM MODULE DSNTIAR *
* - WHEN AN ERROR OCCURS, THIS MODULE *
* - PRODUCES CORRESPONDING MESSAGES. *
* *
* EXTERNAL REFERENCES = *
* ROUTINES/SERVICES = *
* DSNTIAR - TRANSLATE SQLCA INTO MESSAGES *
* DATA-AREAS = NONE *
* CONTROL-BLOCKS = *
* SQLCA - SQL COMMUNICATION AREA *
* *
* TABLES = NONE *
* CHANGE-ACTIVITY = NONE *
* *
* *PSEUDOCODE* *
* PROCEDURE *
* EXEC SQL DECLARE DT CURSOR FOR SEL END-EXEC. *
* EXEC SQL DECLARE SEL STATEMENT END-EXEC. *
* INITIALIZE THE DATA, OPEN FILES. *
* OBTAIN STORAGE FOR THE SQLDA AND THE DATA RECORDS. *
* READ A TABLE NAME. *
* OPEN SYSREC01. *
* BUILD THE SQL STATEMENT TO BE EXECUTED *
* EXEC SQL PREPARE SQL STATEMENT INTO SQLDA END-EXEC. *
* SET UP ADDRESSES IN THE SQLDA FOR DATA. *
* INITIALIZE DATA RECORD COUNTER TO 0. *

Chapter 6. Coding SQL statements in COBOL application programs 337

* EXEC SQL OPEN DT END-EXEC. *
* DO WHILE SQLCODE IS 0. *
* EXEC SQL FETCH DT USING DESCRIPTOR SQLDA END-EXEC. *
* ADD IN MARKERS TO DENOTE NULLS. *
* WRITE THE DATA TO SYSREC01. *
* INCREMENT DATA RECORD COUNTER. *
* END. *
* EXEC SQL CLOSE DT END-EXEC. *
* INDICATE THE RESULTS OF THE UNLOAD OPERATION. *
* CLOSE THE SYSIN, SYSPRINT, AND SYSREC01 FILES. *
* END. *
*---------------------------------------------------------------*
/
IDENTIFICATION DIVISION.
*-----------------------
PROGRAM-ID. DSN8BCU2
*
ENVIRONMENT DIVISION.
*--------------------
CONFIGURATION SECTION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT SYSIN
ASSIGN TO DA-S-SYSIN.
SELECT SYSPRINT
ASSIGN TO UT-S-SYSPRINT.
SELECT SYSREC01
ASSIGN TO DA-S-SYSREC01.
*
DATA DIVISION.
*-------------
*
FILE SECTION.
FD SYSIN
RECORD CONTAINS 80 CHARACTERS
BLOCK CONTAINS 0 RECORDS
LABEL RECORDS ARE OMITTED
RECORDING MODE IS F.
01 CARDREC PIC X(80).
*
FD SYSPRINT
RECORD CONTAINS 120 CHARACTERS
LABEL RECORDS ARE OMITTED
DATA RECORD IS MSGREC
RECORDING MODE IS F.
01 MSGREC PIC X(120).
*
FD SYSREC01
RECORD CONTAINS 5 TO 32704 CHARACTERS
LABEL RECORDS ARE OMITTED
DATA RECORD IS REC01
RECORDING MODE IS V.
01 REC01.
02 REC01-LEN PIC S9(8) COMP.
02 REC01-CHAR PIC X(1) OCCURS 1 TO 32700 TIMES
DEPENDING ON REC01-LEN.
/
WORKING-STORAGE SECTION.
*
*****************************************************
* STRUCTURE FOR INPUT *
*****************************************************
01 IOAREA.
02 TNAME PIC X(72).
02 FILLER PIC X(08).
01 STMTBUF.
49 STMTLEN PIC S9(4) COMP VALUE 92.

338 Application Programming and SQL Guide

49 STMTCHAR PIC X(92).
01 STMTBLD.
02 FILLER PIC X(20) VALUE 'SELECT * FROM'.
02 STMTTAB PIC X(72).
*
*****************************************************
* REPORT HEADER STRUCTURE *
*****************************************************
01 HEADER.
02 FILLER PIC X(35)
VALUE ' DSNT490I SAMPLE COBOL DATA UNLOAD '.
02 FILLER PIC X(85) VALUE 'PROGRAM RELEASE 3.0'.
01 MSG-SQLERR.
02 FILLER PIC X(31)
VALUE ' DSNT493I SQL ERROR, SQLCODE = '.
02 MSG-MINUS PIC X(1).
02 MSG-PRINT-CODE PIC 9(8).
02 FILLER PIC X(81) VALUE ' '.
01 UNLOADED.
02 FILLER PIC X(28)
VALUE ' DSNT495I SUCCESSFUL UNLOAD '.
02 ROWS PIC 9(8).
02 FILLER PIC X(15) VALUE ' ROWS OF TABLE '.
02 TABLENAM PIC X(72) VALUE ' '.
01 BADTYPE.
02 FILLER PIC X(42)
VALUE ' DSNT496I UNRECOGNIZED DATA TYPE CODE OF '.
02 TYPCOD PIC 9(8).
02 FILLER PIC X(71) VALUE ' '.
01 MSGRETCD.
02 FILLER PIC X(42)
VALUE ' DSNT497I RETURN CODE FROM MESSAGE ROUTINE'.
02 FILLER PIC X(9) VALUE 'DSNTIAR '.
02 RETCODE PIC 9(8).
02 FILLER PIC X(62) VALUE ' '.
01 MSGNOCOL.
02 FILLER PIC X(120)
VALUE ' DSNT498I ERROR, NO VALID COLUMNS FOUND'.
01 MSG-NOROW.
02 FILLER PIC X(120)
VALUE ' DSNT499I NO ROWS FOUND IN TABLE OR VIEW'.
*****************************************************
* WORKAREAS *
*****************************************************
77 NOT-FOUND PIC S9(8) COMP VALUE +100.
*****************************************************
* VARIABLES FOR ERROR-MESSAGE FORMATTING *
00
*****************************************************
01 ERROR-MESSAGE.
02 ERROR-LEN PIC S9(4) COMP VALUE +960.
02 ERROR-TEXT PIC X(120) OCCURS 8 TIMES
INDEXED BY ERROR-INDEX.
77 ERROR-TEXT-LEN PIC S9(8) COMP VALUE +120.
*****************************************************
* SQL DESCRIPTOR AREA *
*****************************************************
EXEC SQL INCLUDE SQLDA END-EXEC.
*
* DATA TYPES FOUND IN SQLTYPE, AFTER REMOVING THE NULL BIT
*
77 VARCTYPE PIC S9(4) COMP VALUE +448.
77 CHARTYPE PIC S9(4) COMP VALUE +452.
77 VARLTYPE PIC S9(4) COMP VALUE +456.
77 VARGTYPE PIC S9(4) COMP VALUE +464.
77 GTYPE PIC S9(4) COMP VALUE +468.
77 LVARGTYP PIC S9(4) COMP VALUE +472.

Chapter 6. Coding SQL statements in COBOL application programs 339

77 FLOATYPE PIC S9(4) COMP VALUE +480.
77 DECTYPE PIC S9(4) COMP VALUE +484.
77 INTTYPE PIC S9(4) COMP VALUE +496.
77 HWTYPE PIC S9(4) COMP VALUE +500.
77 DATETYP PIC S9(4) COMP VALUE +384.
77 TIMETYP PIC S9(4) COMP VALUE +388.
77 TIMESTMP PIC S9(4) COMP VALUE +392.
*
*****************************************************
* THE REDEFINES CLAUSES BELOW ARE FOR 31-BIT ADDRESSING.
* IF YOUR COMPILER SUPPORTS ONLY 24-BIT ADDRESSING,
* CHANGE THE DECLARATIONS TO THESE:
* 01 RECNUM REDEFINES RECPTR PICTURE S9(8) COMPUTATIONAL.
* 01 IRECNUM REDEFINES IRECPTR PICTURE S9(8) COMPUTATIONAL.
*****************************************************
01 RECPTR POINTER.
01 RECNUM REDEFINES RECPTR PICTURE S9(9) COMPUTATIONAL.
01 IRECPTR POINTER.
01 IRECNUM REDEFINES IRECPTR PICTURE S9(9) COMPUTATIONAL.
01 I PICTURE S9(4) COMPUTATIONAL.
01 J PICTURE S9(4) COMPUTATIONAL.
01 DUMMY PICTURE S9(4) COMPUTATIONAL.
01 MYTYPE PICTURE S9(4) COMPUTATIONAL.
01 COLUMN-IND PICTURE S9(4) COMPUTATIONAL.
01 COLUMN-LEN PICTURE S9(4) COMPUTATIONAL.
01 COLUMN-PREC PICTURE S9(4) COMPUTATIONAL.
01 COLUMN-SCALE PICTURE S9(4) COMPUTATIONAL.
01 INDCOUNT PIC S9(4) COMPUTATIONAL.
01 ROWCOUNT PIC S9(4) COMPUTATIONAL.
01 WORKAREA2.
02 WORKINDPTR POINTER OCCURS 750 TIMES.
*****************************************************
* DECLARE CURSOR AND STATEMENT FOR DYNAMIC SQL
*****************************************************
*
EXEC SQL DECLARE DT CURSOR FOR SEL END-EXEC.
EXEC SQL DECLARE SEL STATEMENT END-EXEC.
*
*****************************************************
* SQL INCLUDE FOR SQLCA *
*****************************************************
EXEC SQL INCLUDE SQLCA END-EXEC.
*
77 ONE PIC S9(4) COMP VALUE +1.
77 TWO PIC S9(4) COMP VALUE +2.
77 FOUR PIC S9(4) COMP VALUE +4.
77 QMARK PIC X(1) VALUE '?'.
*
LINKAGE SECTION.
01 LINKAREA-IND.
02 IND PIC S9(4) COMP OCCURS 750 TIMES.
01 LINKAREA-REC.
02 REC1-LEN PIC S9(8) COMP.
02 REC1-CHAR PIC X(1) OCCURS 1 TO 32700 TIMES
DEPENDING ON REC1-LEN.
01 LINKAREA-QMARK.
02 INDREC PIC X(1).
/
PROCEDURE DIVISION USING LINKAREA-IND LINKAREA-REC.
*
*****************************************************
* SQL RETURN CODE HANDLING *
*****************************************************
EXEC SQL WHENEVER SQLERROR GOTO DBERROR END-EXEC.
EXEC SQL WHENEVER SQLWARNING GOTO DBERROR END-EXEC.
EXEC SQL WHENEVER NOT FOUND CONTINUE END-EXEC.

340 Application Programming and SQL Guide

*
*****************************************************
* MAIN PROGRAM ROUTINE *
*****************************************************
SET IRECPTR TO ADDRESS OF REC1-CHAR(1).
* **OPEN FILES
OPEN INPUT SYSIN
OUTPUT SYSPRINT
OUTPUT SYSREC01.
* **WRITE HEADER
WRITE MSGREC FROM HEADER
AFTER ADVANCING 2 LINES.
* **GET FIRST INPUT
READ SYSIN RECORD INTO IOAREA.
* **MAIN ROUTINE
PERFORM PROCESS-INPUT THROUGH IND-RESULT.
*
PROG-END.
* **CLOSE FILES
CLOSE SYSIN
SYSPRINT
SYSREC01.
GOBACK.
/
***************************************************************
* *
* PERFORMED SECTION: *
* PROCESSING FOR THE TABLE OR VIEW JUST READ *
* *
***************************************************************
PROCESS-INPUT.
*
MOVE TNAME TO STMTTAB.
MOVE STMTBLD TO STMTCHAR.
EXEC SQL PREPARE SEL INTO :SQLDA FROM :STMTBUF END-EXEC.
***************************************************************
* *
* SET UP ADDRESSES IN THE SQLDA FOR DATA. *
* *
***************************************************************
IF SQLD = ZERO THEN
WRITE MSGREC FROM MSGNOCOL
AFTER ADVANCING 2 LINES
GO TO IND-RESULT.
MOVE ZERO TO ROWCOUNT.
MOVE ZERO TO REC1-LEN.
SET RECPTR TO IRECPTR.
MOVE ONE TO I.
PERFORM COLADDR UNTIL I > SQLD.
****************************************************************
* *
* SET LENGTH OF OUTPUT RECORD. *
* EXEC SQL OPEN DT END-EXEC. *
* DO WHILE SQLCODE IS 0. *
* EXEC SQL FETCH DT USING DESCRIPTOR :SQLDA END-EXEC. *
* ADD IN MARKERS TO DENOTE NULLS. *
* WRITE THE DATA TO SYSREC01. *
* INCREMENT DATA RECORD COUNTER. *
* END. *
* *
****************************************************************
* **OPEN CURSOR
EXEC SQL OPEN DT END-EXEC.
PERFORM BLANK-REC.
EXEC SQL FETCH DT USING DESCRIPTOR :SQLDA END-EXEC.
* **NO ROWS FOUND
* **PRINT ERROR MESSAGE

Chapter 6. Coding SQL statements in COBOL application programs 341

IF SQLCODE = NOT-FOUND
WRITE MSGREC FROM MSG-NOROW
AFTER ADVANCING 2 LINES
ELSE
* **WRITE ROW AND
* **CONTINUE UNTIL
* **NO MORE ROWS
PERFORM WRITE-AND-FETCH
UNTIL SQLCODE IS NOT EQUAL TO ZERO.
*
EXEC SQL WHENEVER NOT FOUND GOTO CLOSEDT END-EXEC.
*
CLOSEDT.
EXEC SQL CLOSE DT END-EXEC.
*
****************************************************************
* *
* INDICATE THE RESULTS OF THE UNLOAD OPERATION. *
* *
****************************************************************
IND-RESULT.
MOVE TNAME TO TABLENAM.
MOVE ROWCOUNT TO ROWS.
WRITE MSGREC FROM UNLOADED
AFTER ADVANCING 2 LINES.
GO TO PROG-END.
*
WRITE-AND-FETCH.
* ADD IN MARKERS TO DENOTE NULLS.
MOVE ONE TO INDCOUNT.
PERFORM NULLCHK UNTIL INDCOUNT = SQLD.
MOVE REC1-LEN TO REC01-LEN.
WRITE REC01 FROM LINKAREA-REC.
ADD ONE TO ROWCOUNT.
PERFORM BLANK-REC.
EXEC SQL FETCH DT USING DESCRIPTOR :SQLDA END-EXEC.
*
NULLCHK.
IF IND(INDCOUNT) < 0 THEN
SET ADDRESS OF LINKAREA-QMARK TO WORKINDPTR(INDCOUNT)
MOVE QMARK TO INDREC.
ADD ONE TO INDCOUNT.
*****************************************************
* BLANK OUT RECORD TEXT FIRST *
*****************************************************
BLANK-REC.
MOVE ONE TO J.
PERFORM BLANK-MORE UNTIL J > REC1-LEN.
BLANK-MORE.
MOVE ' ' TO REC1-CHAR(J).
ADD ONE TO J.
*
COLADDR.
SET SQLDATA(I) TO RECPTR.
****************************************************************
*
* DETERMINE THE LENGTH OF THIS COLUMN (COLUMN-LEN)
* THIS DEPENDS ON THE DATA TYPE. MOST DATA TYPES HAVE
* THE LENGTH SET, BUT VARCHAR, GRAPHIC, VARGRAPHIC, AND
* DECIMAL DATA NEED TO HAVE THE BYTES CALCULATED.
* THE NULL ATTRIBUTE MUST BE SEPARATED TO SIMPLIFY MATTERS.
*
****************************************************************
MOVE SQLLEN(I) TO COLUMN-LEN.
* COLUMN-IND IS 0 FOR NO NULLS AND 1 FOR NULLS
DIVIDE SQLTYPE(I) BY TWO GIVING DUMMY REMAINDER COLUMN-IND.
* MYTYPE IS JUST THE SQLTYPE WITHOUT THE NULL BIT

342 Application Programming and SQL Guide

MOVE SQLTYPE(I) TO MYTYPE.
SUBTRACT COLUMN-IND FROM MYTYPE.
* SET THE COLUMN LENGTH, DEPENDENT ON DATA TYPE
EVALUATE MYTYPE
WHEN CHARTYPE CONTINUE,
WHEN DATETYP CONTINUE,
WHEN TIMETYP CONTINUE,
WHEN TIMESTMP CONTINUE,
WHEN FLOATYPE CONTINUE,
WHEN VARCTYPE
ADD TWO TO COLUMN-LEN,
WHEN VARLTYPE
ADD TWO TO COLUMN-LEN,
WHEN GTYPE
MULTIPLY COLUMN-LEN BY TWO GIVING COLUMN-LEN,
WHEN VARGTYPE
PERFORM CALC-VARG-LEN,
WHEN LVARGTYP
PERFORM CALC-VARG-LEN,
WHEN HWTYPE
MOVE TWO TO COLUMN-LEN,
WHEN INTTYPE
MOVE FOUR TO COLUMN-LEN,
WHEN DECTYPE
PERFORM CALC-DECIMAL-LEN,
WHEN OTHER
PERFORM UNRECOGNIZED-ERROR,
END-EVALUATE.
ADD COLUMN-LEN TO RECNUM.
ADD COLUMN-LEN TO REC1-LEN.
****************************************************************
* *
* IF THIS COLUMN CAN BE NULL, AN INDICATOR VARIABLE IS *
* NEEDED. WE ALSO RESERVE SPACE IN THE OUTPUT RECORD TO *
* NOTE THAT THE VALUE IS NULL. *
* *
****************************************************************
MOVE ZERO TO IND(I).
IF COLUMN-IND = ONE THEN
SET SQLIND(I) TO ADDRESS OF IND(I)
SET WORKINDPTR(I) TO RECPTR
ADD ONE TO RECNUM
ADD ONE TO REC1-LEN.
*
ADD ONE TO I.
* PERFORMED PARAGRAPH TO CALCULATE COLUMN LENGTH
* FOR A DECIMAL DATA TYPE COLUMN
CALC-DECIMAL-LEN.
DIVIDE COLUMN-LEN BY 256 GIVING COLUMN-PREC
REMAINDER COLUMN-SCALE.
MOVE COLUMN-PREC TO COLUMN-LEN.
ADD ONE TO COLUMN-LEN.
DIVIDE COLUMN-LEN BY TWO GIVING COLUMN-LEN.
* PERFORMED PARAGRAPH TO CALCULATE COLUMN LENGTH
* FOR A VARGRAPHIC DATA TYPE COLUMN
CALC-VARG-LEN.
MULTIPLY COLUMN-LEN BY TWO GIVING COLUMN-LEN.
ADD TWO TO COLUMN-LEN.
* PERFORMED PARAGRAPH TO NOTE AN UNRECOGNIZED
* DATA TYPE COLUMN
UNRECOGNIZED-ERROR.
*
* ERROR MESSAGE FOR UNRECOGNIZED DATA TYPE
*
MOVE SQLTYPE(I) TO TYPCOD.
WRITE MSGREC FROM BADTYPE
AFTER ADVANCING 2 LINES.

Chapter 6. Coding SQL statements in COBOL application programs 343

GO TO IND-RESULT.
*
*****************************************************
* SQL ERROR OCCURRED - GET MESSAGE *
*****************************************************
DBERROR.
* **SQL ERROR
MOVE SQLCODE TO MSG-PRINT-CODE.
IF SQLCODE < 0 THEN MOVE '-' TO MSG-MINUS.
WRITE MSGREC FROM MSG-SQLERR
AFTER ADVANCING 2 LINES.
CALL 'DSNTIAR' USING SQLCA ERROR-MESSAGE ERROR-TEXT-LEN.
IF RETURN-CODE = ZERO
PERFORM ERROR-PRINT VARYING ERROR-INDEX
FROM 1 BY 1 UNTIL ERROR-INDEX GREATER THAN 8
ELSE
* **ERROR FOUND IN DSNTIAR
* **PRINT ERROR MESSAGE
MOVE RETURN-CODE TO RETCODE
WRITE MSGREC FROM MSGRETCD
AFTER ADVANCING 2 LINES.
GO TO PROG-END.
*
*****************************************************
* PRINT MESSAGE TEXT *
*****************************************************
ERROR-PRINT.
WRITE MSGREC FROM ERROR-TEXT (ERROR-INDEX)
AFTER ADVANCING 1 LINE.

Sample COBOL program using DRDA access with CONNECT

statements
This example demonstrates how to access distributed data by using DRDA access
in a COBOL program.

The following figure contains a sample COBOL program that uses two-phase
commit and DRDA to access distributed data.
IDENTIFICATION DIVISION.
PROGRAM-ID. TWOPHASE.
AUTHOR.
REMARKS.
*****************************************************************
* *
* MODULE NAME = TWOPHASE *
* *
* DESCRIPTIVE NAME = DB2 SAMPLE APPLICATION USING *
* TWO PHASE COMMIT AND THE DRDA DISTRIBUTED *
* ACCESS METHOD WITH CONNECT STATEMENTS *
* *
* COPYRIGHT = 5665-DB2 (C) COPYRIGHT IBM CORP 1982, 1989 *
* REFER TO COPYRIGHT INSTRUCTIONS FORM NUMBER G120-2083 *
* *
* STATUS = VERSION 5 *
* *
* FUNCTION = THIS MODULE DEMONSTRATES DISTRIBUTED DATA ACCESS *
* USING 2 PHASE COMMIT BY TRANSFERRING AN EMPLOYEE *
* FROM ONE LOCATION TO ANOTHER. *
* *
* NOTE: THIS PROGRAM ASSUMES THE EXISTENCE OF THE *
* TABLE SYSADM.EMP AT LOCATIONS STLEC1 AND *
* STLEC2. *
* *
* MODULE TYPE = COBOL PROGRAM *
* PROCESSOR = DB2 PRECOMPILER, ENTERPRISE COBOL FOR Z/OS *
* MODULE SIZE = SEE LINK EDIT *

344 Application Programming and SQL Guide

* ATTRIBUTES = NOT REENTRANT OR REUSABLE *
* *
* ENTRY POINT = *
* PURPOSE = TO ILLUSTRATE 2 PHASE COMMIT *
* LINKAGE = INVOKE FROM DSN RUN *
* INPUT = NONE *
* OUTPUT = *
* SYMBOLIC LABEL/NAME = SYSPRINT *
* DESCRIPTION = PRINT OUT THE DESCRIPTION OF EACH *
* STEP AND THE RESULTANT SQLCA *
* *
* EXIT NORMAL = RETURN CODE 0 FROM NORMAL COMPLETION *
* *
* EXIT ERROR = NONE *
* *
* EXTERNAL REFERENCES = *
* ROUTINE SERVICES = NONE *
* DATA-AREAS = NONE *
* CONTROL-BLOCKS = *
* SQLCA - SQL COMMUNICATION AREA *
* *
* TABLES = NONE *
* *
* CHANGE-ACTIVITY = NONE *
* *
* *
* *
* PSEUDOCODE *
* *
* MAINLINE. *
* Perform CONNECT-TO-SITE-1 to establish *
* a connection to the local connection. *
* If the previous operation was successful Then *
* Do. *
* | Perform PROCESS-CURSOR-SITE-1 to obtain the *
* | information about an employee that is *
* | transferring to another location. *
* | If the information about the employee was obtained *
* | successfully Then *
* | Do. *
* | | Perform UPDATE-ADDRESS to update the information *
* | | to contain current information about the *
* | | employee. *
* | | Perform CONNECT-TO-SITE-2 to establish *
* | | a connection to the site where the employee is *
* | | transferring to. *
* | | If the connection is established successfully *
* | | Then *
* | | Do. *
* | | | Perform PROCESS-SITE-2 to insert the *
* | | | employee information at the location *
* | | | where the employee is transferring to. *
* | | End if the connection was established *
* | | successfully. *
* | End if the employee information was obtained *
* | successfully. *
* End if the previous operation was successful. *
* Perform COMMIT-WORK to COMMIT the changes made to STLEC1 *
* and STLEC2. *
* *
* PROG-END. *
* Close the printer. *
* Return. *
* *
* CONNECT-TO-SITE-1. *
* Provide a text description of the following step. *
* Establish a connection to the location where the *

Chapter 6. Coding SQL statements in COBOL application programs 345

* employee is transferring from. *
* Print the SQLCA out. *
* *
* PROCESS-CURSOR-SITE-1. *
* Provide a text description of the following step. *
* Open a cursor that will be used to retrieve information *
* about the transferring employee from this site. *
* Print the SQLCA out. *
* If the cursor was opened successfully Then *
* Do. *
* | Perform FETCH-DELETE-SITE-1 to retrieve and *
* | delete the information about the transferring *
* | employee from this site. *
* | Perform CLOSE-CURSOR-SITE-1 to close the cursor. *
* End if the cursor was opened successfully. *
* *
* FETCH-DELETE-SITE-1. *
* Provide a text description of the following step. *
* Fetch information about the transferring employee. *
* Print the SQLCA out. *
* If the information was retrieved successfully Then *
* Do. *
* | Perform DELETE-SITE-1 to delete the employee *
* | at this site. *
* End if the information was retrieved successfully. *
* *
* DELETE-SITE-1. *
* Provide a text description of the following step. *
* Delete the information about the transferring employee *
* from this site. *
* Print the SQLCA out. *
* *
* CLOSE-CURSOR-SITE-1. *
* Provide a text description of the following step. *
* Close the cursor used to retrieve information about *
* the transferring employee. *
* Print the SQLCA out. *
* *
* UPDATE-ADDRESS. *
* Update the address of the employee. *
* Update the city of the employee. *
* Update the location of the employee. *
* *
* CONNECT-TO-SITE-2. *
* Provide a text description of the following step. *
* Establish a connection to the location where the *
* employee is transferring to. *
* Print the SQLCA out. *
* *
* PROCESS-SITE-2. *
* Provide a text description of the following step. *
* Insert the employee information at the location where *
* the employee is being transferred to. *
* Print the SQLCA out. *
* *
* COMMIT-WORK. *
* COMMIT all the changes made to STLEC1 and STLEC2. *
* *
*****************************************************************

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT PRINTER, ASSIGN TO S-OUT1.

DATA DIVISION.

346 Application Programming and SQL Guide

FILE SECTION.
FD PRINTER
RECORD CONTAINS 120 CHARACTERS
DATA RECORD IS PRT-TC-RESULTS
LABEL RECORD IS OMITTED.
01 PRT-TC-RESULTS.
03 PRT-BLANK PIC X(120).
WORKING-STORAGE SECTION.

*****************************************************************
* Variable declarations *
*****************************************************************

01 H-EMPTBL.
05 H-EMPNO PIC X(6).
05 H-NAME.
49 H-NAME-LN PIC S9(4) COMP-4.
49 H-NAME-DA PIC X(32).
05 H-ADDRESS.
49 H-ADDRESS-LN PIC S9(4) COMP-4.
49 H-ADDRESS-DA PIC X(36).
05 H-CITY.
49 H-CITY-LN PIC S9(4) COMP-4.
49 H-CITY-DA PIC X(36).
05 H-EMPLOC PIC X(4).
05 H-SSNO PIC X(11).
05 H-BORN PIC X(10).
05 H-SEX PIC X(1).
05 H-HIRED PIC X(10).
05 H-DEPTNO PIC X(3).
05 H-JOBCODE PIC S9(3)V COMP-3.
05 H-SRATE PIC S9(5) COMP.
05 H-EDUC PIC S9(5) COMP.
05 H-SAL PIC S9(6)V9(2) COMP-3.
05 H-VALIDCHK PIC S9(6)V COMP-3.

01 H-EMPTBL-IND-TABLE.
02 H-EMPTBL-IND PIC S9(4) COMP OCCURS 15 TIMES.

*****************************************************************
* Includes for the variables used in the COBOL standard *
* language procedures and the SQLCA. *
*****************************************************************

EXEC SQL INCLUDE COBSVAR END-EXEC.

EXEC SQL INCLUDE SQLCA END-EXEC.

*****************************************************************
* Declaration for the table that contains employee information *
*****************************************************************

EXEC SQL DECLARE SYSADM.EMP TABLE

(EMPNO CHAR(6) NOT NULL,
NAME VARCHAR(32),
ADDRESS VARCHAR(36) ,
CITY VARCHAR(36) ,
EMPLOC CHAR(4) NOT NULL,
SSNO CHAR(11),
BORN DATE,
SEX CHAR(1),
HIRED CHAR(10),
DEPTNO CHAR(3) NOT NULL,
JOBCODE DECIMAL(3),
SRATE SMALLINT,
EDUC SMALLINT,

Chapter 6. Coding SQL statements in COBOL application programs 347

SAL DECIMAL(8,2) NOT NULL,
VALCHK DECIMAL(6))
END-EXEC.

*****************************************************************
* Constants *
*****************************************************************

77 SITE-1 PIC X(16) VALUE 'STLEC1'.

77 SITE-2 PIC X(16) VALUE 'STLEC2'.
77 TEMP-EMPNO PIC X(6) VALUE '080000'.
77 TEMP-ADDRESS-LN PIC 99 VALUE 15.
77 TEMP-CITY-LN PIC 99 VALUE 18.

*****************************************************************
* Declaration of the cursor that will be used to retrieve *
* information about a transferring employee *
*****************************************************************

EXEC SQL DECLARE C1 CURSOR FOR

SELECT EMPNO, NAME, ADDRESS, CITY, EMPLOC,
SSNO, BORN, SEX, HIRED, DEPTNO, JOBCODE,
SRATE, EDUC, SAL, VALCHK
FROM SYSADM.EMP
WHERE EMPNO = :TEMP-EMPNO
END-EXEC.

PROCEDURE DIVISION.
A101-HOUSE-KEEPING.
OPEN OUTPUT PRINTER.

*****************************************************************
* An employee is transferring from location STLEC1 to STLEC2. *
* Retrieve information about the employee from STLEC1, delete *
* the employee from STLEC1 and insert the employee at STLEC2 *
* using the information obtained from STLEC1. *
*****************************************************************

MAINLINE.
PERFORM CONNECT-TO-SITE-1
IF SQLCODE IS EQUAL TO 0
PERFORM PROCESS-CURSOR-SITE-1
IF SQLCODE IS EQUAL TO 0
PERFORM UPDATE-ADDRESS
PERFORM CONNECT-TO-SITE-2
IF SQLCODE IS EQUAL TO 0
PERFORM PROCESS-SITE-2.
PERFORM COMMIT-WORK.
PROG-END.
CLOSE PRINTER.
GOBACK.

*****************************************************************
* Establish a connection to STLEC1 *
*****************************************************************

CONNECT-TO-SITE-1.

MOVE 'CONNECT TO STLEC1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
CONNECT TO :SITE-1
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* When a connection has been established successfully at STLEC1,*

348 Application Programming and SQL Guide

* open the cursor that will be used to retrieve information *
* about the transferring employee. *
*****************************************************************

PROCESS-CURSOR-SITE-1.

MOVE 'OPEN CURSOR C1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
OPEN C1
END-EXEC.
PERFORM PTSQLCA.
IF SQLCODE IS EQUAL TO ZERO
PERFORM FETCH-DELETE-SITE-1
PERFORM CLOSE-CURSOR-SITE-1.

*****************************************************************
* Retrieve information about the transferring employee. *
* Provided that the employee exists, perform DELETE-SITE-1 to *
* delete the employee from STLEC1. *
*****************************************************************

FETCH-DELETE-SITE-1.

MOVE 'FETCH C1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
FETCH C1 INTO :H-EMPTBL:H-EMPTBL-IND
END-EXEC.
PERFORM PTSQLCA.
IF SQLCODE IS EQUAL TO ZERO
PERFORM DELETE-SITE-1.
*****************************************************************
* Delete the employee from STLEC1. *
*****************************************************************

DELETE-SITE-1.

MOVE 'DELETE EMPLOYEE ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
MOVE 'DELETE EMPLOYEE ' TO STNAME
EXEC SQL
DELETE FROM SYSADM.EMP
WHERE EMPNO = :TEMP-EMPNO
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* Close the cursor used to retrieve information about the *
* transferring employee. *
*****************************************************************

CLOSE-CURSOR-SITE-1.

MOVE 'CLOSE CURSOR C1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
CLOSE C1
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* Update certain employee information in order to make it *
* current. *
*****************************************************************

UPDATE-ADDRESS.

Chapter 6. Coding SQL statements in COBOL application programs 349

MOVE TEMP-ADDRESS-LN TO H-ADDRESS-LN.
MOVE '1500 NEW STREET' TO H-ADDRESS-DA.
MOVE TEMP-CITY-LN TO H-CITY-LN.
MOVE 'NEW CITY, CA 97804' TO H-CITY-DA.
MOVE 'SJCA' TO H-EMPLOC.

*****************************************************************
* Establish a connection to STLEC2 *
*****************************************************************

CONNECT-TO-SITE-2.

MOVE 'CONNECT TO STLEC2 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
CONNECT TO :SITE-2
END-EXEC.
PERFORM PTSQLCA.
*****************************************************************
* Using the employee information that was retrieved from STLEC1 *
* and updated previously, insert the employee at STLEC2. *
*****************************************************************

PROCESS-SITE-2.

MOVE 'INSERT EMPLOYEE ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
INSERT INTO SYSADM.EMP VALUES
(:H-EMPNO,
:H-NAME,
:H-ADDRESS,
:H-CITY,
:H-EMPLOC,
:H-SSNO,
:H-BORN,
:H-SEX,
:H-HIRED,
:H-DEPTNO,
:H-JOBCODE,
:H-SRATE,
:H-EDUC,
:H-SAL,
:H-VALIDCHK)
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* COMMIT any changes that were made at STLEC1 and STLEC2. *
*****************************************************************

COMMIT-WORK.

MOVE 'COMMIT WORK ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
COMMIT
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* Include COBOL standard language procedures *
*****************************************************************

INCLUDE-SUBS.
EXEC SQL INCLUDE COBSSUB END-EXEC.

350 Application Programming and SQL Guide

Sample COBOL program using private protocol access
This example demonstrates how to access distributed data by using DB2 private
protocol access in a COBOL program.

The following sample program demonstrates distributed access data using DB2
private protocol access with two-phase commit.
IDENTIFICATION DIVISION.
PROGRAM-ID. TWOPHASE.
AUTHOR.
REMARKS.
*****************************************************************
* *
* MODULE NAME = TWOPHASE *
* *
* DESCRIPTIVE NAME = DB2 SAMPLE APPLICATION USING *
* TWO PHASE COMMIT AND DRDA WITH *
* THREE-PART NAMES *
* *
* COPYRIGHT = 5665-DB2 (C) COPYRIGHT IBM CORP 1982, 1989 *
* REFER TO COPYRIGHT INSTRUCTIONS FORM NUMBER G120-2083 *
* *
* STATUS = VERSION 5 *
* *
* FUNCTION = THIS MODULE DEMONSTRATES DISTRIBUTED DATA ACCESS *
* USING 2 PHASE COMMIT BY TRANSFERRING AN EMPLOYEE *
* FROM ONE LOCATION TO ANOTHER. *
* *
* NOTE: THIS PROGRAM ASSUMES THE EXISTENCE OF THE *
* TABLE SYSADM.EMP AT LOCATIONS STLEC1 AND *
* STLEC2. *
* *
* MODULE TYPE = COBOL PROGRAM *
* PROCESSOR = DB2 PRECOMPILER, ENTERPRISE COBOL FOR Z/OS *
* MODULE SIZE = SEE LINK EDIT *
* ATTRIBUTES = NOT REENTRANT OR REUSABLE *
* *
* ENTRY POINT = *
* PURPOSE = TO ILLUSTRATE 2 PHASE COMMIT *
* LINKAGE = INVOKE FROM DSN RUN *
* INPUT = NONE *
* OUTPUT = *
* SYMBOLIC LABEL/NAME = SYSPRINT *
* DESCRIPTION = PRINT OUT THE DESCRIPTION OF EACH *
* STEP AND THE RESULTANT SQLCA *
* *
* EXIT NORMAL = RETURN CODE 0 FROM NORMAL COMPLETION *
* *
* EXIT ERROR = NONE *
* *
* EXTERNAL REFERENCES = *
* ROUTINE SERVICES = NONE *
* DATA-AREAS = NONE *
* CONTROL-BLOCKS = *
* SQLCA - SQL COMMUNICATION AREA *
* *
* TABLES = NONE *
* *
* CHANGE-ACTIVITY = NONE *
* *
* *
* *
* PSEUDOCODE *
* *
* MAINLINE. *
* Perform PROCESS-CURSOR-SITE-1 to obtain the information *

Chapter 6. Coding SQL statements in COBOL application programs 351

* about an employee that is transferring to another *
* location. *
* If the information about the employee was obtained *
* successfully Then *
* Do. *
* | Perform UPDATE-ADDRESS to update the information to *
* | contain current information about the employee. *
* | Perform PROCESS-SITE-2 to insert the employee *
* | information at the location where the employee is *
* | transferring to. *
* End if the employee information was obtained *
* successfully. *
* Perform COMMIT-WORK to COMMIT the changes made to STLEC1*
* and STLEC2. *
* *
* PROG-END. *
* Close the printer. *
* Return. *
* *
* PROCESS-CURSOR-SITE-1. *
* Provide a text description of the following step. *
* Open a cursor that will be used to retrieve information *
* about the transferring employee from this site. *
* Print the SQLCA out. *
* If the cursor was opened successfully Then *
* Do. *
* | Perform FETCH-DELETE-SITE-1 to retrieve and *
* | delete the information about the transferring *
* | employee from this site. *
* | Perform CLOSE-CURSOR-SITE-1 to close the cursor. *
* End if the cursor was opened successfully. *
* *
* FETCH-DELETE-SITE-1. *
* Provide a text description of the following step. *
* Fetch information about the transferring employee. *
* Print the SQLCA out. *
* If the information was retrieved successfully Then *
* Do. *
* | Perform DELETE-SITE-1 to delete the employee *
* | at this site. *
* End if the information was retrieved successfully. *
* *
* DELETE-SITE-1. *
* Provide a text description of the following step. *
* Delete the information about the transferring employee *
* from this site. *
* Print the SQLCA out. *
* *
* CLOSE-CURSOR-SITE-1. *
* Provide a text description of the following step. *
* Close the cursor used to retrieve information about *
* the transferring employee. *
* Print the SQLCA out. *
* *
* UPDATE-ADDRESS. *
* Update the address of the employee. *
* Update the city of the employee. *
* Update the location of the employee. *
* *
* PROCESS-SITE-2. *
* Provide a text description of the following step. *
* Insert the employee information at the location where *
* the employee is being transferred to. *
* Print the SQLCA out. *
* *
* COMMIT-WORK. *
* COMMIT all the changes made to STLEC1 and STLEC2. *

352 Application Programming and SQL Guide

* *
*****************************************************************

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT PRINTER, ASSIGN TO S-OUT1.

DATA DIVISION.
FILE SECTION.
FD PRINTER
RECORD CONTAINS 120 CHARACTERS
DATA RECORD IS PRT-TC-RESULTS
LABEL RECORD IS OMITTED.
01 PRT-TC-RESULTS.
03 PRT-BLANK PIC X(120).

WORKING-STORAGE SECTION.

*****************************************************************
* Variable declarations *
*****************************************************************

01 H-EMPTBL.
05 H-EMPNO PIC X(6).
05 H-NAME.
49 H-NAME-LN PIC S9(4) COMP-4.
49 H-NAME-DA PIC X(32).
05 H-ADDRESS.
49 H-ADDRESS-LN PIC S9(4) COMP-4.
49 H-ADDRESS-DA PIC X(36).
05 H-CITY.
49 H-CITY-LN PIC S9(4) COMP-4.
49 H-CITY-DA PIC X(36).
05 H-EMPLOC PIC X(4).
05 H-SSNO PIC X(11).
05 H-BORN PIC X(10).
05 H-SEX PIC X(1).
05 H-HIRED PIC X(10).
05 H-DEPTNO PIC X(3).
05 H-JOBCODE PIC S9(3)V COMP-3.
05 H-SRATE PIC S9(5) COMP.
05 H-EDUC PIC S9(5) COMP.
05 H-SAL PIC S9(6)V9(2) COMP-3.
05 H-VALIDCHK PIC S9(6)V COMP-3.
01 H-EMPTBL-IND-TABLE.
02 H-EMPTBL-IND PIC S9(4) COMP OCCURS 15 TIMES.

*****************************************************************
* Includes for the variables used in the COBOL standard *
* language procedures and the SQLCA. *
*****************************************************************

EXEC SQL INCLUDE COBSVAR END-EXEC.

EXEC SQL INCLUDE SQLCA END-EXEC.

*****************************************************************
* Declaration for the table that contains employee information *
*****************************************************************

EXEC SQL DECLARE SYSADM.EMP TABLE

(EMPNO CHAR(6) NOT NULL,
NAME VARCHAR(32),
ADDRESS VARCHAR(36) ,
CITY VARCHAR(36) ,
EMPLOC CHAR(4) NOT NULL,

Chapter 6. Coding SQL statements in COBOL application programs 353

SSNO CHAR(11),
BORN DATE,
SEX CHAR(1),
HIRED CHAR(10),
DEPTNO CHAR(3) NOT NULL,
JOBCODE DECIMAL(3),
SRATE SMALLINT,
EDUC SMALLINT,
SAL DECIMAL(8,2) NOT NULL,
VALCHK DECIMAL(6))
END-EXEC.

*****************************************************************
* Constants *
*****************************************************************

77 TEMP-EMPNO PIC X(6) VALUE '080000'.

77 TEMP-ADDRESS-LN PIC 99 VALUE 15.
77 TEMP-CITY-LN PIC 99 VALUE 18.

*****************************************************************
* Declaration of the cursor that will be used to retrieve *
* information about a transferring employee *
*****************************************************************

EXEC SQL DECLARE C1 CURSOR FOR

SELECT EMPNO, NAME, ADDRESS, CITY, EMPLOC,
SSNO, BORN, SEX, HIRED, DEPTNO, JOBCODE,
SRATE, EDUC, SAL, VALCHK
FROM STLEC1.SYSADM.EMP
WHERE EMPNO = :TEMP-EMPNO
END-EXEC.
PROCEDURE DIVISION.
A101-HOUSE-KEEPING.
OPEN OUTPUT PRINTER.

*****************************************************************
* An employee is transferring from location STLEC1 to STLEC2. *
* Retrieve information about the employee from STLEC1, delete *
* the employee from STLEC1 and insert the employee at STLEC2 *
* using the information obtained from STLEC1. *
*****************************************************************

MAINLINE.
PERFORM PROCESS-CURSOR-SITE-1
IF SQLCODE IS EQUAL TO 0
PERFORM UPDATE-ADDRESS
PERFORM PROCESS-SITE-2.
PERFORM COMMIT-WORK.

PROG-END.
CLOSE PRINTER.
GOBACK.

*****************************************************************
* Open the cursor that will be used to retrieve information *
* about the transferring employee. *
*****************************************************************

PROCESS-CURSOR-SITE-1.

MOVE 'OPEN CURSOR C1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
OPEN C1
END-EXEC.
PERFORM PTSQLCA.

354 Application Programming and SQL Guide

IF SQLCODE IS EQUAL TO ZERO
PERFORM FETCH-DELETE-SITE-1
PERFORM CLOSE-CURSOR-SITE-1.

*****************************************************************
* Retrieve information about the transferring employee. *
* Provided that the employee exists, perform DELETE-SITE-1 to *
* delete the employee from STLEC1. *
*****************************************************************

FETCH-DELETE-SITE-1.

MOVE 'FETCH C1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
FETCH C1 INTO :H-EMPTBL:H-EMPTBL-IND
END-EXEC. PERFORM PTSQLCA.
IF SQLCODE IS EQUAL TO ZERO
PERFORM DELETE-SITE-1.

*****************************************************************
* Delete the employee from STLEC1. *
*****************************************************************

DELETE-SITE-1.

MOVE 'DELETE EMPLOYEE ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
MOVE 'DELETE EMPLOYEE ' TO STNAME
EXEC SQL
DELETE FROM STLEC1.SYSADM.EMP
WHERE EMPNO = :TEMP-EMPNO
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* Close the cursor used to retrieve information about the *
* transferring employee. *
*****************************************************************

CLOSE-CURSOR-SITE-1.

MOVE 'CLOSE CURSOR C1 ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
CLOSE C1
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* Update certain employee information in order to make it *
* current. *
*****************************************************************

UPDATE-ADDRESS.
MOVE TEMP-ADDRESS-LN TO H-ADDRESS-LN.
MOVE '1500 NEW STREET' TO H-ADDRESS-DA.
MOVE TEMP-CITY-LN TO H-CITY-LN.
MOVE 'NEW CITY, CA 97804' TO H-CITY-DA.
MOVE 'SJCA' TO H-EMPLOC.
****************************************************************
* Using the employee information that was retrieved from STLEC1 *
* and updated previously, insert the employee at STLEC2. *
*****************************************************************

PROCESS-SITE-2.

Chapter 6. Coding SQL statements in COBOL application programs 355

MOVE 'INSERT EMPLOYEE ' TO STNAME
WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
INSERT INTO STLEC2.SYSADM.EMP VALUES
(:H-EMPNO,
:H-NAME,
:H-ADDRESS,
:H-CITY,
:H-EMPLOC,
:H-SSNO,
:H-BORN,
:H-SEX,
:H-HIRED,
:H-DEPTNO,
:H-JOBCODE,
:H-SRATE,
:H-EDUC,
:H-SAL,
:H-VALIDCHK)
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* COMMIT any changes that were made at STLEC1 and STLEC2. *
*****************************************************************

COMMIT-WORK.

MOVE 'COMMIT WORK ' TO STNAME

WRITE PRT-TC-RESULTS FROM STNAME
EXEC SQL
COMMIT
END-EXEC.
PERFORM PTSQLCA.

*****************************************************************
* Include COBOL standard language procedures *
*****************************************************************

INCLUDE-SUBS.
EXEC SQL INCLUDE COBSSUB END-EXEC.

Example COBOL stored procedure with a GENERAL WITH

NULLS linkage convention
This example shows how to call a stored procedure that uses the GENERAL WITH
NULLS linkage convention from a COBOL program.

This example stored procedure does the following:

v Searches the DB2 SYSIBM.SYSROUTINES catalog table for a row that matches
the input parameters from the client program. The two input parameters contain
values for NAME and SCHEMA.
v Searches the DB2 catalog table SYSTABLES for all tables in which the value of
CREATOR matches the value of input parameter SCHEMA. The stored
procedure uses a cursor to return the table names.

The linkage convention for this stored procedure is GENERAL WITH NULLS.

The output parameters from this stored procedure contain the SQLCODE from the
SELECT operation, and the value of the RUNOPTS column retrieved from the
SYSIBM.SYSROUTINES table.

356 Application Programming and SQL Guide

The CREATE PROCEDURE statement for this stored procedure might look like
this:
CREATE PROCEDURE GETPRML(PROCNM CHAR(18) IN, SCHEMA CHAR(8) IN,
OUTCODE INTEGER OUT, PARMLST VARCHAR(254) OUT)
LANGUAGE COBOL
DETERMINISTIC
READS SQL DATA
EXTERNAL NAME "GETPRML"
COLLID GETPRML
ASUTIME NO LIMIT
PARAMETER STYLE GENERAL WITH NULLS
STAY RESIDENT NO
RUN OPTIONS "MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)"
WLM ENVIRONMENT SAMPPROG
PROGRAM TYPE MAIN
SECURITY DB2
RESULT SETS 2
COMMIT ON RETURN NO;

The following example is a COBOL stored procedure with linkage convention

GENERAL WITH NULLS.
CBL RENT
IDENTIFICATION DIVISION.
PROGRAM-ID. GETPRML.
AUTHOR. EXAMPLE.
DATE-WRITTEN. 03/25/98.

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
DATA DIVISION.
FILE SECTION.
*
WORKING-STORAGE SECTION.
*
EXEC SQL INCLUDE SQLCA END-EXEC.
*
***************************************************
* DECLARE A HOST VARIABLE TO HOLD INPUT SCHEMA
***************************************************
01 INSCHEMA PIC X(8).
***************************************************
* DECLARE CURSOR FOR RETURNING RESULT SETS
***************************************************
*
EXEC SQL DECLARE C1 CURSOR WITH RETURN FOR
SELECT NAME FROM SYSIBM.SYSTABLES WHERE CREATOR=:INSCHEMA
END-EXEC.
*
LINKAGE SECTION.
***************************************************
* DECLARE THE INPUT PARAMETERS FOR THE PROCEDURE
***************************************************
01 PROCNM PIC X(18).
01 SCHEMA PIC X(8).
***************************************************
* DECLARE THE OUTPUT PARAMETERS FOR THE PROCEDURE
***************************************************
01 OUT-CODE PIC S9(9) USAGE BINARY.
01 PARMLST.
49 PARMLST-LEN PIC S9(4) USAGE BINARY.
49 PARMLST-TEXT PIC X(254).
***************************************************
* DECLARE THE STRUCTURE CONTAINING THE NULL
* INDICATORS FOR THE INPUT AND OUTPUT PARAMETERS.

Chapter 6. Coding SQL statements in COBOL application programs 357

***************************************************
01 IND-PARM.
03 PROCNM-IND PIC S9(4) USAGE BINARY.
03 SCHEMA-IND PIC S9(4) USAGE BINARY.
03 OUT-CODE-IND PIC S9(4) USAGE BINARY.
03 PARMLST-IND PIC S9(4) USAGE BINARY.
PROCEDURE DIVISION USING PROCNM, SCHEMA,
OUT-CODE, PARMLST, IND-PARM.
*******************************************************
* If any input parameter is null, return a null value
* for PARMLST and set the output return code to 9999.
*******************************************************
IF PROCNM-IND < 0 OR
SCHEMA-IND < 0
MOVE 9999 TO OUT-CODE
MOVE 0 TO OUT-CODE-IND
MOVE -1 TO PARMLST-IND
ELSE
*******************************************************
* Issue the SQL SELECT against the SYSIBM.SYSROUTINES
* DB2 catalog table.
*******************************************************
EXEC SQL
SELECT RUNOPTS INTO :PARMLST
FROM SYSIBM.SYSROUTINES
WHERE NAME=:PROCNM AND
SCHEMA=:SCHEMA
END-EXEC
MOVE 0 TO PARMLST-IND
*******************************************************
* COPY SQLCODE INTO THE OUTPUT PARAMETER AREA
*******************************************************
MOVE SQLCODE TO OUT-CODE
MOVE 0 TO OUT-CODE-IND.
*
*******************************************************
* OPEN CURSOR C1 TO CAUSE DB2 TO RETURN A RESULT SET
* TO THE CALLER.
*******************************************************
EXEC SQL OPEN C1
END-EXEC.
PROG-END.
GOBACK.

Example COBOL stored procedure with a GENERAL linkage

convention
This example shows how to call a stored procedure that uses the GENERAL
linkage convention from a COBOL program.

This example stored procedure does the following:

v Searches the catalog table SYSROUTINES for a row matching the input
parameters from the client program. The two input parameters contain values
for NAME and SCHEMA.
v Searches the DB2 catalog table SYSTABLES for all tables in which the value of
CREATOR matches the value of input parameter SCHEMA. The stored
procedure uses a cursor to return the table names.
This stored procedure is able to return a NULL value for the output host variables.

The linkage convention for this stored procedure is GENERAL.

358 Application Programming and SQL Guide

The output parameters from this stored procedure contain the SQLCODE from the
SELECT operation, and the value of the RUNOPTS column retrieved from the
SYSROUTINES table.

The CREATE PROCEDURE statement for this stored procedure might look like
this:
CREATE PROCEDURE GETPRML(PROCNM CHAR(18) IN, SCHEMA CHAR(8) IN,
OUTCODE INTEGER OUT, PARMLST VARCHAR(254) OUT)
LANGUAGE COBOL
DETERMINISTIC
READS SQL DATA
EXTERNAL NAME "GETPRML"
COLLID GETPRML
ASUTIME NO LIMIT
PARAMETER STYLE GENERAL
STAY RESIDENT NO
RUN OPTIONS "MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)"
WLM ENVIRONMENT SAMPPROG
PROGRAM TYPE MAIN
SECURITY DB2
RESULT SETS 2
COMMIT ON RETURN NO;
CBL RENT
IDENTIFICATION DIVISION.
PROGRAM-ID. GETPRML.
AUTHOR. EXAMPLE.
DATE-WRITTEN. 03/25/98.

ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
DATA DIVISION.
FILE SECTION.

WORKING-STORAGE SECTION.

EXEC SQL INCLUDE SQLCA END-EXEC.

***************************************************
* DECLARE A HOST VARIABLE TO HOLD INPUT SCHEMA
***************************************************
01 INSCHEMA PIC X(8).

***************************************************
* DECLARE CURSOR FOR RETURNING RESULT SETS
***************************************************
*
EXEC SQL DECLARE C1 CURSOR WITH RETURN FOR
SELECT NAME FROM SYSIBM.SYSTABLES WHERE CREATOR=:INSCHEMA
END-EXEC.
*
LINKAGE SECTION.
***************************************************
* DECLARE THE INPUT PARAMETERS FOR THE PROCEDURE
***************************************************
01 PROCNM PIC X(18).
01 SCHEMA PIC X(8).
*******************************************************
* DECLARE THE OUTPUT PARAMETERS FOR THE PROCEDURE
*******************************************************
01 OUT-CODE PIC S9(9) USAGE BINARY.
01 PARMLST.
49 PARMLST-LEN PIC S9(4) USAGE BINARY.

Chapter 6. Coding SQL statements in COBOL application programs 359

49 PARMLST-TEXT PIC X(254).

PROCEDURE DIVISION USING PROCNM, SCHEMA,

OUT-CODE, PARMLST.
*******************************************************
* Issue the SQL SELECT against the SYSIBM.SYSROUTINES
* DB2 catalog table.
*******************************************************
EXEC SQL
SELECT RUNOPTS INTO :PARMLST
FROM SYSIBM.ROUTINES
WHERE NAME=:PROCNM AND
SCHEMA=:SCHEMA
END-EXEC.

*******************************************************
* COPY SQLCODE INTO THE OUTPUT PARAMETER AREA
*******************************************************
MOVE SQLCODE TO OUT-CODE.
*******************************************************
* OPEN CURSOR C1 TO CAUSE DB2 TO RETURN A RESULT SET
* TO THE CALLER.
*******************************************************
EXEC SQL OPEN C1
END-EXEC.
PROG-END.
GOBACK.

Example COBOL program that calls a stored procedure

This example shows how to call the GETPRML stored procedure that uses the
GENERAL WITH NULLS linkage convention from a COBOL program on an z/OS
system. Because the stored procedure returns result sets, this program checks for
result sets and retrieves the contents of the result sets.

The following figure contains the example COBOL program that calls the
GETPRML stored procedure.
IDENTIFICATION DIVISION.
PROGRAM-ID. CALPRML.

ENVIRONMENT DIVISION.
CONFIGURATION SECTION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
SELECT REPOUT
ASSIGN TO UT-S-SYSPRINT.

DATA DIVISION.
FILE SECTION.
FD REPOUT
RECORD CONTAINS 127 CHARACTERS
LABEL RECORDS ARE OMITTED
DATA RECORD IS REPREC.
01 REPREC PIC X(127).

WORKING-STORAGE SECTION.
*****************************************************
* MESSAGES FOR SQL CALL *
*****************************************************
01 SQLREC.
02 BADMSG PIC X(34) VALUE
' SQL CALL FAILED DUE TO SQLCODE = '.
02 BADCODE PIC +9(5) USAGE DISPLAY.
02 FILLER PIC X(80) VALUE SPACES.
01 ERRMREC.
02 ERRMMSG PIC X(12) VALUE ' SQLERRMC = '.

360 Application Programming and SQL Guide

02 ERRMCODE PIC X(70).
02 FILLER PIC X(38) VALUE SPACES.
01 CALLREC.
02 CALLMSG PIC X(28) VALUE
' GETPRML FAILED DUE TO RC = '.
02 CALLCODE PIC +9(5) USAGE DISPLAY.
02 FILLER PIC X(42) VALUE SPACES.
01 RSLTREC.
02 RSLTMSG PIC X(15) VALUE
' TABLE NAME IS '.
02 TBLNAME PIC X(18) VALUE SPACES.
02 FILLER PIC X(87) VALUE SPACES.
*****************************************************
* WORK AREAS *
*****************************************************
01 PROCNM PIC X(18).
01 SCHEMA PIC X(8).
01 OUT-CODE PIC S9(9) USAGE COMP.
01 PARMLST.
49 PARMLEN PIC S9(4) USAGE COMP.
49 PARMTXT PIC X(254).
01 PARMBUF REDEFINES PARMLST.
49 PARBLEN PIC S9(4) USAGE COMP.
49 PARMARRY PIC X(127) OCCURS 2 TIMES.
01 NAME.
49 NAMELEN PIC S9(4) USAGE COMP.
49 NAMETXT PIC X(18).
77 PARMIND PIC S9(4) COMP.
77 I PIC S9(4) COMP.
77 NUMLINES PIC S9(4) COMP.
*****************************************************
* DECLARE A RESULT SET LOCATOR FOR THE RESULT SET *
* THAT IS RETURNED. *
*****************************************************
01 LOC USAGE SQL TYPE IS
RESULT-SET-LOCATOR VARYING.

*****************************************************
* SQL INCLUDE FOR SQLCA *
*****************************************************
EXEC SQL INCLUDE SQLCA END-EXEC.

PROCEDURE DIVISION.
*------------------
PROG-START.
OPEN OUTPUT REPOUT.
* OPEN OUTPUT FILE
MOVE 'DSN8EP2 ' TO PROCNM.
* INPUT PARAMETER -- PROCEDURE TO BE FOUND
MOVE SPACES TO SCHEMA.
* INPUT PARAMETER -- SCHEMA IN SYSROUTINES
MOVE -1 TO PARMIND.
* THE PARMLST PARAMETER IS AN OUTPUT PARM.
* MARK PARMLST PARAMETER AS NULL, SO THE DB2
* REQUESTER DOESN'T HAVE TO SEND THE ENTIRE
* PARMLST VARIABLE TO THE SERVER. THIS
* HELPS REDUCE NETWORK I/O TIME, BECAUSE
* PARMLST IS FAIRLY LARGE.
EXEC SQL
CALL GETPRML(:PROCNM,
:SCHEMA,
:OUT-CODE,
:PARMLST INDICATOR :PARMIND)
END-EXEC.

Chapter 6. Coding SQL statements in COBOL application programs 361

* MAKE THE CALL
IF SQLCODE NOT EQUAL TO +466 THEN
* IF CALL RETURNED BAD SQLCODE
MOVE SQLCODE TO BADCODE
WRITE REPREC FROM SQLREC
MOVE SQLERRMC TO ERRMCODE
WRITE REPREC FROM ERRMREC
ELSE
PERFORM GET-PARMS
PERFORM GET-RESULT-SET.
PROG-END.
CLOSE REPOUT.
* CLOSE OUTPUT FILE
GOBACK.
PARMPRT.
MOVE SPACES TO REPREC.
WRITE REPREC FROM PARMARRY(I)
AFTER ADVANCING 1 LINE.
GET-PARMS.
* IF THE CALL WORKED,
IF OUT-CODE NOT EQUAL TO 0 THEN
* DID GETPRML HIT AN ERROR?
MOVE OUT-CODE TO CALLCODE
WRITE REPREC FROM CALLREC
ELSE
* EVERYTHING WORKED
DIVIDE 127 INTO PARMLEN GIVING NUMLINES ROUNDED
* FIND OUT HOW MANY LINES TO PRINT
PERFORM PARMPRT VARYING I
FROM 1 BY 1 UNTIL I GREATER THAN NUMLINES.
GET-RESULT-SET.
*****************************************************
* ASSUME YOU KNOW THAT ONE RESULT SET IS RETURNED, *
* AND YOU KNOW THE FORMAT OF THAT RESULT SET. *
* ALLOCATE A CURSOR FOR THE RESULT SET, AND FETCH *
* THE CONTENTS OF THE RESULT SET. *
*****************************************************
EXEC SQL ASSOCIATE LOCATORS (:LOC)
WITH PROCEDURE GETPRML
END-EXEC.
* LINK THE RESULT SET TO THE LOCATOR
EXEC SQL ALLOCATE C1 CURSOR FOR RESULT SET :LOC
END-EXEC.
* LINK THE CURSOR TO THE RESULT SET
PERFORM GET-ROWS VARYING I
FROM 1 BY 1 UNTIL SQLCODE EQUAL TO +100.
GET-ROWS.
EXEC SQL FETCH C1 INTO :NAME
END-EXEC.
MOVE NAME TO TBLNAME.
WRITE REPREC FROM RSLTREC
AFTER ADVANCING 1 LINE.

362 Application Programming and SQL Guide

Chapter 7. Coding SQL statements in Fortran application
programs
When you code SQL statements in Fortran application programs, you should
follow certain guidelines.

Defining the SQL communications area, SQLSTATE, and SQLCODE in

Fortran
Fortran programs that contain SQL statements can include an SQL communications
area (SQLCA) to check whether an SQL statement executed successfully.
Alternatively, these programs can declare individual SQLCODE and SQLSTATE
host variables.

If you specify the SQL processing option STDSQL(YES), do not define an SQLCA.
If you do, DB2 ignores your SQLCA, and your SQLCA definition causes
compile-time errors. If you specify the SQL processing option STDSQL(NO),
include an SQLCA explicitly.

If your application contains SQL statements and does not include an SQL
communications area (SQLCA), you must declare individual SQLCODE and
SQLSTATE host variables. Your program can use these variables to check whether
an SQL statement executed successfully.

To define the SQL communications area, SQLSTATE, and SQLCODE:

Option Description
To define the SQL communications area: 1. Code the SQLCA directly in the program
or use the following SQL INCLUDE
statement to request a standard SQLCA
declaration:
EXEC SQL INCLUDE SQLCA
DB2 sets the SQLCODE and SQLSTATE
values in the SQLCA after each SQL
statement executes. Your application should
check these values to determine whether the
last SQL statement was successful.

© Copyright IBM Corp. 1983, 2009 363

Option Description
To declare SQLCODE and SQLSTATE host 1. Declare the SQLCODE variable within a
variables: BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as INTEGER*4.
This variable can also be called
SQLCOD.
2. Declare the SQLSTATE variable within a
BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as CHARACTER*5.
This variable can also be called
SQLCOD.
Restriction: Do not declare an SQLSTATE
variable as an element of a structure.
Requirement: After you declare the
SQLCODE and SQLSTATE variables, ensure
that all SQL statements in the program are
within the scope of the declaration of these
variables.

Related tasks
“Checking the execution of SQL statements” on page 202
“Checking the execution of SQL statements by using the SQLCA” on page 203
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the items that your program can use to check whether an SQL statement
executed successfully” on page 141

Defining SQL descriptor areas in Fortran

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

To define SQL descriptor areas:

Call a subroutine that is written in C, PL/I, or assembler language and that uses
the INCLUDE SQLDA statement to define the SQLDA. The subroutine can also
include SQL statements for any dynamic SQL functions that you need.

Restrictions:
v You must place SQLDA declarations before the first SQL statement that
references the data descriptor, unless you use the TWOPASS SQL processing
option.
v You cannot use the SQL INCLUDE statement for the SQLDA, because it is not
supported in COBOL.

364 Application Programming and SQL Guide

Related tasks
“Defining SQL descriptor areas” on page 141

Declaring host variables and indicator variables in Fortran

You can use host variables, host variable arrays, and host structures in SQL
statements in your program to pass data between DB2 and your application.

To declare host variables, host variable arrays, and host structures:

1. Declare the variables according to the following rules and guidelines:
v When you declare a character host variable, do not use an expression to
define the length of the character variable. You can use a character host
variable with an undefined length (for example, CHARACTER *(*)). The
length of any such variable is determined when the associated SQL statement
executes.
v Host variables must be scalar variables; they cannot be elements of vectors or
arrays (subscripted variables).
v Be careful when calling subroutines that might change the attributes of a host
variable. Such alteration can cause an error while the program is running.
v If you specify the ONEPASS SQL processing option, you must explicitly
declare each host variable and each host variable array before using them in
an SQL statement. If you specify the TWOPASS precompiler option, you
must declare each host variable before using it in the DECLARE CURSOR
statement.
v If you specify the STDSQL(YES) SQL processing option, you must precede
the host language statements that define the host variables and host variable
arrays with the BEGIN DECLARE SECTION statement and follow the host
language statements with the END DECLARE SECTION statement.
Otherwise, these statements are optional.
v Ensure that any SQL statement that uses a host variable or host variable
array is within the scope of the statement that declares that variable or array.
| v If you are using the DB2 precompiler, ensure that the names of host variables
| and host variable arrays are unique within the program, even if the variables
| and variable arrays are in different blocks, classes, procedures, functions, or
| subroutines. You can qualify the names with a structure name to make them
| unique.
2. Optional: Define any associated indicator variables, arrays, and structures.
Related tasks
“Declaring host variables and indicator variables” on page 142

Host variables in Fortran

In Fortran programs, you can specify numeric, character, LOB, and ROWID host
variables. You can also specify result set and LOB locators.

Restrictions:
v Only some of the valid Fortran declarations are valid host variable declarations.
If the declaration for a variable is not valid, any SQL statement that references
the variable might result in the message UNDECLARED HOST VARIABLE.
v Fortran supports some data types with no SQL equivalent (for example,
REAL*16 and COMPLEX). In most cases, you can use Fortran statements to
convert between the unsupported data types and the data types that SQL allows.
v You can not use locators as column types.

Chapter 7. Coding SQL statements in Fortran application programs 365

The following locator data types are Fortran data types and SQL data types:
– Result set locator
– LOB locators
v Because Fortran does not support graphic data types, Fortran applications can
process only Unicode tables that use UTF-8 encoding.

Recommendations:
v Be careful of overflow. For example, if you retrieve an INTEGER column value
into a INTEGER*2 host variable and the column value is larger than 32767 or
-32768, you get an overflow warning or an error, depending on whether you
provided an indicator variable.
v Be careful of truncation. For example, if you retrieve an 80-character CHAR
column value into a CHARACTER*70 host variable, the rightmost ten characters
of the retrieved string are truncated. Retrieving a double-precision floating-point
or decimal column value into an INTEGER*4 host variable removes any
fractional value.

Numeric host variables

The following diagram shows the syntax for declaring numeric host variables.

INTEGER*2  variable-name

*4 / numeric-constant /
INTEGER
*4
REAL
REAL*8
DOUBLE PRECISION

Restrictions:
v Fortran does not provide an equivalent for the decimal data type. To hold a
decimal value, use one of the following variables:
– An integer or floating-point variable, which converts the value. If you use an
integer variable, you lose the fractional part of the number. If the decimal
number can exceed the maximum value for an integer or you want to
preserve a fractional value, use a floating-point variable. Floating-point
numbers are approximations of real numbers. Therefore, when you assign a
decimal number to a floating-point variable, the result might be different from
the original number.
– A character string host variable. Use the CHAR function to retrieve a decimal
value into it.
| v The SQL data type DECFLOAT has no equivalent in Fortran.

Character host variables

The following diagram shows the syntax for declaring character host variables
other than CLOBs.

366 Application Programming and SQL Guide

,

CHARACTER  variable-name

*n *n / character-constant /

Result set locators

The following diagram shows the syntax for declaring result set locators.

SQL TYPE IS RESULT_SET_LOCATOR VARYING  variable-name


LOB variables and locators

The following diagram shows the syntax for declaring BLOB and CLOB host
variables and locators.

SQL TYPE IS BINARY LARGE OBJECT ( length )

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
BLOB_LOCATOR
CLOB_LOCATOR

variable-name


ROWID host variables

The following diagram shows the syntax for declarations of ROWID variables.

SQL TYPE IS ROWID variable-name


Constants

The syntax for constants in Fortran programs differs from the syntax for constants
in SQL statements in the following ways:
v Fortran interprets a string of digits with a decimal point to be a real constant.
An SQL statement interprets such a string to be a decimal constant. Therefore,
use exponent notation when specifying a real (that is, floating-point) constant in
an SQL statement.
v In Fortran, a real (floating-point) constant that has a length of 8 bytes uses a D
as the exponent indicator (for example, 3.14159D+04). An 8-byte floating-point
constant in an SQL statement must use an E (for example, 3.14159E+04).

Chapter 7. Coding SQL statements in Fortran application programs 367

Related concepts
“Host variables” on page 143
“Rules for host variables in an SQL statement” on page 151
“Large objects (LOBs)” on page 430
Related tasks
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Indicator variables in Fortran

An indicator variable is a 2-byte integer (INTEGER*2). You declare indicator
variables in the same way as host variables. You can mix the declarations of the
two types of variables.

The following diagram shows the syntax for declaring an indicator variable in
Fortran.

INTEGER*2  variable-name

/ numeric-constant /

Example

The following example shows a FETCH statement with the declarations of the host
variables that are needed for the FETCH statement and their associated indicator
variables.
EXEC SQL FETCH CLS_CURSOR INTO :CLSCD,
C :DAY :DAYIND,
C :BGN :BGNIND,
C :END :ENDIND

You can declare these variables as follows:

CHARACTER*7 CLSCD
INTEGER*2 DAY
CHARACTER*8 BGN, END
INTEGER*2 DAYIND, BGNIND, ENDIND

368 Application Programming and SQL Guide

Related concepts
“Indicator variables, arrays, and structures” on page 145
Related tasks
“Inserting null values into columns by using indicator variables or arrays” on page
158

Equivalent SQL and Fortran data types

When you declare host variables in your Fortran programs, the precompiler uses
equivalent SQL data types. When you retrieve data of a particular SQL data type
into a host variable, you need to ensure that the host variable is of an equivalent
data type.

The following table describes the SQL data type and the base SQLTYPE and
SQLLEN values that the precompiler uses for host variables in SQL statements.
Table 68. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in
Fortran programs
SQLTYPE of host
Fortran host variable data type variable1 SQLLEN of host variable SQL data type
INTEGER*2 500 2 SMALLINT
INTEGER*4 496 4 INTEGER
REAL*4 480 4 FLOAT (single precision)
REAL*8 480 8 FLOAT (double precision)
CHARACTER*n 452 n CHAR(n)
SQL TYPE IS 972 4 Result set locator. Do not use
RESULT_SET_LOCATOR this data type as a column type.
SQL TYPE IS BLOB_LOCATOR 960 4 BLOB locator. Do not use this
data type as a column type.
SQL TYPE IS CLOB_LOCATOR 964 4 CLOB locator. Do not use this
data type as a column type.
SQL TYPE IS BLOB(n) 404 n BLOB(n)
1≤n≤2147483647
SQL TYPE IS CLOB(n) 408 n CLOB(n)
1≤n≤2147483647
SQL TYPE IS ROWID 904 40 ROWID

Notes:
1. If a host variable includes an indicator variable, the SQLTYPE value is the base
SQLTYPE value plus 1.

The following table shows equivalent Fortran host variables for each SQL data
type. Use this table to determine the Fortran data type for host variables that you
define to receive output from the database. For example, if you retrieve
TIMESTAMP data, you can define a variable of type CHARACTER*n.

This table shows direct conversions between SQL data types and Fortran data
types. However, a number of SQL data types are compatible. When you do
assignments or comparisons of data that have compatible data types, DB2 converts
those compatible data types.

Chapter 7. Coding SQL statements in Fortran application programs 369

Table 69. Fortran host variable equivalents that you can use when retrieving data of a particular SQL data type
SQL data type Fortran host variable equivalent Notes
SMALLINT INTEGER*2
INTEGER INTEGER*4
| BIGINT not supported
DECIMAL(p,s) or no exact equivalent Use REAL*8
NUMERIC(p,s)
FLOAT(n) single precision REAL*4 1<=n<=21
FLOAT(n) double precision REAL*8 22<=n<=53
CHAR(n) CHARACTER*n 1<=n<=255
VARCHAR(n) no exact equivalent Use a character host variable that is large
enough to contain the largest expected
VARCHAR value.
| BINARY not supported
| VARBINARY not supported
GRAPHIC(n) not supported
VARGRAPHIC(n) not supported
DATE CHARACTER*n If you are using a date exit routine, n is
determined by that routine; otherwise, n
must be at least 10.
TIME CHARACTER*n If you are using a time exit routine, n is
determined by that routine. Otherwise, n
must be at least 6; to include seconds, n
must be at least 8.
TIMESTAMP CHARACTER*n n must be at least 19. To include
microseconds, n must be 26; if n is less
than 26, truncation occurs on the
microseconds part.
Result set locator SQL TYPE IS RESULT_SET_LOCATOR Use this data type only for receiving result
sets. Do not use this data type as a
column type.
BLOB locator SQL TYPE IS BLOB_LOCATOR Use this data type only to manipulate data
in BLOB columns. Do not use this data
type as a column type.1
CLOB locator SQL TYPE IS CLOB_LOCATOR Use this data type only to manipulate data
in CLOB columns. Do not use this data
type as a column type.1
DBCLOB locator not supported
BLOB(n) SQL TYPE IS BLOB(n) 1≤n≤21474836471
CLOB(n) SQL TYPE IS CLOB(n) 1≤n≤21474836471
DBCLOB(n) not supported
ROWID SQL TYPE IS ROWID
| XML not supported

370 Application Programming and SQL Guide

Related concepts
“Compatibility of SQL and language data types” on page 148
“LOB host variable, LOB locator, and LOB file reference variable declarations” on
page 705

SQL statements in Fortran programs

You can code SQL statements in a Fortran program wherever you can place
executable statements. If the SQL statement is within an IF statement, the
precompiler generates any necessary THEN and END IF statements.

Fortran source statements must be fixed-length 80-byte records. The DB2

precompiler does not support free-form source input.

Each SQL statement in a Fortran program must begin with EXEC SQL. The EXEC
and SQL keywords must appear on one line, but the remainder of the statement
can appear on subsequent lines.

You might code the UPDATE statement in a Fortran program as follows:

EXEC SQL
C UPDATE DSN8910.DEPT
C SET MGRNO = :MGRNUM
C WHERE DEPTNO = :INTDEPT

You cannot follow an SQL statement with another SQL statement or Fortran
statement on the same line.

Fortran does not require blanks to delimit words within a statement, but the SQL
language requires blanks. The rules for embedded SQL follow the rules for SQL
syntax, which require you to use one or more blanks as a delimiter.

Comments: You can include Fortran comment lines within embedded SQL
statements wherever you can use a blank, except between the keywords EXEC and
SQL. You can include SQL comments in any embedded SQL statement.

The DB2 precompiler does not support the exclamation point (!) as a comment
recognition character in Fortran programs.

Continuation for SQL statements: The line continuation rules for SQL statements
are the same as those for Fortran statements, except that you must specify EXEC
SQL on one line. The SQL examples in this topic have Cs in the sixth column to
indicate that they are continuations of EXEC SQL.

Declaring tables and views: Your Fortran program should also include the
DECLARE TABLE statement to describe each table and view the program accesses.

Dynamic SQL in a Fortran program: In general, Fortran programs can easily

handle dynamic SQL statements. SELECT statements can be handled if the data
types and the number of returned fields are fixed. If you want to use variable-list
SELECT statements, you need to use an SQLDA, as described in “Defining SQL
descriptor areas” on page 141.

You can use a Fortran character variable in the statements PREPARE and
EXECUTE IMMEDIATE, even if it is fixed-length.

Chapter 7. Coding SQL statements in Fortran application programs 371

Including code: To include SQL statements or Fortran host variable declarations
from a member of a partitioned data set, use the following SQL statement in the
source code where you want to include the statements:
EXEC SQL INCLUDE member-name

You cannot nest SQL INCLUDE statements. You cannot use the Fortran INCLUDE
compiler directive to include SQL statements or Fortran host variable declarations.

Margins: Code the SQL statements between columns 7 through 72, inclusive. If
EXEC SQL starts before the specified left margin, the DB2 precompiler does not
recognize the SQL statement.

Names: You can use any valid Fortran name for a host variable. Do not use
external entry names that begin with ’DSN’ or host variable names that begin with
’SQL’. These names are reserved for DB2.

Do not use the word DEBUG, except when defining a Fortran DEBUG packet. Do
not use the words FUNCTION, IMPLICIT, PROGRAM, and SUBROUTINE to
define variables.

Sequence numbers: The source statements that the DB2 precompiler generates do
not include sequence numbers.

Statement labels: You can specify statement numbers for SQL statements in
columns 1 to 5. However, during program preparation, a labeled SQL statement
generates a Fortran CONTINUE statement with that label before it generates the
code that executes the SQL statement. Therefore, a labeled SQL statement should
never be the last statement in a DO loop. In addition, you should not label SQL
statements (such as INCLUDE and BEGIN DECLARE SECTION) that occur before
the first executable SQL statement, because an error might occur.

WHENEVER statement: The target for the GOTO clause in the SQL WHENEVER
statement must be a label in the Fortran source code and must refer to a statement
in the same subprogram. The WHENEVER statement only applies to SQL
statements in the same subprogram.

Special Fortran considerations: The following considerations apply to programs

written in Fortran:
v You cannot use the @PROCESS statement in your source code. Instead, specify
the compiler options in the PARM field.
v You cannot use the SQL INCLUDE statement to include the following
statements: PROGRAM, SUBROUTINE, BLOCK, FUNCTION, or IMPLICIT.

DB2 supports Version 3 Release 1 (or later) of VS Fortran with the following
restrictions:
v The parallel option is not supported. Applications that contain SQL statements
must not use Fortran parallelism.
v You cannot use the byte data type within embedded SQL, because byte is not a
recognizable host data type.

Handling SQL error return codes in Fortran:

You can use the subroutine DSNTIR to convert an SQL return code into a text
message. DSNTIR builds a parameter list and calls DSNTIAR for you. DSNTIAR
takes data from the SQLCA, formats it into a message, and places the result in a

372 Application Programming and SQL Guide

message output area that you provide in your application program. For concepts
and more information on the behavior of DSNTIAR, see “Displaying SQLCA fields
by calling DSNTIAR” on page 204.

You can also use the MESSAGE_TEXT condition item field of the GET
DIAGNOSTICS statement to convert an SQL return code into a text message.
Programs that require long token message support should code the GET
DIAGNOSTICS statement instead of DSNTIAR. For more information about GET
DIAGNOSTICS, see “Checking the execution of SQL statements by using the GET
DIAGNOSTICS statement” on page 209.

DSNTIR syntax:

CALL DSNTIR ( error-length, message, return-code )

The DSNTIR parameters have the following meanings:

error-length
The total length of the message output area.
message
An output area, in VARCHAR format, in which DSNTIAR places the message
text. The first halfword contains the length of the remaining area; its minimum
value is 240.
The output lines of text are put into this area. For example, you could specify
the format of the output area as:
INTEGER ERRLEN /1320/
CHARACTER*132 ERRTXT(10)
INTEGER
. ICODE
.
.
CALL DSNTIR ( ERRLEN, ERRTXT, ICODE )

where ERRLEN is the total length of the message output area, ERRTXT is the
name of the message output area, and ICODE is the return code.
return-code
Accepts a return code from DSNTIAR.

An example of calling DSNTIR (which then calls DSNTIAR) from an application

appears in the DB2 sample assembler program DSN8BF3, which is contained in the
library DSN8910.SDSNSAMP. See “DB2 sample applications” on page 1069 for
instructions on how to access and print the source code for the sample program.

Chapter 7. Coding SQL statements in Fortran application programs 373

Related concepts
“Dynamic SQL” on page 162
“Rules for host variables in an SQL statement” on page 151
“Possible host languages for dynamic SQL applications” on page 166
Related tasks
“Determining whether a column value is null” on page 156
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Dynamically executing a data change statement” on page 191
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189
“Enabling the dynamic statement cache” on page 195
“Handling SQL error codes” on page 215
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Limiting CPU time for dynamic SQL statements by using the resource limit
facility” on page 200
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Delimiters in SQL statements in Fortran programs

You must delimit SQL statements in your Fortran program so that DB2 knows
when a particular SQL statement ends.

Delimit an SQL statement in your Fortran program with the beginning keyword
EXEC SQL and an end of line or end of last continued line.
Related reference
“Programming examples” on page 227

374 Application Programming and SQL Guide

Chapter 8. Coding SQL statements in PL/I application
programs
When you code SQL statements in PL/I application programs, you should follow
certain guidelines.

Defining the SQL communications area, SQLSTATE, and SQLCODE in

PL/I
PL/I programs that contain SQL statements can include an SQL communications
area (SQLCA) to check whether an SQL statement executed successfully.
Alternatively, these programs can declare individual SQLCODE and SQLSTATE
host variables.

If you specify the SQL processing option STDSQL(YES), do not define an SQLCA.
If you do, DB2 ignores your SQLCA, and your SQLCA definition causes
compile-time errors. If you specify the SQL processing option STDSQL(NO),
include an SQLCA explicitly.

If your application contains SQL statements and does not include an SQL
communications area (SQLCA), you must declare individual SQLCODE and
SQLSTATE host variables. Your program can use these variables to check whether
an SQL statement executed successfully.

To define the SQL communications area, SQLSTATE, and SQLCODE:

Option Description
To define the SQL communications area: 1. Code the SQLCA directly in the program
or use the following SQL INCLUDE
statement to request a standard SQLCA
declaration:
EXEC SQL INCLUDE SQLCA
DB2 sets the SQLCODE and SQLSTATE
values in the SQLCA after each SQL
statement executes. Your application should
check these values to determine whether the
last SQL statement was successful.

© Copyright IBM Corp. 1983, 2009 375

Option Description
To declare SQLCODE and SQLSTATE host 1. Declare the SQLCODE variable within a
variables: BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as BIN FIXED (31).
2. Declare the SQLSTATE variable within a
BEGIN DECLARE SECTION statement
and an END DECLARE SECTION
statement in your program declarations
as CHARACTER(5).
Restriction: Do not declare an SQLSTATE
variable as an element of a structure.
Requirement: After you declare the
SQLCODE and SQLSTATE variables, ensure
that all SQL statements in the program are
within the scope of the declaration of these
variables.

Related tasks
“Checking the execution of SQL statements” on page 202
“Checking the execution of SQL statements by using the SQLCA” on page 203
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the items that your program can use to check whether an SQL statement
executed successfully” on page 141

Defining SQL descriptor areas in PL/I

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

To define SQL descriptor areas:

Code the SQLDA directly in the program, or use the following SQL INCLUDE
statement to request a standard SQLDA declaration:
EXEC SQL INCLUDE SQLDA

Restriction: You must place SQLDA declarations before the first SQL statement
that references the data descriptor, unless you use the TWOPASS SQL processing
option.
Related tasks
“Defining SQL descriptor areas” on page 141

Declaring host variables and indicator variables in PL/I

You can use host variables, host variable arrays, and host structures in SQL
statements in your program to pass data between DB2 and your application.

To declare host variables, host variable arrays, and host structures:

1. Declare the variables according to the following rules and guidelines:

376 Application Programming and SQL Guide

v If you specify the ONEPASS SQL processing option, you must explicitly
declare each host variable and each host variable array before using them in
an SQL statement. If you specify the TWOPASS precompiler option, you
must declare each host variable before using it in the DECLARE CURSOR
statement.
v If you specify the STDSQL(YES) SQL processing option, you must precede
the host language statements that define the host variables and host variable
arrays with the BEGIN DECLARE SECTION statement and follow the host
language statements with the END DECLARE SECTION statement.
Otherwise, these statements are optional.
v Ensure that any SQL statement that uses a host variable or host variable
array is within the scope of the statement that declares that variable or array.
| v If you are using the DB2 precompiler, ensure that the names of host variables
| and host variable arrays are unique within the program, even if the variables
| and variable arrays are in different blocks, classes, procedures, functions, or
| subroutines. You can qualify the names with a structure name to make them
| unique.
2. Optional: Define any associated indicator variables, arrays, and structures.
Related tasks
“Declaring host variables and indicator variables” on page 142

Host variables in PL/I

In PL/I programs, you can specify numeric, character, graphic, binary, LOB, XML,
and ROWID host variables. You can also specify result set, table, and LOB locators
and LOB and XML file reference variables.

Restrictions:
v Only some of the valid PL/I declarations are valid host variable declarations.
The precompiler uses the data attribute defaults that are specified in the PL/I
DEFAULT statement. If the declaration for a host variable is not valid, any SQL
statement that references the variable might result in the message
UNDECLARED HOST VARIABLE.
v The alignment, scope, and storage attributes of host variables have the following
restrictions:
– A declaration with the EXTERNAL scope attribute and the STATIC storage
attribute must also have the INITIAL storage attribute.
– If you use the BASED storage attribute, you must follow it with a PL/I
element-locator-expression.
– Host variables can be STATIC, CONTROLLED, BASED, or AUTOMATIC
storage class, or options. However, CICS requires that programs be reentrant.
Although the precompiler uses only the names and data attributes of variables
and ignores the alignment, scope, and storage attributes, you should not ignore
these restrictions. If you do ignore them, you might have problems compiling
the PL/I source code that the precompiler generates.
v PL/I supports some data types with no SQL equivalent (COMPLEX and BIT
variables, for example). In most cases, you can use PL/I statements to convert
between the unsupported PL/I data types and the data types that SQL supports.
v You can not use locators as column types.
The following locator data types are PL/I data types as well as SQL data types:
– Result set locator
– Table locator

Chapter 8. Coding SQL statements in PL/I application programs 377

– LOB locators
v The precompiler does not support PL/I scoping rules.

Recommendations:
v Be careful of overflow. For example, if you retrieve an INTEGER column value
into a BIN FIXED(15) host variable and the column value is larger than 32767 or
smaller than -32768, you get an overflow warning or an error, depending on
whether you provided an indicator variable.
v Be careful of truncation. For example, if you retrieve an 80-character CHAR
column value into a CHAR(70) host variable, the rightmost ten characters of the
retrieved string are truncated. Retrieving a double-precision floating-point or
decimal column value into a BIN FIXED(31) host variable removes any fractional
part of the value. Similarly, retrieving a column value with a DECIMAL data
type into a PL/I decimal variable with a lower precision might truncate the
value.

Numeric host variables

The following diagram shows the syntax for declaring numeric host variables.

DECLARE variable-name BINARY

DCL , BIN
DECIMAL
(  variable-name ) DEC

(2)

FIXED

( precision )
(1)
,scale
FLOAT ( precision )


Alignment and/or Scope and/or Storage

Notes:
1 You can specify a scale only for DECIMAL FIXED.
2 You can specify host variable attributes in any order that is acceptable to
PL/I. For example, BIN FIXED(31), BINARY FIXED(31), BIN(31) FIXED, and
FIXED BIN(31) are all acceptable.

For floating-point data types, use the FLOAT SQL processing option to specify
whether the host variable is in IEEE binary floating-point or z/Architecture
hexadecimal floating-point format. DB2 does not check if the format of the host
variable contents match the format that you specified with the FLOAT SQL
processing option. Therefore, you need to ensure that your floating-point host
variable contents match the format that you specified with the FLOAT SQL
processing option. DB2 converts all floating-point input data to z/Architecture
hexadecimal floating-point format before storing it.

If the PL/I compiler that you are using does not support a decimal data type with
a precision greater than 15, use one of the following variable types for decimal
data:

378 Application Programming and SQL Guide

v Decimal variables with precision less than or equal to 15, if the actual data
values fit. If you retrieve a decimal value into a decimal variable with a scale
that is less than the source column in the database, the fractional part of the
value might truncate.
v An integer or a floating-point variable, which converts the value. If you use an
integer variable, you lose the fractional part of the number. If the decimal
number can exceed the maximum value for an integer or you want to preserve a
fractional value, use a floating-point variable. Floating-point numbers are
approximations of real numbers. Therefore, when you assign a decimal number
to a floating-point variable, the result might be different from the original
number.
v A character string host variable. Use the CHAR function to retrieve a decimal
value into it.

Character host variables

The following diagram shows the syntax for declaring character host variables,
other than CLOBs.

DECLARE variable-name

DCL ,

(  variable-name )

CHARACTER ( length )

CHAR VARYING
VAR


Alignment and/or Scope and/or Storage

Graphic host variables

The following diagram shows the syntax for declaring graphic host variables other
than DBCLOBs.

DECLARE variable-name

DCL ,

(  variable-name )

GRAPHIC ( length )

VARYING
VAR


Alignment and/or Scope and/or Storage

| Binary host variables

| You can specify the following forms of binary host variables:

| v Fixed-length strings
| v Varying-length strings
| v BLOBs

Chapter 8. Coding SQL statements in PL/I application programs 379

| The following diagram shows the syntax for declaring BINARY host variables.

|

DECLARE variable-name SQL TYPE IS BINARY

| DCL , VARBINARY
BINARY VARYING
 ( variable-name )

| (1)
|
( length ) ;

|
| Notes:
| 1 For BINARY host variables, the length must be in the range from 1 to 255.
| For VARBINARY host variables, the length must be in the range from 1 to
| 32 704.

| PL/I does not have variables that correspond to the SQL binary data types
| BINARY and VARBINARY. To create host variables that can be used with these
| data types, use the SQL TYPE IS clause.

| When you reference a BINARY or VARBINARY host variable in an SQL statement,

| you must use the variable that you specify in the SQL TYPE declaration. When
| you reference the host variable in a host language statement, you must use the
| variable that DB2 generates.

| Examples of binary variable declarations: The following table shows examples of

| variables that DB2 generates when you declare binary host variables.
| Table 70. Examples of BINARY and VARBINARY variable declarations for PL/I
| Variable declaration that you include in Corresponding variable that DB2 generates
| your PL/I program in the output source member

| DCL BIN_VAR SQL TYPE IS BINARY(10); DCL BIN_VAR CHAR(10);

| DCL VBIN_VAR SQL TYPE IS VARBINARY(10); DCL VBIN_VAR CHAR(10) VAR;

|

| Result set locators

The following diagram shows the syntax for declaring result set locators.

DECLARE variable-name

DCL ,

(  variable-name )

SQL TYPE IS RESULT_SET_LOCATOR VARYING


Alignment and/or Scope and/or Storage

380 Application Programming and SQL Guide

Table locators

The following diagram shows the syntax for declaring table locators.

DCL variable-name

DECLARE ,

(  variable-name )

SQL TYPE IS TABLE LIKE table-name AS LOCATOR


LOB variables, locators, and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variables, locators, and file reference variables.

DCL variable-name SQL TYPE IS

(1) ,
DECLARE
(  variable-name )

| (2)

BINARY LARGE OBJECT ( length )

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_LOCATOR
CLOB_LOCATOR
DBCLOB_LOCATOR
BLOB_FILE
CLOB_FILE
DBCLOB_FILE

Notes:
1 A single PL/I declaration that contains a LOB variable declaration is limited
to no more than 1000 lines of source code.
2 Variable attributes such as STATIC and AUTOMATIC are ignored if specified
on a LOB variable declaration.

| Note: Variable attributes such as STATIC and AUTOMATIC are ignored if

| specified on a LOB variable declaration.

| XML data host and file reference variables

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variables and file reference variables for XML data types.

|

DCL variable-name SQL TYPE IS XML AS

| DECLARE ,

(  variable-name )

|
Chapter 8. Coding SQL statements in PL/I application programs 381
|
|
BINARY LARGE OBJECT ( length )

BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_FILE
CLOB_FILE
DBCLOB_FILE
|

| ROWID host variables

The following diagram shows the syntax for declaring ROWID host variables.

DCL variable-name SQL TYPE IS ROWID


DECLARE ,

(  variable-name )

Related concepts
“Host variables” on page 143
“Rules for host variables in an SQL statement” on page 151
“Large objects (LOBs)” on page 430
Related tasks
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Retrieving a single row of data into a host structure” on page 161
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Host variable arrays in PL/I

In PL/I programs, you can specify numeric, character, graphic, binary, LOB, XML,
and ROWID host variable arrays. You can also specify LOB locators and LOB and
XML file reference variables.

Restrictions:
v Only some of the valid PL/I declarations are valid host variable declarations.
The precompiler uses the data attribute defaults that are specified in the PL/I
DEFAULT statement. If the declaration for a host variable is not valid, any SQL
statement that references the host variable array might result in the message
UNDECLARED HOST VARIABLE ARRAY.
v The alignment, scope, and storage attributes of host variable arrays have the
following restrictions:
– A declaration with the EXTERNAL scope attribute and the STATIC storage
attribute must also have the INITIAL storage attribute.
– If you use the BASED storage attribute, you must follow it with a PL/I
element-locator-expression.

382 Application Programming and SQL Guide

– Host variables can be STATIC, CONTROLLED, BASED, or AUTOMATIC
storage class, or options. However, CICS requires that programs be reentrant.
Although the precompiler uses only the names and data attributes of variable
arrays and ignores the alignment, scope, and storage attributes, you should not
ignore these restrictions. If you do ignore them, you might have problems
compiling the PL/I source code that the precompiler generates.
v You must specify the ALIGNED attribute when you declare varying-length
character arrays or varying-length graphic arrays that are to be used in
multiple-row INSERT and FETCH statements.

Numeric host variable arrays

The following diagram shows the syntax for declaring numeric host variable
arrays.

(1)


DECLARE variable-name ( dimension )

DCL ,

(  variable-name )
,
(1)
(  variable-name ( dimension ) )

(3)

BINARY FIXED

BIN ( precision )
DECIMAL (2)
DEC ,scale
FLOAT ( precision )


Alignment and/or Scope and/or Storage

Notes:
1 dimension must be an integer constant between 1 and 32767.
2 You can specify the scale for only DECIMAL FIXED.
3 You can specify host variable array attributes in any order that is acceptable
to PL/I. For example, BIN FIXED(31), BINARY FIXED(31), BIN(31) FIXED,
and FIXED BIN(31) are all acceptable.

Example: The following example shows a declaration of an indicator array.

DCL IND_ARRAY(100) BIN FIXED(15); /* DCL ARRAY of 100 indicator variables */

Character host variable arrays

The following diagram shows the syntax for declaring character host variable
arrays other than CLOBs.

Chapter 8. Coding SQL statements in PL/I application programs 383

(1)


DECLARE variable-name ( dimension )

DCL ,

(  variable-name )
,
(1)
(  variable-name ( dimension ) )

CHARACTER ( length )

CHAR VARYING Alignment and/or Scope and/or Storage
VAR

Notes:
1 dimension must be an integer constant between 1 and 32767.

Example: The following example shows the declarations needed to retrieve 10

rows of the department number and name from the department table:
DCL DEPTNO(10) CHAR(3); /* Array of ten CHAR(3) variables */
DCL DEPTNAME(10) CHAR(29) VAR; /* Array of ten VARCHAR(29) variables */

Graphic host variable arrays

The following diagram shows the syntax for declaring graphic host variable arrays
other than DBCLOBs.

(1)


DECLARE variable-name ( dimension )

DCL ,

(  variable-name )
,
(1)
(  variable-name ( dimension ) )

GRAPHIC ( length )

VARYING Alignment and/or Scope and/or Storage
VAR

Notes:
1 dimension must be an integer constant between 1 and 32767.

| Binary host variable arrays

| The following diagram shows the syntax for declaring binary variable arrays.

|

DCL variable-name ( dimension )

| DECLARE ,

(  variable-name )
,

(  variable-name ( dimension ) )

|
SQL TYPE IS BINARY


| VARBINARY
|

384 Application Programming and SQL Guide

| LOB, locator, and file reference variable arrays

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variable, locator, and file reference variable arrays.

| (1)
|

DCL variable-name ( dimension )

DECLARE ,

(  variable-name )
,
(1)
(  variable-name ( dimension ) )

|
SQL TYPE IS BINARY LARGE OBJECT ( length )


| BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_LOCATOR
CLOB_LOCATOR
DBCLOB_LOCATOR
BLOB_FILE
CLOB_FILE
DBCLOB_FILE

|
| Notes:
| 1 dimension must be an integer constant between 1 and 32767.

| XML host and file reference variable arrays

| The following diagram shows the syntax for declaring BLOB, CLOB, and DBCLOB
| host variable arrays and file reference variable arrays for XML data types.

| (1)
|

DCL variable-name ( dimension )

DECLARE ,

(  variable-name )
,
(1)
(  variable-name ( dimension ) )

|
SQL TYPE IS XML AS BINARY LARGE OBJECT ( length )


| BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_FILE
CLOB_FILE
DBCLOB_FILE

Chapter 8. Coding SQL statements in PL/I application programs 385

| Notes:
| 1 dimension must be an integer constant between 1 and 32767.

| ROWID variable arrays

The following diagram shows the syntax for declaring ROWID variable arrays.

(1)


DCL variable-name ( dimension )

DECLARE ,

(  variable-name )
,
(1)
(  variable-name ( dimension ) )

SQL TYPE IS ROWID


Notes:
1 dimension must be an integer constant between 1 and 32767.
Related concepts
“Host variable arrays” on page 144
“Host variable arrays in an SQL statement” on page 159
“Large objects (LOBs)” on page 430
Related tasks
“Inserting multiple rows of data from host variable arrays” on page 160
“Retrieving multiple rows of data into host variable arrays” on page 160

Host structures in PL/I

A PL/I host structure is a structure that contains subordinate levels of scalars. You
can use the name of the structure as shorthand notation to reference the list of
scalars.

Requirements: Host structure declarations in PL/I must satisfy the following

requirements:
v Host structures are limited to two levels.
v You must terminate the host structure variable by ending the declaration with a
semicolon.

Example:
DCL 1 A,
2 B CHAR,
2 (C, D) CHAR;
DCL (E, F) CHAR;
v You can specify host variable attributes in any order that is acceptable to PL/I.
For example, BIN FIXED(31), BIN(31) FIXED, and FIXED BIN(31) are all
acceptable.

When you reference a host variable, you can qualify it with a structure name. For
example, you can specify STRUCTURE.FIELD.

386 Application Programming and SQL Guide

Host structures

The following diagram shows the syntax for declaring host structures.

DECLARE level-1 variable-name ,

DCL Scope and/or storage

 level-2 var-1 data-type-specification ;


,

(  var-2 )

Data types

The following diagram shows the syntax for data types that are used within
declarations of host structures.

|

CHARACTER

CHAR ( integer ) VARYING
VAR
GRAPHIC
( integer ) VARYING
VAR
BINARY FIXED
BIN ( precision )
DECIMAL , scale
DEC FLOAT
( precision )
SQL TYPE IS ROWID
LOB data type

LOB data types

The following diagram shows the syntax for LOB data types that are used within
declarations of host structures.

|

SQL TYPE IS CHARACTER LARGE OBJECT ( length )


CHAR LARGE OBJECT K
CLOB M
DBCLOB G
BINARY LARGE OBJECT
BLOB
CLOB_LOCATOR
DBCLOB_LOCATOR
BLOB_LOCATOR
CLOB_FILE
DBCLOB_FILE
BLOB_FILE

Chapter 8. Coding SQL statements in PL/I application programs 387

| LOB data types for XML data

| The following diagram shows the syntax for LOB data types that are used within
| declarations of host structures for XML data.

|

SQL TYPE IS XML AS BINARY LARGE OBJECT ( length )


BLOB K
CHARACTER LARGE OBJECT M
CHAR LARGE OBJECT G
CLOB
DBCLOB
BLOB_FILE
CLOB_FILE
DBCLOB_FILE
|

| Example

In the following example, B is the name of a host structure that contains the scalars
C1 and C2.
DCL 1 A,
2 B,
3 C1 CHAR(...),
3 C2 CHAR(...);
Related concepts
“Host structures” on page 144

Indicator variables in PL/I

An indicator variable is a 2-byte integer (or an integer declared as BIN FIXED(15)).
An indicator variable array is an array of 2-byte integers. You declare indicator
variables in the same way as host variables. You can mix the declarations of the
two types of variables.

The following diagram shows the syntax for declaring an indicator variable in
PL/I.

,
(1)


DECLARE (  variable-name ) BINARY FIXED(15) ;

DCL BIN

Notes:
1 You can specify host variable attributes in any order that is acceptable to
PL/I. For example, BIN FIXED(31), BIN(31) FIXED, and FIXED BIN(31) are all
acceptable.

The following diagram shows the syntax for declaring an indicator array in PL/I.

DECLARE variable-name ( dimension ) BINARY

DCL , BIN
(1)
(  variable-name ( dimension ) )

388 Application Programming and SQL Guide

FIXED(15) ;

Alignment and/or Scope and/or Storage

Notes:
1 dimension must be an integer constant between 1 and 32767.

Example

The following example shows a FETCH statement with the declarations of the host
variables that are needed for the FETCH statement and their associated indicator
variables.
EXEC SQL FETCH CLS_CURSOR INTO :CLS_CD,
:DAY :DAY_IND,
:BGN :BGN_IND,
:END :END_IND;

You can declare these variables as follows:

DCL CLS_CD CHAR(7);
DCL DAY BIN FIXED(15);
DCL BGN CHAR(8);
DCL END CHAR(8);
DCL (DAY_IND, BGN_IND, END_IND) BIN FIXED(15);
Related concepts
“Indicator variables, arrays, and structures” on page 145
Related tasks
“Inserting null values into columns by using indicator variables or arrays” on page
158

Equivalent SQL and PL/I data types

When you declare host variables in your PL/I programs, the precompiler uses
equivalent SQL data types. When you retrieve data of a particular SQL data type
into a host variable, you need to ensure that the host variable is of an equivalent
data type.

The following table describes the SQL data type and the base SQLTYPE and
SQLLEN values that the precompiler uses for host variables in SQL statements.
Table 71. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in PL/I
programs
SQLTYPE of host
PL/I host variable data type variable1 SQLLEN of host variable SQL data type
BIN FIXED(n) 1<=n<=15 500 2 SMALLINT
BIN FIXED(n) 16<=n<=31 496 4 INTEGER
| FIXED BIN(63) 492 8 BIGINT
DEC FIXED(p,s) 0<=p<=31 and 484 p in byte 1, s in byte 2 DECIMAL(p,s)
0<=s<=p2
BIN FLOAT(p) 1<=p<=21 480 4 REAL or FLOAT(n) 1<=n<=21
BIN FLOAT(p) 22<=p<=53 480 8 DOUBLE PRECISION or
FLOAT(n) 22<=n<=53
DEC FLOAT(m) 1<=m<=6 480 4 FLOAT (single precision)
DEC FLOAT(m) 7<=m<=16 480 8 FLOAT (double precision)

Chapter 8. Coding SQL statements in PL/I application programs 389

Table 71. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in PL/I
programs (continued)
SQLTYPE of host
PL/I host variable data type variable1 SQLLEN of host variable SQL data type
CHAR(n) 452 n CHAR(n)
CHAR(n) VARYING 1<=n<=255 448 n VARCHAR(n)
CHAR(n) VARYING n>255 456 n VARCHAR(n)
GRAPHIC(n) 468 n GRAPHIC(n)
GRAPHIC(n) VARYING 464 n VARGRAPHIC(n)
1<=n<=127
GRAPHIC(n) VARYING n>127 472 n VARGRAPHIC(n)
| SQL TYPE IS BINARY(n), 912 n BINARY(n)
| 1<=n<=255
| SQL TYPE IS VARBINARY(n), 908 n VARBINARY(n)
| 1<=n<=32 704
SQL TYPE IS 972 4 Result set locator3
RESULT_SET_LOCATOR
SQL TYPE IS TABLE LIKE 976 4 Table locator3
table-name AS LOCATOR
SQL TYPE IS BLOB_LOCATOR 960 4 BLOB locator3
SQL TYPE IS CLOB_LOCATOR 964 4 CLOB locator3
SQL TYPE IS 968 4 DBCLOB locator3
DBCLOB_LOCATOR
SQL TYPE IS BLOB(n) 404 n BLOB(n)
1≤n≤2147483647
SQL TYPE IS CLOB(n) 408 n CLOB(n)
1≤n≤2147483647
SQL TYPE IS DBCLOB(n) 412 n DBCLOB(n)4
1≤n≤10737418234
| SQL TYPE IS XML AS BLOB(n) 404 0 XML
| SQL TYPE IS XML AS CLOB(n) 408 0 XML
| SQL TYPE IS XML AS 412 0 XML
| DBCLOB(n)
| SQL TYPE IS BLOB_FILE 916/917 267 BLOB file reference3
| SQL TYPE IS CLOB_FILE 920/921 267 CLOB file reference3
| SQL TYPE IS DBCLOB_FILE 924/925 267 DBCLOB file reference3
| SQL TYPE IS XML AS 916/917 267 XML BLOB file reference3
| BLOB_FILE
| SQL TYPE IS XML AS 920/921 267 XML CLOB file reference3
| CLOB_FILE
| SQL TYPE IS XML AS 924/925 267 XML DBCLOB file reference3
| DBCLOB_FILE
SQL TYPE IS ROWID 904 40 ROWID

390 Application Programming and SQL Guide

Table 71. SQL data types, SQLLEN values, and SQLTYPE values that the precompiler uses for host variables in PL/I
programs (continued)
SQLTYPE of host
PL/I host variable data type variable1 SQLLEN of host variable SQL data type
Notes:
1. If a host variable includes an indicator variable, the SQLTYPE value is the base SQLTYPE value plus 1.
2. If p=0, DB2 interprets it as DECIMAL(31). For example, DB2 interprets a PL/I data type of DEC FIXED(0,0) to be
DECIMAL(31,0), which equates to the SQL data type of DECIMAL(31,0).
3. Do not use this data type as a column type.
4. n is the number of double-byte characters.

The following table shows equivalent PL/I host variables for each SQL data type.
Use this table to determine the PL/I data type for host variables that you define to
receive output from the database. For example, if you retrieve TIMESTAMP data,
you can define a variable of type CHAR(n).

This table shows direct conversions between SQL data types and PL/I data types.
However, a number of SQL data types are compatible. When you do assignments
or comparisons of data that have compatible data types, DB2 converts those
compatible data types.
Table 72. PL/I host variable equivalents that you can use when retrieving data of a particular SQL data type
SQL data type PL/I host variable equivalent Notes
SMALLINT BIN FIXED(n) 1<=n<=15
INTEGER BIN FIXED(n) 16<=n<=31
| BIGINT FIXED BIN(63)
DECIMAL(p,s) or If p<16: DEC FIXED(p) or DEC p is precision; s is scale. 1<=p<=31 and
NUMERIC(p,s) FIXED(p,s) 0<=s<=p

If p>15, the PL/I compiler must support

31-digit decimal variables.
REAL or FLOAT(n) BIN FLOAT(p) or DEC FLOAT(m) 1<=n<=21, 1<=p<=21, and 1<=m<=6
DOUBLE PRECISION, BIN FLOAT(p) or DEC FLOAT(m) 22<=n<=53, 22<=p<=53, and 7<=m<=16
DOUBLE, or FLOAT(n)
CHAR(n) CHAR(n) 1<=n<=255
VARCHAR(n) CHAR(n) VAR
GRAPHIC(n) GRAPHIC(n) n refers to the number of double-byte
characters, not to the number of bytes.
1<=n<=127
VARGRAPHIC(n) GRAPHIC(n) VAR n refers to the number of double-byte
characters, not to the number of bytes.
| BINARY(n) SQL TYPE IS BINARY(n) 1<=n<=255
| VARBINARY(n) SQL TYPE IS VARBINARY(n) 1<=n<=32 704
DATE CHAR(n) If you are using a date exit routine, that
routine determines n; otherwise, n must be
at least 10.
TIME CHAR(n) If you are using a time exit routine, that
routine determines n. Otherwise, n must
be at least 6; to include seconds, n must be
at least 8.

Chapter 8. Coding SQL statements in PL/I application programs 391

Table 72. PL/I host variable equivalents that you can use when retrieving data of a particular SQL data
type (continued)
SQL data type PL/I host variable equivalent Notes
TIMESTAMP CHAR(n) n must be at least 19. To include
microseconds, n must be 26; if n is less
than 26, the microseconds part is
truncated.
Result set locator SQL TYPE IS RESULT_SET_LOCATOR Use this data type only for receiving result
sets. Do not use this data type as a
column type.
Table locator SQL TYPE IS TABLE LIKE table-name AS Use this data type only in a user-defined
LOCATOR function or stored procedure to receive
rows of a transition table. Do not use this
data type as a column type.
BLOB locator SQL TYPE IS BLOB_LOCATOR Use this data type only to manipulate data
in BLOB columns. Do not use this data
type as a column type.1
CLOB locator SQL TYPE IS CLOB_LOCATOR Use this data type only to manipulate data
in CLOB columns. Do not use this data
type as a column type.1
DBCLOB locator SQL TYPE IS DBCLOB_LOCATOR Use this data type only to manipulate data
in DBCLOB columns. Do not use this data
type as a column type.1
BLOB(n) SQL TYPE IS BLOB(n) 1≤n≤21474836471
CLOB(n) SQL TYPE IS CLOB(n) 1≤n≤21474836471
DBCLOB(n) SQL TYPE IS DBCLOB(n) n is the number of double-byte characters.
1≤n≤10737418231
2
| XML SQL TYPE IS XML AS BLOB(n) 1≤n≤2147483647
2
| XML SQL TYPE IS XML AS CLOB(n) 1≤n≤2147483647
| XML SQL TYPE IS XML AS DBCLOB(n) n is the number of double-byte characters.
| 1≤n≤1073741823 2
| BLOB file reference SQL TYPE IS BLOB_FILE Use this data type only to manipulate data
| in BLOB columns. Do not use this data
| type as a column type.1
| CLOB file reference SQL TYPE IS CLOB_FILE Use this data type only to manipulate data
| in CLOB columns. Do not use this data
| type as a column type.1
| DBCLOB file reference SQL TYPE IS DBCLOB_FILE Use this data type only to manipulate data
| in DBCLOB columns. Do not use this data
| type as a column type.1
| XML BLOB file reference SQL TYPE IS XML AS BLOB_FILE Use this data type only to manipulate
| XML data as BLOB files. Do not use this
| data type as a column type. 2
| XML CLOB file reference SQL TYPE IS XML AS CLOB_FILE Use this data type only to manipulate
| XML data as CLOB files. Do not use this
| data type as a column type. 2
| XML DBCLOB file reference SQL TYPE IS XML AS DBCLOB_FILE Use this data type only to manipulate
| XML data as DBCLOB files. Do not use
| this data type as a column type.2
ROWID SQL TYPE IS ROWID

392 Application Programming and SQL Guide

Related concepts
“Compatibility of SQL and language data types” on page 148
“LOB host variable, LOB locator, and LOB file reference variable declarations” on
page 705
“Host variable data types for XML data in embedded SQL applications” on page
217

SQL statements in PL/I programs

You can code SQL statements in a PL/I program wherever you can use executable
statements.

The first statement of the PL/I program must be the PROCEDURE statement with
OPTIONS(MAIN), unless the program is a stored procedure. A stored procedure
application can run as a subroutine.

Each SQL statement in a PL/I program must begin with EXEC SQL and end with
a semicolon (;). The EXEC and SQL keywords must appear must appear on one
line, but the remainder of the statement can appear on subsequent lines.

You might code an UPDATE statement in a PL/I program as follows:

EXEC SQL UPDATE DSN8910.DEPT
SET MGRNO = :MGR_NUM
WHERE DEPTNO = :INT_DEPT ;

Comments: You can include PL/I comments in embedded SQL statements

wherever you can use a blank, except between the keywords EXEC and SQL. You
can also include SQL comments in any SQL statement.

To include DBCS characters in comments, you must delimit the characters by a

shift-out and shift-in control character; the first shift-in character in the DBCS
string signals the end of the DBCS string.

Continuation for SQL statements: The line continuation rules for SQL statements
are the same as those for other PL/I statements, except that you must specify
EXEC SQL on one line.

Declaring tables and views: Your PL/I program should include a DECLARE
TABLE statement to describe each table and view the program accesses. You can
use the DB2 declarations generator (DCLGEN) to generate the DECLARE TABLE
statements. For more information, see “DCLGEN (declarations generator)” on page
129.

Including code: You can use SQL statements or PL/I host variable declarations
from a member of a partitioned data set by using the following SQL statement in
the source code where you want to include the statements:
EXEC SQL INCLUDE member-name;

You cannot nest SQL INCLUDE statements. Do not use the PL/I %INCLUDE
statement to include SQL statements or host variable DCL statements. You must
use the PL/I preprocessor to resolve any %INCLUDE statements before you use
the DB2 precompiler. Do not use PL/I preprocessor directives within SQL
statements.

Chapter 8. Coding SQL statements in PL/I application programs 393

Margins: Code SQL statements in columns 2 through 72, unless you have specified
other margins to the DB2 precompiler. If EXEC SQL starts before the specified left
margin, the DB2 precompiler does not recognize the SQL statement.

Names: You can use any valid PL/I name for a host variable. Do not use external
entry names or access plan names that begin with ’DSN’, and do not use host
variable names that begin with ’SQL’. These names are reserved for DB2.

Sequence numbers: The source statements that the DB2 precompiler generates do
not include sequence numbers. IEL0378I messages from the PL/I compiler identify
lines of code without sequence numbers. You can ignore these messages.

Statement labels: You can specify a statement label for executable SQL statements.
However, the INCLUDE text-file-name and END DECLARE SECTION statements
cannot have statement labels.

Whenever statement: The target for the GOTO clause in an SQL statement
WHENEVER must be a label in the PL/I source code and must be within the
scope of any SQL statements that WHENEVER affects.

Using double-byte character set (DBCS) characters: The following considerations

apply to using DBCS in PL/I programs with SQL statements:
v If you use DBCS in the PL/I source, DB2 rules for the following language
elements apply:
– Graphic strings
– Graphic string constants
– Host identifiers
– Mixed data in character strings
– MIXED DATA option
v The PL/I preprocessor transforms the format of DBCS constants. If you do not
want that transformation, run the DB2 precompiler before the preprocessor.
v If you use graphic string constants or mixed data in dynamically prepared SQL
statements, and if your application requires the PL/I Version 2 (or later)
compiler, the dynamically prepared statements must use the PL/I mixed
constant format.
– If you prepare the statement from a host variable, change the string
assignment to a PL/I mixed string.
– If you prepare the statement from a PL/I string, change that to a host
variable, and then change the string assignment to a PL/I mixed string.
Example:
SQLSTMT = 'SELECT <dbdb> FROM table-name'M;
EXEC SQL PREPARE STMT FROM :SQLSTMT;

For instructions on preparing SQL statements dynamically, see “Dynamic SQL”

on page 162.
v If you want a DBCS identifier to resemble a PL/I graphic string, you must use a
delimited identifier.
v If you include DBCS characters in comments, you must delimit the characters
with a shift-out and shift-in control character. The first shift-in character signals
the end of the DBCS string.
v You can declare host variable names that use DBCS characters in PL/I
application programs. The rules for using DBCS variable names in PL/I follow
existing rules for DBCS SQL ordinary identifiers, except for length. The

394 Application Programming and SQL Guide

maximum length for a host variable is 128 Unicode bytes in DB2. For
information about the rules for DBCS SQL ordinary identifiers, see the topic
“SQL identifiers” in DB2 SQL Reference.
Restrictions:
– DBCS variable names must contain DBCS characters only. Mixing single-byte
character set (SBCS) characters with DBCS characters in a DBCS variable
name produces unpredictable results.
– A DBCS variable name cannot continue to the next line.
v The PL/I preprocessor changes non-Kanji DBCS characters into extended binary
coded decimal interchange code (EBCDIC) SBCS characters. To avoid this
change, use Kanji DBCS characters for DBCS variable names, or run the PL/I
compiler without the PL/I preprocessor.

Special PL/I considerations: The following considerations apply to programs

written in PL/I:
v When compiling a PL/I program that includes SQL statements, you must use
the PL/I compiler option CHARSET (60 EBCDIC).
v In unusual cases, the generated comments in PL/I can contain a semicolon. The
semicolon generates compiler message IEL0239I, which you can ignore.
v The generated code in a PL/I declaration can contain the ADDR function of a
field defined as character varying. This produces either message IBM105l l or
IBM1180l W, both of which you can ignore.
v The precompiler generated code in PL/I source can contain the NULL()
function. This produces message IEL0533I, which you can ignore unless you also
use NULL as a PL/I variable. If you use NULL as a PL/I variable in a DB2
application, you must also declare NULL as a built-in function (DCL NULL
BUILTIN;) to avoid PL/I compiler errors.
v The PL/I macro processor can generate SQL statements or host variable DCL
statements if you run the macro processor before running the DB2 precompiler.
If you use the PL/I macro processor, do not use the PL/I *PROCESS statement
in the source to pass options to the PL/I compiler. You can specify the needed
options on the COPTION parameter of the DSNH command or the option
PARM.PLI=options of the EXEC statement in the DSNHPLI procedure.
v Using the PL/I multitasking facility, in which multiple tasks execute SQL
statements, causes unpredictable results.

You can use the subroutine DSNTIAR to convert an SQL return code into a text
message. DSNTIAR takes data from the SQLCA, formats it into a message, and
places the result in a message output area that you provide in your application
program. For concepts and more information on the behavior of DSNTIAR, see
“Displaying SQLCA fields by calling DSNTIAR” on page 204.

You can also use the MESSAGE_TEXT condition item field of the GET
DIAGNOSTICS statement to convert an SQL return code into a text message.
Programs that require long token message support should code the GET
DIAGNOSTICS statement instead of DSNTIAR. For more information about GET
DIAGNOSTICS, see “Checking the execution of SQL statements by using the GET
DIAGNOSTICS statement” on page 209.

DSNTIAR syntax:

CALL DSNTIAR ( sqlca, message, lrecl );

Chapter 8. Coding SQL statements in PL/I application programs 395

The DSNTIAR parameters have the following meanings:
sqlca
An SQL communication area.
message
An output area, in VARCHAR format, in which DSNTIAR places the message
text. The first halfword contains the length of the remaining area; its minimum
value is 240.
The output lines of text, each line being the length specified in lrecl, are put
into this area. For example, you could specify the format of the output area as:
DCL DATA_LEN FIXED BIN(31) INIT(132);
DCL DATA_DIM FIXED BIN(31) INIT(10);
DCL 1 ERROR_MESSAGE AUTOMATIC,
3 ERROR_LEN FIXED BIN(15) UNAL INIT((DATA_LEN*DATA_DIM)),
. 3 ERROR_TEXT(DATA_DIM) CHAR(DATA_LEN);
.
.
CALL DSNTIAR ( SQLCA, ERROR_MESSAGE, DATA_LEN );

where ERROR_MESSAGE is the name of the message output area, DATA_DIM

is the number of lines in the message output area, and DATA_LEN is the
length of each line.
lrecl
A fullword containing the logical record length of output messages, between 72
and 240.

Because DSNTIAR is an assembler language program, you must include the

following directives in your PL/I application:
DCL DSNTIAR ENTRY OPTIONS (ASM,INTER,RETCODE);

An example of calling DSNTIAR from an application appears in the DB2 sample

assembler program DSN8BP3, contained in the library DSN8910.SDSNSAMP. See
“DB2 sample applications” on page 1069 for instructions on how to access and
print the source code for the sample program.

CICS: If your CICS application requires CICS storage handling, you must use the
subroutine DSNTIAC instead of DSNTIAR. DSNTIAC has the following syntax:
CALL DSNTIAC (eib, commarea, sqlca, msg, lrecl);

DSNTIAC has extra parameters, which you must use for calls to routines that use
CICS commands.
eib EXEC interface block
commarea
communication area

For more information on these parameters, see the appropriate application

programming guide for CICS. The remaining parameter descriptions are the same
as those for DSNTIAR. Both DSNTIAC and DSNTIAR format the SQLCA in the
same way.

You must define DSNTIA1 in the CSD. If you load DSNTIAR or DSNTIAC, you
must also define them in the CSD. For an example of CSD entry generation
statements for use with DSNTIAC, see job DSNTEJ5A.

396 Application Programming and SQL Guide

The assembler source code for DSNTIAC and job DSNTEJ5A, which assembles and
link-edits DSNTIAC, are in the data set prefix.SDSNSAMP.
Related concepts
“Dynamic SQL” on page 162
“Host variable arrays in an SQL statement” on page 159
“Rules for host variables in an SQL statement” on page 151
“Possible host languages for dynamic SQL applications” on page 166
Related tasks
“Determining whether a column value is null” on page 156
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Dynamically executing a data change statement” on page 191
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189
“Enabling the dynamic statement cache” on page 195
“Handling SQL error codes” on page 215
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
“Inserting a single row by using a host variable” on page 158
“Inserting multiple rows of data from host variable arrays” on page 160
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Limiting CPU time for dynamic SQL statements by using the resource limit
facility” on page 200
“Retrieving multiple rows of data into host variable arrays” on page 160
“Retrieving a single row of data into a host structure” on page 161
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Delimiters in SQL statements in PL/I programs

You must delimit SQL statements in your PL/I program so that DB2 knows when
a particular SQL statement ends.

Delimit an SQL statement in your PL/I program with the beginning keyword EXEC
SQL and a Semicolon (;).

Programming examples in PL/I

You can write DB2 programs in PL/I. These programs can access a local or remote
DB2 subsystem and can execute static or dynamic SQL statements. This
information contains several such programming examples.

To prepare and run these applications, use the JCL in DSN910.SDSNSAMP as a

model for your JCL.

Chapter 8. Coding SQL statements in PL/I application programs 397

Related reference
“Programming examples” on page 227

Example PL/I program that calls a stored procedure

This example shows how to call the GETPRML stored procedure that uses the
GENERAL WITH NULLS linkage convention from a PL/I program on an z/OS
system.

The following figure contains the example PL/I program that calls the GETPRML
stored procedure.

398 Application Programming and SQL Guide

*PROCESS SYSTEM(MVS);
CALPRML:
PROC OPTIONS(MAIN);

/************************************************************/
/* Declare the parameters used to call the GETPRML */
/* stored procedure. */
/************************************************************/
DECLARE PROCNM CHAR(18), /* INPUT parm -- PROCEDURE name */
SCHEMA CHAR(8), /* INPUT parm -- User's schema */
OUT_CODE FIXED BIN(31),
/* OUTPUT -- SQLCODE from the */
/* SELECT operation. */
PARMLST CHAR(254) /* OUTPUT -- RUNOPTS for */
VARYING, /* the matching row in the */
/* catalog table SYSROUTINES */
PARMIND FIXED BIN(15);
/* PARMLST indicator variable */
/************************************************************/
/* Include the SQLCA */
/************************************************************/
EXEC SQL INCLUDE SQLCA;
/************************************************************/
/* Call the GETPRML stored procedure to retrieve the */
/* RUNOPTS values for the stored procedure. In this */
/* example, we request the RUNOPTS values for the */
/* stored procedure named DSN8EP2. */
/************************************************************/
PROCNM = 'DSN8EP2';
/* Input parameter -- PROCEDURE to be found */
SCHEMA = ' ';
/* Input parameter -- SCHEMA in SYSROUTINES */
PARMIND = -1; /* The PARMLST parameter is an output parm. */
/* Mark PARMLST parameter as null, so the DB2 */
/* requester doesn't have to send the entire */
/* PARMLST variable to the server. This */
/* helps reduce network I/O time, because */
/* PARMLST is fairly large. */
EXEC SQL
CALL GETPRML(:PROCNM,
:SCHEMA,
:OUT_CODE,
:PARMLST INDICATOR :PARMIND);
IF SQLCODE¬=0 THEN /* If SQL CALL failed, */
DO;
PUT SKIP EDIT('SQL CALL failed due to SQLCODE = ',
SQLCODE) (A(34),A(14));
PUT SKIP EDIT('SQLERRM = ',
SQLERRM) (A(10),A(70));
END;
ELSE /* If the CALL worked, */
IF OUT_CODE¬=0 THEN /* Did GETPRML hit an error? */
PUT SKIP EDIT('GETPRML failed due to RC = ',
OUT_CODE) (A(33),A(14));
ELSE /* Everything worked. */
PUT SKIP EDIT('RUNOPTS = ', PARMLST) (A(11),A(200));
RETURN;
END CALPRML;

Figure 23. Calling a stored procedure from a PL/I program

Chapter 8. Coding SQL statements in PL/I application programs 399

Example PL/I stored procedure with a GENERAL linkage
convention
This example shows how to call a stored procedure that uses the GENERAL
linkage convention from a PL/I program.

This example stored procedure searches the DB2 SYSIBM.SYSROUTINES catalog

table for a row that matches the input parameters from the client program. The
two input parameters contain values for NAME and SCHEMA.

The linkage convention for this stored procedure is GENERAL.

The output parameters from this stored procedure contain the SQLCODE from the
SELECT operation, and the value of the RUNOPTS column retrieved from the
SYSIBM.SYSROUTINES table.

The CREATE PROCEDURE statement for this stored procedure might look like
this:
CREATE PROCEDURE GETPRML(PROCNM CHAR(18) IN, SCHEMA CHAR(8) IN,
OUTCODE INTEGER OUT, PARMLST VARCHAR(254) OUT)
LANGUAGE PLI
DETERMINISTIC
READS SQL DATA
EXTERNAL NAME "GETPRML"
COLLID GETPRML
ASUTIME NO LIMIT
PARAMETER STYLE GENERAL
STAY RESIDENT NO
RUN OPTIONS "MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)"
WLM ENVIRONMENT SAMPPROG
PROGRAM TYPE MAIN
SECURITY DB2
RESULT SETS 0
COMMIT ON RETURN NO;

The following example is a PL/I stored procedure with linkage convention

GENERAL.
*PROCESS SYSTEM(MVS);

GETPRML:
PROC(PROCNM, SCHEMA, OUT_CODE, PARMLST)
OPTIONS(MAIN NOEXECOPS REENTRANT);

DECLARE PROCNM CHAR(18), /* INPUT parm -- PROCEDURE name */

SCHEMA CHAR(8), /* INPUT parm -- User's SCHEMA */

OUT_CODE FIXED BIN(31), /* OUTPUT -- SQLCODE from */

/* the SELECT operation. */
PARMLST CHAR(254) /* OUTPUT -- RUNOPTS for */
VARYING; /* the matching row in */
/* SYSIBM.SYSROUTINES */

EXEC SQL INCLUDE SQLCA;

/************************************************************/
/* Execute SELECT from SYSIBM.SYSROUTINES in the catalog. */
/************************************************************/
EXEC SQL
SELECT RUNOPTS INTO :PARMLST
FROM SYSIBM.SYSROUTINES
WHERE NAME=:PROCNM AND
SCHEMA=:SCHEMA;

400 Application Programming and SQL Guide

OUT_CODE = SQLCODE; /* return SQLCODE to caller */
RETURN;
END GETPRML;

Example PL/I stored procedure with a GENERAL WITH NULLS

linkage convention
This example shows how to call a stored procedure that uses the GENERAL WITH
NULLS linkage convention from a PL/I program.

This example stored procedure searches the DB2 SYSIBM.SYSROUTINES catalog

table for a row that matches the input parameters from the client program. The
two input parameters contain values for NAME and SCHEMA.

The linkage convention for this stored procedure is GENERAL WITH NULLS.

The output parameters from this stored procedure contain the SQLCODE from the
SELECT operation, and the value of the RUNOPTS column retrieved from the
SYSIBM.SYSROUTINES table.

The CREATE PROCEDURE statement for this stored procedure might look like
this:
CREATE PROCEDURE GETPRML(PROCNM CHAR(18) IN, SCHEMA CHAR(8) IN,
OUTCODE INTEGER OUT, PARMLST VARCHAR(254) OUT)
LANGUAGE PLI
DETERMINISTIC
READS SQL DATA
EXTERNAL NAME "GETPRML"
COLLID GETPRML
ASUTIME NO LIMIT
PARAMETER STYLE GENERAL WITH NULLS
STAY RESIDENT NO
RUN OPTIONS "MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)"
WLM ENVIRONMENT SAMPPROG
PROGRAM TYPE MAIN
SECURITY DB2
RESULT SETS 0
COMMIT ON RETURN NO;

The following example is a PL/I stored procedure with linkage convention

GENERAL WITH NULLS.
*PROCESS SYSTEM(MVS);

GETPRML:
PROC(PROCNM, SCHEMA, OUT_CODE, PARMLST, INDICATORS)
OPTIONS(MAIN NOEXECOPS REENTRANT);

DECLARE PROCNM CHAR(18), /* INPUT parm -- PROCEDURE name */

SCHEMA CHAR(8), /* INPUT parm -- User's schema */

OUT_CODE FIXED BIN(31), /* OUTPUT -- SQLCODE from */

/* the SELECT operation. */
PARMLST CHAR(254) /* OUTPUT -- PARMLIST for */
VARYING; /* the matching row in */
/* SYSIBM.SYSROUTINES */
DECLARE 1 INDICATORS, /* Declare null indicators for */
/* input and output parameters. */
3 PROCNM_IND FIXED BIN(15),
3 SCHEMA_IND FIXED BIN(15),
3 OUT_CODE_IND FIXED BIN(15),
3 PARMLST_IND FIXED BIN(15);

Chapter 8. Coding SQL statements in PL/I application programs 401

EXEC SQL INCLUDE SQLCA;

IF PROCNM_IND<0 |
SCHEMA_IND<0 THEN
DO; /* If any input parm is NULL, */
OUT_CODE = 9999; /* Set output return code. */
OUT_CODE_IND = 0;
/* Output return code is not NULL.*/
PARMLST_IND = -1; /* Assign NULL value to PARMLST. */
END;
ELSE /* If input parms are not NULL, */
DO; /* */
/************************************************************/
/* Issue the SQL SELECT against the SYSIBM.SYSROUTINES */
/* DB2 catalog table. */
/************************************************************/
EXEC SQL
SELECT RUNOPTS INTO :PARMLST
FROM SYSIBM.SYSROUTINES
WHERE NAME=:PROCNM AND
SCHEMA=:SCHEMA;
PARMLST_IND = 0; /* Mark PARMLST as not NULL. */

OUT_CODE = SQLCODE; /* return SQLCODE to caller */

OUT_CODE_IND = 0;
OUT_CODE_IND = 0; /* Output return code is not NULL.*/
END;
RETURN;

END GETPRML;

402 Application Programming and SQL Guide

Chapter 9. Coding SQL statements in REXX application
programs
When you code SQL statements in REXX application programs, you should follow
certain guidelines.

Defining the SQL communications area, SQLSTATE, and SQLCODE in

REXX
When DB2 prepares a REXX procedure that contains SQL statements, DB2
automatically includes an SQLCA in the procedure.

The REXX SQLCA differs from the SQLCA for other languages. The REXX SQLCA
consists of a set of separate variables, rather than a structure. If you use the
ADDRESS DSNREXX 'CONNECT' ssid syntax to connect to DB2, the SQLCA variables
are a set of simple variables. If you use the CALL SQLDBS 'ATTACH TO' syntax to
connect to DB2, the SQLCA variables are compound variables that begin with the
stem SQLCA.
Related tasks
“Checking the execution of SQL statements” on page 202
“Checking the execution of SQL statements by using the SQLCA” on page 203
“Checking the execution of SQL statements by using SQLCODE and SQLSTATE”
on page 207
“Defining the items that your program can use to check whether an SQL statement
executed successfully” on page 141

Defining SQL descriptor areas in REXX

If your program includes certain SQL statements, you must define at least one SQL
descriptor area (SQLDA). Depending on the context in which it is used, the
SQLDA stores information about prepared SQL statements or host variables. This
information can then be read by either the application program or DB2.

To define SQL descriptor areas:

Code the SQLDA declarations directly in your program.

Each SQLDA consists of a set of REXX variables with a common stem. The stem
must be a REXX variable name that contains no periods and is the same as the
value of descriptor-name that you specify when you use the SQLDA in an SQL
statement.

Restrictions:
v You must place SQLDA declarations before the first SQL statement that
references the data descriptor, unless you use the TWOPASS SQL processing
option.
v You cannot use the SQL INCLUDE statement for the SQLDA, because it is not
supported in COBOL.

© Copyright IBM Corp. 1983, 2009 403

Related tasks
“Defining SQL descriptor areas” on page 141

Equivalent SQL and REXX data types

All REXX data is string data. Therefore, when a REXX procedure assigns input
data to a column, DB2 converts the data from a string type to the column type.
When a REXX procedure assigns column data to an output variable, DB2 converts
the data from the column type to a string type.

When you assign input data to a DB2 table column, you can either let DB2
determine the type that your input data represents, or you can use an SQLDA to
tell DB2 the intended type of the input data.

When a REXX procedure assigns data to a column, it can either let DB2 determine
the data type or use an SQLDA to specify the intended data type. If the procedure
lets DB2 assign a data type for the input data, DB2 bases its choice on the input
string format.

The following table shows the SQL data types that DB2 assigns to input data and
the corresponding formats for that data. The two SQLTYPE values that are listed
for each data type are the value for a column that does not accept null values and
the value for a column that accepts null values.
Table 73. SQL input data types and REXX data formats
SQL data type SQLTYPE for
assigned by DB2 data type REXX input data format
INTEGER 496/497 A string of numerics that does not contain a decimal point or exponent
identifier. The first character can be a plus (+) or minus (-) sign. The
number that is represented must be between -2147483647 and 2147483647,
inclusive.
| BIGINT 492/493 A string of numbers that does not contain a decimal point or an exponent
| identifier. The first character can be a plus (+) or minus (-) sign. The
| number that is represented must be between -9223372036854775808 and
| -2147483648, inclusive, or between 2147483648 and 9223372036854775807.
DECIMAL(p,s) 484/485 One of the following formats:
v A string of numerics that contains a decimal point but no exponent
identifier. p represents the precision and s represents the scale of the
decimal number that the string represents. The first character can be a
plus (+) or minus (-) sign.
| v A string of numerics that does not contain a decimal point or an
| exponent identifier. The first character can be a plus (+) or minus (-)
| sign. The number that is represented is less than -9223372036854775808
| or greater than 9223372036854775807.
FLOAT 480/481 A string that represents a number in scientific notation. The string consists
of a series of numerics followed by an exponent identifier (an E or e
followed by an optional plus (+) or minus (-) sign and a series of
numerics). The string can begin with a plus (+) or minus (-) sign.

404 Application Programming and SQL Guide

Table 73. SQL input data types and REXX data formats (continued)
SQL data type SQLTYPE for
assigned by DB2 data type REXX input data format
VARCHAR(n) 448/449 One of the following formats:
v A string of length n, enclosed in single or double quotation marks.
v The character X or x, followed by a string enclosed in single or double
quotation marks. The string within the quotation marks has a length of
2*n bytes and is the hexadecimal representation of a string of n
characters.
v A string of length n that does not have a numeric or graphic format, and
does not satisfy either of the previous conditions.
VARGRAPHIC(n) 464/465 One of the following formats:
v The character G, g, N, or n, followed by a string enclosed in single or
double quotation marks. The string within the quotation marks begins
with a shift-out character (X’0E’) and ends with a shift-in character
(X’0F’). Between the shift-out character and shift-in character are n
double-byte characters.
v The characters GX, Gx, gX, or gx, followed by a string enclosed in single
or double quotation marks. The string within the quotation marks has a
length of 4*n bytes and is the hexadecimal representation of a string of n
double-byte characters.

For example, when DB2 executes the following statements to update the MIDINIT
column of the EMP table, DB2 must determine a data type for HVMIDINIT:
SQLSTMT="UPDATE EMP" ,
"SET MIDINIT = ?" ,
"WHERE EMPNO = '000200'"
"EXECSQL PREPARE S100 FROM :SQLSTMT"
HVMIDINIT='H'
"EXECSQL EXECUTE S100 USING" ,
":HVMIDINIT"

Because the data that is assigned to HVMIDINIT has a format that fits a character
data type, DB2 REXX Language Support assigns a VARCHAR type to the input
data.

If you do not assign a value to a host variable before you assign the host variable
to a column, DB2 returns an error code.
Related concepts
“Compatibility of SQL and language data types” on page 148

SQL statements in REXX programs

You can code SQL statements in a REXX procedure wherever you can use REXX
commands.

| DB2 REXX Language Support supports all dynamic SQL statements and the
| following static SQL statements:
| v CALL
| v CLOSE
| v CONNECT
| v DECLARE CURSOR
| v DESCRIBE prepared statement or table
| v DESCRIBE CURSOR

Chapter 9. Coding SQL statements in REXX application programs 405

| v DESCRIBE INPUT
| v DESCRIBE PROCEDURE
| v EXECUTE
| v EXECUTE IMMEDIATE
| v FETCH
| v OPEN
| v PREPARE
| v RELEASE connection
| v SET CONNECTION
| v SET CURRENT PACKAGE PATH
| v SET CURRENT PACKAGESET
| v SET host-variable = CURRENT DATE
| v SET host-variable = CURRENT DEGREE
| v SET host-variable = CURRENT MEMBER
| v SET host-variable = CURRENT PACKAGESET
| v SET host-variable = CURRENT PATH
| v SET host-variable = CURRENT SERVER
| v SET host-variable = CURRENT SQLID
| v SET host-variable = CURRENT TIME
| v SET host-variable = CURRENT TIMESTAMP
| v SET host-variable = CURRENT TIMEZONE

Each SQL statement in a REXX procedure must begin with EXECSQL, in either
upper-, lower-, or mixed-case. One of the following items must follow EXECSQL:
v An SQL statement enclosed in single or double quotation marks.
v A REXX variable that contains an SQL statement. The REXX variable must not
be preceded by a colon.

For example, you can use either of the following methods to execute the COMMIT
statement in a REXX procedure:
EXECSQL "COMMIT"
rexxvar="COMMIT"
EXECSQL rexxvar

| The following dynamic statements must be executed using EXECUTE IMMEDIATE

| or PREPARE and EXECUTE under DSNREXX:
| v DECLARE GLOBAL TEMPORARY TABLE
| v SET CURRENT DEBUG MODE
| v SET CURRENT DECFLOAT ROUNDING MODE
| v SET CURRENT MAINTAINED TABLE TYPES FOR OPTIMIZATION
| v SET CURRENT REFRESH AGE
| v SET CURRENT ROUTINE VERSION
| v SET SCHEMA

| You cannot execute a SELECT, INSERT, UPDATE, MERGE, or DELETE statement

| that contains host variables. Instead, you must execute PREPARE on the statement,
| with parameter markers substituted for the host variables, and then use the host
| variables in an EXECUTE, OPEN, or FETCH statement. See “Host variables” on
| page 143 for more information.

An SQL statement follows rules that apply to REXX commands. The SQL statement
can optionally end with a semicolon and can be enclosed in single or double
quotation marks, as in the following example:

406 Application Programming and SQL Guide

'EXECSQL COMMIT';

Comments: You cannot include REXX comments (/* ... */) or SQL comments (--)
within SQL statements. However, you can include REXX comments anywhere else
in the procedure.

Names:Continuation for SQL statements: SQL statements that span lines follow
REXX rules for statement continuation. You can break the statement into several
strings, each of which fits on a line, and separate the strings with commas or with
concatenation operators followed by commas. For example, either of the following
statements is valid:
EXECSQL ,
"UPDATE DSN8910.DEPT" ,
"SET MGRNO = '000010'" ,
"WHERE DEPTNO = 'D11'"
"EXECSQL " || ,
" UPDATE DSN8910.DEPT " || ,
" SET MGRNO = '000010'" || ,
" WHERE DEPTNO = 'D11'"

Including code: The EXECSQL INCLUDE statement is not valid for REXX. You
therefore cannot include externally defined SQL statements in a procedure.

Margins: Like REXX commands, SQL statements can begin and end anywhere on a
line.

You can use any valid REXX name that does not end with a period as a host
variable. However, host variable names should not begin with ’SQL’, ’RDI’, ’DSN’,
’RXSQL’, or ’QRW’. Variable names can be at most 64 bytes.

Nulls: A REXX null value and an SQL null value are different. The REXX language
has a null string (a string of length 0) and a null clause (a clause that contains only
blanks and comments). The SQL null value is a special value that is distinct from
all nonnull values and denotes the absence of a value. Assigning a REXX null
value to a DB2 column does not make the column value null.

Statement labels: You can precede an SQL statement with a label, in the same way
that you label REXX commands.

Handling errors and warnings: DB2 does not support the SQL WHENEVER
statement in a REXX procedure. To handle SQL errors and warnings, use the
following methods:
v To test for SQL errors or warnings, test the SQLCODE or SQLSTATE value and
the SQLWARN. values after each EXECSQL call. This method does not detect
errors in the REXX interface to DB2.
v To test for SQL errors or warnings or errors or warnings from the REXX
interface to DB2, test the REXX RC variable after each EXECSQL call. The
following table lists the values of the RC variable.
You can also use the REXX SIGNAL ON ERROR and SIGNAL ON FAILURE
keyword instructions to detect negative values of the RC variable and transfer
control to an error routine.
Table 74. REXX return codes after SQL statements
Return code Meaning
0 No SQL warning or error occurred.

Chapter 9. Coding SQL statements in REXX application programs 407

Table 74. REXX return codes after SQL statements (continued)
Return code Meaning
+1 An SQL warning occurred.
-1 An SQL error occurred.
-3 The first token after ADDRESS DSNREXX is in error. For a description of
the tokens allowed, see “Accessing the DB2 REXX language support
application programming interfaces” on page 409.

Related concepts
“Dynamic SQL” on page 162
“Rules for host variables in an SQL statement” on page 151
“Possible host languages for dynamic SQL applications” on page 166
Related tasks
“Determining whether a column value is null” on page 156
“Determining whether a retrieved value in a host variable is null or truncated” on
page 154
“Dynamically executing a data change statement” on page 191
“Dynamically executing an SQL statement by using EXECUTE IMMEDIATE” on
page 187
“Dynamically executing an SQL statement by using PREPARE and EXECUTE” on
page 189
“Enabling the dynamic statement cache” on page 195
“Handling SQL error codes” on page 215
“Including dynamic SQL for fixed-list SELECT statements in your program” on
page 167
“Including dynamic SQL for non-SELECT statements in your program” on page
166
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
“Inserting a single row by using a host variable” on page 158
“Inserting null values into columns by using indicator variables or arrays” on page
158
“Limiting CPU time for dynamic SQL statements by using the resource limit
facility” on page 200
“Retrieving a single row of data into host variables” on page 152
“Updating data by using host variables” on page 157

Delimiters in SQL statements in REXX programs

You must delimit SQL statements in your REXX program so that DB2 knows when
a particular SQL statement ends.

Delimit an SQL statement in your REXX program by preceding the statement with
EXECSQL. If the statement is in a literal string, enclose it in single or double
quotation marks.

408 Application Programming and SQL Guide

Accessing the DB2 REXX language support application
programming interfaces
DB2 REXX Language Support includes several application programming interfaces
that enable your REXX procedure to connect to a DB2 subsystem and execute SQL
statements.

DB2 REXX Language Support includes the following application programming

interfaces:
CONNECT
Connects the REXX procedure to a DB2 subsystem. You must execute
CONNECT before you can execute SQL statements. The syntax of CONNECT
is:

’CONNECT’ ’subsystem-ID’

ADDRESS DSNREXX REXX-variable

Note: CALL SQLDBS ’ATTACH TO’ ssid is equivalent to ADDRESS DSNREXX ’CONNECT’ ssid.

EXECSQL
Executes SQL statements in REXX procedures. The syntax of EXECSQL is:

EXECSQL ″SQL-statement″

ADDRESS DSNREXX REXX-variable

Notes:
1. CALL SQLEXEC is equivalent to EXECSQL.
2. EXECSQL can be enclosed in single or double quotation marks.

DISCONNECT
Disconnects the REXX procedure from a DB2 subsystem. You should execute
DISCONNECT to release resources that are held by DB2. The syntax of
DISCONNECT is:

’DISCONNECT’

ADDRESS DSNREXX

Note: CALL SQLDBS ’DETACH’ is equivalent to DISCONNECT.

These application programming interfaces are available through the DSNREXX

host command environment. To make DSNREXX available to the application,
invoke the RXSUBCOM function. The syntax is:

Chapter 9. Coding SQL statements in REXX application programs 409

RXSUBCOM ( ’ADD’ , ’DSNREXX’ , ’DSNREXX’ )

’DELETE’

The ADD function adds DSNREXX to the REXX host command environment table.
The DELETE function deletes DSNREXX from the REXX host command
environment table.

The following figure shows an example of REXX code that makes DSNREXX
available to an application.
'SUBCOM DSNREXX' /* HOST CMD ENV AVAILABLE? */
IF RC THEN /* IF NOT, MAKE IT AVAILABLE */
S_RC = RXSUBCOM('ADD','DSNREXX','DSNREXX')
/* ADD HOST CMD ENVIRONMENT */
ADDRESS DSNREXX /* SEND ALL COMMANDS OTHER */
/* THAN REXX INSTRUCTIONS TO */
/* DSNREXX */
/* CALL CONNECT, EXECSQL, AND */
. /* DISCONNECT INTERFACES */
.
.
S_RC = RXSUBCOM('DELETE','DSNREXX','DSNREXX')
/* WHEN DONE WITH */
/* DSNREXX, REMOVE IT. */

Ensuring that DB2 correctly interprets character input data in

REXX programs
DB2 REXX Language Support can incorrectly interpret character literals as graphic
or numeric literals unless you mark them correctly.

To ensure that DB2 correctly interprets character input data in REXX programs:

Precede and follow character literals with a double quotation mark, followed by a
single quotation mark, followed by another double quotation mark ("'").

Example: Specify the string the string 100 as "'"100"'".

Enclosing the string in apostrophes is not adequate, because REXX removes the
apostrophes when it assigns a literal to a variable. For example, suppose that you
want to pass the value in a host variable called stringvar to DB2. The value that
you want to pass is the string ’100’. First, you assign the string to the host variable
by issuing the following REXX command:
stringvar = '100'

After the command executes, stringvar contains the characters 100 (without the
apostrophes). DB2 REXX Language Support then passes the numeric value 100 to
DB2, which is not what you intended.
However, suppose that you write the following command:
stringvar = "'"100"'"

In this case, REXX assigns the string ’100’ to stringvar, including the single
quotation marks. DB2 REXX Language Support then passes the string ’100’ to DB2,
which is the desired result.

410 Application Programming and SQL Guide

Passing the data type of an input data type to DB2 for REXX
programs
In certain situations, you should tell DB2 the data type to use for input data in a
REXX program. For example, if you are assigning or comparing input data to
columns of type SMALLINT, CHAR, or GRAPHIC, you should tell DB2 to use
those data types.

DB2 does not assign data types of SMALLINT, CHAR, or GRAPHIC to input data.
If you assign or compare this data to columns of type SMALLINT, CHAR, or
GRAPHIC, DB2 must do more work than if the data types of the input data and
columns match.

To pass the data type of an input data type to DB2 for REXX programs:

Use an SQLDA.

Examples

Example of specifying CHAR as an input data type: Suppose that you want to
tell DB2 that the data with which you update the MIDINIT column of the EMP
table is of type CHAR, rather than VARCHAR. You need to set up an SQLDA that
contains a description of a CHAR column, and then prepare and execute the
UPDATE statement using that SQLDA, as shown in the following example.
INSQLDA.SQLD = 1 /* SQLDA contains one variable */
INSQLDA.1.SQLTYPE = 453 /* Type of the variable is CHAR, */
/* and the value can be null */
INSQLDA.1.SQLLEN = 1 /* Length of the variable is 1 */
INSQLDA.1.SQLDATA = 'H' /* Value in variable is H */
INSQLDA.1.SQLIND = 0 /* Input variable is not null */
SQLSTMT="UPDATE EMP" ,
"SET MIDINIT = ?" ,
"WHERE EMPNO = '000200'"
"EXECSQL PREPARE S100 FROM :SQLSTMT"
"EXECSQL EXECUTE S100 USING DESCRIPTOR :INSQLDA"

Example of specifying the input data type as DECIMAL with precision and
scale: Suppose that you want to tell DB2 that the data is of type DECIMAL with
precision and nonzero scale. You need to set up an SQLDA that contains a
description of a DECIMAL column, as shown in the following example.
INSQLDA.SQLD = 1 /* SQLDA contains one variable */
INSQLDA.1.SQLTYPE = 484 /* Type of variable is DECIMAL */
INSQLDA.1.SQLLEN.SQLPRECISION = 18 /* Precision of variable is 18 */
INSQLDA.1.SQLLEN.SQLSCALE = 8 /* Scale of variable is 8 */
INSQLDA.1.SQLDATA = 9876543210.87654321 /* Value in variable */

Setting the isolation level of SQL statements in a REXX

procedure
Isolation levels specify the locking behavior for SQL statements. You can set the
isolation level for SQL statements in your REXX procedures to repeatable read
(RR), read stability (RS), cursor stability (CS), or uncommitted read (UR).

To set the isolation level of SQL statements in a REXX procedure:

Execute the SET CURRENT PACKAGESET statement to select one of the following
DB2 REXX Language Support packages with the isolation level that you need.

Chapter 9. Coding SQL statements in REXX application programs 411

Table 75. DB2 REXX Language Support packages and associated isolation levels
Package namea Isolation level
DSNREXRR Repeatable read (RR)
DSNREXRS Read stability (RS)
DSNREXCS Cursor stability (CS)
DSNREXUR Uncommitted read (UR)

Note:
1. These packages enable your procedure to access DB2 and are bound when you
install DB2 REXX Language Support.
For example, to change the isolation level to cursor stability, execute the following
SQL statement:
"EXECSQL SET CURRENT PACKAGESET='DSNREXCS'"

Retrieving data from DB2 tables in REXX programs

Although all output data in REXX programs is string data, you can determine the
data type that the data represents from its format and from the data type of the
column from which the data was retrieved.

The following table gives the format for each type of output data.
Table 76. SQL output data types and REXX data formats
SQL data type REXX output data format
| SMALLINTINTEGERBIGINT A string of numerics that does not contain leading zeroes, a decimal point, or
| an exponent identifier. If the string represents a negative number, it begins
| with a minus (-) sign. The numeric value is between -9223372036854775808 and
| 9223372036854775807, inclusive.
DECIMAL(p,s) A string of numerics with one of the following formats:
v Contains a decimal point but not an exponent identifier. The string is
padded with zeroes to match the scale of the corresponding table column. If
the value represents a negative number, it begins with a minus (-) sign.
v Does not contain a decimal point or an exponent identifier. The numeric
value is less than -2147483647 or greater than 2147483647. If the value is
negative, it begins with a minus (-) sign.
FLOAT(n) REALDOUBLE A string that represents a number in scientific notation. The string consists of a
numeric, a decimal point, a series of numerics, and an exponent identifier. The
exponent identifier is an E followed by a minus (-) sign and a series of
numerics if the number is between -1 and 1. Otherwise, the exponent identifier
is an E followed by a series of numerics. If the string represents a negative
number, it begins with a minus (-) sign.
| DECFLOAT REXX emulates the DECFLOAT data type with DOUBLE, so support for
| DECFLOAT is limited to the REXX support for DOUBLE. The following special
| values are not supported:
| v INFINITY
| v SNAN
| v NAN
CHAR(n)VARCHAR(n) A character string of length n bytes. The string is not enclosed in single or
double quotation marks.
GRAPHIC(n) VARGRAPHIC(n) A string of length 2*n bytes. Each pair of bytes represents a double-byte
character. This string does not contain a leading G, is not enclosed in quotation
marks, and does not contain shift-out or shift-in characters.

412 Application Programming and SQL Guide

Because you cannot use the SELECT INTO statement in a REXX procedure, to
retrieve data from a DB2 table you must prepare a SELECT statement, open a
cursor for the prepared statement, and then fetch rows into host variables or an
SQLDA using the cursor. The following example demonstrates how you can
retrieve data from a DB2 table using an SQLDA:
SQLSTMT= ,
'SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME,' ,
' WORKDEPT, PHONENO, HIREDATE, JOB,' ,
' EDLEVEL, SEX, BIRTHDATE, SALARY,' ,
' BONUS, COMM' ,
' FROM EMP'
EXECSQL DECLARE C1 CURSOR FOR S1
EXECSQL PREPARE S1 INTO :OUTSQLDA FROM :SQLSTMT
EXECSQL OPEN C1
Do Until(SQLCODE ¬= 0)
EXECSQL FETCH C1 USING DESCRIPTOR :OUTSQLDA
If SQLCODE = 0 Then Do
Line = ''
Do I = 1 To OUTSQLDA.SQLD
Line = Line OUTSQLDA.I.SQLDATA
End I
Say Line
End
End

Cursors and statement names in REXX

In REXX applications that contain SQL statements, you must use a predefined set
of names for cursors or prepared statements.

The following names are valid for cursors and prepared statements in REXX
applications:
c1 to c100
Cursor names for DECLARE CURSOR, OPEN, CLOSE, and FETCH statements.
By default, c1 to c100 are defined with the WITH RETURN clause, and c51 to
c100 are defined with the WITH HOLD clause. You can use the ATTRIBUTES
clause of the PREPARE statement to override these attributes or add additional
attributes. For example, you might want to add attributes to make your cursor
scrollable.
c101 to c200
Cursor names for ALLOCATE, DESCRIBE, FETCH, and CLOSE statements that
are used to retrieve result sets in a program that calls a stored procedure.
s1 to s100
Prepared statement names for DECLARE STATEMENT, PREPARE, DESCRIBE,
and EXECUTE statements.

Use only the predefined names for cursors and statements. When you associate a
cursor name with a statement name in a DECLARE CURSOR statement, the cursor
name and the statement must have the same number. For example, if you declare
cursor c1, you need to declare it for statement s1:
EXECSQL 'DECLARE C1 CURSOR FOR S1'

Do not use any of the predefined names as host variables names.

Chapter 9. Coding SQL statements in REXX application programs 413

Programming examples in REXX
You can write DB2 programs in REXX. These programs can access a local or
remote DB2 subsystem and can execute static or dynamic SQL statements. This
information contains several such programming examples.

To prepare and run these applications, use the JCL in DSN910.SDSNSAMP as a

model for your JCL.
Related reference
“Programming examples” on page 227

Sample DB2 REXX application

This example REXX application accepts a table name as input and produces a
SELECT, INSERT, or UPDATE SQL statement or a LOAD utility statement for the
specified table as output.

The following example shows a complete DB2 REXX application named DRAW.
DRAW must be invoked from the command line of an ISPF edit session. DRAW
takes a table or view name as input and produces a SELECT, INSERT, or UPDATE
SQL statement or a LOAD utility control statement that includes the columns of
the table as output.

DRAW syntax:

%DRAW object-name (

SSID=ssid SELECT
TYPE= INSERT
UPDATE
LOAD

DRAW parameters:
object-name
The name of the table or view for which DRAW builds an SQL statement or
utility control statement. The name can be a one-, two-, or three-part name.
The table or view to which object-name refers must exist before DRAW can run.
object-name is a required parameter.
SSID=ssid
Specifies the name of the local DB2 subsystem.
S can be used as an abbreviation for SSID.
If you invoke DRAW from the command line of the edit session in SPUFI,
SSID=ssid is an optional parameter. DRAW uses the subsystem ID from the
DB2I Defaults panel.
TYPE=operation-type
The type of statement that DRAW builds.
T can be used as an abbreviation for TYPE.
operation-type has one of the following values:

414 Application Programming and SQL Guide

SELECT
Builds a SELECT statement in which the result table contains all
columns of object-name.
S can be used as an abbreviation for SELECT.
INSERT
Builds a template for an INSERT statement that inserts values into all
columns of object-name. The template contains comments that indicate
where the user can place column values.
I can be used as an abbreviation for INSERT.
UPDATE
Builds a template for an UPDATE statement that updates columns of
object-name. The template contains comments that indicate where the
user can place column values and qualify the update operation for
selected rows.
U can be used as an abbreviation for UPDATE.
LOAD
Builds a template for a LOAD utility control statement for object-name.
L can be used as an abbreviation for LOAD.
TYPE=operation-type is an optional parameter. The default is TYPE=SELECT.

DRAW data sets:

Edit data set
The data set from which you issue the DRAW command when you are in an
ISPF edit session. If you issue the DRAW command from a SPUFI session, this
data set is the data set that you specify in field 1 of the main SPUFI panel
(DSNESP01). The output from the DRAW command goes into this data set.

DRAW return codes:

Return code
Meaning
0 Successful completion.
12 An error occurred when DRAW edited the input file.
20 One of the following errors occurred:
v No input parameters were specified.
v One of the input parameters was not valid.
v An SQL error occurred when the output statement was generated.

Examples of DRAW invocation:

Generate a SELECT statement for table DSN8910.EMP at the local subsystem. Use
the default DB2I subsystem ID.

The DRAW invocation is:

DRAW DSN8910.EMP (TYPE=SELECT

The output is:

SELECT "EMPNO" , "FIRSTNME" , "MIDINIT" , "LASTNAME" , "WORKDEPT" ,
"PHONENO" , "HIREDATE" , "JOB" , "EDLEVEL" , "SEX" , "BIRTHDATE" ,
"SALARY" , "BONUS" , "COMM"
FROM DSN8910.EMP

Chapter 9. Coding SQL statements in REXX application programs 415

Generate a template for an INSERT statement that inserts values into table
DSN8910.EMP at location SAN_JOSE. The local subsystem ID is DSN.

The DRAW invocation is:

DRAW SAN_JOSE.DSN8910.EMP (TYPE=INSERT SSID=DSN

The output is:

INSERT INTO SAN_JOSE.DSN8910.EMP ( "EMPNO" , "FIRSTNME" , "MIDINIT" ,
"LASTNAME" , "WORKDEPT" , "PHONENO" , "HIREDATE" , "JOB" ,
"EDLEVEL" , "SEX" , "BIRTHDATE" , "SALARY" , "BONUS" , "COMM" )
VALUES (
-- ENTER VALUES BELOW COLUMN NAME DATA TYPE
, -- EMPNO CHAR(6) NOT NULL
, -- FIRSTNME VARCHAR(12) NOT NULL
, -- MIDINIT CHAR(1) NOT NULL
, -- LASTNAME VARCHAR(15) NOT NULL
, -- WORKDEPT CHAR(3)
, -- PHONENO CHAR(4)
, -- HIREDATE DATE
, -- JOB CHAR(8)
, -- EDLEVEL SMALLINT
, -- SEX CHAR(1)
, -- BIRTHDATE DATE
, -- SALARY DECIMAL(9,2)
, -- BONUS DECIMAL(9,2)
) -- COMM DECIMAL(9,2)

Generate a template for an UPDATE statement that updates values of table

DSN8910.EMP. The local subsystem ID is DSN.

The DRAW invocation is:

DRAW DSN8910.EMP (TYPE=UPDATE SSID=DSN

The output is:

UPDATE DSN8910.EMP SET
-- COLUMN NAME ENTER VALUES BELOW DATA TYPE
"EMPNO"= -- CHAR(6) NOT NULL
, "FIRSTNME"= -- VARCHAR(12) NOT NULL
, "MIDINIT"= -- CHAR(1) NOT NULL
, "LASTNAME"= -- VARCHAR(15) NOT NULL
, "WORKDEPT"= -- CHAR(3)
, "PHONENO"= -- CHAR(4)
, "HIREDATE"= -- DATE
, "JOB"= -- CHAR(8)
, "EDLEVEL"= -- SMALLINT
, "SEX"= -- CHAR(1)
, "BIRTHDATE"= -- DATE
, "SALARY"= -- DECIMAL(9,2)
, "BONUS"= -- DECIMAL(9,2)
, "COMM"= -- DECIMAL(9,2)
WHERE

Generate a LOAD control statement to load values into table DSN8910.EMP. The
local subsystem ID is DSN.

The draw invocation is:

DRAW DSN8910.EMP (TYPE=LOAD SSID=DSN

The output is:

416 Application Programming and SQL Guide

LOAD DATA INDDN SYSREC INTO TABLE DSN8910.EMP
( "EMPNO" POSITION( 1) CHAR(6)
, "FIRSTNME" POSITION( 8) VARCHAR
, "MIDINIT" POSITION( 21) CHAR(1)
, "LASTNAME" POSITION( 23) VARCHAR
, "WORKDEPT" POSITION( 39) CHAR(3)
NULLIF( 39)='?'
, "PHONENO" POSITION( 43) CHAR(4)
NULLIF( 43)='?'
, "HIREDATE" POSITION( 48) DATE EXTERNAL
NULLIF( 48)='?'
, "JOB" POSITION( 59) CHAR(8)
NULLIF( 59)='?'
, "EDLEVEL" POSITION( 68) SMALLINT
NULLIF( 68)='?'
, "SEX" POSITION( 71) CHAR(1)
NULLIF( 71)='?'
, "BIRTHDATE" POSITION( 73) DATE EXTERNAL
NULLIF( 73)='?'
, "SALARY" POSITION( 84) DECIMAL EXTERNAL(9,2)
NULLIF( 84)='?'
, "BONUS" POSITION( 90) DECIMAL EXTERNAL(9,2)
NULLIF( 90)='?'
, "COMM" POSITION( 96) DECIMAL EXTERNAL(9,2)
NULLIF( 96)='?'
)

DRAW source code:

/* REXX ***************************************************************/
L1 = WHEREAMI()
/*
DRAW creates basic SQL queries by retrieving the description of a
table. You must specify the name of the table or view to be queried.
You can specify the type of query you want to compose. You might need
to specify the name of the DB2 subsystem.
>>--DRAW-----tablename-----|---------------------------|-------><
|-(-|-Ssid=subsystem-name-|-|
| +-Select-+ |
|-Type=-|-Insert-|----|
|-Update-|
+--Load--+
Ssid=subsystem-name
subsystem-name specified the name of a DB2 subsystem.
Select
Composes a basic query for selecting data from the columns of a
table or view. If TYPE is not specified, SELECT is assumed.
Using SELECT with the DRAW command produces a query that would
retrieve all rows and all columns from the specified table. You
can then modify the query as needed.
A SELECT query of EMP composed by DRAW looks like this:
SELECT "EMPNO" , "FIRSTNME" , "MIDINIT" , "LASTNAME" , "WORKDEPT" ,
"PHONENO" , "HIREDATE" , "JOB" , "EDLEVEL" , "SEX" , "BIRTHDATE" ,
"SALARY" , "BONUS" , "COMM"
FROM DSN8910.EMP
If you include a location qualifier, the query looks like this:
SELECT "EMPNO" , "FIRSTNME" , "MIDINIT" , "LASTNAME" , "WORKDEPT" ,
"PHONENO" , "HIREDATE" , "JOB" , "EDLEVEL" , "SEX" , "BIRTHDATE" ,
"SALARY" , "BONUS" , "COMM"
FROM STLEC1.DSN8910.EMP
To use this SELECT query, type the other clauses you need. If
you are selecting from more than one table, use a DRAW command
for each table name you want represented.
Insert
Composes a basic query to insert data into the columns of a table
or view.
The following example shows an INSERT query of EMP that

Chapter 9. Coding SQL statements in REXX application programs 417

DRAW composed:
INSERT INTO DSN8910.EMP ( "EMPNO" , "FIRSTNME" , "MIDINIT" , "LASTNAME" ,
"WORKDEPT" , "PHONENO" , "HIREDATE" , "JOB" , "EDLEVEL" , "SEX" ,
"BIRTHDATE" , "SALARY" , "BONUS" , "COMM" )
VALUES (
-- ENTER VALUES BELOW COLUMN NAME DATA TYPE
, -- EMPNO CHAR(6) NOT NULL
, -- FIRSTNME VARCHAR(12) NOT NULL
, -- MIDINIT CHAR(1) NOT NULL
, -- LASTNAME VARCHAR(15) NOT NULL
, -- WORKDEPT CHAR(3)
, -- PHONENO CHAR(4)
, -- HIREDATE DATE
, -- JOB CHAR(8)
, -- EDLEVEL SMALLINT
, -- SEX CHAR(1)
, -- BIRTHDATE DATE
, -- SALARY DECIMAL(9,2)
, -- BONUS DECIMAL(9,2)
) -- COMM DECIMAL(9,2)
To insert values into EMP, type values to the left of the
column names.
Update
Composes a basic query to change the data in a table or view.
The following example shows an UPDATE query of EMP composed
by DRAW:
UPDATE DSN8910.EMP SET
-- COLUMN NAME ENTER VALUES BELOW DATA TYPE
"EMPNO"= -- CHAR(6) NOT NULL
, "FIRSTNME"= -- VARCHAR(12) NOT NULL
, "MIDINIT"= -- CHAR(1) NOT NULL
, "LASTNAME"= -- VARCHAR(15) NOT NULL
, "WORKDEPT"= -- CHAR(3)
, "PHONENO"= -- CHAR(4)
, "HIREDATE"= -- DATE
, "JOB"= -- CHAR(8)
, "EDLEVEL"= -- SMALLINT
, "SEX"= -- CHAR(1)
, "BIRTHDATE"= -- DATE
, "SALARY"= -- DECIMAL(9,2)
, "BONUS"= -- DECIMAL(9,2)
, "COMM"= -- DECIMAL(9,2)
WHERE
To use this UPDATE query, type the changes you want to make to
the right of the column names, and delete the lines you don't
need. Be sure to complete the WHERE clause.
Load
Composes a load statement to load the data in a table.
The following example shows a LOAD statement of EMP composed
by DRAW:
LOAD DATA INDDN SYSREC INTO TABLE DSN8910 .EMP
( "EMPNO" POSITION( 1) CHAR(6)
, "FIRSTNME" POSITION( 8) VARCHAR
, "MIDINIT" POSITION( 21) CHAR(1)
, "LASTNAME" POSITION( 23) VARCHAR
, "WORKDEPT" POSITION( 39) CHAR(3)
NULLIF( 39)='?'
, "PHONENO" POSITION( 43) CHAR(4)
NULLIF( 43)='?'
, "HIREDATE" POSITION( 48) DATE EXTERNAL
NULLIF( 48)='?'
, "JOB" POSITION( 59) CHAR(8)
NULLIF( 59)='?'
, "EDLEVEL" POSITION( 68) SMALLINT
NULLIF( 68)='?'
, "SEX" POSITION( 71) CHAR(1)
NULLIF( 71)='?'

418 Application Programming and SQL Guide

, "BIRTHDATE" POSITION( 73) DATE EXTERNAL
NULLIF( 73)='?'
, "SALARY" POSITION( 84) DECIMAL EXTERNAL(9,2)
NULLIF( 84)='?'
, "BONUS" POSITION( 90) DECIMAL EXTERNAL(9,2)
NULLIF( 90)='?'
, "COMM" POSITION( 96) DECIMAL EXTERNAL(9,2)
NULLIF( 96)='?'
)
To use this LOAD statement, type the changes you want to make,
and delete the lines you don't need.
*/
L2 = WHEREAMI()
/**********************************************************************/
/* TRACE ?R */
/**********************************************************************/
Address ISPEXEC
"ISREDIT MACRO (ARGS) NOPROCESS"
If ARGS = "" Then
Do
Do I = L1+2 To L2-2;Say SourceLine(I);End
Exit (20)
End
Parse Upper Var Args Table "(" Parms
Parms = Translate(Parms," ",",")
Type = "SELECT" /* Default */
SSID = "" /* Default */
"VGET (DSNEOV01)"
If RC = 0 Then SSID = DSNEOV01
If (Parms <> "") Then
Do Until(Parms = "")
Parse Var Parms Var "=" Value Parms
If Var = "T" | Var = "TYPE" Then Type = Value
Else
If Var = "S" | Var = "SSID" Then SSID = Value
Else
Exit (20)
End
"CONTROL ERRORS RETURN"
"ISREDIT (LEFTBND,RIGHTBND) = BOUNDS"
"ISREDIT (LRECL) = DATA_WIDTH" /*LRECL*/
BndSize = RightBnd - LeftBnd + 1
If BndSize > 72 Then BndSize = 72
"ISREDIT PROCESS DEST"
Select
When rc = 0 Then
'ISREDIT (ZDEST) = LINENUM .ZDEST'
When rc <= 8 Then /* No A or B entered */
Do
zedsmsg = 'Enter "A"/"B" line cmd'
zedlmsg = 'DRAW requires an "A" or "B" line command'
'SETMSG MSG(ISRZ001)'
Exit 12
End
When rc < 20 Then /* Conflicting line commands - edit sets message */
Exit 12
When rc = 20 Then
zdest = 0
Otherwise
Exit 12
End
SQLTYPE. = "UNKNOWN TYPE"
VCHTYPE = 448; SQLTYPES.VCHTYPE = 'VARCHAR'
CHTYPE = 452; SQLTYPES.CHTYPE = 'CHAR'
LVCHTYPE = 456; SQLTYPES.LVCHTYPE = 'VARCHAR'
VGRTYP = 464; SQLTYPES.VGRTYP = 'VARGRAPHIC'

Chapter 9. Coding SQL statements in REXX application programs 419

GRTYP = 468; SQLTYPES.GRTYP = 'GRAPHIC'
LVGRTYP = 472; SQLTYPES.LVGRTYP = 'VARGRAPHIC'
FLOTYPE = 480; SQLTYPES.FLOTYPE = 'FLOAT'
DCTYPE = 484; SQLTYPES.DCTYPE = 'DECIMAL'
INTYPE = 496; SQLTYPES.INTYPE = 'INTEGER'
SMTYPE = 500; SQLTYPES.SMTYPE = 'SMALLINT'
DATYPE = 384; SQLTYPES.DATYPE = 'DATE'
TITYPE = 388; SQLTYPES.TITYPE = 'TIME'
TSTYPE = 392; SQLTYPES.TSTYPE = 'TIMESTAMP'
Address TSO "SUBCOM DSNREXX" /* HOST CMD ENV AVAILABLE? */
IF RC THEN /* NO, LET'S MAKE ONE */
S_RC = RXSUBCOM('ADD','DSNREXX','DSNREXX') /* ADD HOST CMD ENV */
Address DSNREXX "CONNECT" SSID
If SQLCODE ^= 0 Then Call SQLCA
Address DSNREXX "EXECSQL DESCRIBE TABLE :TABLE INTO :SQLDA"
If SQLCODE ^= 0 Then Call SQLCA
Address DSNREXX "EXECSQL COMMIT"
Address DSNREXX "DISCONNECT"
If SQLCODE ^= 0 Then Call SQLCA
Select
When (Left(Type,1) = "S") Then
Call DrawSelect
When (Left(Type,1) = "I") Then
Call DrawInsert
When (Left(Type,1) = "U") Then
Call DrawUpdate
When (Left(Type,1) = "L") Then
Call DrawLoad
Otherwise EXIT (20)
End
Do I = LINE.0 To 1 By -1
LINE = COPIES(" ",LEFTBND-1)||LINE.I
'ISREDIT LINE_AFTER 'zdest' = DATALINE (Line)'
End
line1 = zdest + 1
'ISREDIT CURSOR = 'line1 0
Exit
/**********************************************************************/
WHEREAMI:; RETURN SIGL
/**********************************************************************/
/* Draw SELECT */
/**********************************************************************/
DrawSelect:
Line.0 = 0
Line = "SELECT"
Do I = 1 To SQLDA.SQLD
If I > 1 Then Line = Line ','
ColName = '"'SQLDA.I.SQLNAME'"'
Null = SQLDA.I.SQLTYPE//2
If Length(Line)+Length(ColName)+LENGTH(" ,") > BndSize THEN
Do
L = Line.0 + 1; Line.0 = L
Line.L = Line
Line = " "
End
Line = Line ColName
End I
If Line ^= "" Then
Do
L = Line.0 + 1; Line.0 = L
Line.L = Line
Line = " "
End
L = Line.0 + 1; Line.0 = L
Line.L = "FROM" TABLE
Return
/**********************************************************************/

420 Application Programming and SQL Guide

/* Draw INSERT */
/**********************************************************************/
DrawInsert:
Line.0 = 0
Line = "INSERT INTO" TABLE "("
Do I = 1 To SQLDA.SQLD
If I > 1 Then Line = Line ','
ColName = '"'SQLDA.I.SQLNAME'"'
If Length(Line)+Length(ColName) > BndSize THEN
Do
L = Line.0 + 1; Line.0 = L
Line.L = Line
Line = " "
End
Line = Line ColName
If I = SQLDA.SQLD Then Line = Line ')'
End I
If Line ^= "" Then
Do
L = Line.0 + 1; Line.0 = L
Line.L = Line
Line = " "
End
L = Line.0 + 1; Line.0 = L
Line.L = " VALUES ("
L = Line.0 + 1; Line.0 = L
Line.L = ,
"-- ENTER VALUES BELOW COLUMN NAME DATA TYPE"
Do I = 1 To SQLDA.SQLD
If SQLDA.SQLD > 1 & I < SQLDA.SQLD Then
Line = " , --"
Else
Line = " ) --"
Line = Line Left(SQLDA.I.SQLNAME,18)
Type = SQLDA.I.SQLTYPE
Null = Type//2
If Null Then Type = Type - 1
Len = SQLDA.I.SQLLEN
Prcsn = SQLDA.I.SQLLEN.SQLPRECISION
Scale = SQLDA.I.SQLLEN.SQLSCALE
Select
When (Type = CHTYPE ,
|Type = VCHTYPE ,
|Type = LVCHTYPE ,
|Type = GRTYP ,
|Type = VGRTYP ,
|Type = LVGRTYP ) THEN
Type = SQLTYPES.Type"("STRIP(LEN)")"
When (Type = FLOTYPE ) THEN
Type = SQLTYPES.Type"("STRIP((LEN*4)-11) ")"
When (Type = DCTYPE ) THEN
Type = SQLTYPES.Type"("STRIP(PRCSN)","STRIP(SCALE)")"
Otherwise
Type = SQLTYPES.Type
End
Line = Line Type
If Null = 0 Then
Line = Line "NOT NULL"
L = Line.0 + 1; Line.0 = L
Line.L = Line
End I
Return
/**********************************************************************/
/* Draw UPDATE */
/**********************************************************************/
DrawUpdate:

Chapter 9. Coding SQL statements in REXX application programs 421

Line.0 = 1
Line.1 = "UPDATE" TABLE "SET"
L = Line.0 + 1; Line.0 = L
Line.L = ,
"-- COLUMN NAME ENTER VALUES BELOW DATA TYPE"
Do I = 1 To SQLDA.SQLD
If I = 1 Then
Line = " "
Else
Line = " ,"
Line = Line Left('"'SQLDA.I.SQLNAME'"=',21)
Line = Line Left(" ",20)
Type = SQLDA.I.SQLTYPE
Null = Type//2
If Null Then Type = Type - 1
Len = SQLDA.I.SQLLEN
Prcsn = SQLDA.I.SQLLEN.SQLPRECISION
Scale = SQLDA.I.SQLLEN.SQLSCALE
Select
When (Type = CHTYPE ,
|Type = VCHTYPE ,
|Type = LVCHTYPE ,
|Type = GRTYP ,
|Type = VGRTYP ,
|Type = LVGRTYP ) THEN
Type = SQLTYPES.Type"("STRIP(LEN)")"
When (Type = FLOTYPE ) THEN
Type = SQLTYPES.Type"("STRIP((LEN*4)-11) ")"
When (Type = DCTYPE ) THEN
Type = SQLTYPES.Type"("STRIP(PRCSN)","STRIP(SCALE)")"
Otherwise
Type = SQLTYPES.Type
End
Line = Line "--" Type
If Null = 0 Then
Line = Line "NOT NULL"
L = Line.0 + 1; Line.0 = L
Line.L = Line
End I
L = Line.0 + 1; Line.0 = L
Line.L = "WHERE"
Return
/**********************************************************************/
/* Draw LOAD */
/**********************************************************************/
DrawLoad:
Line.0 = 1
Line.1 = "LOAD DATA INDDN SYSREC INTO TABLE" TABLE
Position = 1
Do I = 1 To SQLDA.SQLD
If I = 1 Then
Line = " ("
Else
Line = " ,"
Line = Line Left('"'SQLDA.I.SQLNAME'"',20)
Line = Line "POSITION("RIGHT(POSITION,5)")"
Type = SQLDA.I.SQLTYPE
Null = Type//2
If Null Then Type = Type - 1
Len = SQLDA.I.SQLLEN
Prcsn = SQLDA.I.SQLLEN.SQLPRECISION
Scale = SQLDA.I.SQLLEN.SQLSCALE
Select
When (Type = CHTYPE ,
|Type = GRTYP ) THEN
Type = SQLTYPES.Type"("STRIP(LEN)")"
When (Type = FLOTYPE ) THEN

422 Application Programming and SQL Guide

Type = SQLTYPES.Type"("STRIP((LEN*4)-11) ")"
When (Type = DCTYPE ) THEN
Do
Type = SQLTYPES.Type "EXTERNAL"
Type = Type"("STRIP(PRCSN)","STRIP(SCALE)")"
Len = (PRCSN+2)%2
End
When (Type = DATYPE ,
|Type = TITYPE ,
|Type = TSTYPE ) THEN
Type = SQLTYPES.Type "EXTERNAL"
Otherwise
Type = SQLTYPES.Type
End
If (Type = GRTYP ,
|Type = VGRTYP ,
|Type = LVGRTYP ) THEN
Len = Len * 2
If (Type = VCHTYPE ,
|Type = LVCHTYPE ,
|Type = VGRTYP ,
|Type = LVGRTYP ) THEN
Len = Len + 2
Line = Line Type
L = Line.0 + 1; Line.0 = L
Line.L = Line
If Null = 1 Then
Do
Line = " "
Line = Line Left('',20)
Line = Line " NULLIF("RIGHT(POSITION,5)")='?'"
L = Line.0 + 1; Line.0 = L
Line.L = Line
End
Position = Position + Len + 1
End I
L = Line.0 + 1; Line.0 = L
Line.L = " )"
Return
/**********************************************************************/
/* Display SQLCA */
/**********************************************************************/
SQLCA:
"ISREDIT LINE_AFTER "zdest" = MSGLINE 'SQLSTATE="SQLSTATE"'"
"ISREDIT LINE_AFTER "zdest" = MSGLINE 'SQLWARN ="SQLWARN.0",",
|| SQLWARN.1",",
|| SQLWARN.2",",
|| SQLWARN.3",",
|| SQLWARN.4",",
|| SQLWARN.5",",
|| SQLWARN.6",",
|| SQLWARN.7",",
|| SQLWARN.8",",
|| SQLWARN.9",",
|| SQLWARN.10"'"
"ISREDIT LINE_AFTER "zdest" = MSGLINE 'SQLERRD ="SQLERRD.1",",
|| SQLERRD.2",",
|| SQLERRD.3",",
|| SQLERRD.4",",
|| SQLERRD.5",",
|| SQLERRD.6"'"
"ISREDIT LINE_AFTER "zdest" = MSGLINE 'SQLERRP ="SQLERRP"'"
"ISREDIT LINE_AFTER "zdest" = MSGLINE 'SQLERRMC ="SQLERRMC"'"
"ISREDIT LINE_AFTER "zdest" = MSGLINE 'SQLCODE ="SQLCODE"'"
Exit 20

Chapter 9. Coding SQL statements in REXX application programs 423

Example of how an indicator variable is used in a REXX program
The way that you use indicator variables for input host variables in REXX
procedures is slightly different than the way that you use indicator variables in
other languages. When you want to pass a null value to a DB2 column, in addition
to putting a negative value in an indicator variable, you also need to put a valid
value in the corresponding host variable.

For example, the following statements set a value in the WORKDEPT column in
table EMP to null:
SQLSTMT="UPDATE EMP" ,
"SET WORKDEPT = ?"
HVWORKDEPT='000'
INDWORKDEPT=-1
"EXECSQL PREPARE S100 FROM :SQLSTMT"
"EXECSQL EXECUTE S100 USING :HVWORKDEPT :INDWORKDEPT"

In the following program, the phone number for employee Haas is selected into
variable HVPhone. After the SELECT statement executes, if no phone number for
employee Haas is found, indicator variable INDPhone contains -1.
'SUBCOM DSNREXX'
IF RC THEN ,
S_RC = RXSUBCOM('ADD','DSNREXX','DSNREXX')
ADDRESS DSNREXX
'CONNECT' 'DSN'
SQLSTMT = ,
"SELECT PHONENO FROM DSN8910.EMP WHERE LASTNAME='HAAS'"
"EXECSQL DECLARE C1 CURSOR FOR S1"
"EXECSQL PREPARE S1 FROM :SQLSTMT"
Say "SQLCODE from PREPARE is "SQLCODE
"EXECSQL OPEN C1"
Say "SQLCODE from OPEN is "SQLCODE
"EXECSQL FETCH C1 INTO :HVPhone :INDPhone"
Say "SQLCODE from FETCH is "SQLCODE
If INDPhone < 0 Then ,
Say 'Phone number for Haas is null.'
"EXECSQL CLOSE C1"
Say "SQLCODE from CLOSE is "SQLCODE
S_RC = RXSUBCOM('DELETE','DSNREXX','DSNREXX')

424 Application Programming and SQL Guide

Chapter 10. Creating and modifying DB2 objects
Your application program can create and manipulate DB2 objects, such as tables,
views, triggers, distinct types, user-defined functions, and stored procedures. You
must have the appropriate authorizations to create such objects.

Creating tables
Creating a table provides a logically place to store related data on a DB2
subsystem.

To create a table, use a CREATE TABLE statement that includes the following
elements:
v The name of the table
v A list of the columns that make up the table. For each column, specify the
following information:
– The column’s name (for example, SERIAL).
– The data type and length attribute (for example, CHAR(8)).
– Optionally, a default value.
– Optionally, a referential constraint or check constraint.
Separate each column description from the next with a comma, and enclose the
entire list of column descriptions in parentheses.

Example:The following SQL statement creates a table named PRODUCT:

CREATE TABLE PRODUCT
(SERIAL CHAR(8) NOT NULL,
DESCRIPTION VARCHAR(60) DEFAULT,
MFGCOST DECIMAL(8,2),
MFGDEPT CHAR(3),
MARKUP SMALLINT,
SALESDEPT CHAR(3),
CURDATE DATE DEFAULT);

For more information about referential constraints, see “Referential constraints” on

page 435

For more information about check constraints, see “Check constraints” on page
434.

Identifying column defaults and constraining column inputs:

If you want to constrain the input or identify the default of a column, you can use
the following values:
v NOT NULL, when the column cannot contain null values.
v UNIQUE, when the value for each row must be unique, and the column cannot
contain null values.
v DEFAULT, when the column has one of the following DB2-assigned defaults:
– For numeric columns, 0 (zero) is the default value.
– For character or graphic fixed-length strings, blank is the default value.
– For binary fixed-length strings, a set of hexadecimal zeros is the default value.

© Copyright IBM Corp. 1983, 2009 425

– For variable-length strings, including LOB strings, the empty string (a string
of zero-length) is the default value.
– For datetime columns, the current value of the associated special register is
the default value.
v DEFAULT value, when you want to identify one of the following values as the
default value:
– A constant
– NULL
– SESSION_USER, which specifies the value of the SESSION_USER special
register at the time when a default value is needed for the column
– CURRENT SQLID, which specifies the value of the CURRENT SQLID special
register at the time when a default value is needed for the column
– The name of a cast function that casts a default value (of a built-in data type)
to the distinct type of a column

Data types
When you create a DB2 table, you define each column to have a specific data type.
The data type of a column determines what you can and cannot do with the
column.

When you perform operations on columns, the data must be compatible with the
data type of the referenced column. For example, you cannot insert character data,
such as a last name, into a column whose data type is numeric. Similarly, you
cannot compare columns that contain incompatible data types.

The data type for a column can be a distinct type, which is a user-defined data
type, or a DB2 built-in data type. As shown in the following figure, DB2 built-in
data types have four general categories: datetime, string, numeric, and row
identifier (ROWID).

426 Application Programming and SQL Guide

Figure 24. DB2 built-in data types

The following table shows whether operands of any two data types are compatible,
Y (Yes), or incompatible, N (No). Notes are indicated either as a superscript
number next to Y or N or as a value in the column of the table.
Table 77. Supported casts between built-in data types
To data type1

V
| A V T
| S D R A I
| M I D E V G G R M
| A N B E C D A R R D B B E
| L T I C F O R A A B I I S R
| L E G I L R U C C C P P C N N B D T T O
| I G I M O E B H H L H H L A A L A I A W X
| Cast from N E N A A A L A A O I I O R R O T M M I M
| data type – T R T L T L E R R B C C B Y Y B E E P D L
SMALLINT Y Y Y Y Y Y Y Y Y
INTEGER Y Y Y Y Y Y Y Y Y
BIGINT Y Y Y Y Y Y Y Y Y
DECIMAL Y Y Y Y Y Y Y Y Y
| DECFLOAT Y Y Y Y Y Y Y Y Y
REAL Y Y Y Y Y Y Y Y Y
DOUBLE Y Y Y Y Y Y Y Y Y

Chapter 10. Creating and modifying DB2 objects 427

Table 77. Supported casts between built-in data types (continued)
To data type1

V
| A V T
| S D R A I
| M I D E V G G R M
| A N B E C D A R R D B B E
| L T I C F O R A A B I I S R
| L E G I L R U C C C P P C N N B D T T O
| I G I M O E B H H L H H L A A L A I A W X
| Cast from N E N A A A L A A O I I O R R O T M M I M
| data type – T R T L T L E R R B C C B Y Y B E E P D L
CHAR Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
VARCHAR Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y
CLOB Y Y Y Y Y Y Y Y Y
2 2 2
GRAPHIC Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y3 Y3 Y3
VARGRAPHIC Y Y Y Y Y Y Y Y2 Y2 Y2 Y Y Y Y Y Y Y Y Y
2 2 2
DBCLOB Y Y Y Y Y Y Y Y Y
BINARY Y Y Y
VARBINARY Y Y Y
BLOB Y Y Y
DATE Y Y Y
TIME Y Y Y
TIMESTAMP Y Y Y Y Y
ROWID Y Y Y Y Y Y
| XML Y
Note:
1. Other synonyms for the listed data types are considered to be the same as the synonym listed. Some exceptions
exist when the cast involves character string data if the subtype is FOR BIT DATA.
2. The result length for these casts is 3 * LENGTH(graphic string).
3. These data types are castable between each other only if the data is Unicode.

Related concepts
“Distinct types” on page 477
Data types (SQL Reference)

Storing LOB data in a table

Because DB2 handles LOB data differently than other kinds of data, in some cases,
you need to take additional actions when defining LOB columns and inserting the
LOB data.

To store LOB data in DB2:

1. Define one or more columns of the appropriate LOB type and optionally a row
identifier (ROWID) column by executing a CREATE TABLE statement or one or
more ALTER TABLE statements.

428 Application Programming and SQL Guide

Define only one ROWID column, even if the table is to have multiple LOB
columns. If you do not create a ROWID column before you define a LOB
column, DB2 creates an implicitly hidden ROWID column and appends it as
the last column of the table.
If you add a ROWID column after you add a LOB column, the table has two
ROWID columns: the implicitly-created, hidden, column and the
explicitly-created column. In this case, DB2 ensures that the values of the two
ROWID columns are always identical.
| If DB2 implicitly creates the table space for this table or CURRENT RULES is
| set to STD, DB2 creates the necessary auxiliary objects for you and you can
| skip steps 2 and 3.
2. If you explicitly created the table space for this table and the CURRENT RULES
special register is not set to STD, create a LOB table space and auxiliary table
by using the CREATE LOB TABLESPACE and CREATE AUXILIARY TABLE
statements.
v If your base table is nonpartitioned, create one LOB table space and for each
column create one auxiliary table.
v If your base table is partitioned, create one LOB table space for each partition
and one auxiliary table for each column. For example, if your base table has
three partitions, you must create three LOB table spaces and three auxiliary
tables for each LOB column.
3. If you explicitly created the table space for this table and the CURRENT RULES
special register is not set to STD, create one index for each auxiliary table by
using the CREATE INDEX statement.
4. Insert the LOB data into DB2 by using one of the following techniques:
v If the total length of a LOB column and the base table row is less than 32 KB,
use the LOAD utility and specify the base table.
| v Otherwise, use INSERT, UPDATE, or MERGE statements and specify the
| base table. If you use the INSERT statement, ensure that you application has
| enough storage available to hold the entire value that is to be put into the
| LOB column.

Example: Adding a CLOB column: Suppose that you want to add a resume for
each employee to the employee table. The employee resumes are no more than 5
MB in size. Because the employee resumes contain single-byte characters, you can
define the resumes to DB2 as CLOBs. You therefore need to add a column of data
type CLOB with a length of 5 MB to the employee table. If you want to define a
ROWID column explicitly, you must define it before you define the CLOB column.

First, execute an ALTER TABLE statement to add the ROWID column, and then
execute another ALTER TABLE statement to add the CLOB column. The following
statements create these columns:
ALTER TABLE EMP
ADD ROW_ID ROWID NOT NULL GENERATED ALWAYS;
COMMIT;
ALTER TABLE EMP
ADD EMP_RESUME CLOB(5M);
COMMIT;

| If you explicitly created the table space for this table and the CURRENT RULES
| special register is not set to STD, you then need to define a LOB table space and an
| auxiliary table to hold the employee resumes. You also need to define an index on
| the auxiliary table. You must define the LOB table space in the same database as
| the associated base table. The following statements create these objects:

Chapter 10. Creating and modifying DB2 objects 429

| CREATE LOB TABLESPACE RESUMETS
| IN DSN8D91A
| LOG NO
| COMPRESS YES;
| COMMIT;
| CREATE AUXILIARY TABLE EMP_RESUME_TAB
| IN DSN8D91A.RESUMETS
| STORES DSN8910.EMP
| COLUMN EMP_RESUME;
| CREATE UNIQUE INDEX XEMP_RESUME
| ON EMP_RESUME_TAB;
| COMMIT;

| You can then load your employee resumes into DB2. In your application, you can
define a host variable to hold the resume, copy the resume data from a file into the
host variable, and then execute an UPDATE statement to copy the data into DB2.
Although the LOB data is stored in the auxiliary table, your UPDATE statement
specifies the name of the base table. The following code declares a host variable to
store the resume in the C language:
SQL TYPE is CLOB (5M) resumedata;

The following UPDATE statement copies the data into DB2:

UPDATE EMP SET EMP_RESUME=:resumedata
WHERE EMPNO=:employeenum;

In this statement, employeenum is a host variable that identifies the employee who
is associated with a resume.

Large objects (LOBs)

The term large object and the acronym LOB refer to DB2 objects that you can use to
store large amounts of data. A LOB is a varying-length character string that can
contain up to 2 GB - 1 of data.

The three LOB data types are:

v Binary large object (BLOB)
Use a BLOB to store binary data such as pictures, voice, and mixed media.
v Character large object (CLOB)
Use a CLOB to store SBCS or mixed character data, such as documents.
v Double-byte character large object (DBCLOB)
Use a DBCLOB to store data that consists of only DBCS data.

You can use DB2 to store LOB data, but this data is stored differently than other
kinds of data.

Although a table can have a LOB column, the actual LOB data is stored in a
another table, which called the auxiliary table. This auxiliary table exists in a
separate table space called a LOB table space. One auxiliary table must exist for
each LOB column. The table with the LOB column is called the base table. The
base table has a ROWID column that DB2 uses to locate the data in the auxiliary
table. The auxiliary table must have exactly one index.

Implicitly hidden ROWID columns

If you do not create a ROWID column before you define a LOB column, DB2
creates an implicitly hidden ROWID column for you. This column is accessible
only if you reference the column directly. It is not included in the results of
SELECT * statements or DESCRIBE statements.

430 Application Programming and SQL Guide

DB2 assigns the GENERATED ALWAYS attribute and the name
DB2_GENERATED_ROWID_FOR_LOBSnn to a an implicitly hidden ROWID
column. DB2 appends the identifier nn only if the column name already exists in
the table. If so, DB2 appends 00 and increments by 1 until the name is unique
within the row.

For more information about when DB2 creates implicitly hidden ROWID columns,
see the following topics in DB2 SQL Reference:
v “CREATE TABLE”
v “ALTER TABLE”
v “ALTER VIEW”

For more information about selecting hidden columns, see the topic “select-clause”
in DB2 SQL Reference.

Identity columns
An identity column contains a unique numeric value for each row in the table.
DB2 can automatically generate sequential numeric values for this column as rows
are inserted into the table. Thus, identity columns are ideal for primary key values,
such as employee numbers or product numbers.

Using identity columns as keys:

If you define a column with the AS IDENTITY attribute, and with the
GENERATED ALWAYS and NO CYCLE attributes, DB2 automatically generates a
monotonically increasing or decreasing sequential number for the value of that
column when a new row is inserted into the table. However, for DB2 to guarantee
that the values of the identity column are unique, you should define a unique
index on that column.

You can use identity columns for primary keys that are typically unique sequential
numbers, for example, order numbers or employee numbers. By doing so, you can
avoid the concurrency problems that can result when an application generates its
own unique counter outside the database.

Recommendation: Set the values of the foreign keys in the dependent tables after
loading the parent table. If you use an identity column as a parent key in a
referential integrity structure, loading data into that structure could be quite
complicated. The values for the identity column are not known until the table is
loaded because the column is defined as GENERATED ALWAYS.

You might have gaps in identity column values for the following reasons:
v If other applications are inserting values into the same identity column
v If DB2 terminates abnormally before it assigns all the cached values
v If your application rolls back a transaction that inserts identity values

Defining an identity column:

You can define an identity column as either GENERATED BY DEFAULT or

GENERATED ALWAYS:
v If you define the column as GENERATED BY DEFAULT, you can insert a value,
and DB2 provides a default value if you do not supply one.
v If you define the column as GENERATED ALWAYS, DB2 always generates a
value for the column, and you cannot insert data into that column. If you want

Chapter 10. Creating and modifying DB2 objects 431

the values to be unique, you must define the identity column with GENERATED
ALWAYS and NO CYCLE and define a unique index on that column.
For more information, see “Rules for inserting data into an identity column” on
page 608.

The values that DB2 generates for an identity column depend on how the column
is defined. The START WITH option determines the first value that DB2 generates.
The values advance by the INCREMENT BY value in ascending or descending
order.

The MINVALUE and MAXVALUE options determine the minimum and maximum
values that DB2 generates. The CYCLE or NO CYCLE option determines whether
DB2 wraps values when it has generated all values between the START WITH
value and MAXVALUE if the values are ascending, or between the START WITH
value and MINVALUE if the values are descending.

Example: Suppose that table T1 is defined with GENERATED ALWAYS and

CYCLE:
CREATE TABLE T1
(CHARCOL1 CHAR(1),
IDENTCOL1 SMALLINT GENERATED ALWAYS AS IDENTITY
(START WITH -1,
INCREMENT BY 1,
CYCLE,
MINVALUE -3,
MAXVALUE 3));

Now suppose that you execute the following INSERT statement eight times:
INSERT INTO T1 (CHARCOL1) VALUES ('A');

When DB2 generates values for IDENTCOL1, it starts with -1 and increments by 1
until it reaches the MAXVALUE of 3 on the fifth INSERT. To generate the value for
the sixth INSERT, DB2 cycles back to MINVALUE, which is -3. T1 looks like this
after the eight INSERTs are executed:
CHARCOL1 IDENTCOL1
======== =========
A -1
A 0
A 1
A 2
A 3
A -3
A -2
A -1

The value of IDENTCOL1 for the eighth INSERT repeats the value of IDENTCOL1
for the first INSERT.

Identity columns as primary keys:

The SELECT from INSERT statement enables you to insert a row into a parent
table with its primary key defined as a DB2-generated identity column, and
retrieve the value of the primary or parent key. You can then use this generated
value as a foreign key in a dependent table. For information about the SELECT
from INSERT statement, see “Selecting values while inserting data” on page 613.

432 Application Programming and SQL Guide

In addition, you can use the IDENTITY_VAL_LOCAL function to return the most
recently assigned value for an identity column. For more information about the
IDENTITY_VAL_LOCAL function, see the topic “IDENTITY_VAL_LOCAL” in DB2
SQL Reference.

Example: Using SELECT from INSERT: Suppose that an EMPLOYEE table and a
DEPARTMENT table are defined in the following way:
CREATE TABLE EMPLOYEE
(EMPNO INTEGER GENERATED ALWAYS AS IDENTITY
PRIMARY KEY NOT NULL,
NAME CHAR(30) NOT NULL,
SALARY DECIMAL(7,2) NOT NULL,
WORKDEPT SMALLINT);

CREATE TABLE DEPARTMENT

(DEPTNO SMALLINT NOT NULL PRIMARY KEY,
DEPTNAME VARCHAR(30),
MGRNO INTEGER NOT NULL,
CONSTRAINT REF_EMPNO FOREIGN KEY (MGRNO)
REFERENCES EMPLOYEE (EMPNO) ON DELETE RESTRICT);

ALTER TABLE EMPLOYEE ADD

CONSTRAINT REF_DEPTNO FOREIGN KEY (WORKDEPT)
REFERENCES DEPARTMENT (DEPTNO) ON DELETE SET NULL;

When you insert a new employee into the EMPLOYEE table, to retrieve the value
for the EMPNO column, you can use the following SELECT from INSERT
statement:
EXEC SQL
SELECT EMPNO INTO :hv_empno
FROM FINAL TABLE (INSERT INTO EMPLOYEE (NAME, SALARY, WORKDEPT)
VALUES ('New Employee', 75000.00, 11));

The SELECT statement returns the DB2-generated identity value for the EMPNO
column in the host variable :hv_empno.

You can then use the value in :hv_empno to update the MGRNO column in the
DEPARTMENT table with the new employee as the department manager:
EXEC SQL
UPDATE DEPARTMENT
SET MGRNO = :hv_empno
WHERE DEPTNO = 11;

Creating tables for data integrity

You can use entities such as constraints, triggers, and unique indexes to ensure that
only valid data is added to your tables. For example, you might need to ensure
that all items in your inventory table have valid item numbers and prevent items
without valid item numbers from being added.

Ways to maintain data integrity

When you add or modify data in a DB2 table, you need to ensure that the data is
valid. Two techniques that you can use to ensure valid data are constraints and
triggers.

Constraints are rules that limit the values that you can insert, delete, or update in a
table. There are two types of constraints:
v Check constraints determine the values that a column can contain. Check
constraints are discussed in “Check constraints” on page 434.

Chapter 10. Creating and modifying DB2 objects 433

v Referential constraints preserve relationships between tables. Referential
constraints are discussed in “Referential constraints” on page 435. A specific type
of referential constraints, the informational referential constraint, is discussed in
“Informational referential constraints” on page 438.

Triggers are a series of actions that are invoked when a table is updated. Triggers
are discussed in “Creating triggers” on page 457.

Check constraints:

A check constraint is a rule that specifies the values that are allowed in one or more
columns of every row of a base table. For example, you can define a check
constraint to ensure that all values in a column that contains ages are positive
numbers.

Check constraints designate the values that specific columns of a base table can
contain, providing you a method of controlling the integrity of data entered into
tables. You can create tables with check constraints using the CREATE TABLE
statement, or you can add the constraints with the ALTER TABLE statement.
However, if the check integrity is compromised or cannot be guaranteed for a
table, the table space or partition that contains the table is placed in a check
pending state. Check integrity is the condition that exists when each row of a table
conforms to the check constraints defined on that table.

For example, you might want to make sure that no salary can be below 15000
dollars. To do this, you can create the following check constraint:
CREATE TABLE EMPSAL
(ID INTEGER NOT NULL,
SALARY INTEGER CHECK (SALARY >= 15000));

Using check constraints makes your programming task easier, because you do not
need to enforce those constraints within application programs or with a validation
routine. Define check constraints on one or more columns in a table when that
table is created or altered.

Check constraint considerations

The syntax of a check constraint is checked when the constraint is defined, but the
meaning of the constraint is not checked. The following examples show mistakes
that are not caught. Column C1 is defined as INTEGER NOT NULL.

Allowable but mistaken check constraints:

v A self-contradictory check constraint:
CHECK (C1 > 5 AND C1 < 2)
v Two check constraints that contradict each other:
CHECK (C1 > 5)
CHECK (C1 < 2)
v Two check constraints, one of which is redundant:
CHECK (C1 > 0)
CHECK (C1 >= 1)
v A check constraint that contradicts the column definition:
CHECK (C1 IS NULL)
v A check constraint that repeats the column definition:
CHECK (C1 IS NOT NULL)

434 Application Programming and SQL Guide

A check constraint is not checked for consistency with other types of constraints.
For example, a column in a dependent table can have a referential constraint with
a delete rule of SET NULL. You can also define a check constraint that prohibits
nulls in the column. As a result, an attempt to delete a parent row fails, because
setting the dependent row to null violates the check constraint.

Similarly, a check constraint is not checked for consistency with a validation

routine, which is applied to a table before a check constraint. If the routine requires
a column to be greater than or equal to 10 and a check constraint requires the same
column to be less than 10, table inserts are not possible. Plans and packages do not
need to be rebound after check constraints are defined on or removed from a table.

When check constraints are enforced

After check constraints are defined on a table, any change must satisfy those
constraints if it is made by:
v The LOAD utility with the option ENFORCE CONSTRAINT
| v An SQL insert operation
| v An SQL update operation
A row satisfies a check constraint if its condition evaluates either to true or to
unknown. A condition can evaluate to unknown for a row if one of the named
columns contains the null value for that row.

Any constraint defined on columns of a base table applies to the views defined on
that base table.

When you use ALTER TABLE to add a check constraint to already populated
tables, the enforcement of the check constraint is determined by the value of the
CURRENT RULES special register as follows:
v If the value is STD, the check constraint is enforced immediately when it is
defined. If a row does not conform, the check constraint is not added to the
table and an error occurs.
v If the value is DB2, the check constraint is added to the table description but its
enforcement is deferred. Because there might be rows in the table that violate
the check constraint, the table is placed in CHECK-pending status.

CHECK-pending status:

To maintain data integrity DB2 enforces check constraints and referential

constraints on data in a table. When either of these constraints are violated or
might be violated, DB2 places the table space or partition that contains the table in
CHECK-pending status.

Table check violations place a table space or partition in CHECK-pending status

when any of these conditions exist:
v A check constraint is defined on a populated table using the ALTER TABLE
statement, and the value of the CURRENT RULES special register is DB2.
v The LOAD utility is run with CONSTRAINTS NO, and check constraints are
defined on the table.
v CHECK DATA is run on a table that contains violations of check constraints.
v A point-in-time RECOVER introduces violations of check constraints.

Referential constraints:

Chapter 10. Creating and modifying DB2 objects 435

A referential constraint is a rule that specifies that the only valid values for a
particular column are those values that exist in another specified table column. For
example, this constraint can ensure that all customer IDs in a transaction table exist
in the ID column of a customer table.

A table can serve as the “master list” of all occurrences of an entity. In the sample
application, the employee table serves that purpose for employees; the numbers
that appear in that table are the only valid employee numbers. Likewise, the
department table provides a master list of all valid department numbers; the
project activity table provides a master list of activities performed for projects; and
so on.

The following figure shows the relationships that exist among the tables in the
sample application. Arrows point from parent tables to dependent tables.

CASCADE
DEPT

SET SET
NULL NULL

RESTRICT EMP

RESTRICT

CASCADE ACT

PROJ
RESTRICT RESTRICT

PROJACT
RESTRICT

RESTRICT

EMPPROJACT

Figure 25. Relationships among tables in the sample application

When a table refers to an entity for which there is a master list, it should identify
an occurrence of the entity that actually appears in the master list; otherwise, either
the reference is invalid or the master list is incomplete. Referential constraints
enforce the relationship between a table and a master list.

Restrictions on cycles of dependent tables:

A cycle is a set of two or more tables that are ordered so that each is a dependent
of the one before it, and the first is a dependent of the last. Every table in the cycle
is a descendent of itself. DB2 restricts certain operations on cycles.

In the sample application, the employee and department tables are a cycle; each is
a dependent of the other.

436 Application Programming and SQL Guide

DB2 does not allow you to create a cycle in which a delete operation on a table
involves that same table. Enforcing that principle creates rules about adding a
foreign key to a table:
v In a cycle of two tables, neither delete rule can be CASCADE.
v In a cycle of more than two tables, two or more delete rules must not be
CASCADE. For example, in a cycle with three tables, two of the delete rules
must be other than CASCADE. This concept is illustrated in The following
figure. The cycle on the left is valid because two or more of the delete rules are
not CASCADE. The cycle on the right is invalid because it contains two
cascading deletes.

Valid Invalid
cycle cycle
TABLE1 TABLE1

RESTRICT CASCADE CASCADE CASCADE

TABLE2 TABLE3 TABLE2 TABLE3

SET NULL SET NULL

Figure 26. Valid and invalid delete cycles

Alternatively, a delete operation on a self-referencing table must involve the same

table, and the delete rule there must be CASCADE or NO ACTION.

Recommendation: Avoid creating a cycle in which all the delete rules are
RESTRICT and none of the foreign keys allows nulls. If you do this, no row of any
of the tables can ever be deleted.

Referential constraints on tables with multilevel security with row-level granularity:

You cannot use referential constraints on a security label column, which is used for
multilevel security with row-level granularity. However, you can use referential
constraints on other columns in the row.

DB2 does not enforce multilevel security with row-level granularity when it is
already enforcing referential constraints. Referential constraints are enforced when
the following situations occur:
v An insert operation is applied to a dependent table.
v An update operation is applied to a foreign key of a dependent table, or to the
parent key of a parent table.
v A delete operation is applied to a parent table. In addition to all referential
constraints being enforced, the DB2 system enforces all delete rules for all
dependent rows that are affected by the delete operation. If all referential
constraints and delete rules are not satisfied, the delete operation will not
succeed.
v The LOAD utility with the ENFORCE CONSTRAINTS option is run on a
dependent table.
v The CHECK DATA utility is run.

For more information about multilevel security with row-level granularity, see the
topic “Multilevel security” in DB2 Administration Guide.

Chapter 10. Creating and modifying DB2 objects 437

Informational referential constraints:

An informational referential constraint is a referential constraint that DB2 does not

enforce during normal operations. Use these constraints only when referential
integrity can be enforced by another means, such as when retrieving data from
other sources. These constraints might improve performance by enabling the query
to qualify for automatic query rewrite.

DB2 ignores informational referential constraints during insert, update, and delete
operations. Some utilities ignore these constraints; other utilities recognize them.
For example, CHECK DATA and LOAD ignore these constraints. QUIESCE
TABLESPACESET recognizes these constraints by quiescing all table spaces related
to the specified table space.

You should use this type of referential constraint only when an application process
verifies the data in a referential integrity relationship. For example, when inserting
a row in a dependent table, the application should verify that a foreign key exists
as a primary or unique key in the parent table. To define an informational
referential constraint, use the NOT ENFORCED option of the referential constraint
definition in a CREATE TABLE or ALTER TABLE statement. For more information
about the NOT ENFORCED option, see the topic “CREATE TABLE” in DB2 SQL
Reference.

Informational referential constraints are often useful, especially in a data

warehouse environment, for several reasons:
v To avoid the overhead of enforcement by DB2.
Typically, data in a data warehouse has been extracted and cleansed from other
sources. Referential integrity might already be guaranteed. In this situation,
enforcement by DB2 is unnecessary.
v To allow more queries to qualify for automatic query rewrite.
Automatic query rewrite is a process that examines a submitted query that
references source tables and, if appropriate, rewrites the query so that it executes
against a materialized query table that has been derived from those source
tables. This process uses informational referential constraints to determine
whether the query can use a materialized query table. Automatic query rewrite
results in a significant reduction in query run time, especially for
decision-support queries that operate over huge amounts of data. For more
information about materialized query tables and automatic query rewrite, see
the topic “Using materialized query tables” in DB2 Performance Monitoring and
Tuning Guide.

Defining a parent key and unique index

A parent key is either a primary key or a unique key in the parent table of a
referential constraint. The values of a parent key determine the valid values of the
foreign key in the constraint. You must create a unique index on a parent key.

The primary key of a table, if one exists, uniquely identifies each occurrence of an
entity in the table. The PRIMARY KEY clause of the CREATE TABLE or ALTER
TABLE statements identifies the column or columns of the primary key. Each
identified column must be defined as NOT NULL.

| Another way to allow only unique values in a column is to specify the UNIQUE
| clause when you create or alter a table. For more information about the UNIQUE
| clause, see the topics “CREATE TABLE” and “ALTER TABLE” in DB2 SQL
| Reference.

438 Application Programming and SQL Guide

A table that is to be a parent of dependent tables must have a primary or a unique
key; the foreign keys of the dependent tables refer to the primary or unique key.
Otherwise, a primary key is optional. Consider defining a primary key if each row
of your table does pertain to a unique occurrence of some entity. If you define a
primary key, an index must be created (the primary index) on the same set of
columns, in the same order as those columns. If you are defining referential
constraints for DB2 to enforce, read “Ways to maintain data integrity” on page 433
before creating or altering any of the tables involved.

A table can have no more than one primary key. A primary key has the same
restrictions as index keys:
v The key can include no more than 64 columns.
v You cannot specify a column name twice.
v The sum of the column length attributes cannot be greater than 2000.

You define a list of columns as the primary key of a table with the PRIMARY KEY
clause in the CREATE TABLE statement.

To add a primary key to an existing table, use the PRIMARY KEY clause in an
ALTER TABLE statement. In this case, a unique index must already exist.

Recommendations for defining primary keys:

Consider the following items when you plan for primary keys:
v The theoretical model of a relational database suggests that every table should
have a primary key to uniquely identify the entities it describes. However, you
must weigh that model against the potential cost of index maintenance
overhead. DB2 does not require you to define a primary key for tables with no
dependents.
v Choose a primary key whose values will not change over time. Choosing a
primary key with persistent values enforces the good practice of having unique
identifiers that remain the same for the lifetime of the entity occurrence.
v A primary key column should not have default values unless the primary key is
a single TIMESTAMP column.
v Choose the minimum number of columns to ensure uniqueness of the primary
key.
v A view that can be updated that is defined on a table with a primary key should
include all columns of the key. Although this is necessary only if the view is
used for inserts, the unique identification of rows can be useful if the view is
used for updates, deletes, or selects.
v Drop a primary key later if you change your database or application using SQL.

Parent key columns:

A parent key is either a primary key or a unique key in the parent table of a
referential constraint. This key consists of a column or set of columns. The values
of a parent key determine the valid values of the foreign key in the constraint.

If every row in a table represents relationships for a unique entity, the table should
have one column or a set of columns that provides a unique identifier for the rows
of the table. This column (or set of columns) is called the parent key of the table. To
ensure that the parent key does not contain duplicate values, you must create a
unique index on the column or columns that constitute the parent key. Defining
the parent key is called entity integrity, because it requires each entity to have a
unique key.
Chapter 10. Creating and modifying DB2 objects 439
In some cases, using a timestamp as part of the key can be helpful, for example
when a table does not have a “natural” unique key or if arrival sequence is the
key.

Primary keys for some of the sample tables are:

Table Key Column
Employee table
EMPNO
Department table
DEPTNO
Project table
PROJNO

Table 78 shows part of the project table which has the primary key column,
PROJNO.
Table 78. Part of the project table with the primary key column, PROJNO
PROJNO PROJNAME DEPTNO

MA2100 WELD LINE AUTOMATION D01

MA2110 W L PROGRAMMING D11

Table 79 shows part of the project activity table, which has a primary key that
contains more than one column. The primary key is a composite key, which consists
of the PRONNO, ACTNO, and ACSTDATE columns.
Table 79. Part of the Project activities table with a composite primary key
PROJNO ACTNO ACSTAFF ACSTDATE ACENDATE

AD3100 10 .50 1982-01-01 1982-07-01

AD3110 10 1.00 1982-01-01 1983-01-01

AD3111 60 .50 1982-03-15 1982-04-15

Defining a foreign key

Use foreign keys to enforce referential relationships between tables. A foreign key
is a column or set of columns that reference the parent key in the parent table.

You define a list of columns as a foreign key of a table with the FOREIGN KEY
clause in the CREATE TABLE statement.

A foreign key can refer to either a unique or a primary key of the parent table. If
the foreign key refers to a non-primary unique key, you must specify the column
names of the key explicitly. If the column names of the key are not specified
explicitly, the default is to refer to the column names of the primary key of the
parent table.

The column names you specify identify the columns of the parent key. The
privilege set must include the ALTER or the REFERENCES privilege on the
columns of the parent key. A unique index must exist on the parent key columns of
the parent table.

The relationship name: You can choose a constraint name for the relationship that
is defined by a foreign key. If you do not choose a name, DB2 generates one from
440 Application Programming and SQL Guide
the name of the first column of the foreign key, in the same way that it generates
the name of an implicitly created table space.

For example, the names of the relationships in which the employee-to-project

activity table is a dependent would, by default, be recorded (in column RELNAME
of SYSIBM.SYSFOREIGNKEYS) as EMPNO and PROJNO. The following example
shows a CREATE TABLE statement that specifies constraint names REPAPA and
REPAE for the foreign keys in the employee-to-project activity table.
CREATE TABLE DSN8910.EMPPROJACT
(EMPNO CHAR(6) NOT NULL,
PROJNO CHAR(6) NOT NULL,
ACTNO SMALLINT NOT NULL,
CONSTRAINT REPAPA FOREIGN KEY (PROJNO, ACTNO)
REFERENCES DSN8910.PROJACT ON DELETE RESTRICT,
CONSTRAINT REPAE FOREIGN KEY (EMPNO)
REFERENCES DSN8910.EMP ON DELETE RESTRICT)
IN DATABASE DSN8D91A;

The name is used in error messages, queries to the catalog, and DROP FOREIGN
KEY statements. Hence, you might want to choose one if you are experimenting
with your database design and have more than one foreign key beginning with the
same column (otherwise DB2 generates the name).

Indexes on foreign keys: Although not required, an index on a foreign key is

strongly recommended if rows of the parent table are often deleted. The validity of
the delete statement, and its possible effect on the dependent table, can be checked
through the index.

You can create an index on the columns of a foreign key in the same way you
create one on any other set of columns. Most often it is not a unique index. If you
do create a unique index on a foreign key, it introduces an additional constraint on
the values of the columns.

To let an index on the foreign key be used on the dependent table for a delete
operation on a parent table, the columns of the index on the foreign key must be
identical to and in the same order as the columns in the foreign key.

A foreign key can also be the primary key; then the primary index is also a unique
index on the foreign key. In that case, every row of the parent table has at most
one dependent row. The dependent table might be used to hold information that
pertains to only a few of the occurrences of the entity described by the parent
table. For example, a dependent of the employee table might contain information
that applies only to employees working in a different country.

The primary key can share columns of the foreign key if the first n columns of the
foreign key are the same as the primary key’s columns. Again, the primary index
serves as an index on the foreign key. In the sample project activity table, the
primary index (on PROJNO, ACTNO, ACSTDATE) serves as an index on the
foreign key on PROJNO. It does not serve as an index on the foreign key on
ACTNO, because ACTNO is not the first column of the index.

The FOREIGN KEY clause in ALTER TABLE:

You can add a foreign key to an existing table; in fact, that is sometimes the only
way to proceed. To make a table self-referencing, you must add a foreign key after
creating it.

Chapter 10. Creating and modifying DB2 objects 441

When a foreign key is added to a populated table, the table space is put into check
pending status.

Maintaining referential integrity when using data encryption

If you use encrypted data in a referential constraint, the primary key of the parent
table and the foreign key of the dependent table must have the same encrypted
value.

The encrypted value should be extracted from the parent table (the primary key)
and used for the dependent table (the foreign key). You can do this in one of the
following two ways:
| v Use the FINAL TABLE clause on a SELECT from UPDATE, SELECT from
| INSERT, or SELECT from MERGE statement.
v Use the ENCRYPT_TDES function to encrypt the foreign key using the same
password as the primary key. The encrypted value of the foreign key will be the
same as the encrypted value of the primary key.
The SET ENCRYPTION PASSWORD statement sets the password that will be used
for the ENCRYPT_TDES function.

For more information about the SET ENCRYPTION PASSWORD special register,
see the topic “ENCRYPTION PASSWORD” in DB2 SQL Reference.

For more information about the ENCRYPT_TDES statement, see the topic
“ENCRYPT_TDES” in DB2 SQL Reference.

Creating work tables for the EMP and DEPT sample tables
Before testing SQL statements that insert, update, and delete rows in the
DSN8910.EMP and DSN8910.DEPT sample tables, you should create duplicates of
these tables, so that the original sample tables remain intact. These duplicate tables
are called work tables.

This topic shows how to create the department and employee work tables and
how to fill a work table with the contents of another table:

Each of these topics assumes that you logged on by using your own authorization
ID. The authorization ID qualifies the name of each object that you create. For
example, if your authorization ID is SMITH, and you create table YDEPT, the name
of the table is SMITH.YDEPT. If you want to access table DSN8910.DEPT, you
must refer to it by its complete name. If you want to access your own table
YDEPT, you need only to refer to it as YDEPT.

Use the following statements to create a new department table called YDEPT,
modeled after the existing table, DSN8910.DEPT, and an index for YDEPT:
CREATE TABLE YDEPT
LIKE DSN8910.DEPT;
CREATE UNIQUE INDEX YDEPTX
ON YDEPT (DEPTNO);

If you want DEPTNO to be a primary key, as in the sample table, explicitly define
the key. Use an ALTER TABLE statement, as in the following example:
ALTER TABLE YDEPT
PRIMARY KEY(DEPTNO);

442 Application Programming and SQL Guide

You can use an INSERT statement to copy the rows of the result table of a
fullselect from one table to another. The following statement copies all of the rows
from DSN8910.DEPT to your own YDEPT work table:
INSERT INTO YDEPT
SELECT *
FROM DSN8910.DEPT;

For information about using the INSERT statement, see “Inserting rows by using
the INSERT statement” on page 605.

You can use the following statements to create a new employee table called YEMP:
CREATE TABLE YEMP
(EMPNO CHAR(6) PRIMARY KEY NOT NULL,
FIRSTNME VARCHAR(12) NOT NULL,
MIDINIT CHAR(1) NOT NULL,
LASTNAME VARCHAR(15) NOT NULL,
WORKDEPT CHAR(3) REFERENCES YDEPT
ON DELETE SET NULL,
PHONENO CHAR(4) UNIQUE NOT NULL,
HIREDATE DATE ,
JOB CHAR(8) ,
EDLEVEL SMALLINT ,
SEX CHAR(1) ,
BIRTHDATE DATE ,
SALARY DECIMAL(9, 2) ,
BONUS DECIMAL(9, 2) ,
COMM DECIMAL(9, 2) );

This statement also creates a referential constraint between the foreign key in
YEMP (WORKDEPT) and the primary key in YDEPT (DEPTNO). It also restricts all
phone numbers to unique numbers.

If you want to change a table definition after you create it, use the ALTER TABLE
statement with a RENAME clause. If you want to change a table name after you
create it, use the RENAME statement.

You can change a table definition by using the ALTER TABLE statement only in
certain ways. For example, you can add and drop constraints on columns in a
table. You can also change the data type of a column within character data types,
within numeric data types, and within graphic data types. You can add a column
to a table. However, you cannot use the ALTER TABLE statement to drop a
column from a table.
Related tasks
Altering DB2 tables (DB2 Administration Guide)
Related reference
ALTER TABLE (SQL Reference)
RENAME (SQL Reference)

Creating created temporary tables

Use created temporary tables when you need to store data for only the life of an
application process, but you want to share the table definition. DB2 does not
perform logging and locking operations for created temporary tables, so that SQL
statements that use these tables can execute queries efficiently.

Each application process has its own instance of the created temporary table.

Chapter 10. Creating and modifying DB2 objects 443

You create the definition of a created temporary table using the SQL CREATE
GLOBAL TEMPORARY TABLE statement.

Example: The following statement creates the definition of a table called

TEMPPROD:
CREATE GLOBAL TEMPORARY TABLE TEMPPROD
(SERIAL CHAR(8) NOT NULL,
DESCRIPTION VARCHAR(60) NOT NULL,
MFGCOST DECIMAL(8,2),
MFGDEPT CHAR(3),
MARKUP SMALLINT,
SALESDEPT CHAR(3),
CURDATE DATE NOT NULL);

Example: You can also create this same definition by copying the definition of a
base table (named PROD) by using the LIKE clause:
CREATE GLOBAL TEMPORARY TABLE TEMPPROD LIKE PROD;

The SQL statements in the previous examples create identical definitions for the
TEMPPROD table, but these tables differ slightly from the PROD sample table
PROD. The PROD sample table contains two columns, DESCRIPTION and
CURDATE, that are defined as NOT NULL WITH DEFAULT. Because created
temporary tables do not support non-null default values, the DESCRIPTION and
CURDATE columns in the TEMPPROD table are defined as NOT NULL and do
not have defaults.

After you run one of the two CREATE statements, the definition of TEMPPROD
exists, but no instances of the table exist. To create an instance of TEMPPROD, you
must use TEMPPROD in an application. DB2 creates an instance of the table when
TEMPPROD is specified in one of the following SQL statements:
v OPEN
v SELECT
v INSERT
v DELETE
Restriction: You cannot use the MERGE statement with created temporary tables.

An instance of a created temporary table exists at the current server until one of
the following actions occurs:
v The application process ends.
v The remote server connection through which the instance was created
terminates.
v The unit of work in which the instance was created completes.
When you run a ROLLBACK statement, DB2 deletes the instance of the created
temporary table. When you run a COMMIT statement, DB2 deletes the instance
of the created temporary table unless a cursor for accessing the created
temporary table is defined with the WITH HOLD clause and is open.

Example: Suppose that you create a definition of TEMPPROD and then run an
application that contains the following statements:
EXEC SQL DECLARE C1 CURSOR FOR SELECT * FROM TEMPPROD;
EXEC SQL INSERT INTO TEMPPROD SELECT * FROM PROD;
EXEC
. SQL OPEN C1;
.
.
EXEC
. SQL COMMIT;
.
.
EXEC SQL CLOSE C1;

444 Application Programming and SQL Guide

When you run the INSERT statement, DB2 creates an instance of TEMPPROD and
populates that instance with rows from table PROD. When the COMMIT statement
runs, DB2 deletes all rows from TEMPPROD. However, assume that you change
the declaration of cursor C1 to the following declaration:
EXEC SQL DECLARE C1 CURSOR WITH HOLD
FOR SELECT * FROM TEMPPROD;

In this case, DB2 does not delete the contents of TEMPPROD until the application
ends because C1, a cursor that is defined with the WITH HOLD clause, is open
when the COMMIT statement runs. In either case, DB2 drops the instance of
TEMPPROD when the application ends.

To drop the definition of TEMPPROD, you must run the following statement:
DROP TABLE TEMPPROD;

Temporary tables
Use temporary tables when you need to store data for only the duration of an
application process. Depending on whether you want to share the table definition,
you can create a created temporary table or a declared temporary table.

The two kinds of temporary tables are:

v Created temporary tables, which you define using a CREATE GLOBAL
TEMPORARY TABLE statement
v Declared temporary tables, which you define using a DECLARE GLOBAL
TEMPORARY TABLE statement
SQL statements that use temporary tables can run faster because of the following
reasons:
v DB2 does no logging (for created temporary tables) or limited logging (for
declared temporary tables).
v DB2 does no locking (for created temporary tables) or limited locking (for
declared temporary tables).

Temporary tables are especially useful when you need to sort or query
intermediate result tables that contain a large number of rows, but you want to
store only a small subset of those rows permanently.

Temporary tables can also return result sets from stored procedures. The following
topics provide more details about created temporary tables and declared temporary
tables:
v “Creating created temporary tables” on page 443
v “Creating declared temporary tables”
For more information, see “Writing an external procedure to return result sets to a
DRDA client” on page 584.

Creating declared temporary tables

Use declared temporary tables when you need to store data for only the life of an
application process and do not need to share the table definition. The definition of
this table exists only while the application process runs. DB2 performs limited
logging and locking operations for declared temporary tables.

You create an instance of a declared temporary table by using the SQL DECLARE
GLOBAL TEMPORARY TABLE statement. That instance is known only to the

Chapter 10. Creating and modifying DB2 objects 445

application process in which the table is declared, so you can declare temporary
tables with the same name in different applications. The qualifier for a declared
temporary table is SESSION.

| Before you can define declared temporary tables, you must have a WORKFILE
| database that has at least one table space with a 32-KB page size.

To create a declared temporary table, specify the DECLARE GLOBAL

TEMPORARY TABLE statement. In that statement, specify the columns that the
table is to contain by performing one of the following actions:
v Specify all the columns in the table.
Unlike columns of created temporary tables, columns of declared temporary
tables can include the WITH DEFAULT clause.
v Use a LIKE clause to copy the definition of a base table, created temporary table,
or view.
If the base table, created temporary table, or view from which you select
columns has identity columns, you can specify that the corresponding columns
in the declared temporary table are also identity columns. To include these
identity columns, specify the INCLUDING IDENTITY COLUMN ATTRIBUTES
clause when you define the declared temporary table.
| If the source table has a row change timestamp column, you can specify that
| those column attributes are inherited in the declared temporary table by
| specifying INCLUDING ROW CHANGE TIMESTAMP COLUMN ATTRIBUTES.
v Use a fullselect to choose specific columns from a base table, created temporary
table, or view.
If you want the declared temporary table columns to inherit the defaults for
columns of the table or view that is named in the fullselect, specify the
INCLUDING COLUMN DEFAULTS clause. If you want the declared temporary
table columns to have default values that correspond to their data types, specify
the USING TYPE DEFAULTS clause.

Example: The following statement defines a declared temporary table called

TEMPPROD by explicitly specifying the columns.
DECLARE GLOBAL TEMPORARY TABLE TEMPPROD
(SERIAL CHAR(8) NOT NULL WITH DEFAULT '99999999',
DESCRIPTION VARCHAR(60) NOT NULL,
PRODCOUNT INTEGER GENERATED ALWAYS AS IDENTITY,
MFGCOST DECIMAL(8,2),
MFGDEPT CHAR(3),
MARKUP SMALLINT,
SALESDEPT CHAR(3),
CURDATE DATE NOT NULL);

Example: The following statement defines a declared temporary table called

TEMPPROD by copying the definition of a base table. The base table has an
identity column that the declared temporary table also uses as an identity column.
DECLARE GLOBAL TEMPORARY TABLE TEMPPROD LIKE BASEPROD
INCLUDING IDENTITY COLUMN ATTRIBUTES;

Example: The following statement defines a declared temporary table called

TEMPPROD by selecting columns from a view. The view has an identity column
that the declared temporary table also uses as an identity column. The declared
temporary table inherits its default column values from the default column values
of a base table on which the view is based.

446 Application Programming and SQL Guide

DECLARE GLOBAL TEMPORARY TABLE TEMPPROD
AS (SELECT * FROM PRODVIEW)
DEFINITION ONLY
INCLUDING IDENTITY COLUMN ATTRIBUTES
INCLUDING COLUMN DEFAULTS;

After you run a DECLARE GLOBAL TEMPORARY TABLE statement, the

definition of the declared temporary table exists as long as the application process
runs.

If you need to delete the definition before the application process completes, you
can do that with the DROP TABLE statement. For example, to drop the definition
of TEMPPROD, run the following statement:
DROP TABLE SESSION.TEMPPROD;

DB2 creates an empty instance of a declared temporary table when it runs the
DECLARE GLOBAL TEMPORARY TABLE statement. You can then perform the
following actions:
v Populate the declared temporary table by using INSERT statements
v Modify the table using searched or positioned UPDATE or DELETE statements
v Query the table using SELECT statements
v Create indexes on the declared temporary table

The ON COMMIT clause that you specify in the DECLARE GLOBAL

TEMPORARY TABLE statement determines whether DB2 keeps or deletes all the
rows from the table when you run a COMMIT statement in an application with a
declared temporary table. ON COMMIT DELETE ROWS, which is the default,
causes all rows to be deleted from the table at a commit point, unless a held cursor
is open on the table at the commit point. ON COMMIT PRESERVE ROWS causes
the rows to remain past the commit point.

Example: Suppose that you run the following statement in an application program:
EXEC SQL DECLARE GLOBAL TEMPORARY TABLE TEMPPROD
AS (SELECT * FROM BASEPROD)
DEFINITION ONLY
INCLUDING IDENTITY COLUMN ATTRIBUTES
INCLUDING COLUMN DEFAULTS
ON COMMIT PRESERVE ROWS;
EXEC
. SQL INSERT INTO SESSION.TEMPPROD SELECT * FROM BASEPROD;
.
.
EXEC
. SQL COMMIT;
.
.

When DB2 runs the preceding DECLARE GLOBAL TEMPORARY TABLE

statement, DB2 creates an empty instance of TEMPPROD. The INSERT statement
populates that instance with rows from table BASEPROD. The qualifier, SESSION,
must be specified in any statement that references TEMPPROD. When DB2
executes the COMMIT statement, DB2 keeps all rows in TEMPPROD because
TEMPPROD is defined with ON COMMIT PRESERVE ROWS. When the program
ends, DB2 drops TEMPPROD.

Providing a unique key for a table

Use ROWID columns or identity columns to store unique values for each row in a
table.

Chapter 10. Creating and modifying DB2 objects 447

Question: How can I provide a unique identifier for a table that has no unique
column?

Answer: Add a column with the data type ROWID or an identity column. ROWID
columns and identity columns contain a unique value for each row in the table.
You can define the column as GENERATED ALWAYS, which means that you
cannot insert values into the column, or GENERATED BY DEFAULT, which means
that DB2 generates a value if you do not specify one. If you define the ROWID or
identity column as GENERATED BY DEFAULT, you need to define a unique index
that includes only that column to guarantee uniqueness.

| Fixing tables with incomplete definitions

| If a table has an incomplete definition, you cannot load the table, insert data,
| retrieve data, update data, or delete data. You can drop the table, create the
| primary index, and drop or create other indexes.

| To check if a table has an incomplete definition, look at the STATUS column in

| SYSIBM.SYSTABLES. The value I indicates that the definition is incomplete.

| A table definition is incomplete in any of the following circumstances:

| v If the table is defined with a primary or unique key and all of the following
| conditions are true:
| – The table space for the table was explicitly created.
| – The statement is not being run with schema processor.
| – The table does not have a primary or unique index for the defined primary or
| unique key.
| v If the table has a ROWID column that is defined as generated by default and
| all of the following conditions are true:
| – The table space for the table was explicitly created.
| – The SET CURRENT RULES special register is not set to STD.
| – No unique index is defined on the ROWID column.
| v If the table has a LOB column and all of the following conditions are true:
| – The table space for the table was explicitly created.
| – The SET CURRENT RULES special register is not set to STD.
| – No all auxiliary LOB objects are defined for the LOB column.

| You can complete the table definition by performing one of the following actions,
| depending on why the table definition was incomplete:
| v Creating a primary index or altering the table to drop the primary key.
| v Creating a unique index on the unique key or altering the table to drop the
| unique key.
| v Defining a unique index on the ROWID column.
| v Creating the necessary LOB objects.

| Example of creating a primary index: To create the primary index for the project
| activity table, issue the following SQL statement:
| CREATE UNIQUE INDEX XPROJAC1
| ON DSN8910.PROJACT (PROJNO, ACTNO, ACSTDATE);

448 Application Programming and SQL Guide

|
Dropping tables
When you drop a table, you delete the data and the table definition. You also
delete all synonyms, views, indexes, and referential and check constraints that are
associated with that table.

The following SQL statement drops the YEMP table:

DROP TABLE YEMP;

Use the DROP TABLE statement with care: Dropping a table is not equivalent to
deleting all its rows. When you drop a table, you lose more than its data and its
definition. You lose all synonyms, views, indexes, and referential and check
constraints that are associated with that table. You also lose all authorities that are
granted on the table.

For more information about the syntax of the DROP statement, see the topic
“DROP” in DB2 SQL Reference.

Defining a view
A view is a named specification of a result table. Use views to control which users
have access to certain data or to simplify writing SQL statements.

Use the CREATE VIEW statement to define a view and give the view a name, just
as you do for a table. The view that is created with the following statement shows
each department manager’s name with the department data in the DSN8910.DEPT
table.
CREATE VIEW VDEPTM AS
SELECT DEPTNO, MGRNO, LASTNAME, ADMRDEPT
FROM DSN8910.DEPT, DSN8910.EMP
WHERE DSN8910.EMP.EMPNO = DSN8910.DEPT.MGRNO;

When a program accesses the data that is defined by a view, DB2 uses the view
definition to return a set of rows that the program can access with SQL statements.

Example: To see the departments that are administered by department D01 and the
managers of those departments, run the following statement, which returns
information from the VDEPTM view:
SELECT DEPTNO, LASTNAME
FROM VDEPTM
WHERE ADMRDEPT = 'DO1';

| When you create a view, you can reference the SESSION_USER and CURRENT
| SQLID special registers in the CREATE VIEW statement. When referencing the
| view, DB2 uses the value of the SESSION_USER or CURRENT SQLID special
| register that belongs to the user of the SQL statement (SELECT, UPDATE, INSERT,
| or DELETE) rather than the creator of the view. In other words, a reference to a
| special register in a view definition refers to its run-time value.

A column in a view might be based on a column in a base table that is an identity

column. The column in the view is also an identity column,except under any of the
following circumstances:
v The column appears more than once in the view.
v The view is based on a join of two or more tables.
v The view is based on the union of two or more tables.

Chapter 10. Creating and modifying DB2 objects 449

v Any column in the view is derived from an expression that refers to an identity
column.

| You can use views to limit access to certain kinds of data, such as salary
| information. Alternatively, you can use the IMPLICITLY HIDDEN clause of a
| CREATE TABLE statement define a column of a table to be hidden from some
| operations.

You can also use views for the following actions:

v Make a subset of a table’s data available to an application. For example, a view
based on the employee table might contain rows only for a particular
department.
v Combine columns from two or more tables and make the combined data
available to an application. By using a SELECT statement that matches values in
one table with those in another table, you can create a view that presents data
from both tables. However, you can only select data from this type of view. You
cannot update, delete, or insert data using a view that joins two or more
tables.
v Combine rows from two or more tables and make the combined data available
to an application. By using two or more subselects that are connected by a set
operator such as UNION, you can create a view that presents data from several
tables. However, you can only select data from this type of view. You cannot
update, delete, or insert data using a view that contains UNION operations.
v Present computed data, and make the resulting data available to an application.
You can compute such data using any function or operation that you can use in
a SELECT statement.

Views
A view does not contain data; it is a stored definition of a set of rows and
columns. A view can present any or all of the data in one or more tables and, in
most cases, is interchangeable with a table.

Although you cannot modify an existing view, you can drop it and create a new
one if your base tables change in a way that affects the view. Dropping and
creating views does not affect the base tables or their data.

Restrictions when changing data through a view

Some views are read-only and thus cannot be used to update the table data. For
those views that are updatable, several restrictions apply.

Consider the following restrictions when changing data through a view:

v You must have the appropriate authorization to insert, update, or delete rows
using the view.
v When you use a view to insert a row into a table, the view definition must
specify all the columns in the base table that do not have a default value. The
row that is being inserted must contain a value for each of those columns.
v Views that you can use to update data are subject to the same referential
constraints and check constraints as the tables that you used to define the views.
You can use the WITH CHECK option of the CREATE VIEW statement to
specify the constraint that every row that is inserted or updated through the

450 Application Programming and SQL Guide

view must conform to the definition of the view. You can select every row that is
inserted or updated through a view that is created with the WITH CHECK
option.

| For complex views, you can make insert, update and delete operations possible by
| defining INSTEAD OF triggers.

For more information about INSTEAD OF triggers, see “Inserting, updating, and
deleting data in views by using INSTEAD OF triggers” on page 466.

For more information about read-only views, see the topic “CREATE VIEW” in
DB2 SQL Reference.

Dropping a view
When you drop a view, you also drop all views that are defined on that view. The
base table is not affected.

Example: The following SQL statement drops the VDEPTM view:

DROP VIEW VDEPTM;

Creating a common table expression

Creating a common table expression saves you the overhead of creating and
dropping a regular view that you need to use only once. Also, during statement
preparation, DB2 does not need to access the catalog for the view, which saves you
additional overhead.

Use the WITH clause to create a common table expression.

You can use a common table expression in a SELECT statement by using the WITH
clause at the beginning of the statement.

Example: WITH clause in a SELECT statement: The following statement finds the
department with the highest total pay. The query involves two levels of
aggregation. First, you need to determine the total pay for each department by
using the SUM function and order the results by using the GROUP BY clause. You
then need to find the department with highest total pay based on the total pay for
each department.
WITH DTOTAL (deptno, totalpay) AS
(SELECT deptno, sum(salary+bonus)
FROM DSN8810.EMP
GROUP BY deptno)
SELECT deptno
FROM DTOTAL
WHERE totalpay = (SELECT max(totalpay)
FROM DTOTAL);

The result table for the common table expression, DTOTAL, contains the
department number and total pay for each department in the employee table. The
fullselect in the previous example uses the result table for DTOTAL to find the
department with the highest total pay. The result table for the entire statement
looks similar to the following results:
DEPTNO
======
D11

Chapter 10. Creating and modifying DB2 objects 451

Using common table expressions with views:

You can use common table expressions before a fullselect in a CREATE VIEW
statement. This technique is useful if you need to use the results of a common
table expression in more than one query.

Example: Using a WITH clause in a CREATE VIEW statement: The following

statement finds the departments that have a greater-than-average total pay and
saves the results as the view RICH_DEPT:
CREATE VIEW RICH_DEPT (deptno) AS
WITH DTOTAL (deptno, totalpay) AS
(SELECT deptno, sum(salary+bonus)
FROM DSN8910.EMP
GROUP BY deptno)
SELECT deptno
FROM DTOTAL
WHERE totalpay > (SELECT AVG(totalpay)
FROM DTOTAL);

The fullselect in the previous example uses the result table for DTOTAL to find the
departments that have a greater-than-average total pay. The result table is saved as
the RICH_DEPT view and looks similar to the following results:
DEPTNO
======
A00
D11
D21

Using common table expressions when you use INSERT:

You can use common table expressions before a fullselect in an INSERT statement.

Example: Using a common table expression in an INSERT statement: The

following statement uses the result table for VITALDEPT to find the manager’s
number for each department that has a greater-than-average number of senior
engineers. Each manager’s number is then inserted into the vital_mgr table.
INSERT INTO vital_mgr (mgrno)
WITH VITALDEPT (deptno, se_count) AS
(SELECT deptno, count(*)
FROM DSN8910.EMP
WHERE job = 'senior engineer'
GROUP BY deptno)
SELECT d.manager
FROM DSN8910.DEPT d, VITALDEPT s
WHERE d.deptno = s.deptno
AND s.se_count > (SELECT AVG(se_count)
FROM VITALDEPT);

Common table expressions

Acommon table expression is like a temporary view that is defined and used for the
duration of an SQL statement.

| You can define a common table expression wherever you can have a fullselect
| statement. For example, you can include a common table expression in a SELECT,
| INSERT, SELECT INTO, or CREATE VIEW statement.

Each common table expression must have a unique name and be defined only
once. However, you can reference a common table expression many times in the
same SQL statement. Unlike regular views or nested table expressions, which

452 Application Programming and SQL Guide

derive their result tables for each reference, all references to common table
expressions in a given statement share the same result table.

You can use a common table expression in the following situations:

v When you want to avoid creating a view (when general use of the view is not
required, and positioned updates or deletes are not used)
v When the desired result table is based on host variables
v When the same result table needs to be shared in a fullselect
v When the results need to be derived using recursion

Examples of recursive common table expressions

Recursive SQL is very useful in bill of materials (BOM) applications. These
examples illustrate some of the capability of a recursive common table expression
for BOM applications.

Consider a table of parts with associated subparts and the quantity of subparts
required by each part. For more information about recursive SQL, refer to
“Creating recursive SQL by using common table expressions” on page 656.

For the examples in this topic, create the following table:

CREATE TABLE PARTLIST
(PART VARCHAR(8),
SUBPART VARCHAR(8),
QUANTITY INTEGER);

Assume that the PARTLIST table is populated with the values that are in the
following table:
Table 80. PARTLIST table
PART SUBPART QUANTITY
00 01 5
00 05 3
01 02 2
01 03 3
01 04 4
01 06 3
02 05 7
02 06 6
03 07 6
04 08 10
04 09 11
05 10 10
05 11 10
06 12 10
06 13 10
07 14 8
07 12 8

Chapter 10. Creating and modifying DB2 objects 453

Example 1: Single level explosion:

Single level explosion answers the question, ″What parts are needed to build the
part identified by ’01’?″. The list will include the direct subparts, subparts of the
subparts and so on. However, if a part is used multiple times, its subparts are only
listed once.
WITH RPL (PART, SUBPART, QUANTITY) AS
(SELECT ROOT.PART, ROOT.SUBPART, ROOT.QUANTITY
FROM PARTLIST ROOT
WHERE ROOT.PART = '01'
UNION ALL
SELECT CHILD.PART, CHILD.SUBPART, CHILD.QUANTITY
FROM RPL PARENT, PARTLIST CHILD
WHERE PARENT.SUBPART = CHILD.PART)
SELECT DISTINCT PART, SUBPART, QUANTITY
FROM RPL
ORDER BY PART, SUBPART, QUANTITY;

The preceding query includes a common table expression, identified by the name
RPL, that expresses the recursive part of this query. It illustrates the basic elements
of a recursive common table expression.

The first operand (fullselect) of the UNION, referred to as the initialization

fullselect, gets the direct subparts of part ’01’. The FROM clause of this fullselect
refers to the source table and will never refer to itself (RPL in this case). The result
of this first fullselect goes into the common table expression RPL. As in this
example, the UNION must always be a UNION ALL.

The second operand (fullselect) of the UNION uses RPL to compute subparts of
subparts by using the FROM clause to refer to the common table expression RPL
and the source table PARTLIST with a join of a part from the source table (child) to
a subpart of the current result contained in RPL (parent). The result goes then back
to RPL again. The second operand of UNION is used repeatedly until no more
subparts exist.

The SELECT DISTINCT in the main fullselect of this query ensures the same
part/subpart is not listed more than once.

The result of the query is shown in the following table:

Table 81. Result table for example 1
PART SUBPART QUANTITY
01 02 2
01 03 3
01 04 4
01 06 3
02 05 7
02 06 6
03 07 6
04 08 10
04 09 11
05 10 10
05 11 10

454 Application Programming and SQL Guide

Table 81. Result table for example 1 (continued)
PART SUBPART QUANTITY
06 12 10
06 13 10
07 12 8
07 14 8

Observe in the result that part ’01’ contains subpart ’02’ which contains subpart
’06’ and so on. Further, notice that part ’06’ is reached twice, once through part ’01’
directly and another time through part ’02’. In the output, however, the subparts of
part ’06’ are listed only once (this is the result of using a SELECT DISTINCT).

Remember that with recursive common table expressions it is possible to introduce

an infinite loop. In this example, an infinite loop would be created if the search
condition of the second operand that joins the parent and child tables was coded
as follows:
WHERE PARENT.SUBPART = CHILD.SUBPART

This infinite loop is created by not coding what is intended. You should carefully
determining what to code so that there is a definite end of the recursion cycle.

The result produced by this example could be produced in an application program

without using a recursive common table expression. However, such an application
would require coding a different query for every level of recursion. Furthermore,
the application would need to put all of the results back in the database to order
the final result. This approach complicates the application logic and does not
perform well. The application logic becomes more difficult and inefficient for other
bill of material queries, such as summarized and indented explosion queries.

Example 2: Summarized explosion:

A summarized explosion answers the question, ″What is the total quantity of each
part required to build part ’01’?″ The main difference from a single level explosion
is the need to aggregate the quantities. A single level explosion indicates the
quantity of subparts required for the part whenever it is required. It does not
indicate how many of each subpart is needed to build part ’01’.
WITH RPL (PART, SUBPART, QUANTITY) AS
(
SELECT ROOT.PART, ROOT.SUBPART, ROOT.QUANTITY
FROM PARTLIST ROOT
WHERE ROOT.PART = '01'
UNION ALL
SELECT PARENT.PART, CHILD.SUBPART,
PARENT.QUANTITY*CHILD.QUANTITY
FROM RPL PARENT, PARTLIST CHILD
WHERE PARENT.SUBPART = CHILD.PART
)
SELECT PART, SUBPART, SUM(QUANTITY) AS "Total QTY Used"
FROM RPL
GROUP BY PART, SUBPART
ORDER BY PART, SUBPART;

In the preceding query, the select list of the second operand of the UNION in the
recursive common table expression, identified by the name RPL, shows the
aggregation of the quantity. To determine how many of each subpart is used, the

Chapter 10. Creating and modifying DB2 objects 455

quantity of the parent is multiplied by the quantity per parent of a child. If a part
is used multiple times in different places, it requires another final aggregation. This
is done by the grouping the parts and subparts in the common table expression
RPL and using the SUM column function in the select list of the main fullselect.

The result of the query is shown in the following table:

Table 82. Result table for example 2
PART SUBPART Total QTY Used
01 02 2
01 03 3
01 04 4
01 05 14
01 06 15
01 07 18
01 08 40
01 09 44
01 10 140
01 11 140
01 12 294
01 13 150
01 14 144

Consider the total quantity for subpart ’06’. The value of 15 is derived from a
quantity of 3 directly for part ’01’ and a quantity of 6 for part ’02’ which is needed
two times by part ’01’.

Example 3: Controlling depth:

You can control the depth of a recursive query to answer the question, ″What are
the first two levels of parts that are needed to build part ’01’?″ For the sake of
clarity in this example, the level of each part is included in the result table.
WITH RPL (LEVEL, PART, SUBPART, QUANTITY) AS
(
SELECT 1, ROOT.PART, ROOT.SUBPART, ROOT.QUANTITY
FROM PARTLIST ROOT
WHERE ROOT.PART = '01'
UNION ALL
SELECT PARENT.LEVEL+1, CHILD.PART, CHILD.SUBPART, CHILD.QUANTITY
FROM RPL PARENT, PARTLIST CHILD
WHERE PARENT.SUBPART = CHILD.PART
AND PARENT.LEVEL < 2
)
SELECT PART, LEVEL, SUBPART, QUANTITY
FROM RPL;

This query is similar to the query in example 1. The column LEVEL is introduced
to count the level each subpart is from the original part. In the initialization
fullselect, the value for the LEVEL column is initialized to 1. In the subsequent
fullselect, the level from the parent table increments by 1. To control the number of
levels in the result, the second fullselect includes the condition that the level of the
parent must be less than 2. This ensures that the second fullselect only processes
children to the second level.

456 Application Programming and SQL Guide

The result of the query is shown in the following table:
Table 83. Result table for example 3
PART LEVEL SUBPART QUANTITY
01 1 02 2
01 1 03 3
01 1 04 4
01 1 06 3
02 2 05 7
02 2 06 6
03 2 07 6
04 2 08 10
04 2 09 11
06 2 12 10
06 2 13 10

Creating triggers
A trigger is a set of SQL statements that execute when a certain event occurs in a
table. Use triggers to control changes in DB2 databases. Triggers are more powerful
than constraints, because they can monitor a broader range of changes and
perform a broader range of actions than constraints can.

Using triggers for active data:

For example, a constraint can disallow an update to the salary column of the
employee table if the new value is over a certain amount. A trigger can monitor
the amount by which the salary changes, as well as the salary value. If the change
is above a certain amount, the trigger might substitute a valid value and call a
user-defined function to send a notice to an administrator about the invalid
update.

Triggers also move application logic into DB2, which can result in faster
application development and easier maintenance. For example, you can write
applications to control salary changes in the employee table, but each application
program that changes the salary column must include logic to check those changes.
A better method is to define a trigger that controls changes to the salary column.
Then DB2 does the checking for any application that modifies salaries.

Example of creating and using a trigger:

Triggers automatically execute a set of SQL statements whenever a specified event

occurs. These SQL statements can perform tasks such as validation and editing of
table changes, reading and modifying tables, or invoking functions or stored
procedures that perform operations both inside and outside DB2.

You create triggers using the CREATE TRIGGER statement. The following figure
shows an example of a CREATE TRIGGER statement.

1
CREATE TRIGGER REORDER

2
3
4
AFTER UPDATE OF ON_HAND, MAX_STOCKED ON PARTS

Chapter 10. Creating and modifying DB2 objects 457

5
REFERENCING NEW AS N_ROW

6
FOR EACH ROW MODE DB2SQL

7
WHEN (N_ROW.ON_HAND < 0.10 * N_ROW.MAX_STOCKED)

8
BEGIN ATOMIC
CALL ISSUE_SHIP_REQUEST(N_ROW.MAX_STOCKED -
N_ROW.ON_HAND,
N_ROW.PARTNO);
END

The parts of this trigger are:

1 Trigger name (REORDER)

2 Trigger activation time (AFTER)

3 Triggering event (UPDATE)

4 Subject table name (PARTS)

5 New transition variable correlation name (N_ROW)

6 Granularity (FOR EACH ROW)

7 Trigger condition (WHEN...)

8 Trigger body (BEGIN ATOMIC...END;)

When you execute this CREATE TRIGGER statement, DB2 creates a trigger
package called REORDER and associates the trigger package with table PARTS.
DB2 records the timestamp when it creates the trigger. If you define other triggers
on the PARTS table, DB2 uses this timestamp to determine which trigger to
activate first. The trigger is now ready to use.

After DB2 updates columns ON_HAND or MAX_STOCKED in any row of table

PARTS, trigger REORDER is activated. The trigger calls a stored procedure called
ISSUE_SHIP_REQUEST if, after a row is updated, the quantity of parts on hand is
less than 10% of the maximum quantity stocked. In the trigger condition, the
qualifier N_ROW represents a value in a modified row after the triggering event.

When you no longer want to use trigger REORDER, you can delete the trigger by
executing the statement:
DROP TRIGGER REORDER;

Executing this statement drops trigger REORDER and its associated trigger
package named REORDER.

If you drop table PARTS, DB2 also drops trigger REORDER and its trigger
package.

Parts of a trigger:

A trigger contains the following parts:

v trigger name
v subject table
v trigger activation time
v triggering event
v granularity
v transition variables

458 Application Programming and SQL Guide

v transition tables
v triggered action

Trigger name:

Use an ordinary identifier to name your trigger. You can use a qualifier or let DB2
determine the qualifier. When DB2 creates a trigger package for the trigger, it uses
the qualifier for the collection ID of the trigger package. DB2 uses these rules to
determine the qualifier:
v If you use static SQL to execute the CREATE TRIGGER statement, DB2 uses the
authorization ID in the bind option QUALIFIER for the plan or package that
contains the CREATE TRIGGER statement. If the bind command does not
include the QUALIFIER option, DB2 uses the owner of the package or plan.
| v If you use dynamic SQL to execute the CREATE TRIGGER statement, DB2 uses
| the authorization ID in special register CURRENT SCHEMA.

Subject table:

When you perform an insert, update, or delete operation on this table, the trigger
is activated. You must name a local table in the CREATE TRIGGER statement. You
cannot define a trigger on a catalog table or on a view.

Trigger activation time:

The two choices for trigger activation time are NO CASCADE BEFORE and
AFTER. NO CASCADE BEFORE means that the trigger is activated before DB2
makes any changes to the subject table, and that the triggered action does not
activate any other triggers. AFTER means that the trigger is activated after DB2
makes changes to the subject table and can activate other triggers. Triggers with an
activation time of NO CASCADE BEFORE are known as before triggers. Triggers
with an activation time of AFTER are known as after triggers.

Triggering event:

Every trigger is associated with an event. A trigger is activated when the triggering
event occurs in the subject table. The triggering event is one of the following SQL
operations:
v insert
v update
v delete

A triggering event can also be an update or delete operation that occurs as the
result of a referential constraint with ON DELETE SET NULL or ON DELETE
CASCADE.

Triggers are not activated as the result of updates made to tables by DB2 utilities,
with the exception of the LOAD utility when it is specified with the RESUME YES
and SHRLEVEL CHANGE options.

When the triggering event for a trigger is an update operation, the trigger is called
an update trigger. Similarly, triggers for insert operations are called insert triggers,
and triggers for delete operations are called delete triggers.

Chapter 10. Creating and modifying DB2 objects 459

The SQL statement that performs the triggering SQL operation is called the
triggering SQL statement. Each triggering event is associated with one subject table
and one SQL operation.

The following trigger is defined with an insert triggering event:

CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END

If the triggering SQL operation is an update operation, the event can be associated
with specific columns of the subject table. In this case, the trigger is activated only
if the update operation updates any of the specified columns.

The following trigger, PAYROLL1, which invokes user-defined function named

PAYROLL_LOG, is activated only if an update operation is performed on the
SALARY or BONUS column of table PAYROLL:
CREATE TRIGGER PAYROLL1
AFTER UPDATE OF SALARY, BONUS ON PAYROLL
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
VALUES(PAYROLL_LOG(USER, 'UPDATE', CURRENT TIME, CURRENT DATE));
END

Granularity:

The triggering SQL statement might modify multiple rows in the table. The
granularity of the trigger determines whether the trigger is activated only once for
the triggering SQL statement or once for every row that the SQL statement
modifies. The granularity values are:
v FOR EACH ROW
The trigger is activated once for each row that DB2 modifies in the subject table.
If the triggering SQL statement modifies no rows, the trigger is not activated.
However, if the triggering SQL statement updates a value in a row to the same
value, the trigger is activated. For example, if an UPDATE trigger is defined on
table COMPANY_STATS, the following SQL statement will activate the trigger.
UPDATE COMPANY_STATS SET NBEMP = NBEMP;
v FOR EACH STATEMENT
The trigger is activated once when the triggering SQL statement executes. The
trigger is activated even if the triggering SQL statement modifies no rows.

Triggers with a granularity of FOR EACH ROW are known as row triggers.
Triggers with a granularity of FOR EACH STATEMENT are known as statement
triggers. Statement triggers can only be after triggers.

The following statement is an example of a row trigger:

CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END

Trigger NEW_HIRE is activated once for every row inserted into the employee
table.

460 Application Programming and SQL Guide

Transition variables:

When you code a row trigger, you might need to refer to the values of columns in
each updated row of the subject table. To do this, specify transition variables in the
REFERENCING clause of your CREATE TRIGGER statement. The two types of
transition variables are:
v Old transition variables, specified with the OLD transition-variable clause, capture
the values of columns before the triggering SQL statement updates them. You
can define old transition variables for update and delete triggers.
v New transition variables, specified with the NEW transition-variable clause,
capture the values of columns after the triggering SQL statement updates them.
You can define new transition variables for update and insert triggers.

The following example uses transition variables and invocations of the

IDENTITY_VAL_LOCAL function to access values that are assigned to identity
columns.

Suppose that you have created tables T and S, with the following definitions:
CREATE TABLE T
(ID SMALLINT GENERATED BY DEFAULT AS IDENTITY (START WITH 100),
C2 SMALLINT,
C3 SMALLINT,
C4 SMALLINT);
CREATE TABLE S
(ID SMALLINT GENERATED ALWAYS AS IDENTITY,
C1 SMALLINT);

Define a before insert trigger on T that uses the IDENTITY_VAL_LOCAL built-in

function to retrieve the current value of identity column ID, and uses transition
variables to update the other columns of T with the identity column value.
CREATE TRIGGER TR1
NO CASCADE BEFORE INSERT
ON T REFERENCING NEW AS N
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
SET N.C3 =N.ID;
SET N.C4 =IDENTITY_VAL_LOCAL();
SET N.ID =N.C2 *10;
SET N.C2 =IDENTITY_VAL_LOCAL();
END

Now suppose that you execute the following INSERT statement:

INSERT INTO S (C1) VALUES (5);

This statement inserts a row into S with a value of 5 for column C1 and a value of
1 for identity column ID. Next, suppose that you execute the following SQL
statement, which activates trigger TR1:
INSERT INTO T (C2)
VALUES (IDENTITY_VAL_LOCAL());

This insert statement, and the subsequent activation of trigger TR1, have the
following results:
v The INSERT statement obtains the most recent value that was assigned to an
identity column (1), and inserts that value into column C2 of table T. 1 is the
value that DB2 inserted into identity column ID of table S.
v When the INSERT statement executes, DB2 inserts the value 100 into identity
column ID column of C2.

Chapter 10. Creating and modifying DB2 objects 461

v The first statement in the body of trigger TR1 inserts the value of transition
variable N.ID (100) into column C3. N.ID is the value that identity column ID
contains after the INSERT statement executes.
v The second statement in the body of trigger TR1 inserts the null value into
column C4. By definition, the result of the IDENTITY_VAL_LOCAL function in
the triggered action of a before insert trigger is the null value.
v The third statement in the body of trigger TR1 inserts 10 times the value of
transition variable N.C2 (10*1) into identity column ID of table T. N.C2 is the
value that column C2 contains after the INSERT is executed.
v The fourth statement in the body of trigger TR1 inserts the null value into
column C2. By definition, the result of the IDENTITY_VAL_LOCAL function in
the triggered action of a before insert trigger is the null value.

Transition tables:

If you want to refer to the entire set of rows that a triggering SQL statement
modifies, rather than to individual rows, use a transition table. Like transition
variables, transition tables can appear in the REFERENCING clause of a CREATE
TRIGGER statement. Transition tables are valid for both row triggers and statement
triggers. The two types of transition tables are:
v Old transition tables, specified with the OLD TABLE transition-table-name clause,
capture the values of columns before the triggering SQL statement updates
them. You can define old transition tables for update and delete triggers.
v New transition tables, specified with the NEW TABLE transition-table-name
clause, capture the values of columns after the triggering SQL statement updates
them. You can define new transition variables for update and insert triggers.

The scope of old and new transition table names is the trigger body. If another
table exists that has the same name as a transition table, any unqualified reference
to that name in the trigger body points to the transition table. To reference the
other table in the trigger body, you must use the fully qualified table name.

The following example uses a new transition table to capture the set of rows that
are inserted into the INVOICE table:
CREATE TRIGGER LRG_ORDR
AFTER INSERT ON INVOICE
REFERENCING NEW TABLE AS N_TABLE
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
SELECT LARGE_ORDER_ALERT(CUST_NO,
TOTAL_PRICE, DELIVERY_DATE)
FROM N_TABLE WHERE TOTAL_PRICE > 10000;
END

The SELECT statement in LRG_ORDER causes user-defined function

LARGE_ORDER_ALERT to execute for each row in transition table N_TABLE that
satisfies the WHERE clause (TOTAL_PRICE > 10000).

Triggered action:

When a trigger is activated, a triggered action occurs. Every trigger has one
triggered action, which consists of a trigger condition and a trigger body.

Trigger condition:

462 Application Programming and SQL Guide

If you want the triggered action to occur only when certain conditions are true,
code a trigger condition. A trigger condition is similar to a predicate in a SELECT,
except that the trigger condition begins with WHEN, rather than WHERE. If you
do not include a trigger condition in your triggered action, the trigger body
executes every time the trigger is activated.

For a row trigger, DB2 evaluates the trigger condition once for each modified row
of the subject table. For a statement trigger, DB2 evaluates the trigger condition
once for each execution of the triggering SQL statement.

If the trigger condition of a before trigger has a fullselect, the fullselect cannot
reference the subject table.

The following example shows a trigger condition that causes the trigger body to
execute only when the number of ordered items is greater than the number of
available items:
CREATE TRIGGER CK_AVAIL
NO CASCADE BEFORE INSERT ON ORDERS
REFERENCING NEW AS NEW_ORDER
FOR EACH ROW MODE DB2SQL
WHEN (NEW_ORDER.QUANTITY >
(SELECT ON_HAND FROM PARTS
WHERE NEW_ORDER.PARTNO=PARTS.PARTNO))
BEGIN ATOMIC
VALUES(ORDER_ERROR(NEW_ORDER.PARTNO,
NEW_ORDER.QUANTITY));
END

Trigger body:

In the trigger body, you code the SQL statements that you want to execute
whenever the trigger condition is true. If the trigger body consists of more than
one statement, it must begin with BEGIN ATOMIC and end with END. You cannot
include host variables or parameter markers in your trigger body. If the trigger
body contains a WHERE clause that references transition variables, the comparison
operator cannot be LIKE.

The statements you can use in a trigger body depend on the activation time of the
trigger. For a list of valid SQL statements for triggers, see the ″Allowable SQL
statements″ table in the CREATE TRIGGER (SQL Reference) topic.

The following list provides more detailed information about SQL statements that
are valid in triggers:
v fullselect, CALL, and VALUES
Use a fullselect or the VALUES statement in a trigger body to conditionally or
unconditionally invoke a user-defined function. Use the CALL statement to
invoke a stored procedure. See “Invoking stored procedures and user-defined
functions from triggers” on page 465 for more information on invoking
user-defined functions and stored procedures from triggers.
A fullselect in the trigger body of a before trigger cannot reference the subject
table.
v SIGNAL
Use the SIGNAL statement in the trigger body to report an error condition and
back out any changes that are made by the trigger, as well as actions that result
from referential constraints on the subject table. When DB2 executes the SIGNAL

Chapter 10. Creating and modifying DB2 objects 463

statement, it returns an SQLCA to the application with SQLCODE -438. The
SQLCA also includes the following values, which you supply in the SIGNAL
statement:
– A 5-character value that DB2 uses as the SQLSTATE
– An error message that DB2 places in the SQLERRMC field
In the following example, the SIGNAL statement causes DB2 to return an
SQLCA with SQLSTATE 75001 and terminate the salary update operation if an
employee’s salary increase is over 20%:
CREATE TRIGGER SAL_ADJ
BEFORE UPDATE OF SALARY ON EMP
REFERENCING OLD AS OLD_EMP
NEW AS NEW_EMP
FOR EACH ROW MODE DB2SQL
WHEN (NEW_EMP.SALARY > (OLD_EMP.SALARY * 1.20))
BEGIN ATOMIC
SIGNAL SQLSTATE '75001'
('Invalid Salary Increase - Exceeds 20%');
END
v SET transition-variable
Because before triggers operate on rows of a table before those rows are
modified, you cannot perform operations in the body of a before trigger that
directly modify the subject table. You can, however, use the SET
transition-variable statement to modify the values in a row before those values go
into the table. For example, this trigger uses a new transition variable to fill in
today’s date for the new employee’s hire date:
CREATE TRIGGER HIREDATE
NO CASCADE BEFORE INSERT ON EMP
REFERENCING NEW AS NEW_VAR
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
SET NEW_VAR.HIRE_DATE = CURRENT_DATE;
END
| v INSERT, DELETE (searched), UPDATE (searched), and MERGE
| Because you can include INSERT, DELETE (searched), UPDATE (searched), and
| MERGE statements in your trigger body, execution of the trigger body might
| cause activation of other triggers. See “Trigger cascading” on page 468 for more
| information.

If any SQL statement in the trigger body fails during trigger execution, DB2 rolls
back all changes that are made by the triggering SQL statement and the triggered
SQL statements. However, if the trigger body executes actions that are outside of
DB2’s control or are not under the same commit coordination as the DB2
subsystem in which the trigger executes, DB2 cannot undo those actions. Examples
of external actions that are not under DB2’s control are:
v Performing updates that are not under RRS commit control
v Sending an electronic mail message

If the trigger executes external actions that are under the same commit
coordination as the DB2 subsystem under which the trigger executes, and an error
occurs during trigger execution, DB2 places the application process that issued the
triggering statement in a must-rollback state. The application must then execute a
rollback operation to roll back those external actions. Examples of external actions
that are under the same commit coordination as the triggering SQL operation are:
v Executing a distributed update operation
v From a user-defined function or stored procedure, executing an external action
that affects an external resource manager that is under RRS commit control.

464 Application Programming and SQL Guide

Related reference
CREATE TRIGGER (SQL Reference)
LOAD (DB2 Utilities)

Invoking stored procedures and user-defined functions from

triggers
A trigger body can include only SQL statements. To perform actions or use logic
that is not available in SQL statements, create user-defined functions or stored
procedures that can be invoked from within the trigger body.

| Because a before trigger must not modify any table, functions and procedures that
| you invoke from a trigger cannot include INSERT, UPDATE, DELETE, or MERGE
| statements that modify the subject table.

To invoke a user-defined function from a trigger, code a SELECT statement or

VALUES statement. Use a SELECT statement to execute the function conditionally.
The number of times the user-defined function executes depends on the number of
rows in the result table of the SELECT statement. For example, in this trigger, the
SELECT statement causes user-defined function LARGE_ORDER_ALERT to
execute for each row in transition table N_TABLE with an order of more than
10000:
CREATE TRIGGER LRG_ORDR
AFTER INSERT ON INVOICE
REFERENCING NEW TABLE AS N_TABLE
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
SELECT LARGE_ORDER_ALERT(CUST_NO, TOTAL_PRICE, DELIVERY_DATE)
FROM N_TABLE WHERE TOTAL_PRICE > 10000;
END

Use the VALUES statement to execute a function unconditionally; that is, once for
each execution of a statement trigger or once for each row in a row trigger. In this
example, user-defined function PAYROLL_LOG executes every time an update
operation occurs that activates trigger PAYROLL1:
CREATE TRIGGER PAYROLL1
AFTER UPDATE ON PAYROLL
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
VALUES(PAYROLL_LOG(USER, 'UPDATE',
CURRENT TIME, CURRENT DATE));
END

To invoke a stored procedure from a trigger, use a CALL statement. The

parameters of this stored procedure call must be constants, transition variables,
table locators, or expressions.

Passing transition tables to user-defined functions and stored procedures:

When you call a user-defined function or stored procedure from a trigger, you
might want to give the function or procedure access to the entire set of modified
rows. That is, you want to pass a pointer to the old or new transition table. You do
this using table locators.

Most of the code for using a table locator is in the function or stored procedure
that receives the locator. To pass the transition table from a trigger, specify the
parameter TABLE transition-table-name when you invoke the function or stored

Chapter 10. Creating and modifying DB2 objects 465

procedure. This causes DB2 to pass a table locator for the transition table to the
user-defined function or stored procedure. For example, this trigger passes a table
locator for a transition table NEWEMPS to stored procedure CHECKEMP:
CREATE TRIGGER EMPRAISE
AFTER UPDATE ON EMP
REFERENCING NEW TABLE AS NEWEMPS
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
CALL CHECKEMP(TABLE NEWEMPS);
END
Related concepts
“User-defined functions” on page 483
Related tasks
“Accessing transition tables in a user-defined function or stored procedure” on
page 513

| Inserting, updating, and deleting data in views by using

| INSTEAD OF triggers
| INSTEAD OF triggers are triggers that execute instead of the INSERT, UPDATE, or
| DELETE statement that activates the trigger. You can define these triggers on views
| only. Use INSTEAD OF triggers to insert, update, and delete data in complex
| views.

| Complex views are those views that are defined on expressions or multiple tables.
| In some cases, those views are read only. In these cases, INSTEAD OF triggers
| make the insert, update and delete operations possible. If the complex view is not
| read only, you can request an insert, update, or delete operation. However, DB2
| automatically decides how to perform that operation on the base tables that are
| referenced in the view. With INSTEAD OF triggers, you can define exactly how
| DB2 is to execute an insert, update, or delete operation on the view. You no longer
| leave the decision to DB2.

| To insert, update, or delete data in a view by using INSTEAD OF triggers:

| 1. Define one or more INSTEAD OF triggers on the view by using a CREATE
| TRIGGER statement.
| You can create one trigger for each of the following operations: INSERT,
| UPDATE, and DELETE. These triggers define the action that DB2 is to take for
| each of these operations.
| For information about the syntax of the CREATE TRIGGER statement, see the
| topic “CREATE TRIGGERS” in DB2 SQL Reference.
| 2. Submit a INSERT, UPDATE, or DELETE statement on the view.
| DB2 executes the appropriate INSTEAD OF trigger.

| Example: Suppose that you create the following view on the sample tables
| DSN8910.EMP and DSN8910.DEPT:
| CREATE VIEW EMPV (EMPNO, FIRSTNME, MIDINIT, LASTNAME, PHONENO, HIREDATE,DEPTNAME)
| AS SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, PHONENO, HIREDATE, DEPTNAME
| FROM DSN8910.EMP, DSN8910.DEPT WHERE DSN8910.EMP.WORKDEPT
| = DSN8910.DEPT.DEPTNO

| Suppose that you also define the following three INSTEAD OF triggers:
| CREATE TRIGGER EMPV_INSERT INSTEAD OF INSERT ON EMPV
| REFERENCING NEW AS NEWEMP
| FOR EACH ROW MODE DB2SQL

466 Application Programming and SQL Guide

| INSERT INTO DSN8910.EMP (EMPNO, FIRSTNME, MIDINIT, LASTNAME, WORKDEPT,
| PHONENO, HIREDATE)
| VALUES(NEWEMP.EMPNO, NEWEMP.FIRSTNME, NEWEMP.MIDINIT, NEWEMP.LASTNAME,
| COALESCE((SELECT D.DEPTNO FROM DSN8910.DEPT AS D
| WHERE D.DEPTNAME = NEWEMP.DEPTNAME),
| RAISE_ERROR('70001', 'Unknown department name')),
| NEWEMP.PHONENO, NEWEMP.HIREDATE)
|
| CREATE TRIGGER EMPV_UPDATE INSTEAD OF UPDATE ON EMPV
| REFERENCING NEW AS NEWEMP OLD AS OLDEMP
| FOR EACH ROW MODE DB2SQL
| BEGIN ATOMIC
| UPDATE DSN8910.EMP AS E
| SET (E.FIRSTNME, E.MIDINIT, E.LASTNAME, E.WORKDEPT, E.PHONENO,
| E.HIREDATE)
| = (NEWEMP.FIRSTNME, NEWEMP.MIDINIT, NEWEMP.LASTNAME,
| COALESCE((SELECT D.DEPTNO FROM DSN8910.DEPT AS D
| WHERE D.DEPTNAME = OLDEMP.DEPTNAME),
| RAISE_ERROR ('70001', 'Unknown department name'))
| NEWEMP.PHONENO, NEWEMP.HIREDATE)
| WHERE NEWEMP.EMPNO = E.EMPNO;
| UPDATE DSN8910.DEPT D SET D.DEPTNAME=NEWEMP.DEPTNAME
| WHERE D.DEPTNAME=OLDEMP.DEPTNAME;
| END
|
| CREATE TRIGGER EMPV_DELETE INSTEAD OF DELETE ON EMPV
| REFERENCING OLD AS OLDEMP
| FOR EACH ROW MODE DB2SQL
| DELETE FROM DSN8910.EMP AS E WHERE E.EMPNO = OLDEMP.EMPNO

| Because the view is on a query with an inner join, the view is read only. However,
| the INSTEAD OF triggers makes insert, update, and delete operations possible.

| Table 84 describes what happens for various insert, update, and delete operations
| on the EMPV view.
| Table 84. Results of INSTEAD OF triggers
| SQL statement Result
|| INSERT INTO EMPV VALUES (...) The EMPV_INSERT trigger is activated. This
| trigger inserts the row into the base table
| DSN8910.EMP if the department name
| matches a value in the WORKDEPT column
| in the DSN8910.DEPT table. Otherwise, an
| error is returned. If a query had been used
| instead of a VALUES clause on the INSERT
| statement, the trigger body would be
| processed for each row from the query.
|| UPDATE EMPV The EMPV_UPDATE trigger is activated. This
|| SET DEPTNAME='PLANNING & STRATEGY' trigger updates the DEPTNAME column in
| WHERE DEPTNAME='PLANNING' the DSN8910.DEPT for the any qualifying
| rows.
|| DELETE FROM EMPV The EMPV_DELETE trigger is activated. This
|| WHERE HIREDATE<'1910-01-01' trigger deletes the qualifying rows from the
| DSN8910.EMP table.
|

| Trigger packages
A trigger package is a special type of package that is created only when you
execute a CREATE TRIGGER statement. A trigger package executes only when its
associated trigger is activated.

Chapter 10. Creating and modifying DB2 objects 467

As with any other package, DB2 marks a trigger package invalid when you drop a
table, index, or view on which the trigger package depends. DB2 executes an
automatic rebind the next time the trigger is activated. However, if the automatic
rebind fails, DB2 does not mark the trigger package as inoperative.

Unlike other packages, a trigger package is freed if you drop the table on which
the trigger is defined, so you can recreate the trigger package only by recreating
the table and the trigger.

You can use the subcommand REBIND TRIGGER PACKAGE to rebind a trigger
package that DB2 has marked as inoperative. You can also use REBIND TRIGGER
PACKAGE to change the option values with which DB2 originally bound the
trigger package. You can change only a limited subset of the default bind options
that DB2 used when creating the package. For a description of these options, see
the topic “REBIND TRIGGER PACKAGE (DSN)” in DB2 Command Reference.

Trigger cascading
When a trigger performs an SQL operation, it might modify the subject table or
other tables with triggers, so DB2 also activates those triggers. This situation is
called trigger cascading.

A trigger that is activated as the result of another trigger can be activated at the
same level as the original trigger or at a different level. Two triggers, A and B, are
activated at different levels if trigger B is activated after trigger A is activated and
completes before trigger A completes. If trigger B is activated after trigger A is
activated and completes after trigger A completes, then the triggers are at the same
level.

For example, in these cases, trigger A and trigger B are activated at the same level:
v Table X has two triggers that are defined on it, A and B. A is a before trigger and
B is an after trigger. An update to table X causes both trigger A and trigger B to
activate.
v Trigger A updates table X, which has a referential constraint with table Y, which
has trigger B defined on it. The referential constraint causes table Y to be
updated, which activates trigger B.
In these cases, trigger A and trigger B are activated at different levels:
v Trigger A is defined on table X, and trigger B is defined on table Y. Trigger B is
an update trigger. An update to table X activates trigger A, which contains an
UPDATE statement on table B in its trigger body. This UPDATE statement
activates trigger B.
v Trigger A calls a stored procedure. The stored procedure contains an INSERT
statement for table X, which has insert trigger B defined on it. When the INSERT
statement on table X executes, trigger B is activated.

When triggers are activated at different levels, it is called trigger cascading. Trigger
cascading can occur only for after triggers because DB2 does not support cascading
of before triggers.

To prevent the possibility of endless trigger cascading, DB2 supports only 16 levels
of cascading of triggers, stored procedures, and user-defined functions. If a trigger,
user-defined function, or stored procedure at the 17th level is activated, DB2
returns SQLCODE -724 and backs out all SQL changes in the 16 levels of

468 Application Programming and SQL Guide

cascading. However, as with any other SQL error that occurs during trigger
execution, if any action occurs that is outside the control of DB2, that action is not
backed out.

You can write a monitor program that issues IFI READS requests to collect DB2
trace information about the levels of cascading of triggers, user-defined functions,
and stored procedures in your programs. For information on how to write a
monitor program, see the topic “Invoking IFI from your program” in DB2
Performance Monitoring and Tuning Guide.

Order of multiple triggers

You can create multiple triggers for the same subject table, event, and activation
time. The order in which those triggers are activated is the order in which the
triggers were created.

DB2 records the timestamp when each CREATE TRIGGER statement executes.
When an event occurs in a table that activates more than one trigger, DB2 uses the
stored timestamps to determine which trigger to activate first.

DB2 always activates all before triggers that are defined on a table before the after
triggers that are defined on that table, but within the set of before triggers, the
activation order is by timestamp, and within the set of after triggers, the activation
order is by timestamp.

In this example, triggers NEWHIRE1 and NEWHIRE2 have the same triggering
event (INSERT), the same subject table (EMP), and the same activation time
(AFTER). Suppose that the CREATE TRIGGER statement for NEWHIRE1 is run
before the CREATE TRIGGER statement for NEWHIRE2:
CREATE TRIGGER NEWHIRE1
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END

CREATE TRIGGER NEWHIRE2

AFTER INSERT ON EMP
REFERENCING NEW AS N_EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE DEPTS SET NBEMP = NBEMP + 1
WHERE DEPT_ID = N_EMP.DEPT_ID;
END

When an insert operation occurs on table EMP, DB2 activates NEWHIRE1 first
because NEWHIRE1 was created first. Now suppose that someone drops and
re-creates NEWHIRE1. NEWHIRE1 now has a later timestamp than NEWHIRE2,
so the next time an insert operation occurs on EMP, NEWHIRE2 is activated before
NEWHIRE1.

If two row triggers are defined for the same action, the trigger that was created
earlier is activated first for all affected rows. Then the second trigger is activated
for all affected rows. In the previous example, suppose that an INSERT statement
with a fullselect inserts 10 rows into table EMP. NEWHIRE1 is activated for all 10
rows, then NEWHIRE2 is activated for all 10 rows.

Chapter 10. Creating and modifying DB2 objects 469

Interactions between triggers and referential constraints
When you create triggers, you need to understand the interactions among the
triggers and constraints on your tables and the effect that the order of processing
of those constraints and triggers can have on the results.

In general, the following steps occur when triggering SQL statement S1 performs
an insert, update, or delete operation on table T1:
1. DB2 determines the rows of T1 to modify. Call that set of rows M1. The
contents of M1 depend on the SQL operation:
v For a delete operation, all rows that satisfy the search condition of the
statement for a searched delete operation, or the current row for a positioned
delete operation
v For an insert operation, the row identified by the VALUES statement, or the
rows identified by the result table of a SELECT clause within the INSERT
statement
v For an update operation, all rows that satisfy the search condition of the
statement for a searched update operation, or the current row for a
positioned update operation
2. DB2 processes all before triggers that are defined on T1, in order of creation.
Each before trigger executes the triggered action once for each row in M1. If
M1 is empty, the triggered action does not execute.
If an error occurs when the triggered action executes, DB2 rolls back all
changes that are made by S1.
| 3. DB2 makes the changes that are specified in statement S1 to table T1, unless an
| INSTEAD OF trigger is defined for that action. If an appropriate INSTEAD OF
| trigger is defined, DB2 executes the trigger instead of the statement and skips
| the remaining steps in this list.
| If an error occurs, DB2 rolls back all changes that are made by S1.
4. If M1 is not empty, DB2 applies all the following constraints and checks that
are defined on table T1:
v Referential constraints
v Check constraints
v Checks that are due to updates of the table through views defined WITH
CHECK OPTION
Application of referential constraints with rules of DELETE CASCADE or
DELETE SET NULL are activated before delete triggers or before update
triggers on the dependent tables.
If any constraint is violated, DB2 rolls back all changes that are made by
constraint actions or by statement S1.
5. DB2 processes all after triggers that are defined on T1, and all after triggers on
tables that are modified as the result of referential constraint actions, in order of
creation.
Each after row trigger executes the triggered action once for each row in M1. If
M1 is empty, the triggered action does not execute.
Each after statement trigger executes the triggered action once for each
execution of S1, even if M1 is empty.

If any triggered actions contain SQL insert, update, or delete operations, DB2
repeats steps 1 through 5 for each operation.

470 Application Programming and SQL Guide

If an error occurs when the triggered action executes, or if a triggered action is at
the 17th level of trigger cascading, DB2 rolls back all changes that are made in step
5 and all previous steps.

For example, table DEPT is a parent table of EMP, with these conditions:
v The DEPTNO column of DEPT is the primary key.
v The WORKDEPT column of EMP is the foreign key.
v The constraint is ON DELETE SET NULL.
Suppose the following trigger is defined on EMP:
CREATE TRIGGER EMPRAISE
AFTER UPDATE ON EMP
REFERENCING NEW TABLE AS NEWEMPS
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
VALUES(CHECKEMP(TABLE NEWEMPS));
END

Also suppose that an SQL statement deletes the row with department number E21
from DEPT. Because of the constraint, DB2 finds the rows in EMP with a
WORKDEPT value of E21 and sets WORKDEPT in those rows to null. This is
equivalent to an update operation on EMP, which has update trigger EMPRAISE.
Therefore, because EMPRAISE is an after trigger, EMPRAISE is activated after the
constraint action sets WORKDEPT values to null.

Interactions between triggers and tables that have multilevel

security with row-level granularity
A BEFORE trigger affects the value of the transition variable that is associated with
a security label column.

If a subject table has a security label column, the column in the transition table or
transition variable that corresponds to the security label column in the subject table
does not inherit the security label attribute. This means that the multilevel security
check with row-level granularity is not enforced for the transition table or the
transition variable. If you add a security label column to a subject table using the
ALTER TABLE statement, the rules are the same as when you add any column to a
subject table because the column in the transition table or the transition variable
that corresponds to the security label column does not inherit the security label
attribute.

If the ID you are using does not have write-down privilege and you execute an
insert or update operation, the security label value of your ID is assigned to the
security label column for the rows that you are inserting or updating.

When a BEFORE trigger is activated, the value of the transition variable that
corresponds to the security label column is the security label of the ID if either of
the following conditions is true:
v The user does not have write-down privilege
v The value for the security label column is not specified

If the user does not have write-down privilege, and the trigger changes the
transition variable that corresponds to the security label column, the value of the
security label column is changed back to the security label value of the user before
the row is written to the page. For more information about multilevel security with
row-level granularity, see the topic “Multilevel security” in DB2 Administration
Guide.

Chapter 10. Creating and modifying DB2 objects 471

Triggers that return inconsistent results
When you create triggers and write SQL statements that activate those triggers,
you need to ensure that executing those statements on the same set of data always
produces the same results.

Two common reasons that you can get inconsistent results are:
v Positioned UPDATE or DELETE statements that use uncorrelated subqueries
cause triggers to operate on a larger result table than you intended.
v DB2 does not always process rows in the same order, so triggers that propagate
rows of a table can generate different result tables at different times.
The following examples demonstrate these situations.

Example: Effect of an uncorrelated subquery on a triggered action: Suppose that

tables T1 and T2 look like this:
Table T1 Table T2
A1 B1
== ==
1 1
2 2

The following trigger is defined on T1:

CREATE TRIGGER TR1
AFTER UPDATE OF T1
FOR EACH ROW
MODE DB2SQL
BEGIN ATOMIC
DELETE FROM T2 WHERE B1 = 2;
END

Now suppose that an application executes the following statements to perform a

positioned update operation:
EXEC SQL BEGIN DECLARE SECTION;
long hv1;
EXEC
. SQL END DECLARE SECTION;
.
.
EXEC SQL DECLARE C1 CURSOR FOR
SELECT A1 FROM T1
WHERE A1 IN (SELECT B1 FROM T2)
. FOR UPDATE OF A1;
.
.
EXEC
. SQL OPEN C1;
.
.
while(SQLCODE>=0 && SQLCODE!=100)
{
EXEC SQL FETCH C1 INTO :hv1;
UPDATE T1 SET A1=5 WHERE CURRENT OF C1;
}

When DB2 executes the FETCH statement that positions cursor C1 for the first
time, DB2 evaluates the subselect, SELECT B1 FROM T2, to produce a result table
that contains the two rows of column T2:
1
2

When DB2 executes the positioned UPDATE statement for the first time, trigger
TR1 is activated. When the body of trigger TR1 executes, the row with value 2 is
deleted from T2. However, because SELECT B1 FROM T2 is evaluated only once,
when the FETCH statement is executed again, DB2 finds the second row of T1,

472 Application Programming and SQL Guide

even though the second row of T2 was deleted. The FETCH statement positions
the cursor to the second row of T1, and the second row of T1 is updated. The
update operation causes the trigger to be activated again, which causes DB2 to
attempt to delete the second row of T2, even though that row was already deleted.

To avoid processing of the second row after it should have been deleted, use a
correlated subquery in the cursor declaration:
DCL C1 CURSOR FOR
SELECT A1 FROM T1 X
WHERE EXISTS (SELECT B1 FROM T2 WHERE X.A1 = B1)
FOR UPDATE OF A1;

In this case, the subquery, SELECT B1 FROM T2 WHERE X.A1 = B1, is evaluated
for each FETCH statement. The first time that the FETCH statement executes, it
positions the cursor to the first row of T1. The positioned UPDATE operation
activates the trigger, which deletes the second row of T2. Therefore, when the
FETCH statement executes again, no row is selected, so no update operation or
triggered action occurs.

Example: Effect of row processing order on a triggered action: The following

example shows how the order of processing rows can change the outcome of an
after row trigger.

Suppose that tables T1, T2, and T3 look like this:

Table T1 Table T2 Table T3
A1 B1 C1
== == ==
1 (empty) (empty)
2

The following trigger is defined on T1:

CREATE TRIGGER TR1
AFTER UPDATE ON T1
REFERENCING NEW AS N
FOR EACH ROW
MODE DB2SQL
BEGIN ATOMIC
INSERT INTO T2 VALUES(N.C1);
INSERT INTO T3 (SELECT B1 FROM T2);
END

Now suppose that a program executes the following UPDATE statement:

UPDATE T1 SET A1 = A1 + 1;

The contents of tables T2 and T3 after the UPDATE statement executes depend on
the order in which DB2 updates the rows of T1.

If DB2 updates the first row of T1 first, after the UPDATE statement and the
trigger execute for the first time, the values in the three tables are:
Table T1 Table T2 Table T3
A1 B1 C1
== == ==
2 2 2
2

After the second row of T1 is updated, the values in the three tables are:

Chapter 10. Creating and modifying DB2 objects 473

Table T1 Table T2 Table T3
A1 B1 C1
== == ==
2 2 2
3 3 2
3

However, if DB2 updates the second row of T1 first, after the UPDATE statement
and the trigger execute for the first time, the values in the three tables are:
Table T1 Table T2 Table T3
A1 B1 C1
== == ==
1 3 3
3

After the first row of T1 is updated, the values in the three tables are:
Table T1 Table T2 Table T3
A1 B1 C1
== == ==
2 3 3
3 2 3
2

Sequence objects
A sequence is a user-defined object that generates a sequence of numeric values
according to the specification with which the sequence was created. Sequences,
unlike identity columns, are not associated with tables. Applications refer to a
sequence object to get its current or next value.

The sequence of numeric values is generated in a monotonically ascending or

descending order. The relationship between sequences and tables is controlled by
the application, not by DB2.

Your application can reference a sequence object and coordinate the value as keys
across multiple rows and tables. However, a table column that gets its values from
a sequence object does not necessarily have unique values in that column. Even if
the sequence object has been defined with the NO CYCLE clause, some other
application might insert values into that table column other than values you obtain
by referencing that sequence object.

DB2 always generates sequence numbers in order of request. However, in a data

sharing group where the sequence values are cached by multiple DB2 members
simultaneously, the sequence value assignments might not be in numeric order.
Additionally, you might have gaps in sequence number values for the following
reasons:
v If DB2 terminates abnormally before it assigns all the cached values
v If your application rolls back a transaction that increments the sequence
v If the statement containing NEXT VALUE fails after it increments the sequence

You create a sequence object with the CREATE SEQUENCE statement, alter it with
the ALTER SEQUENCE statement, and drop it with the DROP SEQUENCE
statement. You grant access to a sequence with the GRANT (privilege) ON
SEQUENCE statement, and revoke access to the sequence with the REVOKE
(privilege) ON SEQUENCE statement.

474 Application Programming and SQL Guide

The values that DB2 generates for a sequence depend on how the sequence is
created. The START WITH option determines the first value that DB2 generates.
The values advance by the INCREMENT BY value in ascending or descending
order.

The MINVALUE and MAXVALUE options determine the minimum and maximum
values that DB2 generates. The CYCLE or NO CYCLE option determines whether
DB2 wraps values when it has generated all values between the START WITH
value and MAXVALUE if the values are ascending, or between the START WITH
value and MINVALUE if the values are descending.

Keys across multiple tables: You can use the same sequence number as a key
value in two separate tables by first generating the sequence value with a NEXT
VALUE expression to insert the first row in the first table. You can then reference
this same sequence value with a PREVIOUS VALUE expression to insert the other
rows in the second table.

Example: Suppose that an ORDERS table and an ORDER_ITEMS table are defined
in the following way:
CREATE TABLE ORDERS
(ORDERNO INTEGER NOT NULL,
ORDER_DATE DATE DEFAULT,
CUSTNO SMALLINT
PRIMARY KEY (ORDERNO));

CREATE TABLE ORDER_ITEMS

(ORDERNO INTEGER NOT NULL,
PARTNO INTEGER NOT NULL,
QUANTITY SMALLINT NOT NULL,
PRIMARY KEY (ORDERNO,PARTNO),
CONSTRAINT REF_ORDERNO FOREIGN KEY (ORDERNO)
REFERENCES ORDERS (ORDERNO) ON DELETE CASCADE);

You create a sequence named ORDER_SEQ to use as key values for both the
ORDERS and ORDER_ITEMS tables:
CREATE SEQUENCE ORDER_SEQ AS INTEGER
START WITH 1
INCREMENT BY 1
NO MAXVALUE
NO CYCLE
CACHE 20;

You can then use the same sequence number as a primary key value for the
ORDERS table and as part of the primary key value for the ORDER_ITEMS table:
INSERT INTO ORDERS (ORDERNO, CUSTNO)
VALUES (NEXT VALUE FOR ORDER_SEQ, 12345);

INSERT INTO ORDER_ITEMS (ORDERNO, PARTNO, QUANTITY)

VALUES (PREVIOUS VALUE FOR ORDER_SEQ, 987654, 2);

The NEXT VALUE expression in the first INSERT statement generates a sequence
number value for the sequence object ORDER_SEQ. The PREVIOUS VALUE
expression in the second INSERT statement retrieves that same value because it
was the sequence number most recently generated for that sequence object within
the current application process.

Chapter 10. Creating and modifying DB2 objects 475

DB2 object relational extensions
With the object extensions of DB2, you can incorporate object-oriented concepts
and methodologies into your relational database by extending DB2 with richer sets
of data types and functions.

With those extensions, you can store instances of object-oriented data types in
columns of tables and operate on them using functions in SQL statements. In
addition, you can control the types of operations that users can perform on those
data types.

The object extensions that DB2 provides are:

v Large objects (LOBs)
| The VARCHAR, VARGRAPHIC, and VARBINARY data types have a storage
| limit of 32 KB. Although this might be sufficient for small- to medium-size text
| data, applications often need to store large text documents. They might also
| need to store a wide variety of additional data types such as audio, video,
| drawings, mixed text and graphics, and images. DB2 provides three data types
| to store these data objects as strings of up to 2 GB - 1 in size. The three data
| types are binary large objects (BLOBs), character large objects (CLOBs), and
| double-byte character large objects (DBCLOBs).
For a detailed discussion of LOBs, see “Large objects (LOBs)” on page 430.
v Distinct types
A distinct type is a user-defined data type that shares its internal representation
with a built-in data type but is considered to be a separate and incompatible
type for semantic purposes. For example, you might want to define a picture
type or an audio type, both of which have quite different semantics, but which
use the built-in data type BLOB for their internal representation.
For a detailed discussion of distinct types, see “Distinct types” on page 477.
v User-defined functions
| The built-in functions that are supplied with DB2 are a useful set of functions,
| but they might not satisfy all of your requirements. For those cases, you can use
| user-defined functions. For example, a built-in function might perform a
| calculation you need, but the function does not accept the distinct types you
| want to pass to it. You can then define a function based on a built-in function,
| called a sourced user-defined function, that accepts your distinct types. You
| might need to perform another calculation in your SQL statements for which no
| built-in function exists. In that situation, you can define and write an SQL
| function or an external function.
For a detailed discussion of user-defined functions, see “User-defined functions”
on page 483.

Creating a distinct type

Distinct types are useful when you want DB2 to handle certain data differently
than other data of the same data type. For example, even though all currencies can
be declared as type DECIMAL, you do not want euros to be compared to Japanese
yen.

To create a distinct type:

Issue the CREATE DISTINCT TYPE statement. For example, you can create distinct
types for euros and yen by issuing the following SQL statements:

476 Application Programming and SQL Guide

CREATE DISTINCT TYPE EURO AS DECIMAL(9,2);
CREATE DISTINCT TYPE JAPANESE_YEN AS DECIMAL(9,2);
Related reference
CREATE TYPE (SQL Reference)

Distinct types
A distinct type is a user-defined data type that is based on existing built-in DB2
data types. You can use distinct types in the same way that you use built-in data
types, in any type of SQL application except for a DB2 private protocol application.

Each distinct type has the same internal representation as a built-in data type.

Suppose you want to define some audio and video data in a DB2 table. You can
define columns for both types of data as BLOB, but you might want to use a data
type that more specifically describes the data. To do that, define distinct types. You
can then use those types when you define columns in a table or manipulate the
data in those columns. For example, you can define distinct types for the audio
and video data like this:
CREATE DISTINCT TYPE AUDIO AS BLOB (1M);
CREATE DISTINCT TYPE VIDEO AS BLOB (1M);

Then, your CREATE TABLE statement might look like this:

CREATE TABLE VIDEO_CATALOG;
(VIDEO_NUMBER CHAR(6) NOT NULL,
VIDEO_SOUND AUDIO,
VIDEO_PICS VIDEO,
ROW_ID ROWID NOT NULL GENERATED ALWAYS);

For more information on LOB data, see “Large objects (LOBs)” on page 430.

After you define distinct types and columns of those types, you can use those data
types in the same way you use built-in types. You can use the data types in
assignments, comparisons, function invocations, and stored procedure calls.
However, when you assign one column value to another or compare two column
values, those values must be of the same distinct type. For example, you must
assign a column value of type VIDEO to a column of type VIDEO, and you can
compare a column value of type AUDIO only to a column of type AUDIO. When
you assign a host variable value to a column with a distinct type, you can use any
host data type that is compatible with the source data type of the distinct type. For
example, to receive an AUDIO or VIDEO value, you can define a host variable like
this:
SQL TYPE IS BLOB (1M) HVAV;

When you use a distinct type as an argument to a function, a version of that

function that accepts that distinct type must exist. For example, if function SIZE
takes a BLOB type as input, you cannot automatically use a value of type AUDIO
as input. However, you can create a sourced user-defined function that takes the
AUDIO type as input. For example:
CREATE FUNCTION SIZE(AUDIO)
RETURNS INTEGER
SOURCE SIZE(BLOB(1M));

Chapter 10. Creating and modifying DB2 objects 477

Using distinct types in application programs: The main reason to use distinct
types is because DB2 enforces strong typing for distinct types. Strong typing ensures
that only functions, procedures, comparisons, and assignments that are defined for
a data type can be used.

For example, if you have defined a user-defined function to convert U.S. dollars to
euro currency, you do not want anyone to use this same user-defined function to
convert Japanese yen to euros because the U.S. dollars to euros function returns the
wrong amount. Suppose you define three distinct types:
CREATE DISTINCT TYPE US_DOLLAR AS DECIMAL(9,2);
CREATE DISTINCT TYPE EURO AS DECIMAL(9,2);
CREATE DISTINCT TYPE JAPANESE_YEN AS DECIMAL(9,2);

If a conversion function is defined that takes an input parameter of type

US_DOLLAR as input, DB2 returns an error if you try to execute the function with
an input parameter of type JAPANESE_YEN.

Example of distinct types, user-defined functions, and LOBs

This example shows how to create and use a distinct type based on a LOB data
type.

The example in this topic demonstrates the following concepts:

v Creating a distinct type based on a LOB data type
v Defining a user-defined function with a distinct type as an argument
v Creating a table with a distinct type column that is based on a LOB type
v Defining a LOB table space, auxiliary table, and auxiliary index
v Inserting data from a host variable into a distinct type column based on a LOB
column
v Executing a query that contains a user-defined function invocation
v Casting a LOB locator to the input data type of a user-defined function

Suppose that you keep electronic mail documents that are sent to your company in
a DB2 table. The DB2 data type of an electronic mail document is a CLOB, but you
define it as a distinct type so that you can control the types of operations that are
performed on the electronic mail. The distinct type is defined like this:
CREATE DISTINCT TYPE E_MAIL AS CLOB(5M);

You have also defined and written user-defined functions to search for and return
the following information about an electronic mail document:
v Subject
v Sender
v Date sent
v Message content
v Indicator of whether the document contains a user-specified string
The user-defined function definitions look like this:
CREATE FUNCTION SUBJECT(E_MAIL)
RETURNS VARCHAR(200)
EXTERNAL NAME 'SUBJECT'
LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION;
CREATE FUNCTION SENDER(E_MAIL)
RETURNS VARCHAR(200)
EXTERNAL NAME 'SENDER'

478 Application Programming and SQL Guide

LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION;
CREATE FUNCTION SENDING_DATE(E_MAIL)
RETURNS DATE
EXTERNAL NAME 'SENDDATE'
LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION;
CREATE FUNCTION CONTENTS(E_MAIL)
RETURNS CLOB(1M)
EXTERNAL NAME 'CONTENTS'
LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION;
CREATE FUNCTION CONTAINS(E_MAIL, VARCHAR (200))
RETURNS INTEGER
EXTERNAL NAME 'CONTAINS'
LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION;

The table that contains the electronic mail documents is defined like this:
CREATE TABLE DOCUMENTS
(LAST_UPDATE_TIME TIMESTAMP,
DOC_ROWID ROWID NOT NULL GENERATED ALWAYS,
A_DOCUMENT E_MAIL);

Because the table contains a column with a source data type of CLOB, the table
requires an associated LOB table space, auxiliary table, and index on the auxiliary
table. Use statements like this to define the LOB table space, the auxiliary table,
and the index:
CREATE LOB TABLESPACE DOCTSLOB
LOG YES
GBPCACHE SYSTEM;

CREATE AUX TABLE DOCAUX_TABLE

IN DOCTSLOB
STORES DOCUMENTS COLUMN A_DOCUMENT;

CREATE INDEX A_IX_DOC ON DOCAUX_TABLE;

To populate the document table, you write code that executes an INSERT
statement to put the first part of a document in the table, and then executes
multiple UPDATE statements to concatenate the remaining parts of the document.
For example:
EXEC SQL BEGIN DECLARE SECTION;
char hv_current_time[26];
SQL TYPE IS CLOB (1M) hv_doc;
EXEC SQL END DECLARE SECTION;
/* Determine the current time and put this value */
/* into host variable hv_current_time. */
/* Read up to 1 MB of document data from a file */
/* into host variable hv_doc. */

Chapter 10. Creating and modifying DB2 objects 479

.
.
.
/* Insert the time value and the first 1 MB of */
/* document data into the table. */
EXEC SQL INSERT INTO DOCUMENTS
VALUES(:hv_current_time, DEFAULT, E_MAIL(:hv_doc));

/* Although there is more document data in the */

/* file, read up to 1 MB more of data, and then */
/* use an UPDATE statement like this one to */
/* concatenate the data in the host variable */
/* to the existing data in the table. */
EXEC SQL UPDATE DOCUMENTS
SET A_DOCUMENT = A_DOCUMENT || E_MAIL(:hv_doc)
WHERE LAST_UPDATE_TIME = :hv_current_time;

Now that the data is in the table, you can execute queries to learn more about the
documents. For example, you can execute this query to determine which
documents contain the word ″performance″:
SELECT SENDER(A_DOCUMENT), SENDING_DATE(A_DOCUMENT),
SUBJECT(A_DOCUMENT)
FROM DOCUMENTS
WHERE CONTAINS(A_DOCUMENT,'performance') = 1;

Because the electronic mail documents can be very large, you might want to use
LOB locators to manipulate the document data instead of fetching all of a
document into a host variable. You can use a LOB locator on any distinct type that
is defined on one of the LOB types. The following example shows how you can
cast a LOB locator as a distinct type, and then use the result in a user-defined
function that takes a distinct type as an argument:
EXEC SQL BEGIN DECLARE SECTION
long hv_len;
char hv_subject[200];
SQL TYPE IS CLOB_LOCATOR hv_email_locator;
EXEC
. SQL END DECLARE SECTION
.
.
/* Select a document into a CLOB locator. */
EXEC SQL SELECT A_DOCUMENT, SUBJECT(A_DOCUMENT)
INTO :hv_email_locator, :hv_subject
FROM DOCUMENTS
. WHERE LAST_UPDATE_TIME = :hv_current_time;
.
.
/* Extract the subject from the document. The */
/* SUBJECT function takes an argument of type */
/* E_MAIL, so cast the CLOB locator as E_MAIL. */
EXEC SQL SET :hv_subject =
. SUBJECT(CAST(:hv_email_locator AS E_MAIL));
.
.

Defining a user-defined function

User-defined functions are small programs that you can write to perform an
operation. You can create your own external, sourced, or SQL functions. You can
then use that function wherever you can use a built-in function.

To define a user-defined function:

1. Determine the characteristics of the user-defined function, such as the
user-defined function name, schema (qualifier), and number and data types of
the input parameters and the types of the values returned. For information
about the characteristics that you can define for a user-defined function, see
“Components of a user-defined function definition” on page 485.

480 Application Programming and SQL Guide

2. Execute a CREATE FUNCTION statement to register the information in the
DB2 catalog. For examples of CREATE FUNCTION statements, see “Defining a
user-defined function” on page 480.

If you discover after you define the function that any of these characteristics is not
appropriate for the function, you can use an ALTER FUNCTION statement to
change information in the definition. You cannot use ALTER FUNCTION to change
some of the characteristics of a user-defined function definition. For more
information about ALTER FUNCTION, see the topics “ALTER FUNCTION
(external)” and “ALTER FUNCTION (SQL scalar)” in DB2 SQL Reference.

Examples

Example: Definition for an external user-defined scalar function: A programmer

develops a user-defined function that searches for a string of maximum length 200
in a CLOB value whose maximum length is 500 KB. This CREATE FUNCTION
statement defines the user-defined function:
CREATE FUNCTION FINDSTRING (CLOB(500K), VARCHAR(200))
RETURNS INTEGER
CAST FROM FLOAT
SPECIFIC FINDSTRINCLOB
EXTERNAL NAME 'FINDSTR'
LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION
FENCED
STOP AFTER 3 FAILURES;

The output from the user-defined function is of type float, but users require integer
output for their SQL statements. The user-defined function is written in C and
contains no SQL statements. The function is defined to stop when the number of
abnormal terminations is equal to 3.

Example: Definition for an external user-defined scalar function that overloads an

operator: A programmer has written a user-defined function that overloads the
built-in SQL division operator (/). That is, this user-defined function is invoked
when an application program executes a statement like either of the following:
UPDATE TABLE1 SET INTCOL1=INTCOL2/INTCOL3;
UPDATE TABLE1 SET INTCOL1="/"(INTCOL2,INTCOL3);

The user-defined function takes two integer values as input. The output from the
user-defined function is of type integer. The user-defined function is in the MATH
schema, is written in assembler, and contains no SQL statements. This CREATE
FUNCTION statement defines the user-defined function:
CREATE FUNCTION MATH."/" (INT, INT)
RETURNS INTEGER
SPECIFIC DIVIDE
EXTERNAL NAME 'DIVIDE'
LANGUAGE ASSEMBLE
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION
FENCED;

Chapter 10. Creating and modifying DB2 objects 481

Suppose that you want the FINDSTRING user-defined function to work on BLOB
data types, as well as CLOB types. You can define another instance of the
user-defined function that specifies a BLOB type as input:
CREATE FUNCTION FINDSTRING (BLOB(500K), VARCHAR(200))
RETURNS INTEGER
CAST FROM FLOAT
SPECIFIC FINDSTRINBLOB
EXTERNAL NAME 'FNDBLOB'
LANGUAGE C
PARAMETER STYLE SQL
NO SQL
DETERMINISTIC
NO EXTERNAL ACTION
FENCED
STOP AFTER 3 FAILURES;

Each instance of FINDSTRING uses a different application program to implement

the user-defined function.

Example: Definition for a sourced user-defined function: Suppose you need a

user-defined function that finds a string in a value with a distinct type of BOAT.
BOAT is based on a BLOB data type. User-defined function FINDSTRING has
already been defined. FINDSTRING takes a BLOB data type and performs the
required function. The specific name for FINDSTRING is FINDSTRINBLOB.

You can therefore define a sourced user-defined function based on FINDSTRING to

do the string search on values of type BOAT. This CREATE FUNCTION statement
defines the sourced user-defined function:
CREATE FUNCTION FINDSTRING (BOAT, VARCHAR(200))
RETURNS INTEGER
SPECIFIC FINDSTRINBOAT
SOURCE SPECIFIC FINDSTRINBLOB;

Example: Definition for an SQL user-defined function: You can define an SQL
user-defined function for the tangent of a value by using the existing built-in SIN
and COS functions:
CREATE FUNCTION TAN (X DOUBLE)
RETURNS DOUBLE
LANGUAGE SQL
CONTAINS SQL
NO EXTERNAL ACTION
DETERMINISTIC
RETURN SIN(X)/COS(X);

Example: Definition for an external user-defined table function: An application

programmer develops a user-defined function that receives two values and returns
a table. The two input values are:
v A character string of maximum length 30 that describes a subject
v A character string of maximum length 255 that contains text to search for
The user-defined function scans documents on the subject for the search string and
returns a list of documents that match the search criteria, with an abstract for each
document. The list is in the form of a two-column table. The first column is a
character column of length 16 that contains document IDs. The second column is a
varying-character column of maximum length 5000 that contains document
abstracts.

The user-defined function is written in COBOL, uses SQL only to perform queries,
always produces the same output for given input, and should not execute as a

482 Application Programming and SQL Guide

parallel task. The program is reentrant, and successive invocations of the
user-defined function share information. You expect an invocation of the
user-defined function to return about 20 rows.

The following CREATE FUNCTION statement defines the user-defined function:

CREATE FUNCTION DOCMATCH (VARCHAR(30), VARCHAR(255))
RETURNS TABLE (DOC_ID CHAR(16), DOC_ABSTRACT VARCHAR(5000))
EXTERNAL NAME 'DOCMTCH'
LANGUAGE COBOL
PARAMETER STYLE SQL
READS SQL DATA
DETERMINISTIC
NO EXTERNAL ACTION
FENCED
SCRATCHPAD
FINAL CALL
DISALLOW PARALLEL
CARDINALITY 20;

User-defined functions
A user-defined function is an extension to the SQL language. It is a small program
that you write, similar to a host language subprogram or function. However, a
user-defined function is often the better choice for an SQL application because you
can invoke it in an SQL statement.

This section contains information that applies to all user-defined functions and
specific information about user-defined functions in languages other than Java.

The types of user-defined functions are:

v Sourced user-defined functions, which are based on existing built-in functions or
user-defined functions
v External user-defined functions, which a programmer writes in a host language
v SQL user-defined functions, which contain the source code for the user-defined
function in the user-defined function definition

User-defined functions can also be categorized as user-defined scalar functions or

user-defined table functions:
v A user-defined scalar function returns a single-value answer each time it is
invoked
v A user-defined table function returns a table to the SQL statement that references
it

External user-defined functions can be user-defined scalar functions or

user-defined table functions. Sourced and SQL user-defined functions can only be
user-defined scalar functions.

Creating and using a user-defined function involves these steps:

v Setting up the environment for user-defined functions
A systems administrator probably performs this step. The user-defined function
environment is shown in the following figure.

Chapter 10. Creating and modifying DB2 objects 483

WLM-Established
Application Program Stored Procedures
Address Space DB2 System Address Space

Invoking Program Package A Function Program

SELECT
Program A Program B
.. F1(ARG1,ARG2) ..
. FROM TB1; .
EXEC SQL EXEC SQL
SELECT SELECT...
F1(ARG1,ARG2) ..
Package B .
FROM TB1;
.. SELECT...
.

Figure 27. The user-defined function environment

It contains an application address space, from which a program invokes a

user-defined function; a DB2 system, where the packages from the user-defined
function are run; and a WLM-established address space, where the user-defined
function is executed. The steps for setting up and maintaining the user-defined
function environment are the same as for setting up and maintaining the
environment for stored procedures in WLM-established address spaces.
v Writing and preparing the user-defined function
This step is necessary only for an external user-defined function.
The person who performs this step is called the user-defined function
implementer.
v Defining the user-defined function to DB2
The person who performs this step is called the user-defined function definer.
v Invoking the user-defined function from an SQL application
The person who performs this step is called the user-defined function invoker.
Related concepts
Java stored procedures and user-defined functions (Programming for Java)

External user-defined functions

An external user-defined function is a function that is written in a programming
language. These functions can return a single value or a complete table.

You can write an external user-defined function in assembler, C, C++, COBOL,

PL/I, or Java™. User-defined functions that are written in COBOL can include
object-oriented extensions, just as other DB2 COBOL programs can. User-defined
functions that are written in Java follow coding guidelines and restrictions specific
to Java. For information about writing Java user-defined functions, see the topic
″Creating Java stored procedures and user-defined functions″.

SQL scalar functions

An SQL scalar function is a function that is written exclusively in SQL statements
and returns a single value.

An SQL scalar function is a user-defined function in which the CREATE

FUNCTION statement contains the source code. The source code is a single SQL
expression that evaluates to a single value. The SQL scalar function returns a single
484 Application Programming and SQL Guide
value. You specify the SQL expression in the RETURN clause of the CREATE
FUNCTION statement. The value of the SQL expression must be compatible with
the data type of the parameter in the RETURNS clause.

To prepare an SQL scalar function for execution, you execute the CREATE
FUNCTION statement, either statically or dynamically.
Related tasks
“Defining a user-defined function” on page 480
Related reference
CREATE FUNCTION (SQL scalar) (SQL Reference)

| Sourced functions
| A sourced function is a function that invokes another function that already exists at
| the server. The function inherits the attributes of the underlying source function.
| The source function can be either built-in, external, SQL, or sourced.

| Use sourced functions to build upon existing built-in functions or other

| user-defined functions. Sourced functions are useful to extend built-in aggregate
| and scalar functions for use on distinct types.

| To implement a sourced function, issue a CREATE FUNCTION statement with the

| name of the function upon which you want to base the sourced function. For more
| information about the syntax and examples, see “CREATE FUNCTION
| (sourced)”in DB2 SQL Reference.

Components of a user-defined function definition

The characteristics that you specify for a user-defined function depend on whether
the function is sourced, external, or SQL. You specify these characteristics in a
CREATE FUNCTION or ALTER FUNCTION statement.

The following table lists the characteristics of a user-defined function, the

corresponding parameters in the CREATE FUNCTION and ALTER FUNCTION
statements, and which parameters are valid for sourced, external, and SQL
user-defined functions.
Table 85. Characteristics of a user-defined function
Valid in Valid in Valid in
CREATE FUNCTION or sourced external SQL
Characteristic ALTER FUNCTION option function? function? function?
User-defined function name none Yes Yes Yes
Input parameter types and none Yes Yes Yes
encoding schemes
Output parameter types and RETURNS Yes Yes Yes2
encoding schemes RETURNS TABLE1
Specific name SPECIFIC Yes Yes Yes
External name EXTERNAL NAME No Yes No
3
Language LANGUAGE ASSEMBLE No Yes Yes4
LANGUAGE C
LANGUAGE COBOL
LANGUAGE PLI
LANGUAGE JAVA
LANGUAGE SQL

Chapter 10. Creating and modifying DB2 objects 485

Table 85. Characteristics of a user-defined function (continued)
Valid in Valid in Valid in
CREATE FUNCTION or sourced external SQL
Characteristic ALTER FUNCTION option function? function? function?
Deterministic or NOT DETERMINISTIC No Yes Yes
non-deterministic DETERMINISTIC
Types of SQL statements in NO SQL No Yes5 Yes6
the function CONTAINS SQL
READS SQL DATA
MODIFIES SQL DATA
Name of source function SOURCE Yes No No
7
Parameter style PARAMETER STYLE SQL No Yes No
PARAMETER STYLE JAVA
Address space for FENCED No Yes No
user-defined functions
Call with null input RETURNS NULL ON NULL INPUT No Yes Yes8
CALLED ON NULL INPUT
External actions EXTERNAL ACTION No Yes Yes
NO EXTERNAL ACTION
Scratchpad specification NO SCRATCHPAD No Yes No
SCRATCHPAD length
Call function after SQL NO FINAL CALL No Yes No
processing FINAL CALL
Consider function for parallel ALLOW PARALLEL No Yes5 No
processing DISALLOW PARALLEL
Package collection NO COLLID No Yes No
COLLID collection-id
WLM environment WLM ENVIRONMENT name No Yes No
WLM ENVIRONMENT name,*
CPU time for a function ASUTIME NO LIMIT No Yes No
invocation ASUTIME LIMIT integer
Load module stays in STAY RESIDENT NO No Yes No
memory STAY RESIDENT YES
Program type PROGRAM TYPE MAIN No Yes No
PROGRAM TYPE SUB
Security SECURITY DB2 No Yes No
SECURITY USER
SECURITY DEFINER
Run-time options RUN OPTIONS options No Yes No
Pass DB2 environment NO DBINFO No Yes No
information DBINFO
Expected number of rows CARDINALITY integer No Yes1 No
returned
Function resolution is based STATIC DISPATCH No No Yes
on the declared parameter
types
SQL expression that evaluates none No No Yes
to the value returned by the
function

486 Application Programming and SQL Guide

Table 85. Characteristics of a user-defined function (continued)
Valid in Valid in Valid in
CREATE FUNCTION or sourced external SQL
Characteristic ALTER FUNCTION option function? function? function?
Encoding scheme for all PARAMETER CCSID EBCDIC No Yes Yes
string parameters PARAMETER CCSID ASCII
PARAMETER CCSID UNICODE
For functions that are defined PARAMETER VARCHAR NULTERM No Yes No
as LANGUAGE C, the PARAMETER VARCHAR STRUCTURE9
representation of VARCHAR
parameters and, if applicable,
the returned result.
Number of abnormal STOP AFTER SYSTEM DEFAULT No Yes No
terminations before the FAILURES
function is stopped STOP AFTER n FAILURES
CONTINUE AFTER FAILURE
| Identifies the list of package PACKAGE PATH package-path No Yes No
| collections that is to be used NO PACKAGE PATH
| when the stored procedure is
| executed.
Notes:
1. RETURNS TABLE and CARDINALITY are valid only for user-defined table functions. For a single query, you can
override the CARDINALITY value by specifying a CARDINALITY clause for the invocation of a user-defined
table function in the SELECT statement.
2. An SQL user-defined function can return only one scalar value.
3. LANGUAGE SQL is not valid for an external user-defined function.
4. Only LANGUAGE SQL is valid for an SQL user-defined function.
5. MODIFIES SQL DATA and ALLOW PARALLEL are not valid for user-defined table functions.
6. MODIFIES SQL DATA and NO SQL are not valid for SQL user-defined functions.
7. PARAMETER STYLE JAVA is valid only with LANGUAGE JAVA. PARAMETER STYLE SQL is valid only with
LANGUAGE values other than LANGUAGE JAVA.
8. RETURNS NULL ON NULL INPUT is not valid for an SQL user-defined function.
9. The PARAMETER VARCHAR clause can be specified in CREATE FUNCTION statements only.

Related reference
CREATE FUNCTION (SQL Reference)

Writing an external user-defined function

An external user-defined function is a function that is written in a programming
language. It is similar to any other SQL program. You can include static or
dynamic SQL statements, IFI calls, and DB2 commands issued through IFI calls.

Your user-defined function can also access remote data using the following
methods:
v DB2 private protocol access using three-part names or aliases for three-part
names
v DRDA access using three-part names or aliases for three-part names
v DRDA access using CONNECT or SET CONNECTION statements
The user-defined function and the application that calls it can access the same
remote site if both use the same protocol.

Chapter 10. Creating and modifying DB2 objects 487

You can write an external user-defined function in assembler, C, C++, COBOL,
PL/I, or Java. User-defined functions that are written in COBOL can include
object-oriented extensions, just as other DB2 COBOL programs can. User-defined
functions that are written in Java follow coding guidelines and restrictions specific
to Java. For information about writing Java user-defined functions, see the topic
“Creating Java stored procedures and user-defined functions” in DB2 Application
Programming Guide and Reference for Java.

Restrictions on user-defined function programs: Observe these restrictions when

you write a user-defined function:
v Because DB2 uses the Resource Recovery Services attachment facility (RRSAF) as
its interface with your user-defined function, you must not include RRSAF calls
in your user-defined function. DB2 rejects any RRSAF calls that it finds in a
user-defined function.
v If your user-defined function is not defined with parameters SCRATCHPAD or
EXTERNAL ACTION, the user-defined function is not guaranteed to execute
under the same task each time it is invoked.
v You cannot execute COMMIT or ROLLBACK statements in your user-defined
function.
v You must close all cursors that were opened within a user-defined scalar
function. DB2 returns an SQL error if a user-defined scalar function does not
close all cursors that it opened before it completes.
v When you choose the language in which to write a user-defined function
program, be aware of restrictions on the number of parameters that can be
passed to a routine in that language. User-defined table functions in particular
can require large numbers of parameters. Consult the programming guide for
the language in which you plan to write the user-defined function for
information about the number of parameters that can be passed.
| v You cannot pass LOB file reference variables as parameters to user-defined
| functions.
| v User-defined functions cannot return LOB file reference variables.
| v You cannot pass parameters with the type XML to user-defined functions. You
| can specify tables or views that contain XML columns as table locator
| parameters. However, you cannot reference the XML columns in the body of the
| user-defined function.

Coding your user-defined function as a main program or as a subprogram: You

can code your user-defined function as either a main program or a subprogram.
The way that you code your program must agree with the way you defined the
user-defined function: with the PROGRAM TYPE MAIN or PROGRAM TYPE SUB
parameter. The main difference is that when a main program starts, Language
Environment allocates the application program storage that the external
user-defined function uses. When a main program ends, Language Environment
closes files and releases dynamically allocated storage.

If you code your user-defined function as a subprogram and manage the storage
and files yourself, you can get better performance. The user-defined function
should always free any allocated storage before it exits. To keep data between
invocations of the user-defined function, use a scratchpad.

You must code a user-defined table function that accesses external resources as a
subprogram. Also ensure that the definer specifies the EXTERNAL ACTION
parameter in the CREATE FUNCTION or ALTER FUNCTION statement. Program
variables for a subprogram persist between invocations of the user-defined

488 Application Programming and SQL Guide

function, and use of the EXTERNAL ACTION parameter ensures that the
user-defined function stays in the same address space from one invocation to
another.

Parallelism considerations: If the definer specifies the parameter ALLOW

PARALLEL in the definition of a user-defined scalar function, and the invoking
SQL statement runs in parallel, the function can run under a parallel task. DB2
executes a separate instance of the user-defined function for each parallel task.
When you write your function program, you need to understand how the
following parameter values interact with ALLOW PARALLEL so that you can
avoid unexpected results:
v SCRATCHPAD
When an SQL statement invokes a user-defined function that is defined with the
ALLOW PARALLEL parameter, DB2 allocates one scratchpad for each parallel
task of each reference to the function. This can lead to unpredictable or incorrect
results.
For example, suppose that the user-defined function uses the scratchpad to
count the number of times it is invoked. If a scratchpad is allocated for each
parallel task, this count is the number of invocations done by the parallel task
and not for the entire SQL statement, which is not the desired result.
v FINAL CALL
If a user-defined function performs an external action, such as sending a note,
for each final call to the function, one note is sent for each parallel task instead
of once for the function invocation.
v EXTERNAL ACTION
Some user-defined functions with external actions can receive incorrect results if
the function is executed by parallel tasks.
For example, if the function sends a note for each initial call to the function, one
note is sent for each parallel task instead of once for the function invocation.
v NOT DETERMINISTIC
A user-defined function that is non-deterministic can generate incorrect results if
it is run under a parallel task.
For example, suppose that you execute the following query under parallel tasks:
SELECT * FROM T1 WHERE C1 = COUNTER();

COUNTER is a user-defined function that increments a variable in the

scratchpad every time it is invoked. Counter is non-deterministic because the
same input does not always produce the same output. Table T1 contains one
column, C1, that has the following values:
1
2
3
4
5
6
7
8
9
10
When the query is executed with no parallelism, DB2 invokes COUNTER once
for each row of table T1, and there is one scratchpad for counter, which DB2
initializes the first time that COUNTER executes. COUNTER returns 1 the first
time it executes, 2 the second time, and so on. The result table for the query has
the following values:

Chapter 10. Creating and modifying DB2 objects 489

1
2
3
4
5
6
7
8
9
10
Now suppose that the query is run with parallelism, and DB2 creates three
parallel tasks. DB2 executes the predicate WHERE C1 = COUNTER() for each
parallel task. This means that each parallel task invokes its own instance of the
user-defined function and has its own scratchpad. DB2 initializes the scratchpad
to zero on the first call to the user-defined function for each parallel task.
If parallel task 1 processes rows 1 to 3, parallel task 2 processes rows 4 to 6, and
parallel task 3 processes rows 7 to 10, the following results occur:
– When parallel task 1 executes, C1 has values 1, 2, and 3, and COUNTER
returns values 1, 2, and 3, so the query returns values 1, 2, and 3.
– When parallel task 2 executes, C1 has values 4, 5, and 6, but COUNTER
returns values 1, 2, and 3, so the query returns no rows.
– When parallel task 3, executes, C1 has values 7, 8, 9, and 10, but COUNTER
returns values 1, 2, 3, and 4, so the query returns no rows.
Thus, instead of returning the 10 rows that you might expect from the query,
DB2 returns only 3 rows.

Parameters for external user-defined functions

To receive parameters from and pass parameters to an invoker of an external
user-defined function, you must understand the structure of the parameter list, the
meaning of each parameter, and whether DB2 or your user-defined function sets
the value of each parameter.

The following figure shows the structure of the parameter list that DB2 passes to a
user-defined function. An explanation of each parameter follows.

490 Application Programming and SQL Guide

Register 1 Addresses of: Data:

Parameter 1 Parameter 1 data

Parameter 2 Parameter 2 data

1
Result 1 Result 1 data
.
Result 2 Result 2 data

Indicator 1 Indicator 1

Indicator 2 Indicator 2

Result
1
Result indicator 1
indicator 1
Result Result indicator 2
indicator 2

SQLSTATE SQLSTATE

Procedure
name Procedure name

Specific
name Specific name

Message
Message text
text
2
Scratchpad Scratchpad
3
Call type Call type
4, 5
DBINFO DBINFO

1. For a user-defined scalar function, only one result and one result indicator are passed.
2. Passed if the SCRATCHPAD option is specified in the user-defined function definition.
3. Passed if the FINAL CALL option is specified in a user-defined scalar function definition;
always passed for a user-defined table function.
4. For PL/I, this value is the address of a pointer to the DBINFO data.
5. Passed if the DBINFO option is specified in the user-defined function definition.

Figure 28. Parameter conventions for a user-defined function

Input parameter values

DB2 obtains the input parameters from the invoker’s parameter list, and your
user-defined function receives those parameters according to the rules of the host
language in which the user-defined function is written. The number of input
parameters is the same as the number of parameters in the user-defined function
invocation. If one of the parameters in the function invocation is an expression,
DB2 evaluates the expression and assigns the result of the expression to the
parameter.
Chapter 10. Creating and modifying DB2 objects 491
For all data types except LOBs, ROWIDs, locators, and VARCHAR (with C
language), see the tables listed in the following table for the host data types that
are compatible with the data types in the user-defined function definition.
Table 86. Listing of tables of compatible data types
Language Compatible data types table
Assembler “Compatibility of SQL and language data types”
on page 148
C “Compatibility of SQL and language data types”
on page 148
COBOL “Compatibility of SQL and language data types”
on page 148
PL/I “Compatibility of SQL and language data types”
on page 148

For LOBs, ROWIDs, and locators, see the following table for the assembler data
types that are compatible with the data types in the user-defined function
definition.
Table 87. Compatible assembler language declarations for LOBs, ROWIDs, and locators
SQL data type in definition Assembler declaration
TABLE LOCATOR DS FL4
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR
BLOB(n) If n <= 65535:
var DS 0FL4
var_length DS FL4
var_data DS CLn

If n > 65535:
var DS 0FL4
var_length DS FL4
var_data DS CL65535
ORG var_data+(n-65535)
CLOB(n) If n <= 65535:
var DS 0FL4
var_length DS FL4
var_data DS CLn

If n > 65535:
var DS 0FL4
var_length DS FL4
var_data DS CL65535
ORG var_data+(n-65535)
DBCLOB(n) If n (=2*n) <= 65534:
var DS 0FL4
var_length DS FL4
var_data DS CLm

If n > 65534:
var DS 0FL4
var_length DS FL4
var_data DS CL65534
ORG var_data+(m-65534)

492 Application Programming and SQL Guide

Table 87. Compatible assembler language declarations for LOBs, ROWIDs, and
locators (continued)
SQL data type in definition Assembler declaration
ROWID DS HL2,CL40

For LOBs, ROWIDs, VARCHARs, and locators see the following table for the C
data types that are compatible with the data types in the user-defined function
definition.
Table 88. Compatible C language declarations for LOBs, ROWIDs, VARCHARs, and locators
SQL data type in definition1 C declaration
TABLE LOCATOR unsigned long
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR
BLOB(n) struct
{unsigned long length;
char data[n];
} var;
CLOB(n) struct
{unsigned long length;
char var_data[n];
} var;
DBCLOB(n) struct
{unsigned long length;
sqldbchar data[n];
} var;
ROWID struct {
short int length;
char data[40];
} var;
VARCHAR(n)2 If PARAMETER VARCHAR NULTERM is
specified or implied:
char data[n+1];

If PARAMETER VARCHAR STRUCTURE is

specified:
struct
{short len;
char data[n];
} var;
Note:
1. The SQLUDF file, which is in data set DSN910.SDSNC.H, includes the typedef
sqldbchar. Using sqldbchar lets you manipulate DBCS and Unicode UTF-16 data in the
same format in which it is stored in DB2. sqldbchar also makes applications easier to
port to other DB2 platforms.
2. This row does not apply to VARCHAR(n) FOR BIT DATA. BIT DATA is always passed
in a structured representation.

For LOBs, ROWIDs, and locators, see the following table for the COBOL data types
that are compatible with the data types in the user-defined function definition.

Chapter 10. Creating and modifying DB2 objects 493

Table 89. Compatible COBOL declarations for LOBs, ROWIDs, and locators
SQL data type in definition COBOL declaration

TABLE LOCATOR 01 var PIC S9(9)

USAGE IS BINARY.
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR
BLOB(n) If n <= 32767:
01 var.
49 var-LENGTH PIC 9(9)
USAGE COMP.
49 var-DATA PIC X(n).

If length > 32767:

01 var.
02var-LENGTH PIC S9(9)
USAGE COMP.
02 var-DATA.
49 FILLER
PIC X(32767).
49 FILLER
.. PIC X(32767).
.
49 FILLER
PIC X(mod(n,32767)).
If n <= 32767:
CLOB(n)
01 var.
49 var-LENGTH PIC 9(9)
USAGE COMP.
49 var-DATA PIC X(n).

If length > 32767:

01 var.
02 var-LENGTH PIC S9(9)
USAGE COMP.
02 var-DATA.
49 FILLER
PIC X(32767).
49 FILLER
.. PIC X(32767).
.
49 FILLER
PIC X(mod(n,32767)).

494 Application Programming and SQL Guide

Table 89. Compatible COBOL declarations for LOBs, ROWIDs, and locators (continued)
SQL data type in definition COBOL declaration
If n <= 32767:
DBCLOB(n)
01 var.
49 var-LENGTH PIC 9(9)
USAGE COMP.
49 var-DATA PIC G(n)
USAGE DISPLAY-1.

If length > 32767:

01 var.
02var-LENGTH PIC S9(9)
USAGE COMP.
02 var-DATA.
49 FILLER
PIC G(32767)
USAGE DISPLAY-1.
49 FILLER
PIC G(32767).
.. USAGE DISPLAY-1.
.
49 FILLER
PIC G(mod(n,32767))
USAGE DISPLAY-1.
ROWID 01 var.
49 var-LEN PIC 9(4)
USAGE COMP.
49 var-DATA PIC X(40).

For LOBs, ROWIDs, and locators, see the following table for the PL/I data types
that are compatible with the data types in the user-defined function definition.
Table 90. Compatible PL/I declarations for LOBs, ROWIDs, and locators
SQL data type in definition PL/I
TABLE LOCATOR BIN FIXED(31)
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR
BLOB(n) If n <= 32767:
01 var,
03 var_LENGTH
BIN FIXED(31),
03 var_DATA
CHAR(n);

If n > 32767:
01 var,
02 var_LENGTH
BIN FIXED(31),
02 var_DATA,
03 var_DATA1(n)
CHAR(32767),
03 var_DATA2
CHAR(mod(n,32767));

Chapter 10. Creating and modifying DB2 objects 495

Table 90. Compatible PL/I declarations for LOBs, ROWIDs, and locators (continued)
SQL data type in definition PL/I
CLOB(n) If n <= 32767:
01 var,
03 var_LENGTH
BIN FIXED(31),
03 var_DATA
CHAR(n);

If n > 32767:
01 var,
02 var_LENGTH
BIN FIXED(31),
02 var_DATA,
03 var_DATA1(n)
CHAR(32767),
03 var_DATA2
CHAR(mod(n,32767));
DBCLOB(n) If n <= 16383:
01 var,
03 var_LENGTH
BIN FIXED(31),
03 var_DATA
GRAPHIC(n);

If n > 16383:
01 var,
02 var_LENGTH
BIN FIXED(31),
02 var_DATA,
03 var_DATA1(n)
GRAPHIC(16383),
03 var_DATA2
GRAPHIC(mod(n,16383));
ROWID CHAR(40) VAR;

Result parameters: Set these values in your user-defined function before exiting.
For a user-defined scalar function, you return one result parameter. For a
user-defined table function, you return the same number of parameters as columns
in the RETURNS TABLE clause of the CREATE FUNCTION statement. DB2
allocates a buffer for each result parameter value and passes the buffer address to
the user-defined function. Your user-defined function places each result parameter
value in its buffer. You must ensure that the length of the value you place in each
output buffer does not exceed the buffer length. Use the SQL data type and length
in the CREATE FUNCTION statement to determine the buffer length.

See “Parameters for external user-defined functions” on page 490 to determine the
host data type to use for each result parameter value. If the CREATE FUNCTION
statement contains a CAST FROM clause, use a data type that corresponds to the
SQL data type in the CAST FROM clause. Otherwise, use a data type that
corresponds to the SQL data type in the RETURNS or RETURNS TABLE clause.

To improve performance for user-defined table functions that return many

columns, you can pass values for a subset of columns to the invoker. For example,
a user-defined table function might be defined to return 100 columns, but the
invoker needs values for only two columns. Use the DBINFO parameter to indicate

496 Application Programming and SQL Guide

to DB2 the columns for which you will return values. Then return values for only
those columns. See DBINFO for information about how to indicate the columns of
interest.

Input parameter indicators: These are SMALLINT values, which DB2 sets before it
passes control to the user-defined function. You use the indicators to determine
whether the corresponding input parameters are null. The number and order of the
indicators are the same as the number and order of the input parameters. On entry
to the user-defined function, each indicator contains one of these values:
0 The input parameter value is not null.
negative
The input parameter value is null.

Code the user-defined function to check all indicators for null values unless the
user-defined function is defined with RETURNS NULL ON NULL INPUT. A
user-defined function defined with RETURNS NULL ON NULL INPUT executes
only if all input parameters are not null.

Result indicators: These are SMALLINT values, which you must set before the
user-defined function ends to indicate to the invoking program whether each result
parameter value is null. A user-defined scalar function has one result indicator. A
user-defined table function has the same number of result indicators as the number
of result parameters. The order of the result indicators is the same as the order of
the result parameters. Set each result indicator to one of these values:
0 or positive
The result parameter is not null.
negative
The result parameter is null.

SQLSTATE value: This CHAR(5) value represents the SQLSTATE that is passed in
to the program from the database manager. The initial value is set to ‘00000’.
Although the SQLSTATE is usually not set by the program, it can be set as the
result SQLSTATE that is used to return an error or a warning. Returned values that
start with anything other than ‘00’, ‘01’, or ‘02’ are error conditions.

User-defined function name: DB2 sets this value in the parameter list before the
user-defined function executes. This value is VARCHAR(257): 128 bytes for the
schema name, 1 byte for a period, and 128 bytes for the user-defined function
name. If you use the same code to implement multiple versions of a user-defined
function, you can use this parameter to determine which version of the function
the invoker wants to execute.

Specific name: DB2 sets this value in the parameter list before the user-defined
function executes. This value is VARCHAR(128) and is either the specific name
from the CREATE FUNCTION statement or a specific name that DB2 generated. If
you use the same code to implement multiple versions of a user-defined function,
you can use this parameter to determine which version of the function the invoker
wants to execute.

Diagnostic message: Your user-defined function can set this CHAR or VARCHAR
value to a character string of up to 1000 bytes before exiting. Use this area to pass
descriptive information about an error or warning to the invoker.

Chapter 10. Creating and modifying DB2 objects 497

DB2 allocates a buffer for this area and passes you the buffer address in the
parameter list. At least the first 17 bytes of the value you put in the buffer appear
in the SQLERRMC field of the SQLCA that is returned to the invoker. The exact
number of bytes depends on the number of other tokens in SQLERRMC. Do not
use X’FF’ in your diagnostic message. DB2 uses this value to delimit tokens.

Scratchpad: If the definer specified SCRATCHPAD in the CREATE FUNCTION

statement, DB2 allocates a buffer for the scratchpad area and passes its address to
the user-defined function. Before the user-defined function is invoked for the first
time in an SQL statement, DB2 sets the length of the scratchpad in the first 4 bytes
of the buffer and then sets the scratchpad area to X’00’. DB2 does not reinitialize
the scratchpad between invocations of a correlated subquery.

You must ensure that your user-defined function does not write more bytes to the
scratchpad than the scratchpad length.

Call type: For a user-defined scalar function, if the definer specified FINAL CALL
in the CREATE FUNCTION statement, DB2 passes this parameter to the
user-defined function. For a user-defined table function, DB2 always passes this
parameter to the user-defined function.

On entry to a user-defined scalar function, the call type parameter has one of the
following values:
-1 This is the first call to the user-defined function for the SQL statement. For
a first call, all input parameters are passed to the user-defined function. In
addition, the scratchpad, if allocated, is set to binary zeros.
0 This is a normal call. For a normal call, all the input parameters are passed
to the user-defined function. If a scratchpad is also passed, DB2 does not
modify it.
1 This is a final call. For a final call, no input parameters are passed to the
user-defined function. If a scratchpad is also passed, DB2 does not modify
it.
This type of final call occurs when the invoking application explicitly
closes a cursor. When a value of 1 is passed to a user-defined function, the
user-defined function can execute SQL statements.
255 This is a final call. For a final call, no input parameters are passed to the
user-defined function. If a scratchpad is also passed, DB2 does not modify
it.
This type of final call occurs when the invoking application executes a
COMMIT or ROLLBACK statement, or when the invoking application
abnormally terminates. When a value of 255 is passed to the user-defined
function, the user-defined function cannot execute any SQL statements,
except for CLOSE CURSOR. If the user-defined function executes any close
cursor statements during this type of final call, the user-defined function
should tolerate SQLCODE -501 because DB2 might have already closed
cursors before the final call.

During the first call, your user-defined scalar function should acquire any system
resources it needs. During the final call, the user-defined scalar function should
release any resources it acquired during the first call. The user-defined scalar
function should return a result value only during normal calls. DB2 ignores any
results that are returned during a final call. However, the user-defined scalar
function can set the SQLSTATE and diagnostic message area during the final call.

498 Application Programming and SQL Guide

If an invoking SQL statement contains more than one user-defined scalar function,
and one of those user-defined functions returns an error SQLSTATE, DB2 invokes
all of the user-defined functions for a final call, and the invoking SQL statement
receives the SQLSTATE of the first user-defined function with an error.

On entry to a user-defined table function, the call type parameter has one of the
following values:
-2 This is the first call to the user-defined function for the SQL statement. A
first call occurs only if the FINAL CALL keyword is specified in the
user-defined function definition. For a first call, all input parameters are
passed to the user-defined function. In addition, the scratchpad, if
allocated, is set to binary zeros.
-1 This is the open call to the user-defined function by an SQL statement. If
FINAL CALL is not specified in the user-defined function definition, all
input parameters are passed to the user-defined function, and the
scratchpad, if allocated, is set to binary zeros during the open call. If
FINAL CALL is specified for the user-defined function, DB2 does not
modify the scratchpad.
0 This is a fetch call to the user-defined function by an SQL statement. For a
fetch call, all input parameters are passed to the user-defined function. If a
scratchpad is also passed, DB2 does not modify it.
1 This is a close call. For a close call, no input parameters are passed to the
user-defined function. If a scratchpad is also passed, DB2 does not modify
it.
2 This is a final call. This type of final call occurs only if FINAL CALL is
specified in the user-defined function definition. For a final call, no input
parameters are passed to the user-defined function. If a scratchpad is also
passed, DB2 does not modify it.
This type of final call occurs when the invoking application executes a
CLOSE CURSOR statement.
255 This is a final call. For a final call, no input parameters are passed to the
user-defined function. If a scratchpad is also passed, DB2 does not modify
it.
This type of final call occurs when the invoking application executes a
COMMIT or ROLLBACK statement, or when the invoking application
abnormally terminates. When a value of 255 is passed to the user-defined
function, the user-defined function cannot execute any SQL statements,
except for CLOSE CURSOR. If the user-defined function executes any close
cursor statements during this type of final call, the user-defined function
should tolerate SQLCODE -501 because DB2 might have already closed
cursors before the final call.

If a user-defined table function is defined with FINAL CALL, the user-defined

function should allocate any resources it needs during the first call and release
those resources during the final call that sets a value of 2.

If a user-defined table function is defined with NO FINAL CALL, the user-defined

function should allocate any resources it needs during the open call and release
those resources during the close call.

Chapter 10. Creating and modifying DB2 objects 499

During a fetch call, the user-defined table function should return a row. If the
user-defined function has no more rows to return, it should set the SQLSTATE to
02000.

During the close call, a user-defined table function can set the SQLSTATE and
diagnostic message area.

If a user-defined table function is invoked from a subquery, the user-defined table

function receives a CLOSE call for each invocation of the subquery within the
higher level query, and a subsequent OPEN call for the next invocation of the
subquery within the higher level query.

DBINFO: If the definer specified DBINFO in the CREATE FUNCTION statement,

DB2 passes the DBINFO structure to the user-defined function. DBINFO contains
information about the environment of the user-defined function caller. It contains
the following fields, in the order shown:
Location name length
An unsigned 2-byte integer field. It contains the length of the location name in
the next field.
Location name
A 128-byte character field. It contains the name of the location to which the
invoker is currently connected.
Authorization ID length
An unsigned 2-byte integer field. It contains the length of the authorization ID
in the next field.
Authorization ID
A 128-byte character field. It contains the authorization ID of the application
from which the user-defined function is invoked, padded on the right with
blanks. If this user-defined function is nested within other user-defined
functions, this value is the authorization ID of the application that invoked the
highest-level user-defined function.
Subsystem code page
A 48-byte structure that consists of 10 integer fields and an eight-byte reserved
area. These fields provide information about the CCSIDs of the subsystem from
which the user-defined function is invoked.
Table qualifier length
An unsigned 2-byte integer field. It contains the length of the table qualifier in
the next field. If the table name field is not used, this field contains 0.
Table qualifier
A 128-byte character field. It contains the qualifier of the table that is specified
in the table name field.
Table name length
An unsigned 2-byte integer field. It contains the length of the table name in the
next field. If the table name field is not used, this field contains 0.
Table name
A 128-byte character field. This field contains the name of the table for the
update or insert operation if the reference to the user-defined function in the
invoking SQL statement is in one of the following places:
v The right side of a SET clause in an update operation
v In the VALUES list of an insert operation
Otherwise, this field is blank.

500 Application Programming and SQL Guide

Column name length
An unsigned 2-byte integer field. It contains the length of the column name in
the next field. If no column name is passed to the user-defined function, this
field contains 0.
Column name
A 128-byte character field. This field contains the name of the column that the
update or insert operation modifies if the reference to the user-defined function
in the invoking SQL statement is in one of the following places:
v The right side of a SET clause in an update operation
v In the VALUES list of an insert operation
Otherwise, this field is blank.
Product information
An 8-byte character field that identifies the product on which the user-defined
function executes. This field has the form pppvvrrm, where:
v ppp is a 3-byte product code:
ARI DB2 Server for VSE & VM
DSN DB2 for z/OS
QSQ DB2 for i
SQL DB2 for Linux®, UNIX, and Windows®
v vv is a 2-digit version identifier.
v rr is a 2-digit release identifier.
v m is a 1-digit maintenance level identifier.
Reserved area
2 bytes.
Operating system
A 4-byte integer field. It identifies the operating system on which the program
that invokes the user-defined function runs. The value is one of these:
0 Unknown
1 OS/2®
3 Windows
4 AIX®
5 Windows NT®
6 HP-UX
7 Solaris
8 z/OS
13 Siemens Nixdorf
15 Windows 95
16 SCO UNIX
18 Linux
19 DYNIX/ptx®
24 Linux for S/390®
25 Linux for System z®

Chapter 10. Creating and modifying DB2 objects 501

26 Linux/IA64
27 Linux/PPC
28 Linux/PPC64
29 Linux/AMD64
400 iSeries®
Number of entries in table function column list
An unsigned 2-byte integer field.
Reserved area
26 bytes.
Table function column list pointer
If a table function is defined, this field is a pointer to an array that contains
1000 2-byte integers. DB2 dynamically allocates the array. If a table function is
not defined, this pointer is null.
Only the first n entries, where n is the value in the field entitled number of
entries in table function column list, are of interest. n is greater than or equal
to 0 and less than or equal to the number result columns defined for the
user-defined function in the RETURNS TABLE clause of the CREATE
FUNCTION statement. The values correspond to the numbers of the columns
that the invoking statement needs from the table function. A value of 1 means
the first defined result column, 2 means the second defined result column, and
so on. The values can be in any order. If n is equal to 0, the first array element
is 0. This is the case for a statement like the following one, where the invoking
statement needs no column values.
SELECT COUNT(*) FROM TABLE(TF(...)) AS QQ
This array represents an opportunity for optimization. The user-defined
function does not need to return all values for all the result columns of the
table function. Instead, the user-defined function can return only those
columns that are needed in the particular context, which you identify by
number in the array. However, if this optimization complicates the
user-defined function logic enough to cancel the performance benefit, you
might choose to return every defined column.
Unique application identifier
This field is a pointer to a string that uniquely identifies the application’s
connection to DB2. The string is regenerated for each connection to DB2.
The string is the LUWID, which consists of a fully-qualified LU network name
followed by a period and an LUW instance number. The LU network name
consists of a 1- to 8-character network ID, a period, and a 1- to 8-character
network LU name. The LUW instance number consists of 12 hexadecimal
characters that uniquely identify the unit of work.
Reserved area
20 bytes.

If you write your user-defined function in C or C++, you can use the declarations
in member SQLUDF of DSN910.SDSNC.H for many of the passed parameters. To
include SQLUDF, make these changes to your program:
v Put this statement in your source code:
#include <sqludf.h>
v Include the DSN910.SDSNC.H data set in the SYSLIB concatenation for the
compile step of your program preparation job.

502 Application Programming and SQL Guide

v Specify the NOMARGINS and NOSEQUENCE options in the compile step of
your program preparation job.

Examples of receiving parameters in a user-defined function:

The following examples show how a user-defined function that is written in each
of the supported host languages receives the parameter list that is passed by DB2.

These examples assume that the user-defined function is defined with the
SCRATCHPAD, FINAL CALL, and DBINFO parameters.

Assembler: The follow figure shows the parameter conventions for a user-defined
scalar function that is written as a main program that receives two parameters and
returns one result. For an assembler language user-defined function that is a
subprogram, the conventions are the same. In either case, you must include the
CEEENTRY and CEEEXIT macros.
MYMAIN CEEENTRY AUTO=PROGSIZE,MAIN=YES,PLIST=OS
USING PROGAREA,R13

L R7,0(R1) GET POINTER TO PARM1

MVC PARM1(4),0(R7) MOVE VALUE INTO LOCAL COPY OF PARM1
L R7,4(R1) GET POINTER TO PARM2
MVC PARM2(4),0(R7) MOVE VALUE INTO LOCAL COPY OF PARM2
L R7,12(R1) GET POINTER TO INDICATOR 1
MVC F_IND1(2),0(R7) MOVE PARM1 INDICATOR TO LOCAL STORAGE
LH R7,F_IND1 MOVE PARM1 INDICATOR INTO R7
LTR R7,R7 CHECK IF IT IS NEGATIVE
BM NULLIN IF SO, PARM1 IS NULL
L R7,16(R1) GET POINTER TO INDICATOR 2
MVC F_IND2(2),0(R7) MOVE PARM2 INDICATOR TO LOCAL STORAGE
LH R7,F_IND2 MOVE PARM2 INDICATOR INTO R7
LTR R7,R7 CHECK IF IT IS NEGATIVE
BM NULLIN IF SO, PARM2 IS NULL
.
.
.
L R7,8(R1) GET ADDRESS OF AREA FOR RESULT
NULLIN MVC 0(9,R7),RESULT MOVE A VALUE INTO RESULT AREA
L R7,20(R1) GET ADDRESS OF AREA FOR RESULT IND
MVC 0(2,R7),=H'0' MOVE A VALUE INTO INDICATOR AREA
.
.
.
CEETERM RC=0
*******************************************************************
* VARIABLE DECLARATIONS AND EQUATES *
*******************************************************************
R1 EQU 1 REGISTER 1
R7 EQU 7 REGISTER 7
PPA CEEPPA , CONSTANTS DESCRIBING THE CODE BLOCK
LTORG , PLACE LITERAL POOL HERE
PROGAREA DSECT
ORG *+CEEDSASZ LEAVE SPACE FOR DSA FIXED PART
PARM1 DS F PARAMETER 1
PARM2 DS F PARAMETER 2
RESULT DS CL9 RESULT
F_IND1 DS H INDICATOR FOR PARAMETER 1
F_IND2 DS H INDICATOR FOR PARAMETER 2
F_INDR DS H INDICATOR FOR RESULT

PROGSIZE EQU *-PROGAREA

CEEDSA , MAPPING OF THE DYNAMIC SAVE AREA
CEECAA , MAPPING OF THE COMMON ANCHOR AREA
END MYMAIN

Chapter 10. Creating and modifying DB2 objects 503

C or C++: For C or C++ user-defined functions, the conventions for passing
parameters are different for main programs and subprograms.

For subprograms, you pass the parameters directly. For main programs, you use
the standard argc and argv variables to access the input and output parameters:
v The argv variable contains an array of pointers to the parameters that are passed
to the user-defined function. All string parameters that are passed back to DB2
must be null terminated.
– argv[0] contains the address of the load module name for the user-defined
function.
– argv[1] through argv[n] contain the addresses of parameters 1 through n.
v The argc variable contains the number of parameters that are passed to the
external user-defined function, including argv[0].

The following figure shows the parameter conventions for a user-defined scalar
function that is written as a main program that receives two parameters and
returns one result.
#include <stdlib.h>
#include <stdio.h>

main(argc,argv)
int argc;
char *argv[];
{
/***************************************************/
/* Assume that the user-defined function invocation*/
/* included 2 input parameters in the parameter */
/* list. Also assume that the definition includes */
/* the SCRATCHPAD, FINAL CALL, and DBINFO options, */
/* so DB2 passes the scratchpad, calltype, and */
/* dbinfo parameters. */
/* The argv vector contains these entries: */
/* argv[0] 1 load module name */
/* argv[1-2] 2 input parms */
/* argv[3] 1 result parm */
/* argv[4-5] 2 null indicators */
/* argv[6] 1 result null indicator */
/* argv[7] 1 SQLSTATE variable */
/* argv[8] 1 qualified func name */
/* argv[9] 1 specific func name */
/* argv[10] 1 diagnostic string */
/* argv[11] 1 scratchpad */
/* argv[12] 1 call type */
/* argv[13] + 1 dbinfo */
/* ------ */
/* 14 for the argc variable */
/***************************************************/
if argc<>14
{
.
.
.
/**********************************************************/
/* This section would contain the code executed if the */
/* user-defined function is invoked with the wrong number */
/* of parameters. */
/**********************************************************/
}
/***************************************************/
/* Assume the first parameter is an integer. */
/* The following code shows how to copy the integer*/
/* parameter into the application storage. */
/***************************************************/

504 Application Programming and SQL Guide

int parm1;
parm1 = *(int *) argv[1];

/***************************************************/
/* Access the null indicator for the first */
/* parameter on the invoked user-defined function */
/* as follows: */
/***************************************************/
short int ind1;
ind1 = *(short int *) argv[4];

/***************************************************/
/* Use the following expression to assign */
/* 'xxxxx' to the SQLSTATE returned to caller on */
/* the SQL statement that contains the invoked */
/* user-defined function. */
/***************************************************/
strcpy(argv[7],"xxxxx/0");

/***************************************************/
/* Obtain the value of the qualified function */
/* name with this expression. */
/***************************************************/
char f_func[28];
strcpy(f_func,argv[8]);
/***************************************************/
/* Obtain the value of the specific function */
/* name with this expression. */
/***************************************************/
char f_spec[19];
strcpy(f_spec,argv[9]);

/***************************************************/
/* Use the following expression to assign */
/* 'yyyyyyyy' to the diagnostic string returned */
/* in the SQLCA associated with the invoked */
/* user-defined function. */
/***************************************************/
strcpy(argv[10],"yyyyyyyy/0");

/***************************************************/
/* Use the following expression to assign the */
/* result of the function. */
/***************************************************/
char l_result[11];
strcpy(argv[3],l_result);

.
.
.
}

The following figure shows the parameter conventions for a user-defined scalar
function written as a C subprogram that receives two parameters and returns one
result.
#pragma runopts(plist(os))
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sqludf.h>

void myfunc(long *parm1, char parm2[11], char result[11],

short *f_ind1, short *f_ind2, short *f_indr,
char udf_sqlstate[6], char udf_fname[138],
char udf_specname[129], char udf_msgtext[71],
struct sqludf_scratchpad *udf_scratchpad,
long *udf_call_type,

Chapter 10. Creating and modifying DB2 objects 505

struct sql_dbinfo *udf_dbinfo);
{
/***************************************************/
/* Declare local copies of parameters */
/***************************************************/
int l_p1;
char l_p2[11];
short int l_ind1;
short int l_ind2;
char ludf_sqlstate[6]; /* SQLSTATE */
char ludf_fname[138]; /* function name */
char ludf_specname[129]; /* specific function name */
char ludf_msgtext[71] /* diagnostic message text*/
sqludf_scratchpad *ludf_scratchpad; /* scratchpad */
long *ludf_call_type; /* call type */
sqludf_dbinfo *ludf_dbinfo /* dbinfo */
/***************************************************/
/* Copy each of the parameters in the parameter */
/* list into a local variable to demonstrate */
/* how the parameters can be referenced. */
/***************************************************/

l_p1 = *parm1;
strcpy(l_p2,parm2);
l_ind1 = *f_ind1;
l_ind1 = *f_ind2;
strcpy(ludf_sqlstate,udf_sqlstate);
strcpy(ludf_fname,udf_fname);
strcpy(ludf_specname,udf_specname);
l_udf_call_type = *udf_call_type;
strcpy(ludf_msgtext,udf_msgtext);
memcpy(&ludf_scratchpad,udf_scratchpad,sizeof(ludf_scratchpad));
memcpy(&ludf_dbinfo,udf_dbinfo,sizeof(ludf_dbinfo));
.
.
.
}

The following figure shows the parameter conventions for a user-defined scalar
function that is written as a C++ subprogram that receives two parameters and
returns one result. This example demonstrates that you must use an extern ″C″
modifier to indicate that you want the C++ subprogram to receive parameters
according to the C linkage convention. This modifier is necessary because the
CEEPIPI CALL_SUB interface, which DB2 uses to call the user-defined function,
passes parameters using the C linkage convention.
#pragma runopts(plist(os))
#include <stdlib.h>
#include <stdio.h>
#include <sqludf.h>

extern "C" void myfunc(long *parm1, char parm2[11],

char result[11], short *f_ind1, short *f_ind2, short *f_indr,
char udf_sqlstate[6], char udf_fname[138],
char udf_specname[129], char udf_msgtext[71],
struct sqludf_scratchpad *udf_scratchpad,
long *udf_call_type,
struct sql_dbinfo *udf_dbinfo);

{
/***************************************************/
/* Define local copies of parameters. */
/***************************************************/
int l_p1;
char l_p2[11];
short int l_ind1;
short int l_ind2;

506 Application Programming and SQL Guide

char ludf_sqlstate[6]; /* SQLSTATE */
char ludf_fname[138]; /* function name */
char ludf_specname[129]; /* specific function name */
char ludf_msgtext[71] /* diagnostic message text*/
sqludf_scratchpad *ludf_scratchpad; /* scratchpad */
long *ludf_call_type; /* call type */
sqludf_dbinfo *ludf_dbinfo /* dbinfo */
/***************************************************/
/* Copy each of the parameters in the parameter */
/* list into a local variable to demonstrate */
/* how the parameters can be referenced. */
/***************************************************/
l_p1 = *parm1;
strcpy(l_p2,parm2);
l_ind1 = *f_ind1;
l_ind1 = *f_ind2;
strcpy(ludf_sqlstate,udf_sqlstate);
strcpy(ludf_fname,udf_fname);
strcpy(ludf_specname,udf_specname);
l_udf_call_type = *udf_call_type;
strcpy(ludf_msgtext,udf_msgtext);
memcpy(&ludf_scratchpad,udf_scratchpad,sizeof(ludf_scratchpad));
memcpy(&ludf_dbinfo,udf_dbinfo,sizeof(ludf_dbinfo));
.
.
.
}
CBL APOST,RES,RENT
IDENTIFICATION DIVISION.
.
.
.
DATA DIVISION.
.
.
.
LINKAGE SECTION.
*********************************************************
* Declare each of the parameters *
*********************************************************
01 UDFPARM1 PIC S9(9) USAGE COMP.
01 UDFPARM2 PIC X(10).
.
.
.
*********************************************************
* Declare these variables for result parameters *
*********************************************************
01 UDFRESULT1 PIC X(10).
01 UDFRESULT2 PIC X(10).
.
.
.
*********************************************************
* Declare a null indicator for each parameter *
*********************************************************
01 UDF-IND1 PIC S9(4) USAGE COMP.
01 UDF-IND2 PIC S9(4) USAGE COMP.
.
.
.
*********************************************************
* Declare a null indicator for result parameter *
*********************************************************
01 UDF-RIND1 PIC S9(4) USAGE COMP.
01 UDF-RIND2 PIC S9(4) USAGE COMP.
.
.
.
*********************************************************
* Declare the SQLSTATE that can be set by the *
* user-defined function *

Chapter 10. Creating and modifying DB2 objects 507

*********************************************************
01 UDF-SQLSTATE PIC X(5).
*********************************************************
* Declare the qualified function name *
*********************************************************
01 UDF-FUNC.
49 UDF-FUNC-LEN PIC 9(4) USAGE BINARY.
49 UDF-FUNC-TEXT PIC X(137).
*********************************************************
* Declare the specific function name *
*********************************************************
01 UDF-SPEC.
49 UDF-SPEC-LEN PIC 9(4) USAGE BINARY.
49 UDF-SPEC-TEXT PIC X(128).
*********************************************************
* Declare SQL diagnostic message token *
*********************************************************
01 UDF-DIAG.
49 UDF-DIAG-LEN PIC 9(4) USAGE BINARY.
49 UDF-DIAG-TEXT PIC X(1000).
*********************************************************
* Declare the scratchpad *
*********************************************************
01 UDF-SCRATCHPAD.
49 UDF-SPAD-LEN PIC 9(9) USAGE BINARY.
49 UDF-SPAD-TEXT PIC X(100).
*********************************************************
* Declare the call type *
*********************************************************
01 UDF-CALL-TYPE PIC 9(9) USAGE BINARY.
*********************************************************
* CONSTANTS FOR DB2-EBCODING-SCHEME. *
*********************************************************
77 SQLUDF-ASCII PIC 9(9) VALUE 1.
77 SQLUDF-EBCDIC PIC 9(9) VALUE 2.
77 SQLUDF-UNICODE PIC 9(9) VALUE 3.
*********************************************************
* Structure used for DBINFO *
*********************************************************
01 SQLUDF-DBINFO.
* location name length
05 DBNAMELEN PIC 9(4) USAGE BINARY.
* location name
05 DBNAME PIC X(128).
* authorization ID length
05 AUTHIDLEN PIC 9(4) USAGE BINARY.
* authorization ID
05 AUTHID PIC X(128).
* environment CCSID information
05 CODEPG PIC X(48).
05 CDPG-DB2 REDEFINES CODEPG.
10 DB2-CCSIDS OCCURS 3 TIMES.
15 DB2-SBCS PIC 9(9) USAGE BINARY.
15 DB2-DBCS PIC 9(9) USAGE BINARY.
15 DB2-MIXED PIC 9(9) USAGE BINARY.
10 ENCODING-SCHEME PIC 9(9) USAGE BINARY.
10 RESERVED PIC X(8).
* other platform-specific deprecated CCSID structures not included here
* schema name length
05 TBSCHEMALEN PIC 9(4) USAGE BINARY.
* schema name
05 TBSCHEMA PIC X(128).
* table name length
05 TBNAMELEN PIC 9(4) USAGE BINARY.
* table name
05 TBNAME PIC X(128).
* column name length

508 Application Programming and SQL Guide

05 COLNAMELEN PIC 9(4) USAGE BINARY.
* column name
05 COLNAME PIC X(128).
* product information
05 VER-REL PIC X(8).
* reserved for expansion
05 RESD0 PIC X(2).
* platform type
05 PLATFORM PIC 9(9) USAGE BINARY.
* number of entries in tfcolumn list array (tfcolumn, below)
05 NUMTFCOL PIC 9(4) USAGE BINARY.
* reserved for expansion
05 RESD1 PIC X(26).
* tfcolumn will be allocated dynamically if TF is defined
* otherwise this will be a null pointer
05 TFCOLUMN USAGE IS POINTER.
* Application identifier
05 APPL-ID USAGE IS POINTER.
* reserved for expansion
05 RESD2 PIC X(20). *
PROCEDURE DIVISION USING UDFPARM1, UDFPARM2, UDFRESULT1,
UDFRESULT2, UDF-IND1, UDF-IND2,
UDF-RIND1, UDF-RIND2,
UDF-SQLSTATE, UDF-FUNC, UDF-SPEC,
UDF-DIAG, UDF-SCRATCHPAD,
UDF-CALL-TYPE, SQLUDF-DBINFO.

COBOL: The following figure shows the parameter conventions for a user-defined
table function that is written as a main program that receives two parameters and
returns two results. For a COBOL user-defined function that is a subprogram, the
conventions are the same.

PL/I: The following figure shows the parameter conventions for a user-defined
scalar function that is written as a main program that receives two parameters and
returns one result. For a PL/I user-defined function that is a subprogram, the
conventions are the same.
*PROCESS SYSTEM(MVS);
MYMAIN: PROC(UDF_PARM1, UDF_PARM2, UDF_RESULT,
UDF_IND1, UDF_IND2, UDF_INDR,
UDF_SQLSTATE, UDF_NAME, UDF_SPEC_NAME,
UDF_DIAG_MSG, UDF_SCRATCHPAD,
UDF_CALL_TYPE, UDF_DBINFO)
OPTIONS(MAIN NOEXECOPS REENTRANT);

DCL UDF_PARM1 BIN FIXED(31); /* first parameter */

DCL UDF_PARM2 CHAR(10); /* second parameter */
DCL UDF_RESULT CHAR(10); /* result parameter */
DCL UDF_IND1 BIN FIXED(15); /* indicator for 1st parm */
DCL UDF_IND2 BIN FIXED(15); /* indicator for 2nd parm */
DCL UDF_INDR BIN FIXED(15); /* indicator for result */
DCL UDF_SQLSTATE CHAR(5); /* SQLSTATE returned to DB2 */
DCL UDF_NAME CHAR(137) VARYING; /* Qualified function name */
DCL UDF_SPEC_NAME CHAR(128) VARYING; /* Specific function name */
DCL UDF_DIAG_MSG CHAR(70) VARYING; /* Diagnostic string */
DCL 01 UDF_SCRATCHPAD /* Scratchpad */
03 UDF_SPAD_LEN BIN FIXED(31),
03 UDF_SPAD_TEXT CHAR(100);
DCL UDF_CALL_TYPE BIN FIXED(31); /* Call Type */
DCL DBINFO PTR;
/* CONSTANTS FOR DB2_ENCODING_SCHEME */
DCL SQLUDF_ASCII BIN FIXED(15) INIT(1);
DCL SQLUDF_EBCDIC BIN FIXED(15) INIT(2);
DCL SQLUDF_MIXED BIN FIXED(15) INIT(3);

Chapter 10. Creating and modifying DB2 objects 509

DCL 01 UDF_DBINFO BASED(DBINFO), /* Dbinfo */
03 UDF_DBINFO_LLEN BIN FIXED(15), /* location length */
03 UDF_DBINFO_LOC CHAR(128), /* location name */
03 UDF_DBINFO_ALEN BIN FIXED(15), /* auth ID length */
03 UDF_DBINFO_AUTH CHAR(128), /* authorization ID */
03 UDF_DBINFO_CDPG, /* environment CCSID info */
05 DB2_CCSIDS(3),
07 R1 BIN FIXED(15), /* Reserved */
07 DB2_SBCS BIN FIXED(15), /* SBCS CCSID */
07 R2 BIN FIXED(15), /* Reserved */
07 DB2_DBCS BIN FIXED(15), /* DBCS CCSID */
07 R3 BIN FIXED(15), /* Reserved */
07 DB2_MIXED BIN FIXED(15), /* MIXED CCSID */
05 DB2_ENCODING_SCHEME BIN FIXED(31),
05 DB2_CCSID_RESERVED CHAR(8),
03 UDF_DBINFO_SLEN BIN FIXED(15), /* schema length */
03 UDF_DBINFO_SCHEMA CHAR(128), /* schema name */
03 UDF_DBINFO_TLEN BIN FIXED(15), /* table length */
03 UDF_DBINFO_TABLE CHAR(128), /* table name */
03 UDF_DBINFO_CLEN BIN FIXED(15), /* column length */
03 UDF_DBINFO_COLUMN CHAR(128), /* column name */
03 UDF_DBINFO_RELVER CHAR(8), /* DB2 release level */
03 UDF_DBINFO_RESERV0 CHAR(2), /* reserved */
03 UDF_DBINFO_PLATFORM BIN FIXED(31), /* database platform */
03 UDF_DBINFO_NUMTFCOL BIN FIXED(15), /* # of TF columns used */
03 UDF_DBINFO_RESERV1 CHAR(26), /* reserved */
03 UDF_DBINFO_TFCOLUMN PTR, /* -> TFcolumn list */
03 UDF_DBINFO_APPLID PTR, /* -> application id */
03 UDF_DBINFO_RESERV2 CHAR(20); /* reserved */
.
.
.
Related reference
CREATE FUNCTION (external scalar) (SQL Reference)

Making a user-defined function reentrant

A reentrant user-defined function is a function for which a single copy of the
function can be used concurrently by two or more processes.

Compiling and link-editing your user-defined function as reentrant is

recommended. (For an assembler program, you must also code the user-defined
function to be reentrant.) Reentrant user-defined functions have the following
advantages:
v The operating system does not need to load the user-defined function into
storage every time the user-defined function is called.
v Multiple tasks in a WLM-established stored procedures address space can share
a single copy of the user-defined function. This decreases the amount of virtual
storage that is needed for code in the address space.

Preparing user-defined functions that contain multiple programs: If your

user-defined function consists of several programs, you must bind each program
that contains SQL statements into a separate package. The definer of the
user-defined function must have EXECUTE authority for all packages that are part
of the user-defined function.

When the primary program of a user-defined function calls another program, DB2
uses the CURRENT PACKAGE PATH special register to determine the list of
collections to search for the called program’s package. The primary program can
change this collection ID by executing the statement SET CURRENT PACKAGE
PATH.

510 Application Programming and SQL Guide

If the value of CURRENT PACKAGE PATH is blank or an empty string, DB2 uses
the CURRENT PACKAGESET special register to determine the collection to search
for the called program’s package. The primary program can change this value by
executing the statement SET CURRENT PACKAGESET.

If both special registers CURRENT PACKAGE PATH and CURRENT

PACKAGESET contain a blank value, DB2 uses the method described in “Binding
an application plan” on page 922 to search for the package.

Using special registers in a user-defined function or a stored

procedure
You can use all special registers in a user-defined function or a stored procedure.
However, you can modify only some of those special registers.

After a user-defined function or a stored procedure completes, DB2 restores all

special registers to the values they had before invocation.

The following table shows information you need when you use special registers in
a user-defined function or stored procedure.
Table 91. Characteristics of special registers in a user-defined function or a stored procedure
Routine can
Initial value when INHERIT Initial value when DEFAULT use SET
SPECIAL REGISTERS option SPECIAL REGISTERS option statement to
Special register is specified is specified modify?
CURRENT APPLICATION The value of bind option The value of bind option Yes
ENCODING SCHEME ENCODING for the ENCODING for the
user-defined function or stored user-defined function or stored
procedure package procedure package
CURRENT CLIENT_ACCTNG Inherited from the invoking Inherited from the invoking Not applicable5
application application
CURRENT Inherited from the invoking Inherited from the invoking Not applicable5
CLIENT_APPLNAME application application
CURRENT CLIENT_USERID Inherited from the invoking Inherited from the invoking Not applicable5
application application
CURRENT Inherited from the invoking Inherited from the invoking Not applicable5
CLIENT_WRKSTNNAME application application
CURRENT DATE New value for each SQL New value for each SQL Not applicable5
statement in the user-defined statement in the user-defined
function or stored procedure function or stored procedure
package1 package1
| CURRENT DEBUG MODE Inherited from the invoking DISALLOW Yes
| application
| CURRENT DECFLOAT Inherited from the invoking The value of bind option Yes
| ROUNDING MODE application ROUNDING for the
| user-defined function or stored
| procedure package
CURRENT DEGREE CURRENT DEGREE2 The value of field CURRENT Yes
DEGREE on installation panel
DSNTIP8
CURRENT LOCALE LC_CTYPE Inherited from the invoking The value of field CURRENT Yes
application LC_CTYPE on installation panel
DSNTIPF

Chapter 10. Creating and modifying DB2 objects 511

Table 91. Characteristics of special registers in a user-defined function or a stored procedure (continued)
Routine can
Initial value when INHERIT Initial value when DEFAULT use SET
SPECIAL REGISTERS option SPECIAL REGISTERS option statement to
Special register is specified is specified modify?
CURRENT MAINTAINED Inherited from the invoking System default value Yes
TABLE TYPES FOR application
OPTIMIZATION
| CURRENT MEMBER New value for each SET New value for each SET Not applicable5
| host-variable=CURRENT host-variable=CURRENT
| MEMBER statement MEMBER statement
CURRENT OPTIMIZATION The value of bind option The value of bind option Yes
HINT OPTHINT for the user-defined OPTHINT for the user-defined
function or stored procedure function or stored procedure
package or inherited from the package
invoking application6
CURRENT PACKAGE PATH An empty string if the routine An empty string, regardless of Yes
was defined with a COLLID whether a COLLID value was
value; otherwise, inherited from specified for the routine4
the invoking application4
CURRENT PACKAGESET Inherited from the invoking Inherited from the invoking Yes
application3 application3
CURRENT PATH The value of bind option PATH The value of bind option PATH Yes
for the user-defined function or for the user-defined function or
stored procedure package or stored procedure package
inherited from the invoking
application6
CURRENT PRECISION Inherited from the invoking The value of field DECIMAL Yes
application ARITHMETIC on installation
panel DSNTIP4
CURRENT REFRESH AGE Inherited from the invoking System default value Yes
application
| CURRENT ROUTINE VERSION Inherited from the invoking The empty string Yes
| application
CURRENT RULES Inherited from the invoking The value of bind option Yes
application SQLRULES for the plan that
invokes a user-defined function
or stored procedure
CURRENT SCHEMA Inherited from the invoking The value of CURRENT Yes
application SCHEMA when the routine is
entered
CURRENT SERVER Inherited from the invoking Inherited from the invoking Yes
application application
CURRENT SQLID The primary authorization ID of The primary authorization ID of Yes8
the application process or the application process
inherited from the invoking
application7
CURRENT TIME New value for each SQL New value for each SQL Not applicable5
statement in the user-defined statement in the user-defined
function or stored procedure function or stored procedure
package1 package1

512 Application Programming and SQL Guide

Table 91. Characteristics of special registers in a user-defined function or a stored procedure (continued)
Routine can
Initial value when INHERIT Initial value when DEFAULT use SET
SPECIAL REGISTERS option SPECIAL REGISTERS option statement to
Special register is specified is specified modify?
CURRENT TIMESTAMP New value for each SQL New value for each SQL Not applicable5
statement in the user-defined statement in the user-defined
function or stored procedure function or stored procedure
package1 package1
CURRENT TIMEZONE Inherited from the invoking Inherited from the invoking Not applicable5
application application
| ENCRYPTION PASSWORD Inherited from the invoking Inherited from the invoking Yes
| application application
| SESSION_USER or USER Primary authorization ID of the Primary authorization ID of the Not applicable5
application process application process
Notes:
1. If the user-defined function or stored procedure is invoked within the scope of a trigger, DB2 uses the timestamp
for the triggering SQL statement as the timestamp for all SQL statements in the package.
2. DB2 allows parallelism at only one level of a nested SQL statement. If you set the value of the CURRENT
DEGREE special register to ANY, and parallelism is disabled, DB2 ignores the CURRENT DEGREE value.
| 3. If the routine definition includes a specification for COLLID, DB2 sets CURRENT PACKAGESET to the value of
| COLLID. If both CURRENT PACKAGE PATH and COLLID are specified, the CURRENT PACKAGE PATH value
| takes precedence and COLLID is ignored.
| 4. If the function definition includes a specification for PACKAGE PATH, DB2 sets CURRENT PACKAGE PATH to
| the value of PACKAGE PATH.
5. Not applicable because no SET statement exists for the special register.
6. If a program within the scope of the invoking program issues a SET statement for the special register before the
user-defined function or stored procedure is invoked, the special register inherits the value from the SET
statement. Otherwise, the special register contains the value that is set by the bind option for the user-defined
function or stored procedure package.
7. If a program within the scope of the invoking program issues a SET CURRENT SQLID statement before the
user-defined function or stored procedure is invoked, the special register inherits the value from the SET
statement. Otherwise, CURRENT SQLID contains the authorization ID of the application process.
8. If the user-defined function or stored procedure package uses a value other than RUN for the DYNAMICRULES
bind option, the SET CURRENT SQLID statement can be executed but does not affect the authorization ID that is
used for the dynamic SQL statements in the package. The DYNAMICRULES value determines the authorization
ID that is used for dynamic SQL statements. For more information, see the discussion of DYNAMICRULES in
DB2 Command Reference.

Accessing transition tables in a user-defined function or

stored procedure
If you want to refer to the entire set of rows that a triggering SQL statement
modifies, rather than to individual rows, use a transition table. You can reference a
transition table in user-defined functions and procedures that are invoked from a
trigger.

This topic describes how to access transition variables in a user-defined function,

but the same techniques apply to a stored procedure.

To access transition tables in a user-defined function, use table locators, which are
pointers to the transition tables. You declare table locators as input parameters in
the CREATE FUNCTION statement using the TABLE LIKE table-name AS
LOCATOR clause.

Chapter 10. Creating and modifying DB2 objects 513

The five basic steps to accessing transition tables in a user-defined function are:
1. Declare input parameters to receive table locators. You must define each
parameter that receives a table locator as an unsigned 4-byte integer.
2. Declare table locators. You can declare table locators in assembler, C, C++,
COBOL, PL/I, and in an SQL procedure compound statement.
3. Declare a cursor to access the rows in each transition table.
4. Assign the input parameter values to the table locators.
5. Access rows from the transition tables using the cursors that are declared for
the transition tables.

The following examples show how a user-defined function that is written in C,

C++, COBOL, or PL/I accesses a transition table for a trigger. The transition table,
NEWEMP, contains modified rows of the employee sample table. The trigger is
defined like this:
CREATE TRIGGER EMPRAISE
AFTER UPDATE ON EMP
REFERENCING NEW TABLE AS NEWEMPS
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
VALUES (CHECKEMP(TABLE NEWEMPS));
END;

The user-defined function definition looks like this:

CREATE FUNCTION CHECKEMP(TABLE LIKE EMP AS LOCATOR)
RETURNS INTEGER
EXTERNAL NAME 'CHECKEMP'
PARAMETER STYLE SQL
LANGUAGE language;

Assembler: The following example shows how an assembler program accesses rows
of transition table NEWEMPS.
CHECKEMP CSECT
SAVE (14,12) ANY SAVE SEQUENCE
LR R12,R15 CODE ADDRESSABILITY
USING CHECKEMP,R12 TELL THE ASSEMBLER
LR R7,R1 SAVE THE PARM POINTER
USING PARMAREA,R7 SET ADDRESSABILITY FOR PARMS
USING SQLDSECT,R8 ESTABLISH ADDRESSIBILITY TO SQLDSECT
L R6,PROGSIZE GET SPACE FOR USER PROGRAM
GETMAIN R,LV=(6) GET STORAGE FOR PROGRAM VARIABLES
LR R10,R1 POINT TO THE ACQUIRED STORAGE
LR R2,R10 POINT TO THE FIELD
LR R3,R6 GET ITS LENGTH
SR R4,R4 CLEAR THE INPUT ADDRESS
SR R5,R5 CLEAR THE INPUT LENGTH
MVCL R2,R4 CLEAR OUT THE FIELD
ST R13,FOUR(R10) CHAIN THE SAVEAREA PTRS
ST R10,EIGHT(R13) CHAIN SAVEAREA FORWARD
LR R13,R10 POINT TO THE SAVEAREA
USING PROGAREA,R13 SET ADDRESSABILITY
ST R6,GETLENTH SAVE THE LENGTH OF THE GETMAIN
.
.
.
************************************************************
* Declare table locator host variable TRIGTBL *
************************************************************
TRIGTBL SQL TYPE IS TABLE LIKE EMP AS LOCATOR
************************************************************
* Declare a cursor to retrieve rows from the transition *
* table *
************************************************************

514 Application Programming and SQL Guide

EXEC SQL DECLARE C1 CURSOR FOR X
SELECT LASTNAME FROM TABLE(:TRIGTBL LIKE EMP) X
WHERE SALARY > 100000
************************************************************
* Copy table locator for trigger transition table *
************************************************************
L R2,TABLOC GET ADDRESS OF LOCATOR
L R2,0(0,R2) GET LOCATOR VALUE
ST R2,TRIGTBL
EXEC SQL OPEN C1
EXEC SQL FETCH C1 INTO :NAME
.
.
.
. EXEC SQL CLOSE C1
.
.
PROGAREA DSECT WORKING STORAGE FOR THE PROGRAM
SAVEAREA DS 18F THIS ROUTINE'S SAVE AREA
GETLENTH
. DS A GETMAIN LENGTH FOR THIS AREA
.
.
NAME
. DS CL24
.
.
DS 0D
PROGSIZE EQU *-PROGAREA DYNAMIC WORKAREA SIZE
PARMAREA DSECT
TABLOC
. DS A INPUT PARAMETER FOR TABLE LOCATOR
.
.
END CHECKEMP

C or C++: The following example shows how a C or C++ program accesses rows
of transition table NEWEMPS.
int CHECK_EMP(int trig_tbl_id)
{
.
.
.
/**********************************************************/
/* Declare table locator host variable trig_tbl_id */
/**********************************************************/
EXEC SQL BEGIN DECLARE SECTION;
SQL TYPE IS TABLE LIKE EMP AS LOCATOR trig_tbl_id;
char name[25];
EXEC SQL END DECLARE SECTION;
.
.
.
/**********************************************************/
/* Declare a cursor to retrieve rows from the transition */
/* table */
/**********************************************************/
EXEC SQL DECLARE C1 CURSOR FOR
SELECT NAME FROM TABLE(:trig_tbl_id LIKE EMPLOYEE)
WHERE SALARY > 100000;
/**********************************************************/
/* Fetch a row from transition table */
/**********************************************************/
EXEC SQL OPEN C1;
EXEC SQL FETCH C1 INTO :name;
.
.
.
EXEC SQL CLOSE C1;
.
.
.
}

COBOL: The following example shows how a COBOL program accesses rows of
transition table NEWEMPS.

Chapter 10. Creating and modifying DB2 objects 515

IDENTIFICATION DIVISION.
PROGRAM-ID. CHECKEMP.
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
DATA DIVISION.
WORKING-STORAGE SECTION.
01 NAME PIC X(24).
.
.
.
LINKAGE SECTION.
*********************************************************
* Declare table locator host variable TRIG-TBL-ID *
*********************************************************
01 TRIG-TBL-ID SQL TYPE IS TABLE LIKE EMP AS LOCATOR.
.
.
.
PROCEDURE DIVISION USING TRIG-TBL-ID.
.
.
.
*********************************************************
* Declare cursor to retrieve rows from transition table *
*********************************************************
EXEC SQL DECLARE C1 CURSOR FOR
SELECT NAME FROM TABLE(:TRIG-TBL-ID LIKE EMP)
WHERE SALARY > 100000 END-EXEC.
*********************************************************
* Fetch a row from transition table *
*********************************************************
EXEC SQL OPEN C1 END-EXEC.
EXEC SQL FETCH C1 INTO :NAME END-EXEC.
.
.
.
EXEC SQL CLOSE C1 END-EXEC.
.
.
.
PROG-END.
GOBACK.

PL/I: The following example shows how a PL/I program accesses rows of
transition table NEWEMPS.
CHECK_EMP: PROC(TRIG_TBL_ID) RETURNS(BIN FIXED(31))
OPTIONS(MAIN NOEXECOPS REENTRANT);
/****************************************************/
/* Declare table locator host variable TRIG_TBL_ID */
/****************************************************/
DECLARE TRIG_TBL_ID SQL TYPE IS TABLE LIKE EMP AS LOCATOR;
DECLARE NAME CHAR(24);
.
.
.
/****************************************************/
/* Declare a cursor to retrieve rows from the */
/* transition table */
/****************************************************/
EXEC SQL DECLARE C1 CURSOR FOR
SELECT NAME FROM TABLE(:TRIG_TBL_ID LIKE EMP)
WHERE SALARY > 100000;
/****************************************************/
/* Retrieve rows from the transition table */
/****************************************************/
EXEC SQL OPEN C1;
EXEC SQL FETCH C1 INTO :NAME;
.
.
.
EXEC SQL CLOSE C1;

516 Application Programming and SQL Guide

.
.
.
END CHECK_EMP;

Preparing an external user-defined function for execution

Because an external user-defined function is a function that is written in a
programming language, you need to prepare it similar to the way that you prepare
any other application program.

To prepare an external user-defined function for execution:

1. Precompile the user-defined function program and bind the DBRM into a
package. You need to do this only if your user-defined function contains SQL
statements. You do not need to bind a plan for the user-defined function.
2. Compile the user-defined function program and link-edit it with Language
Environment and RRSAF.
You must compile the program with a compiler that supports Language
Environment and link-edit the appropriate Language Environment components
with the user-defined function. You must also link-edit the user-defined
function with RRSAF.
The program preparation JCL samples DSNHASM, DSNHC, DSNHCPP,
DSNHICOB, and DSNHPLI show you how to precompile, compile, and
link-edit assembler, C, C++, COBOL, and PL/I DB2 programs. For
object-oriented programs in C++, see JCL sample DSNHCPP2 for program
preparation hints.
3. For a user-defined function that contains SQL statements, grant EXECUTE
authority on the user-defined function package to the function definer.

Abnormal termination of an external user-defined function

If an external user-defined function abnormally terminates, your program receives
SQLCODE -430 for invoking the statement.

DB2 also performs the following actions:

v Places the unit of work that contains the invoking statement in a must-rollback
state.
v Stops the user-defined function, and subsequent calls fail, in either of the
following situations:
– The number of abnormal terminations equals the STOP AFTER n FAILURES
value for the user-defined function.
– If the STOP AFTER n FAILURES option is not specified, the number of
abnormal terminations equals the default MAX ABEND COUNT value for the
subsystem.

You should include code in your program to check for a user-defined function
abend and to roll back the unit of work that contains the user-defined function
invocation.

Saving information between invocations of a user-defined

function by using a scratchpad
If you create a scratchpad for a reentrant user-defined function, DB2 can use it to
preserve information between invocations of the function.

Chapter 10. Creating and modifying DB2 objects 517

You can use a scratchpad to save information between invocations of a
user-defined function. To indicate that a scratchpad should be allocated when the
user-defined function executes, the function definer specifies the SCRATCHPAD
parameter in the CREATE FUNCTION statement.

The scratchpad consists of a 4-byte length field, followed by the scratchpad area.
The definer can specify the length of the scratchpad area in the CREATE
FUNCTION statement. The specified length does not include the length field. The
default size is 100 bytes. DB2 initializes the scratchpad for each function to binary
zeros at the beginning of execution for each subquery of an SQL statement and
does not examine or change the content thereafter. On each invocation of the
user-defined function, DB2 passes the scratchpad to the user-defined function. You
can therefore use the scratchpad to preserve information between invocations of a
reentrant user-defined function.

The following example demonstrates how to enter information in a scratchpad for

a user-defined function defined like this:
CREATE FUNCTION COUNTER()
RETURNS INT
SCRATCHPAD
FENCED
NOT DETERMINISTIC
NO SQL
NO EXTERNAL ACTION
LANGUAGE C
PARAMETER STYLE SQL
EXTERNAL NAME 'UDFCTR';

The scratchpad length is not specified, so the scratchpad has the default length of
100 bytes, plus 4 bytes for the length field. The user-defined function increments
an integer value and stores it in the scratchpad on each execution.
#pragma linkage(ctr,fetchable)
#include <stdlib.h>
#include <stdio.h>
/* Structure scr defines the passed scratchpad for function ctr */
struct scr {
long len;
long countr;
char not_used[96];
};
/***************************************************************/
/* Function ctr: Increments a counter and reports the value */
/* from the scratchpad. */
/* */
/* Input: None */
/* Output: INTEGER out the value from the scratchpad */
/***************************************************************/
void ctr(
long *out, /* Output answer (counter) */
short *outnull, /* Output null indicator */
char *sqlstate, /* SQLSTATE */
char *funcname, /* Function name */
char *specname, /* Specific function name */
char *mesgtext, /* Message text insert */
struct scr *scratchptr) /* Scratchpad */
{
*out = ++scratchptr->countr; /* Increment counter and */
/* copy to output variable */
*outnull = 0; /* Set output null indicator*/
return;
}
/* end of user-defined function ctr */

518 Application Programming and SQL Guide

Example of creating and using a user-defined scalar function
This example shows how to create a user-defined scalar function that gets input
from a table and puts the output in a table.

Suppose that your organization needs a user-defined scalar function that calculates
the bonus that each employee receives. All employee data, including salaries,
commissions, and bonuses, is kept in the employee table, EMP. The input fields for
the bonus calculation function are the values of the SALARY and COMM columns.
The output from the function goes into the BONUS column. Because this function
gets its input from a DB2 table and puts the output in a DB2 table, a convenient
way to manipulate the data is through a user-defined function.

The user-defined function’s definer and invoker determine that this new
user-defined function should have these characteristics:
v The user-defined function name is CALC_BONUS.
v The two input fields are of type DECIMAL(9,2).
v The output field is of type DECIMAL(9,2).
v The program for the user-defined function is written in COBOL and has a load
module name of CBONUS.

Because no built-in function or user-defined function exists on which to build a

sourced user-defined function, the function implementer must code an external
user-defined function. The implementer performs the following steps:
v Writes the user-defined function, which is a COBOL program
v Precompiles, compiles, and links the program
v Binds a package if the user-defined function contains SQL statements
v Tests the program thoroughly
v Grants execute authority on the user-defined function package to the definer

The user-defined function definer executes this CREATE FUNCTION statement to

register CALC_BONUS to DB2:
CREATE FUNCTION CALC_BONUS(DECIMAL(9,2),DECIMAL(9,2))
RETURNS DECIMAL(9,2)
EXTERNAL NAME 'CBONUS'
PARAMETER STYLE SQL
LANGUAGE COBOL;

The definer then grants execute authority on CALC_BONUS to all invokers.

User-defined function invokers write and prepare application programs that invoke
CALC_BONUS. An invoker might write a statement like this, which uses the
user-defined function to update the BONUS field in the employee table:
UPDATE EMP
SET BONUS = CALC_BONUS(SALARY,COMM);

An invoker can execute this statement either statically or dynamically.

User-defined function samples that ship with DB2

To assist you in defining, implementing, and invoking your user-defined functions,
DB2 provides a number of sample user-defined functions. All user-defined function
code is in data set DSN910.SDSNSAMP.

The following table summarizes the characteristics of the sample user-defined

functions.

Chapter 10. Creating and modifying DB2 objects 519

Table 92. User-defined function samples shipped with DB2
Member that
User-defined function contains source
name Language code Purpose
1
ALTDATE C DSN8DUAD Converts the current date to a user-specified format
2
ALTDATE C DSN8DUCD Converts a date from one format to another
3
ALTTIME C DSN8DUAT Converts the current time to a user-specified format
4
ALTTIME C DSN8DUCT Converts a time from one format to another
DAYNAME C++ DSN8EUDN Returns the day of the week for a user-specified date
MONTHNAME C++ DSN8EUMN Returns the month for a user-specified date
CURRENCY C DSN8DUCY Formats a floating-point number as a currency value
TABLE_NAME C DSN8DUTI Returns the unqualified table name for a table, view,
or alias
TABLE_QUALIF C DSN8DUTI Returns the qualifier for a table, view, or alias
TABLE_LOCATION C DSN8DUTI Returns the location for a table, view, or alias
WEATHER C DSN8DUWF Returns a table of weather information from a
EBCDIC data set
Notes:
1. This version of ALTDATE has one input parameter, of type VARCHAR(13).
2. This version of ALTDATE has three input parameters, of type VARCHAR(17), VARCHAR(13), and
VARCHAR(13).
3. This version of ALTTIME has one input parameter, of type VARCHAR(14).
4. This version of ALTTIME has three input parameters, of type VARCHAR(11), VARCHAR(14), and VARCHAR(14).

Member DSN8DUWC contains a client program that shows you how to invoke the
WEATHER user-defined table function.

Member DSNTEJ2U shows you how to define and prepare the sample user-defined
functions and the client program.

Determining the authorization cache size for stored

procedures and user-defined functions
DB2 provides a single routine authorization cache for an entire subsystem. This
cache stores a list of authorization IDs that have EXECUTE privilege on
user-defined functions or stored procedures. The size of this cache is set by a
subsystem parameter.

The DB2 installer sets the size of the routine authorization cache by entering a size
in field ROUTINE AUTH CACHE of DB2 installation panel DSNTIPP.
Related reference
Protection panel: DSNTIPP (DB2 Installation and Migration)

Creating a stored procedure

Stored procedures are useful when your application needs to execute multiple
remote SQL statements, access tables from a dynamic SQL environment where
table privileges for the application are undesirable, access host variables for which
you want to guarantee security and integrity, or create a result set to return to the
client application.

520 Application Programming and SQL Guide

Before you can create a stored procedure, you must set up the stored procedures
environment. Then you can create one of the following types of stored procedures:
native SQL procedure
A procedure whose body is written entirely in SQL, that is created entirely
using SQL, and that is executed entirely as native SQL statements that are
bound in a DB2 package.
external SQL procedure
A procedure whose body is written entirely in SQL but that is created,
implemented, and executed like all other external stored procedures. The
DB2 precompiler supports generation of the associated external program
code and DBRM using either JCL or the DB2 SQL procedure processor.
external stored procedures
A procedure that is written in a host language.
Related concepts
“External stored procedures” on page 531
“SQL procedures” on page 527
Related tasks
Implementing DB2 stored procedures (DB2 Administration Guide)

Stored procedures
| A stored procedure is a compiled program, stored at a DB2 local or remote server,
| that can execute SQL statements. You can invoke a stored procedure from an
| application program or from the command line processor.

| A typical stored procedure contains two or more SQL statements and some
| manipulative or logical processing in a host language or SQL procedure
| statements. A client application program uses the SQL statement CALL to invoke
| the stored procedure. You can also invoke a stored procedure from the command
| line processor. For more information about how to invoke the stored procedure
| from the command line processor, see “Running stored procedures from the
| command line processor” on page 1006.

You can create one of the following types of stored procedures:

| SQL procedures
| The procedure is written exclusively in SQL statements. The body of an
| SQL procedure is written in the SQL procedural language. SQL procedures
| can be either external SQL procedures or native SQL procedures. For more
| information about these types of SQL procedures, see “SQL procedures” on
| page 527.
External stored procedures
External stored procedures are written in a host language. The source code
for an external stored procedure is separate from the definition for the
stored procedure. For more information about external stored procedures,
see “External stored procedures” on page 531.

Consider using stored procedures for a client/server application that does at least
one of the following things:
v Executes multiple remote SQL statements.
Remote SQL statements can create many network send and receive operations,
which results in increased processor costs. Stored procedures can encapsulate
many of your application’s SQL statements into a single message to the DB2

Chapter 10. Creating and modifying DB2 objects 521

server, reducing network traffic to a single send and receive operation for a
series of SQL statements. Locks on DB2 tables are not held across network
transmissions, which reduces contention for resources at the server.
v Accesses tables from a dynamic SQL environment where table privileges for the
application that is running are undesirable.
Stored procedures allow static SQL authorization from a dynamic environment.
v Accesses host variables for which you want to guarantee security and integrity.
Stored procedures remove SQL applications from the workstation, which
prevents workstation users from manipulating the contents of sensitive SQL
statements and host variables.
v Creates a result set of rows to return to the client application.
The following two figures illustrate the difference between using stored procedures
and not using stored procedures for processing in a client/server environment.

The following figure shows processing without using stored procedures. A client
application embeds SQL statements and communicates with the server separately
for each statement. This results in increased network traffic and processor costs.

Client DB2 for z/OS

EXEC SQL SELECT …
Perform SQL processing

EXEC SQL UPDATE …

Perform SQL processing

EXEC SQL INSERT …

Perform SQL processing

Figure 29. Processing without stored procedures

The following figure shows processing with stored procedures. The same series of
SQL statements that are illustrated in the following figure uses a single send and
receive operation, reducing network traffic and the cost of processing these
statements.

522 Application Programming and SQL Guide

Figure 30. Processing with stored procedures

Example of a simple stored procedure

This example explains the logical flow of events when a application that runs on a
workstation calls a stored procedure on a DB2 server. The stored procedure
updates a table based on the information that it receives from the application.

Suppose that an application runs on a workstation client and calls a stored

procedure A on the DB2 server at location LOCA. Stored procedure A performs the
following operations:
1. Receives a set of parameters containing the data for one row of the employee to
project activity table (DSN8910.EMPPROJACT). These parameters are input
parameters in the SQL statement CALL:
v EMP: employee number
v PRJ: project number
v ACT: activity ID
v EMT: percent of employee’s time required
v EMS: date the activity starts
v EME: date the activity is due to end
2. Declares a cursor, C1, with the option WITH RETURN, that is used to return a
result set containing all rows in EMPPROJACT to the workstation application
that called the stored procedure.
3. Queries table EMPPROJACT to determine whether a row exists where columns
PROJNO, ACTNO, EMSTDATE, and EMPNO match the values of parameters
PRJ, ACT, EMS, and EMP. (The table has a unique index on those columns.
There is at most one row with those values.)
4. If the row exists, executes an SQL statement UPDATE to assign the values of
parameters EMT and EME to columns EMPTIME and EMENDATE.1
5. If the row does not exist (SQLCODE +100), executes an SQL statement INSERT
to insert a new row with all the values in the parameter list.1
6. Opens cursor C1. This causes the result set to be returned to the caller when
the stored procedure ends.
7. Returns two parameters, containing these values:
v A code to identify the type of SQL statement last executed: UPDATE or
INSERT.

Chapter 10. Creating and modifying DB2 objects 523

v The SQLCODE from that statement.

Note:
| 1. Alternatively, steps 4 and 5 can be accomplished with a single MERGE
| statement.
The following figure illustrates the steps that are involved in executing this stored
procedure.

524 Application Programming and SQL Guide

Notes User Workstation DB2 System DB2 Stored Procedures
Address Space
Stored Procedure A
1 EXEC SQL
CONNECT TO
LOCA;
2 Create Thread
3 EXEC SQL
CALL A(:EMP,
:PRJ,:ACT,:EMT,
:EMS,:EME,
:TYPE,:CODE);
4 Get information
from SYSIBM.
SYSROUTINES
5 Prepare
parameter list and
pass control to
stored procedure
6 EXEC SQL
DECLARE C1 CURSOR
WITH RETURN
FOR SELECT * FROM
EMPPROJACT;
USE SQL UPDATE to
update EMPPROJACT
with input parameter
values
If SQLCODE=+100,
use SQL INSERT to
add a row with the
values in the
parameter list
EXEC SQL OPEN C1;

7 Return output parameters

:TYPE and :CODE and
a result set that contains
all rows in EMPPROJACT

8 Control returns
to application
9 EXEC SQL
COMMIT; Result of
(or ROLLBACK) COMMIT or
ROLLBACK

10 Receive result set

Figure 31. Stored procedure overview

Notes:
1. The workstation application uses the SQL CONNECT statement to create a
conversation with DB2.
2. DB2 creates a DB2 thread to process SQL requests.

Chapter 10. Creating and modifying DB2 objects 525

3. The SQL statement CALL tells the DB2 server that the application is going to
run a stored procedure. The calling application provides the necessary
parameters.
4. The plan for the client application contains information from catalog table
SYSIBM.SYSROUTINES about stored procedure A.
5. DB2 passes information about the request to the stored procedures address
space, and the stored procedure begins execution.
6. The stored procedure executes SQL statements.
DB2 verifies that the owner of the package or plan containing the SQL
statement CALL has EXECUTE authority for the package associated with the
DB2 stored procedure.
One of the SQL statements opens a cursor that has been declared WITH
RETURN. This causes a result set to be returned to the workstation
application when the procedure ends.
Any SQLCODE that is issued within an external stored procedure is not
returned to the workstation application in the SQLCA (as the result of the
CALL statement).
7. If an error is not encountered, the stored procedure assigns values to the
output parameters and exits.
Control returns to the DB2 stored procedures address space, and from there to
the DB2 system. If the stored procedure definition contains COMMIT ON
RETURN NO, DB2 does not commit or roll back any changes from the SQL in
the stored procedure until the calling program executes an explicit COMMIT
or ROLLBACK statement. If the stored procedure definition contains
COMMIT ON RETURN YES, and the stored procedure executed successfully,
DB2 commits all changes. The COMMIT statement closes the cursor unless it
is declared with the WITH HOLD option.
8. Control returns to the calling application, which receives the output
parameters and the result set. DB2 then:
v Closes all cursors that the stored procedure opened, except those that the
stored procedure opened to return result sets.
v Discards all SQL statements that the stored procedure prepared.
v Reclaims the working storage that the stored procedure used.
The application can call more stored procedures, or it can execute more SQL
statements. DB2 receives and processes the COMMIT or ROLLBACK request.
The COMMIT or ROLLBACK operation covers all SQL operations, whether
executed by the application or by stored procedures, for that unit of work.
If the application involves IMS or CICS, similar processing occurs based on
the IMS or CICS sync point rather than on an SQL COMMIT or ROLLBACK
statement.
9. DB2 returns a reply message to the application describing the outcome of the
COMMIT or ROLLBACK operation.
10. The workstation application executes the following steps to retrieve the
contents of table EMPPROJACT, which the stored procedure has returned in a
result set:
a. Declares a result set locator for the result set being returned.
b. Executes the ASSOCIATE LOCATORS statement to associate the result set
locator with the result set.
c. Executes the ALLOCATE CURSOR statement to associate a cursor with the
result set.
d. Executes the FETCH statement with the allocated cursor multiple times to
retrieve the rows in the result set.

526 Application Programming and SQL Guide

| e. Executes the CLOSE statement to close the cursor.

SQL procedures
An SQL procedure is a stored procedure that contains only SQL statements.

The source code for these procedures is specified in an SQL CREATE PROCEDURE
statement. The part of the CREATE PROCEDURE statement that contains SQL
statements is called the procedure body.

| DB2 for z/OS supports the following two types of SQL procedures:
| native SQL procedures
| Native SQL procedures are procedures whose body is written in SQL, and
| DB2 does not generate an associated C program. Native SQL procedures
| have the following advantages
| v You can create them in one step.
| v They do not run in a WLM environment.
| v They might be eligible for zIIP redirect if they are invoked remotely
| through a DRDA client.
| v They usually perform better than external SQL procedures.
| v They support more capabilities, such as nested compound statements,
| than external SQL procedures.
| v DB2 can manage multiple versions of these procedures for you.
| Starting in Version 9.1, all SQL procedures that are created without the
| FENCED or EXTERNAL options in the CREATE PROCEDURE statement
| are native SQL procedures.
| external SQL procedures
| External SQL procedures are procedures whose body is written in SQL, but
| DB2 supports them by generating an associated C program for each
| procedure. All SQL procedures that were created prior to Version 9.1 are
| external SQL procedures. Starting in Version 9.1, you can create an external
| SQL procedure by specifying FENCED or EXTERNAL in the CREATE
| PROCEDURE statement.

SQL procedure body:

| The body of an SQL procedure contains one or more SQL statements. You can also
| declare variables, conditions, and condition handlers and reference parameters,
| variables, and conditions.

Statements that you can include in an SQL procedure body

| An SQL procedure consists of a single SQL procedure statement. That procedure

| statement can be either an SQL control statement or another SQL statement. If the
| SQL control statement is a compound statement or a CASE statement, the
| procedure body can contain multiple statements. For native SQL procedures, you
| can use nested compound statements.

How to distinguish multiple statements in an SQL procedure

Use a semicolon character to separate SQL statements within an SQL procedure.

The procedure body has no terminating character. Therefore, if the procedure

contains only one statement, you do not need to put a semicolon after that

Chapter 10. Creating and modifying DB2 objects 527

statement. If the procedure consists of a set of nested statements, you do not need
to put a semicolon after the outermost statement.

Variables in an SQL procedure

To store data that you use only within an SQL procedure, you can declare SQL
variables. SQL variables are the equivalent of host variables in external stored
procedures. SQL variables can have the same data types and lengths as SQL
procedure parameters.

The general form of an SQL variable declaration is:

DECLARE SQL-variable-name data-type;

The general form of a declaration for an SQL variable that you use as a result set
locator is:
DECLARE SQL-variable-name data-type RESULT_SET_LOCATOR VARYING;

SQL variables in SQL procedures have the following restrictions:

v SQL variable names can be up to 128 bytes in length. They can include
alphanumeric characters and the underscore character. Condition names and
label names also have these restrictions.
v You cannot declare two SQL variables that are the same except for case. For
example, you cannot declare two SQL variables named varx and VARX. (DB2
treats all SQL variable names as uppercase.)
v Although it is not recommended, you can specify an SQL reserved word as the
name of an SQL parameter, SQL variable, or SQL condition in some contexts. If
you specify a reserved word as the name of an SQL parameter, SQL variable, or
SQL condition in a context where its use could be ambiguous, specify the name
as a delimited identifier.
v When you use an SQL variable in an SQL statement, do not precede the variable
with a colon.
| v When you call a user-defined function from an SQL procedure, ensure that you
| pass parameters of the same data type or of a data type that can be promoted to
| the data type of the function definition. For example, DB2 can promote the data
| type CHAR to VARCHAR or SMALLINT to BIGINT.
v Within a procedure body, the following rules apply to IN, OUT, and INOUT
parameters:
– You can use a parameter that you define as IN on the left or right side of an
assignment statement. However, if you assign a value to an IN parameter,
you cannot pass the new value back to the caller. The IN parameter has the
same value before and after the SQL procedure is called.
– You can use a parameter that you define as OUT on the left or right side of
an assignment statement. The last value that you assign to the parameter is
the value that is returned to the caller. The starting value of an OUT
parameter is NULL.
– You can use a parameter that you define as INOUT on the left or right side of
an assignment statement. The caller determines the first value of the INOUT
parameter, and the last value that you assign to the parameter is the value
that is returned to the caller.

You can perform any operations on SQL variables that you can perform on host
variables in SQL statements.

528 Application Programming and SQL Guide

Qualifying SQL variable names and other object names is a good way to avoid
ambiguity. Use the following guidelines to determine when to qualify variable
names:
v When you use an SQL procedure parameter in the procedure body, qualify the
parameter name with the procedure name.
v Specify a label for each compound statement, and qualify all SQL variables with
the label name of the compound statement that declared them.
v Qualify column names with the associated table or view names.
Related concepts
“Nested compound statements in native SQL procedures” on page 537
Promotion of data types (SQL Reference)
SQL control statements for external SQL procedures (SQL Reference)
SQL control statements for native SQL procedures (SQL Reference)
Related tasks
“Raising a condition within an SQL procedure by using the SIGNAL or RESIGNAL
statements” on page 549
“Retrieving diagnostic information by using GET DIAGNOSTICS in a handler” on
page 548
“Returning the procedure status as an integer value” on page 553
Related reference
CASE expressions (SQL Reference)
CALL (SQL Reference)
CREATE PROCEDURE (SQL - external) (SQL Reference)
CREATE PROCEDURE (SQL - native) (SQL Reference)
SQL-procedure-statement (SQL Reference)
SQL statements allowed in SQL procedures (SQL Reference)

Examples of SQL procedures:

These examples show how to use CASE statements, compound statements, and
nested statements within an SQL procedure body.

Example: CASE statement: The following SQL procedure demonstrates how to use
a CASE statement. The procedure receives an employee’s ID number and rating as
input parameters. The CASE statement modifies the employee’s salary and bonus,
using a different UPDATE statement for each of the possible ratings.
CREATE PROCEDURE UPDATESALARY2
(IN EMPNUMBR CHAR(6),
IN RATING INT)
LANGUAGE SQL
MODIFIES SQL DATA
CASE RATING
WHEN 1 THEN
UPDATE CORPDATA.EMPLOYEE
SET SALARY = SALARY * 1.10, BONUS = 1000
WHERE EMPNO = EMPNUMBR;
WHEN 2 THEN
UPDATE CORPDATA.EMPLOYEE
SET SALARY = SALARY * 1.05, BONUS = 500
WHERE EMPNO = EMPNUMBR;

Chapter 10. Creating and modifying DB2 objects 529

ELSE
UPDATE CORPDATA.EMPLOYEE
SET SALARY = SALARY * 1.03, BONUS = 0
WHERE EMPNO = EMPNUMBR;
END CASE

Example: Compound statement with nested IF and WHILE statements: The

following example shows a compound statement that includes an IF statement, a
WHILE statement, and assignment statements. The example also shows how to
declare SQL variables, cursors, and handlers for classes of error codes.

| The procedure receives a department number as an input parameter. A WHILE

| statement in the procedure body fetches the salary and bonus for each employee in
| the department, and uses an SQL variable to calculate a running total of employee
| salaries for the department. An IF statement within the WHILE statement tests for
| positive bonuses and increments an SQL variable that counts the number of
| bonuses in the department. When all employee records in the department have
| been processed, a NOT FOUND condition occurs. A NOT FOUND condition
| handler makes the search condition for the WHILE statement false, so execution of
| the WHILE statement ends. Assignment statements then assign the total employee
| salaries and the number of bonuses for the department to the output parameters
| for the stored procedure.

| If any SQL statement in the compound statement P1 receives an error, the

| SQLEXCEPTION handler receives control. The handler action sets the output
| parameter DEPTSALARY to NULL. After the handler action has completed
| successfully, the original error condition is resolved (SQLSTATE ’00000’, SQLCODE
| 0). Because this handler is an EXIT handler, execution passes to the end of the
| compound statement, and the SQL procedure ends.
CREATE PROCEDURE RETURNDEPTSALARY
(IN DEPTNUMBER CHAR(3),
OUT DEPTSALARY DECIMAL(15,2),
OUT DEPTBONUSCNT INT)
LANGUAGE SQL
READS SQL DATA
P1: BEGIN
DECLARE EMPLOYEE_SALARY DECIMAL(9,2);
DECLARE EMPLOYEE_BONUS DECIMAL(9,2);
DECLARE TOTAL_SALARY DECIMAL(15,2) DEFAULT 0;
DECLARE BONUS_CNT INT DEFAULT 0;
DECLARE END_TABLE INT DEFAULT 0;
DECLARE C1 CURSOR FOR
SELECT SALARY, BONUS FROM CORPDATA.EMPLOYEE
WHERE WORKDEPT = DEPTNUMBER;
DECLARE CONTINUE HANDLER FOR NOT FOUND
SET END_TABLE = 1;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
SET DEPTSALARY = NULL;
OPEN C1;
FETCH C1 INTO EMPLOYEE_SALARY, EMPLOYEE_BONUS;
WHILE END_TABLE = 0 DO
SET TOTAL_SALARY = TOTAL_SALARY + EMPLOYEE_SALARY + EMPLOYEE_BONUS;
IF EMPLOYEE_BONUS > 0 THEN
SET BONUS_CNT = BONUS_CNT + 1;
END IF;
FETCH C1 INTO EMPLOYEE_SALARY, EMPLOYEE_BONUS;
END WHILE;
CLOSE C1;
SET DEPTSALARY = TOTAL_SALARY;
SET DEPTBONUSCNT = BONUS_CNT;
END P1

530 Application Programming and SQL Guide

Example: Compound statement with dynamic SQL statements: The following
example shows a compound statement that includes dynamic SQL statements.

The procedure receives a department number (P_DEPT) as an input parameter. In

the compound statement, three statement strings are built, prepared, and executed:
v The first statement string executes a DROP statement to ensure that the table to
be created does not already exist. This table is named DEPT_deptno_T, where
deptno is the value of input parameter P_DEPT.
v The next statement string executes a CREATE statement to create
DEPT_deptno_T.
v The third statement string inserts rows for employees in department deptno into
DEPT_deptno_T.
Just as statement strings that are prepared in host language programs cannot
contain host variables, statement strings in SQL procedures cannot contain SQL
variables or stored procedure parameters. Therefore, the third statement string
contains a parameter marker that represents P_DEPT. When the prepared
statement is executed, parameter P_DEPT is substituted for the parameter marker.
CREATE PROCEDURE CREATEDEPTTABLE (IN P_DEPT CHAR(3))
LANGUAGE SQL
BEGIN
DECLARE STMT CHAR(1000);
DECLARE MESSAGE CHAR(20);
DECLARE TABLE_NAME CHAR(30);
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
SET MESSAGE = 'ok';
SET TABLE_NAME = 'DEPT_'||P_DEPT||'_T';
SET STMT = 'DROP TABLE '||TABLE_NAME;
PREPARE S1 FROM STMT;
EXECUTE S1;
SET STMT = 'CREATE TABLE '||TABLE_NAME||
'( EMPNO CHAR(6) NOT NULL, '||
'FIRSTNME VARCHAR(6) NOT NULL, '||
'MIDINIT CHAR(1) NOT NULL, '||
'LASTNAME CHAR(15) NOT NULL, '||
'SALARY DECIMAL(9,2))';
PREPARE S2 FROM STMT;
EXECUTE S2;
SET STMT = 'INSERT INTO '||TABLE_NAME ||
'SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY '||
'FROM EMPLOYEE '||
'WHERE WORKDEPT = ?';
PREPARE S3 FROM STMT;
EXECUTE S3 USING P_DEPT;
END

External stored procedures

An external stored procedure is written in a host language. The source code for
this procedure is separate from the definition. An external stored procedure is
much like any other SQL application. It can include static or dynamic SQL
statements, IFI calls, and DB2 commands issued through IFI.

Language requirements for the external stored procedure and its caller

You can write an external stored procedure in Assembler, C, C++, COBOL, Java,
REXX, or PL/I. All programs must be designed to run using Language
Environment. Your COBOL and C++ stored procedures can contain object-oriented
extensions. See “Object-oriented extensions in COBOL” on page 333 for
information about including object-oriented extensions in SQL applications. For
information about writing Java stored procedures, see the topic “Creating Java

Chapter 10. Creating and modifying DB2 objects 531

stored procedures and user-defined functions” in DB2 Application Programming
Guide and Reference for Java. For information about writing REXX stored procedures,
see “REXX stored procedures” on page 594.

The program that calls the stored procedure can be in any language that supports
the SQL CALL statement. ODBC applications can use an escape clause to pass a
stored procedure call to DB2.

Differences between SQL procedures and external procedures

| SQL procedures are written entirely in SQL statements. External procedures are
| written in a host language and can contain SQL statements. You can invoke both
| types of procedures with an SQL CALL statement. However, you should consider
| several important differences in behavior and preparation.

SQL procedures and external procedures consist of a procedure definition and the
code for the procedure program.

Both an SQL procedure definition and an external procedure definition specify the
following information:
v The procedure name.
v Input and output parameter attributes.
v The language in which the procedure is written. For an SQL procedure, the
language is SQL.
v Information that will be used when the procedure is called, such as run-time
options, length of time that the procedure can run, and whether the procedure
returns result sets.

An SQL procedure and external procedure share the same rules for the use of
COMMIT and ROLLBACK statements in a procedure.

An SQL procedure and an external procedure differ in the following ways:

v How they handle errors:
– For an SQL procedure, DB2 automatically returns SQL conditions in the
SQLCA when the procedure does not include a RETURN statement or a
handler. For information about the various ways to handle errors in an SQL
procedure, see “Handling SQL conditions in an SQL procedure” on page 540.
– For an external stored procedure, DB2 does not return SQL conditions in the
SQLCA to the workstation application. If you use PARAMETER STYLE SQL
when you define an external procedure, you can set SQLSTATE to indicate an
error before the procedure ends. For valid SQLSTATE values, see “Parameters
for external user-defined functions” on page 490.
v How they specify the code for the stored procedure. An SQL procedure
definition contains the source code for the stored procedure. An external stored
procedure definition specifies the name of the stored procedure program.
| v How you define the stored procedure. For native SQL procedures and external
| procedures, you define the stored procedure to DB2 by executing the CREATE
| PROCEDURE statement. For external SQL procedures, you define the stored
| procedure to DB2 by preprocessing a CREATE PROCEDURE statement, then
| executing the CREATE PROCEDURE statement dynamically. For all procedures,
| you change the definition by executing the ALTER PROCEDURE statement. See
| “Creating an external SQL procedure” on page 561 for more information about
| defining an SQL procedure to DB2.
| Example: The following example shows a definition for an SQL procedure.

532 Application Programming and SQL Guide

| CREATE PROCEDURE UPDATESALARY1
1
| (IN EMPNUMBR CHAR(10),
2
| IN RATE DECIMAL(6,2))
| LANGUAGE SQL
3
| UPDATE EMP
4
| SET SALARY = SALARY * RATE
| WHERE EMPNO = EMPNUMBR

| Notes:
|
1 The stored procedure name is UPDATESALARY1.
|
2 The two parameters have data types of CHAR(10) and DECIMAL(6,2).
| Both are input parameters.
|
3 LANGUAGE SQL indicates that this is an SQL procedure, so a
| procedure body follows the other parameters.
|
4 The procedure body consists of a single SQL UPDATE statement, which
| updates rows in the employee table.
| Example: The following example shows a definition for an equivalent external
| stored procedure that is written in COBOL. The stored procedure program,
| which updates employee salaries, is called UPDSAL.
| CREATE PROCEDURE UPDATESALARY1
1
| (IN EMPNUMBR CHAR(10),
2
| IN RATE DECIMAL(6,2))
| LANGUAGE COBOL
3
| EXTERNAL NAME UPDSAL;
4

| Notes:
|
1 The stored procedure name is UPDATESALARY1.
|
2 The two parameters have data types of CHAR(10) and DECIMAL(6,2).
| Both are input parameters.
|
3 LANGUAGE COBOL indicates that this is an external procedure, so the
| code for the stored procedure is in a separate, COBOL program.
|
4 The name of the load module that contains the executable stored
| procedure program is UPDSAL.

| Setting up the stored procedures environment

You must set up the stored procedure environment before you create external
stored procedures, external SQL procedures, or certain native SQL procedures. For
example, you must set up WLM application environments for these stored
procedures. You do not need to perform these setup tasks for Java stored
procedures.

For native SQL procedures that satisfy at least one of the following conditions, you
must set up the stored procedure environment:
v The native SQL procedure calls at least one external stored procedure, external
SQL procedure, or user-defined function.
| v The native SQL procedure is defined with ALLOW DEBUG MODE or
| DISALLOW DEBUG MODE. If you specify DISABLE DEBUG MODE, you do
| not need to set up the stored procedure environment.

To set up the stored procedures environment:

Chapter 10. Creating and modifying DB2 objects 533

Configure DB2 for running stored procedures and user-defined function (DB2
Installation Guide).

If you changed the JCL startup procedure for an existing WLM application
environment, refresh the WLM application environment for stored procedures (DB2
Administration Guide).

| Moving stored procedures to a WLM-established environment

| If you have existing stored procedures that use DB2-established address spaces,
| you need to move them to a WLM environment. DB2-established address spaces
| are no longer supported.

| To move stored procedures to a WLM-established environment:

| 1. Define JCL procedures for the stored procedures address spaces. Use the
| sample JCL in member DSNTIJMV of data set DSN910.SDSNSAMP.
| 2. Define WLM application environments for groups of stored procedures, and
| associate a JCL startup procedure with each application environment.
| 3. For each stored procedure, issue ALTER PROCEDURE statements with the
| WLM ENVIRONMENT parameter to specify the name of the application
| environment.
| 4. Relink all of your existing stored procedures with DSNRLI, the language
| interface module for the Resource Recovery Services attachment facility
| (RRSAF). Use JCL and linkage editor control statements that are similar to the
| following statements.
| //LINKRRS EXEC PGM=IEWL,
| // PARM='LIST,XREF,MAP'
| //SYSPRINT DD SYSOUT=*
| //SYSLIB DD DISP=SHR,DSN=USER.RUNLIB.LOAD
| // DD DISP=SHR,DSN=DSN810.SDSNLOAD
| //SYSLMOD DD DISP=SHR,DSN=USER.RUNLIB.LOAD
| //SYSUT1 DD SPACE=(1024,(50,50)),UNIT=SYSDA
| //SYSLIN DD *
| ENTRY STORPROC
| REPLACE DSNALI
| INCLUDE SYSLIB(DSNRLI)
| INCLUDE SYSLMOD(STORPROC)
| NAME STORPROC(R)

| The address spaces start automatically.

| Related tasks
| “Invoking the Resource Recovery Services attachment facility” on page 77
| Setting up a WLM application environment for stored procedures (DB2
| Installation and Migration)
| Related reference
| ALTER PROCEDURE (external) (SQL Reference)
| ALTER PROCEDURE (SQL - external) (SQL Reference)

| Creating a native SQL procedure

| Native SQL procedures are procedures whose body is written entirely in SQL and
| that are executed as SQL statements that are bound in a DB2 package. These
| procedures typically perform better and have more functionality than external SQL
| procedures. You can create multiple versions of native SQL procedures.

534 Application Programming and SQL Guide

| Configure DB2 for running stored procedures and user-defined functions (DB2
| Installation Guide) if the native SQL procedure satisfies at least one of the
| following conditions:
| v The native SQL procedure calls at least one external stored procedure, external
| SQL procedure, or user-defined function.
| v The native SQL procedure is defined with ALLOW DEBUG MODE or
| DISALLOW DEBUG MODE. If you specify DISABLE DEBUG MODE, you do
| not need to set up the stored procedure environment.

| To create a native SQL procedure, perform one of the following actions:

| v Use IBM Optim Development Studio to specify the source statements for the
| SQL procedure and deploy the SQL procedure to DB2. IBM Optim Development
| Studio also allows you to create copies of the procedure package as needed and
| to deploy the procedure to remote servers.
| v Manually deploy the native SQL procedure by completing the following steps:
| 1. Issue the CREATE PROCEDURE statement. Include the procedure body,
| which is written in SQL statements. Do not include the FENCED or
| EXTERNAL keywords. When you execute this CREATE PROCEDURE
| statement, the first version of this procedure is defined to DB2, and a
| package is implicitly bound with the options that you specify on the
| CREATE PROCEDURE statement.
| 2. If the native SQL procedure contains one or more of the following statements
| or references, use the BIND PACKAGE COPY command to make copies of
| the native SQL procedure package, as needed:
| – CONNECT
| – SET CURRENT PACKAGESET
| – SET CURRENT PACKAGE PATH
| – A table reference with a three-part name
| 3. If you plan to call the native SQL procedure at another DB2 server, use the
| BIND PACKAGE DEPLOY command to reproduce the SQL procedure on
| that server. You can customize the bind options at the same time.
| 4. Authorize the appropriate users to call the stored procedure.
| Related concepts
| “SQL procedure body” on page 527
| Related tasks
| Implementing DB2 stored procedures (DB2 Administration Guide)
| Related reference
| Integrated Data Management Information Center
| CREATE PROCEDURE (SQL - native) (SQL Reference)

| Controlling the scope of variables in an SQL procedure

| Use nested compound statements within an SQL procedure to define the scope of
| SQL variables. You can reference the variable only within the compound statement
| in which it was declared and any nested statements.

| To control the scope of a variable in an SQL procedure:

| 1. Declare the variable within the compound statement in which you want to
| reference it. Ensure that the variable name is unique within the compound
| statement, not including any nested statements. You can define variables with
| the same name in other compound statements in the same SQL procedure.

Chapter 10. Creating and modifying DB2 objects 535

| 2. Reference the variable within that compound statement or any nested
| statements.
| Recommendation: If multiple variables with the same name exist within an
| SQL procedure, qualify the variable with the label from the compound
| statement in which it was declared. Otherwise, you might accidentally reference
| the wrong variable.
| If the variable name is unqualified and multiple variables with that name exist
| within the same scope, DB2 uses the variable in the innermost compound
| statement.

| Example: The following example contains three declarations of the variable A. One
| instance is declared in the outer compound statement, which has the label
| OUTER1. The other instances are declared in the inner compound statements with
| the labels INNER1 and INNER2. In the INNER1 compound statement, DB2
| presumes that the unqualified references to A in the assignment statement and
| UPDATE statement refer to the instance of A that is declared in the INNER1
| compound statement. To refer to the instance of A that is declared in the OUTER1
| compound statement, qualify the variable as OUTER1.A.
| CREATE PROCEDURE P2 ()
| LANGUAGE SQL
|
| -- Outermost compound statement ------------------------
| OUTER1: BEGIN
1
| DECLARE A INT DEFAULT 100;
|
| -- Inner compound statement with label INNER1 ---
| INNER1: BEGIN
2
| DECLARE A INT DEFAULT NULL;
| DECLARE W INT DEFAULT NULL;
|
| SET A = A + OUTER1.A;
3
|
| UPDATE T1 SET T1.B = 5
| WHERE T1.B = A;
4
|
| SET OUTER1.A = 100;
5
|
| SET INNER1.A = 200;
6
| END INNER1;
7
| -- End of inner compound statement INNER1 ------
|
| -- Inner compound statement with label INNER2 ---
| INNER2: BEGIN
8
| DECLARE A INT DEFAULT NULL;
| DECLARE Z INT DEFAULT NULL;
|
| SET A = A + OUTER1.A;
|
| END INNER2;
9
| -- End of inner compound statement INNER2 ------
|
| SET OUTER1.A = 100;
10
|
| END OUTER1
11

| The preceding example has the following parts:

| 1. The beginning of the outermost compound statement, which has the label
| OUTER1.
| 2. The beginning of the inner compound statement with the label INNER1.
| 3. The unqualified variable A refers to INNER1.A.

536 Application Programming and SQL Guide

| 4. The unqualified variable A refers to INNER1.A.
| 5. OUTER1.A is a valid reference, because this variable is referenced in a nested
| compound statement.
| 6. INNER1.A is a valid reference, because this variable is referenced in the same
| compound statement in which it is declared. You cannot reference INNER2.A,
| because this variable is not in the scope of this compound statement.
| 7. The end of the inner compound statement with the label INNER1.
| 8. The beginning of the inner compound statement with the label INNER2.
| 9. The end of the inner compound statement with the label INNER2.
| 10. OUTER1.A is a valid reference, because this variable is referenced in the same
| compound statement in which it is declared. You cannot reference INNER1.A,
| because this variable is declared in a nested statement and cannot be
| referenced in the outer statement.
| 11. The end of the outermost compound statement, which has the label OUTER1.

| Nested compound statements in native SQL procedures:

| Nested compound statements are blocks of SQL statements that are contained by
| other blocks of SQL statements. Use nested compound statements in native SQL
| procedures to define condition handlers that execute more than one statement and
| to define different scopes for variables and condition handlers.

| The following pseudo code shows a basic structure of an SQL procedure with
| nested compound statements:
| CREATE PROCEDURE...
| OUTERMOST: BEGIN
| ...
| INNER1: BEGIN
| ...
| INNERMOST: BEGIN
| ...
| ...
| END INNERMOST;
| END INNER1;
| INNER2: BEGIN
| ...
| ...
| END INNER2;
| END OUTERMOST

| In the preceding example, the OUTERMOST compound statement contains two

| nested compound statements: INNER1 and INNER2. INNER1 contains one nested
| compound statement: INNERMOST.

| Statement labels for nested compound statements in native SQL procedures:

| You can define a label for each compound statement in an SQL procedure. This
| label enables you to reference this block of statements in other statements such as
| the GOTO, LEAVE, and ITERATE SQL PL control statements. You can also use the
| label to qualify a variable when necessary. Labels are not required.

| A label name must meet the following criteria:

| v Be unique within the compound statement, including any compound statements
| that are nested within the compound statement.
| v Not be the same as the name of the SQL procedure.

Chapter 10. Creating and modifying DB2 objects 537

| You can reference a label within the compound statement in which it is defined,
| including any compound statements that are nested within that compound
| statement.

| Example of statement labels: The following example shows several statement

| labels and their scope:
| CREATE PROCEDURE P1 ()
| LANGUAGE SQL
|
| --Outermost compound statement ------------------------
| OUTER1: BEGIN
1
|
| --Inner compound statement with label INNER1 ---
| INNER1: BEGIN
2
| IF...
| ABC: LEAVE INNER1;
3
| ELSEIF
| XYZ: LEAVE OUTER1;
4
| END IF
|
| END INNER1;
| --End of inner compound statement INNER1 ------
|
| --Inner compound statement with label INNER2---
| INNER2: BEGIN
5
| XYZ:...statement
6
| END INNER2;
| -- End of inner compound statement INNER2 -----
|
| END OUTER1
7

| The preceding example has the following parts:

| 1. The beginning of the outermost compound statement, which is labeled
| OUTER1
| 2. The beginning of an inner compound statement that is labeled INNER1
| 3. A LEAVE statement that is defined with the label ABC. This LEAVE statement
| specifies that DB2 is to terminate processing of the compound statement
| INNER1 and begin processing the next statement, which is INNER2. This
| LEAVE statement cannot specify INNER2, because that label is not within the
| scope of the INNER1 compound statement.
| 4. A LEAVE statement that is defined with the label XYZ. This LEAVE statement
| specifies that DB2 is to terminate processing of the compound statement
| OUTER1 and begin processing the next statement, if one exists. This example
| does not show the next statement.
| 5. The beginning of an inner compound statement that is labeled INNER2.
| 6. A statement that is defined with the label XYZ. This label is acceptable even
| though another statement in this procedure has the same label, because the two
| labels are in different scopes. Neither label is contained within the scope of the
| other.
| 7. The end of the outermost compound statement that is labeled OUTER1.

| The following examples show valid and invalid uses of labels:

| Invalid example of labels:

538 Application Programming and SQL Guide

| L1: BEGIN
| L2: SET A = B;
| L1: GOTO L2: --This duplicate use of the label L1 causes an error, because
| --the same label is already used in the same scope.
|
| END L1;

| Valid example of labels:

| L1: BEGIN
| L2: BEGIN
| L4: BEGIN --This line contains the first use of the label L4
| DECLARE A CHAR(5);
| SET A = B;
| END L4;
| END L2;
|
| L3: BEGIN
| L4: BEGIN --This second use of the label L4 is valid, because
| --it is used in a different scope.
| DECLARE A CHAR(5);
| SET A = B;
| END L4;
| END L3;
| END L1;

| Declaring cursors in an SQL procedure with nested compound

| statements
| When you declare a cursor in an SQL procedure with nested compound
| statements, you cannot necessarily reference the cursor anywhere in the procedure.
| The scope of the cursor is constrained to the compound statement in which you
| declare it.

| To declare a cursor in an SQL procedure with nested compound statements, specify

| the DECLARE CURSOR statement within the compound statement in which you
| want to reference it. Ensure that the cursor name is unique within the SQL
| procedure.

| You can reference the cursor within the compound statement in which it is
| declared and any nested statements. If the cursor is declared as a result set cursor,
| even if the cursor is not declared in the outermost compound statement, any
| calling application can reference it.

| Example: In the following example, cursor X is declared in the outer compound

| statement. This cursor can be referenced in the outer block in which it was
| declared and within any nested compound statements.
| CREATE PROCEDURE SINGLE_CSR
| (INOUT IR1 INT, INOUT JR1 INT, INOUT IR2 INT, INOUT JR2 INT)
| LANGUAGE SQL
| DYNAMIC RESULT SETS 2
| BEGIN
| DECLARE I INT;
| DECLARE J INT;
| DECLARE X CURSOR WITH RETURN FOR --outer declaration for X
| SELECT * FROM CSRT1;
|
| SUB: BEGIN
| OPEN X; --references X in outer block
| FETCH X INTO I,J; --references X in outer block
| SET IR1 = I;
| SET JR1 = J;
| END;
|

Chapter 10. Creating and modifying DB2 objects 539

| FETCH X INTO I,J; --references X in outer block
| SET IR2 = I;
| SET JR2 = j;
| CLOSE X;
| END

| Handling SQL conditions in an SQL procedure

| In an SQL procedure, you can specify how the program should handle certain SQL
| errors and SQL warnings.

| To handle SQL conditions, use one of the following techniques:

| v Include statements called handlers to tell the procedure to perform some other
| action when an error or warning occurs.
| v Include a RETURN statement in an SQL procedure to return an integer status
| value to the caller.
| v Include a SIGNAL statement or a RESIGNAL statement to raise a specific
| SQLSTATE and to define the message text for that SQLSTATE.
| v Force a negative SQLCODE to be returned by a procedure if a trigger calls the
| procedure.

| If you do not include a handler or a RETURN statement in the SQL procedure,

| DB2 automatically returns any SQL conditions to the caller in the SQLCA.

| Handlers in an SQL procedure:

| If an error occurs when an SQL procedure executes, the procedure ends unless you
| include statements to tell the procedure to perform some other action. These
| statements are called handlers.

| Handlers are similar to WHENEVER statements in external SQL application

| programs. Handlers tell the SQL procedure what to do when an error or warning
| occurs, or when no more rows are returned from a query. In addition, you can
| declare handlers for specific SQLSTATEs. You can refer to an SQLSTATE by its
| number in a handler, or you can declare a name for the SQLSTATE and then use
| that name in the handler.

| The general form of a handler declaration is:

| DECLARE handler-type HANDLER FOR condition SQL-procedure-statement;

| In general, the way that a handler works is that when an error occurs that matches
| condition, the SQL-procedure-statement executes. When the SQL-procedure-statement
| completes, DB2 performs the action that is indicated by handler-type.

| Types of handlers

| The handler type determines what happens after the completion of the
| SQL-procedure-statement. You can declare the handler type to be either CONTINUE
| or EXIT:
| CONTINUE
| Specifies that after SQL-procedure-statement completes, execution continues with
| the statement after the statement that caused the error.
| EXIT
| Specifies that after SQL-procedure-statement completes, execution continues at
| the end of the compound statement that contains the handler.

540 Application Programming and SQL Guide

| Example: CONTINUE handler: This handler sets flag at_end when no more rows
| satisfy a query. The handler then causes execution to continue after the statement
| that returned no rows.
| DECLARE CONTINUE HANDLER FOR NOT FOUND SET at_end=1;

| Example: EXIT handler: This handler places the string ’Table does not exist’ into
| output parameter OUT_BUFFER when condition NO_TABLE occurs. NO_TABLE is
| previously declared as SQLSTATE 42704 (name is an undefined name). The handler
| then causes the SQL procedure to exit the compound statement in which the
| handler is declared.
|| DECLARE
. NO_TABLE CONDITION FOR '42704';
|| .
.
| DECLARE EXIT HANDLER FOR NO_TABLE
| SET OUT_BUFFER='Table does not exist';

| Defining condition handlers that execute more than one statement:

| A condition handler defines the action that an SQL procedure takes when a
| particular condition occurs. You must specify the action as a single SQL procedure
| statement.

| To define a condition handler that executes more than one statement when the
| specified condition occurs, specify a compound statement within the declaration of
| that handler.

| Example: The following example shows a condition handler that captures the
| SQLSTATE value and sets a local flag to TRUE.
| BEGIN
| DECLARE SQLSTATE CHAR(5);
| DECLARE PrvSQLState CHAR(5) DEFAULT '00000';
| DECLARE ExceptState INT;
| DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
| BEGIN
| SET PrvSQLState = SQLSTATE;
| SET ExceptState = TRUE;
| END;
| ...
| END

| Example: The following example declares a condition handler for SQLSTATE

| 72822. The subsequent SIGNAL statement is within the scope of this condition
| handler and thus activates this handler. The condition handler tests the value of
| the SQL variable VAR with an IF statement. Depending on the value of VAR, the
| SQLSTATE is changed and the message text is set.
| DECLARE EXIT HANDLER FOR SQLSTATE '72822'
| IF ( VAR = 'OK' ) THEN
| RESIGNAL SQLSTATE '72623'
| SET MESSAGE_TEXT = 'Got SQLSTATE 72822';
| ELSE
| RESIGNAL SQLSTATE '72319'
| SET MESSAGE_TEXT = VAR;
| END IF;
|
| SIGNAL SQLSTATE '72822';

| Controlling how errors are handled within different scopes in an SQL

| procedure:

Chapter 10. Creating and modifying DB2 objects 541

| You can use nested compound statements in an SQL procedure to specify that
| errors be handled differently within different scopes and to ensure that condition
| handlers are checked only with a particular compound statement.

| To control how errors are handled within different scopes in an SQL procedure:
| 1. Optional: Declare a condition by specifying a DECLARE CONDITION
| statement within the compound statement in which you want to reference it.
| You can reference a condition in the declaration of a condition handler, a
| SIGNAL statement, or a RESIGNAL statement.

| Restriction: If multiple conditions with that name exist within the same scope,
| you cannot explicitly refer to a condition that is not the most local in scope.
| DB2 uses the condition in the innermost compound statement.
| 2. Declare a condition handler by specifying a DECLARE HANDLER statement
| within the compound statement to which you want the condition handler to
| apply. Within the declaration of the condition handler, you can specify a
| previously defined condition.

| Restriction: Condition handlers that are declared in the same compound

| statement cannot handle conditions encountered in each other or themselves.

| Example: In the following example, a condition with the name ABC is declared
| twice, and a condition named XYZ is declared once.
| CREATE PROCEDURE...
| DECLARE ABC CONDITION...
|
| DECLARE XYZ CONDITION...
| BEGIN
| DECLARE ABC CONDITION...
| SIGNAL ABC;
1
| END;
|
| SIGNAL ABC;
2

| The following notes refer to the preceding example:

| 1. ABC refers to the condition that is declared in the innermost block. If this
| statement were changed to SIGNAL XYZ, XYZ would refer to the XYZ
| condition that is declared in the outermost block.
| 2. ABC refers to the condition that is declared in the outermost block.

| Example: The following example contains multiple declarations of a condition with

| the name FOO, and a single declaration of a condition with the name GORP.
| CREATE PROCEDURE MYTEST (INOUT A CHAR(1), INOUT B CHAR(1))
| L1: BEGIN
| DECLARE GORP CONDITION
| FOR SQLSTATE '33333'; -- defines a condition with the name GORP for SQLSTATE 33333
|
| DECLARE EXIT HANDLER FOR GORP --defines a condition handler for SQLSTATE 33333
| L2: BEGIN
| DECLARE FOO CONDITION
| FOR SQLSTATE '12345'; --defines a condition with the name FOO for SQLSTATE 12345
| DECLARE CONTINUE HANDLER FOR FOO --defines a condition handler for SQLSTATE 12345
| L3: BEGIN
| SET A = 'A';
| ...more statements...
| END L3;
| SET B = 'B';
|
| IF...

542 Application Programming and SQL Guide

| SIGNAL FOO; --raises SQLSTATE 12345
| ELSEIF
| SIGNAL GORP; --raises SQLSTATE 33333
| END IF;
|
| END L2;
|
| L4: BEGIN
| DECLARE FOO CONDITION
| FOR SQLSTATE '54321' --defines a condition with the name FOO for SQLSTATE 54321
| DECLARE EXIT HANDLER FOR FOO...; --defines a condition handler for SQLSTATE 54321
|
| SIGNAL FOO SET MESSAGE_TEXT = '...'; --raises SQLSTATE 54321
|
| L5: BEGIN
| DECLARE FOO CONDITION
| FOR SQLSTATE '99999'; --defines a condition with the name FOO for SQLSTATE 99999
| ...more statements...
| END L5;
|
| END L4;
|
| --At this point, the procedure cannot reference FOO, because this condition is not defined
| --in this outer scope
|
| END L1

| Example: In the following example, the compound statement with the label
| OUTER contains two other compound statements: INNER1A and INNER1B. The
| INNER1A compound statement contains another compound statement, which has
| the label INNER1A2, and the declaration for a condition handler HINNER1A. The
| body of the condition handler HINNER1A contains another compound statement,
| which defines another condition handler, HINNER1A_HANDLER.
| OUTER:
| BEGIN <=============.
| -- Handler for OUTER |
| DECLARE ... HANDLER -- HOUTER |
| BEGIN <---. |
| : | |
| END; -- End of handler <---. |
| : |
| : |
| |
| -- Level 1 - first compound statement |
| INNER1A: |
| BEGIN <---------. |
| -- Handler for INNER1A | |
| DECLARE ... HANDLER -- HINNER1A | |
| BEGIN <------. | |
| -- Handler for handler HINNER1A | |
| DECLARE...HANDLER --HINNER1A_HANDLER| | |
| BEGIN <---. | | |
| : | | | |
| END; -- End of handler <---. | | |
| : | | |
| : -- stmt that gets condition | | |
2
| : | | |
| : -- more statements in handler | | |
| END; -- End of HINNER1A handler<------. | |
| | |
| INNER1A2: | |
| BEGIN <--. | |
| DECLARE ... HANDLER...-- HINNER1A2 | | |
| BEGIN; <---. | | |
| : | | | |

Chapter 10. Creating and modifying DB2 objects 543

| END; -- End of handler <---. | | |
| : | | |
| : -- statement that gets condition | | |
1
| : | | |
| : -- statement after statement | | |
| : -- that encountered condition | | |
| END INNER1A2; <--' | |
| : | |
| : -- statements in INNER1A | |
| END INNER1A; <---------' |
| |
| -- Level 1 - second compound statement |
| INNER1B: |
| BEGIN <---------. |
| -- Handler for handler INNER1B | |
| DECLARE ...HANDLER -- HINNER1B | |
| BEGIN <------. | |
| -- Handler for HINNER1B -- | | |
| DECLARE ...HANDLER --HINNER1B_HANDLER| | |
| BEGIN <---. | | |
| : | | | |
| END; -- End of handler <---. | | |
| : | | |
| : -- statements in handler | | |
| END; -- End of HINNER1B handler<-------. | |
| : | |
| : -- statements in INNER1B | |
| END INNER1B; <---------' |
| |
| : -- statements in OUTER |
| END OUTER; <============='

| The following notes apply to the preceding example:

| 1. If an exception, warning, or NOT FOUND condition occurs within the
| INNER1A2 compound statement, the most appropriate handler within that
| compound statement is activated to handle the condition. Then, one of the
| following actions occurs depending on the type of condition handler:
| v If the condition handler (HINNER1A2) is an exit handler, control is returned
| to the end of the compound statement that contained the condition handler.
| v If the condition handler (HINNER1A2) is a continue handler, processing
| continues with the statement after the statement that encountered the
| condition.
| If no appropriate handler exists in the INNER1A2 compound statement, DB2
| considers the following handlers in the specified order:
| a. The most appropriate handler within the INNER1A compound statement.
| b. The most appropriate handler within the OUTER compound statement.
| If no appropriate handler exists in the OUTER compound statement, the
| condition is an unhandled condition. If the condition is an exception condition,
| the procedure terminates and returns an unhandled condition to the invoking
| application. If the condition is a warning or NOT FOUND condition, the
| procedure returns the unhandled warning condition to the invoking
| application.
| 2. If an exception, warning, or NOT FOUND condition occurs within the body of
| the condition handler HINNER1A, and the condition handler
| HINNER1A_HANDLER is the most appropriate handler for the exception, that
| handler is activated. Otherwise, the most appropriate handler within the
| OUTER compound statement handles the condition. If no appropriate handler
| exists within the OUTER compound statement, the condition is treated as an
| unhandled condition.
544 Application Programming and SQL Guide
| Example: In the following example, when statement2 results in a NOT FOUND
| condition, the appropriate condition handler is activated to handle the condition.
| When the condition handler completes, the compound statement that contains that
| condition handler terminates, because the condition handler is an EXIT handler.
| Processing then continues with statement4.
| BEGIN
| DECLARE EXIT HANDLER FOR NOT FOUND
| SET OUT_OF_DATA_FLAG = ON;
| statement1...
| statement2... --assume that this statement results in a NOT FOUND condition
| statement3...
| END;
|
| statement4
| ...

| Example: In the following example, DB2 checks for SQLSTATE 22H11 only for
| statements inside the INNER compound statement. DB2 checks for
| SQLEXCEPTION for all statements in both the OUTER and INNER blocks.
| OUTER: BEGIN
| DECLARE var1 INT;
| DECLARE EXIT HANDLER FOR SQLEXCEPTION
| RETURN -3;
|
| INNER: BEGIN
| DECLARE EXIT HANDLER FOR SQLSTATE '22H11'
| RETURN -1;
| DECLARE C1 CURSOR FOR SELECT col1 FROM table1;
| OPEN C1;
| CLOSE C1;
| :
| : -- more statements
| END INNER;
| :
| : -- more statements

| Example: In the following example, DB2 checks for SQLSTATE 42704 only for
| statements inside the A compound statement.
| CREATE PROCEDURE EXIT_TEST ()
| LANGUAGE SQL
| BEGIN
| DECLARE OUT_BUFFER VARCHAR(80);
| DECLARE NO_TABLE CONDITION FOR SQLSTATE '42704';
|
| A: BEGIN
1
| DECLARE EXIT HANDLER FOR NO_TABLE
3
| BEGIN
| SET OUT_BUFFER ='Table does not exist';
4
| END;
|
| -- Drop potentially nonexistent table:
| DROP TABLE JAVELIN;
2
|
| B: SET OUT_BUFFER ='Table dropped successfully';
| END;
| -- Copy OUT_BUFFER to some message table:
| C: INSERT INTO MESSAGES VALUES (OUT_BUFFER);
5

| The following notes describe a possible flow for the preceding example:
| 1. A nested compound statement with label A confines the scope of the
| NO_TABLE exit handler to the statements that are specified in the A compound
| statement.

Chapter 10. Creating and modifying DB2 objects 545

| 2. If the table JAVELIN does not exist, the DROP statement raises the NO_TABLE
| condition.
| 3. The exit handler for NO_TABLE is activated.
| 4. The variable OUT_BUFFER is set to the string ’Table does not exist.’
| 5. Execution continues with the INSERT statement. No more statements in the A
| compound statement are processed.

| Example: The following example illustrates the scope of different condition

| handlers.
| CREATE PROCEDURE ERROR_HANDLERS(IN PARAM INTEGER)
| LANGUAGE SQL
| OUTER: BEGIN
| DECLARE I INTEGER;
| DECLARE SQLSTATE CHAR(5) DEFAULT '00000';
|
| DECLARE EXIT HANDLER FOR
| SQLSTATE VALUE '38H02',
| SQLSTATE VALUE '38H04',
| SQLSTATE VALUE '38HI4',
| SQLSTATE VALUE '38H06'
| OUTER_HANDLER: BEGIN
| DECLARE TEXT VARCHAR(70);
| SET TEXT = SQLSTATE ||
| ' RECEIVED AND MANAGED BY OUTER ERROR HANDLER' ;
| RESIGNAL SQLSTATE VALUE '38HE0'
| SET MESSAGE_TEXT = TEXT;
| END OUTER_HANDLER;
|
| INNER: BEGIN
| DECLARE EXIT HANDLER FOR SQLSTATE VALUE '38H03'
| RESIGNAL SQLSTATE VALUE '38HI3'
| SET MESSAGE_TEXT = '38H03 MANAGED BY INNER ERROR HANDLER';
|
| DECLARE EXIT HANDLER FOR SQLSTATE VALUE '38H04'
| RESIGNAL SQLSTATE VALUE '38HI4'
| SET MESSAGE_TEXT = '38H04 MANAGED BY INNER ERROR HANDLER';
|
| DECLARE EXIT HANDLER FOR SQLSTATE VALUE '38H05'
| RESIGNAL SQLSTATE VALUE '38HI5'
| SET MESSAGE_TEXT = '38H05 MANAGED BY INNER ERROR HANDLER';
|
| CASE PARAM
| WHEN 1 THEN -- (1)
| SIGNAL SQLSTATE VALUE '38H01'
| SET MESSAGE_TEXT =
| 'EXAMPLE 1: ERROR SIGNALED FROM INNER COMPOUND STMT';
|
| WHEN 2 THEN -- (2)
| SIGNAL SQLSTATE VALUE '38H02'
| SET MESSAGE_TEXT =
| 'EXAMPLE 2: ERROR SIGNALED FROM INNER COMPOUND STMT';
|
| WHEN 3 THEN -- (3)
| SIGNAL SQLSTATE VALUE '38H03'
| SET MESSAGE_TEXT =
| 'EXAMPLE 3: ERROR SIGNALED FROM INNER COMPOUND STMT';
|
| WHEN 4 THEN -- (4)
| SIGNAL SQLSTATE VALUE '38H04'
| SET MESSAGE_TEXT =
| 'EXAMPLE 4: ERROR SIGNALED FROM INNER COMPOUND STMT';
|
| ELSE
| SET I = 1; /*Don't do anything */

546 Application Programming and SQL Guide

| END CASE;
| END INNER;
|
| CASE PARAM
| WHEN 5 THEN -- (5)
| SIGNAL SQLSTATE VALUE '38H05'
| SET MESSAGE_TEXT =
| 'EXAMPLE 5: ERROR SIGNALED FROM OUTER COMPOUND STMT';
| WHEN 6 THEN -- (6)
| SIGNAL SQLSTATE VALUE '38H06'
| SET MESSAGE_TEXT =
| 'EXAMPLE 6: ERROR SIGNALED FROM OUTER COMPOUND STMT';
| ELSE -- (7)
| SET I = 1; /*Don't do anything */
| END CASE;
| END OUTER

| The following table summarizes the behavior of the preceding example:

|| Input
| value
| for
| PARM Expected behavior
| 1 SQLSTATE 38H01 is signaled from the INNER compound statement. Because no
| appropriate handler exists, the procedure terminates and returns the unhandled
| exception condition, 38H01 with SQLCODE -438, to the calling application.
| 2 SQLSTATE 38H02 is signaled from the INNER compound statement. The
| condition handler in the OUTER compound statement is activated. A RESIGNAL
| statement, with SQLSTATE 38HE0, is issued from within the body of the
| condition handler. This exception causes control to be returned to the end of the
| OUTER compound statement with exception condition 38HE0 and SQLCODE
| -438. The procedure terminates and returns the unhandled condition to the calling
| application.
| 3 SQLSTATE 38H03 is signaled from the INNER compound statement. A condition
| handler within the INNER compound statement is activated. A RESIGNAL
| statement, with SQLSTATE 38HI3, is issued from within the body of the condition
| handler. Because no appropriate handler exists, the procedure terminates and
| returns the unhandled exception condition, 38HI3 with SQLCODE -438, to the
| calling application.
| 4 SQLSTATE 38H04 is signaled from the INNER compound statement. A condition
| handler within the INNER compound statement is activated. A RESIGNAL
| statement, with SQLSTATE 38HI4, is issued from within the body of the condition
| handler. A condition handler in the OUTER compound statement is activated. A
| RESIGNAL statement, with SQLSTATE 38HE0, is issued from within the body of
| the condition handler. This exception causes control to be returned to the end of
| the OUTER compound statement with exception condition 38HE0 and SQLCODE
| -438. The procedure terminates and returns the unhandled condition to the calling
| application.
| 5 SQLSTATE 38H05 is signaled from the OUTER compound statement. Because no
| appropriate handler exists, the procedure terminates and returns the unhandled
| exception condition, 38H05 with SQLCODE -438, to the calling application.
| 6 SQLSTATE 38H06 is signaled from the OUTER compound statement. A condition
| handler in the OUTER compound statement is activated. A RESIGNAL statement,
| with SQLSTATE 38HE0, is issued from within the body of the condition handler.
| This exception causes control to be returned to the end of the OUTER compound
| statement with exception condition 38HE0 and SQLCODE -438. The procedure
| terminates and returns the unhandled condition to the calling application.
| 7 The ELSE clause of the CASE statement executes and processes the SET statement.
| A successful completion code is returned to the calling application.

Chapter 10. Creating and modifying DB2 objects 547

|

| Example: In the following example SQL procedure, the condition handler for
| exception1 is not within the scope of the condition handler for exception0. If
| exception condition exception1 is raised in the body of the condition handler for
| exception0, no appropriate handler exists, and the procedure terminates with an
| unhandled exception.
| CREATE PROCEDURE divide ( .....)
| LANGUAGE SQL CONTAINS SQL
| BEGIN
| DECLARE dn_too_long CHAR(5) DEFAULT 'abcde';
|
| -- Declare condition names --------------------------
| DECLARE exception0 CONDITION FOR SQLSTATE '22001';
| DECLARE exception1 CONDITION FOR SQLSTATE 'xxxxx';
|
| -- Declare cursors ----------------------------------
| DECLARE cursor1 CURSOR WITH RETURN FOR
| SELECT * FROM dept;
|
| -- Declare handlers ---------------------------------
| DECLARE CONTINUE HANDLER FOR exception0
| BEGIN
| some SQL statement that causes an error 'xxxxx'
| END
|
| DECLARE CONTINUE HANDLER FOR exception1
| BEGIN
| ...
| END
|
|
| -- Mainline of procedure ----------------------------
| INSERT INTO DEPT (DEPTNO) VALUES (dn_too_long);
| -- Assume that this statement results in SQLSTATE '22001'
|
| OPEN CURSOR1;
| END

| Retrieving diagnostic information by using GET DIAGNOSTICS in a handler:

| Handlers specify the action that an SQL procedure takes when a particular error or
| condition occurs. In some cases, you want to retrieve additional diagnostic
| information about the error or warning condition.

| You can include a GET DIAGNOSTICS statement in a handler to retrieve error or

| warning information. If you include GET DIAGNOSTICS, it must be the first
| statement that is specified in the handler.

| Example: Using GET DIAGNOSTICS to retrieve message text: Suppose that you
| create an SQL procedure, named divide1, that computes the result of the division
| of two integers. You include GET DIAGNOSTICS to return the text of the division
| error message as an output parameter:
| CREATE PROCEDURE divide1
| (IN numerator INTEGER, IN denominator INTEGER,
| OUT divide_result INTEGER, OUT divide_error VARCHAR(1000))
| LANGUAGE SQL
| BEGIN
| DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
| GET DIAGNOSTICS CONDITION 1 divide_error = MESSAGE_TEXT;
| SET divide_result = numerator / denominator;
| END

548 Application Programming and SQL Guide

| Ignoring a condition in an SQL procedure:

| You can create a condition handler to specify that you want to ignore a condition
| within a particular scope of statements in an SQL procedure.

| To ignore a condition, declare a condition handler that contains an empty

| compound statement.

| Example

| The following example shows a condition handler that is declared as a way of

| ignoring a condition. This technique might be useful when you are inserting a row
| into a table that has a unique column. If the value to be inserted for the row
| already exists in the table, the row doesn’t need to be inserted. Although DB2
| recognizes that the value is not unique, DB2 does not need to tell the application.
| Instead, DB2 does not process the INSERT statement.
| DECLARE CONTINUE HANDLER FOR SQLSTATE '23505'
| BEGIN -- ignore error for duplicate value
| END;

| Raising a condition within an SQL procedure by using the

| SIGNAL or RESIGNAL statements
| Within an SQL procedure, you can force a particular condition to occur with a
| specific SQLSTATE and message text.

| You can use either a SIGNAL or RESIGNAL statement to raise a condition with a
| specific SQLSTATE and message text within an SQL procedure. The SIGNAL and
| RESIGNAL statements differ in the following ways:
| v You can use the SIGNAL statement anywhere within an SQL procedure. You
| must specify the SQLSTATE value. In addition, you can use the SIGNAL
| statement in a trigger body. For information about using the SIGNAL statement
| in a trigger, see “Creating triggers” on page 457.
| v You can use the RESIGNAL statement only within a handler of an SQL
| procedure. If you do not specify the SQLSTATE value, DB2 uses the same
| SQLSTATE value that activated the handler.

| You can use any valid SQLSTATE value in a SIGNAL or RESIGNAL statement,
| except an SQLSTATE class with ’00’ as the first two characters.

| The following table summarizes the differences between issuing a RESIGNAL or

| SIGNAL statement within the body of a condition handler. For each row in the
| table, assume that the diagnostics area contains the following information when
| the RESIGNAL or SIGNAL statement is issued:
| RETURNED_SQLSTATE xxxxx
| MESSAGE_TEXT 'this is my message'
| Table 93. Example RESIGNAL and SIGNAL statements
| Specify a new Specify Example RESIGNAL Example SIGNAL
| condition? message text? statement... statement... Result
|| No No RESIGNAL Not possible
| RETURNED_SQLSTATE xxxxx
1
|| MESSAGE_TEXT ’this is my
| message’

Chapter 10. Creating and modifying DB2 objects 549

| Table 93. Example RESIGNAL and SIGNAL statements (continued)
| Specify a new Specify Example RESIGNAL Example SIGNAL
| condition? message text? statement... statement... Result
|| Yes No RESIGNAL '98765' SIGNAL '98765'
| RETURNED_SQLSTATE 98765
2
|| MESSAGE_TEXT ’APPLICATION
| RAISED ERROR WITH
| DIAGNOSTIC TEXT: this is my
| message’
| No Yes Not possible Not possible NA
|| Yes Yes RESIGNAL '98765' SIGNAL '98765'
|| SET MESSAGE_TEXT SET MESSAGE_TEXT RETURNED_SQLSTATE 98765
| = 'xyz' = 'xyz'
| MESSAGE_TEXT ’APPLICATION
| 3 3 RAISED ERROR WITH
|| DIAGNOSTIC TEXT: xyz’
|

| Note:
| 1. This statement raises the current condition with the existing SQLSTATE,
| SQLCODE, message text, and tokens.
| 2. This statement raises a new condition (SQLSTATE ’98765’). Existing message
| text and tokens are reset. The SQLCODE is set to -438 for an error or 438 for a
| warning.
| 3. This statement raises a new condition (SQLSTATE ’98765’) with new message
| text (’xyz’). The SQLCODE is set to -438 for an error or 438 for a warning.

| Example of the SIGNAL statement in an SQL procedure:

| You can use the SIGNAL statement anywhere within an SQL procedure to raise a
| particular condition. This example shows how to use the SIGNAL statement to
| raise a particular SQLSTATE and set the associated message text.

| The following example uses an ORDERS table and a CUSTOMERS table that are
| defined in the following way:
| CREATE TABLE ORDERS
| (ORDERNO INTEGER NOT NULL,
| PARTNO INTEGER NOT NULL,
| ORDER_DATE DATE DEFAULT,
| CUSTNO INTEGER NOT NULL,
| QUANTITY SMALLINT NOT NULL,
| CONSTRAINT REF_CUSTNO FOREIGN KEY (CUSTNO)
| REFERENCES CUSTOMERS (CUSTNO) ON DELETE RESTRICT,
| PRIMARY KEY (ORDERNO,PARTNO));
| CREATE TABLE CUSTOMERS
| (CUSTNO INTEGER NOT NULL,
| CUSTNAME VARCHAR(30),
| CUSTADDR VARCHAR(80),
| PRIMARY KEY (CUSTNO));

| Example: Using SIGNAL to set message text

| Suppose that you have an SQL procedure for an order system that signals an
| application error when a customer number is not known to the application. The
| ORDERS table has a foreign key to the CUSTOMERS table, which requires that the
| CUSTNO exist in the CUSTOMERS table before an order can be inserted:

550 Application Programming and SQL Guide

| CREATE PROCEDURE submit_order
| (IN ONUM INTEGER, IN PNUM INTEGER,
| IN CNUM INTEGER, IN QNUM INTEGER)
| LANGUAGE SQL
| MODIFIES SQL DATA
| BEGIN
| DECLARE EXIT HANDLER FOR SQLSTATE VALUE '23503'
| SIGNAL SQLSTATE '75002'
| SET MESSAGE_TEXT = 'Customer number is not known';
| INSERT INTO ORDERS (ORDERNO, PARTNO, CUSTNO, QUANTITY)
| VALUES (ONUM, PNUM, CNUM, QNUM);
| END

| In this example, the SIGNAL statement is in the handler. However, you can use the
| SIGNAL statement to invoke a handler when a condition occurs that will result in
| an error.
| Related concepts
| “Example of the RESIGNAL statement in a handler”

| Example of the RESIGNAL statement in a handler:

| You can use the RESIGNAL statement in an SQL procedure to assign a different
| value to the condition that activated the handler. This example shows how to use
| the RESIGNAL statement to reset a particular SQLSTATE and the associated
| message text.

| Example: Using RESIGNAL to set an SQLSTATE valu

| Suppose that you create an SQL procedure, named divide2, that computes the
| result of the division of two integers. You include SIGNAL to invoke the handler
| with an overflow condition that is caused by a zero divisor, and you include
| RESIGNAL to set a different SQLSTATE value for that overflow condition:
| CREATE PROCEDURE divide2
| (IN numerator INTEGER, IN denominator INTEGER,
| OUT divide_result INTEGER)
| LANGUAGE SQL
| BEGIN
| DECLARE overflow CONDITION FOR SQLSTATE '22003';
| DECLARE CONTINUE HANDLER FOR overflow
| RESIGNAL SQLSTATE '22375';
| IF denominator = 0 THEN
| SIGNAL overflow;
| ELSE
| SET divide_result = numerator / denominator;
| END IF;
| END

| Example: RESIGNAL in a nested compound statement

| If the following SQL procedure is invoked with argument values 1, 0, and 0, the
| procedure returns a value of 2 for RC and sets the oparm1 parameter to 650.
| CREATE PROCEDURE resig4
| (IN iparm1 INTEGER, INOUT oparm1 INTEGER, INOUT rc INTEGER)
| LANGUAGE SQL
| A1: BEGIN
| DECLARE c1 INT DEFAULT 1;
| DECLARE CONTINUE HANDLER FOR SQLSTATE VALUE '01ABX'
| BEGIN
| .... some other statements
| SET RC = 3;
6
| END;

Chapter 10. Creating and modifying DB2 objects 551

|
| A2: SET oparm1 = 5;
1
|
| A3: BEGIN
| DECLARE c1 INT DEFAULT 1;
| DECLARE CONTINUE HANDLER
| FOR SQLSTATE VALUE '01ABC'
| BEGIN
| SET RC = 1;
4
| RESIGNAL SQLSTATE VALUE '01ABX'
5
| SET MESSAGE_TEXT = 'get out of here';
| SET RC = 2;
7
| END;
|
| A7: SET oparm1 = oparm1 + 110;
2
| SIGNAL SQLSTATE VALUE '01ABC'
3
| SET MESSAGE_TEXT = 'yikes';
| SET oparm1 = oparm1 + 215;
8
| END;
| SET oparm1 = oparm1 + 320;
9
| END

| The following notes refer to the preceding example:

| 1. oparm1 is initially set to 5.
| 2. oparm1 is incremented by 110. The value of oparm1 is now 115.
| 3. The SIGNAL statement causes the condition handler that is contained in the A3
| compound statement to be activated.
| 4. In this condition handler, RC is set to 1.
| 5. The RESIGNAL statement changes the SQLSTATE to 01ABX. This value causes
| the continue handler in the A1 compound statement to be activated.
| 6. RC is set to 3 in this condition handler. Because this condition handler is a
| continue handler, when the handler action completes, control returns to the SET
| statement after the RESIGNAL statement.
| 7. RC is set to 2 in this condition handler. Because this condition handler is a
| continue handler, control returns to the SET statement that follows the SIGNAL
| statement that caused the condition handler to be activated.
| 8. oparm1 is incremented by 215. The value of oparm is now 330.
| 9. oparm1 is incremented by 320. The value of oparm is now 650.

| How SIGNAL and RESIGNAL statements affect the diagnostics area:

| When you issue a SIGNAL statement, a new diagnostics area is logically created.
| When you issue a RESIGNAL statement, the current diagnostics area is updated.

| When you issue a SIGNAL statement, a new diagnostics area is logically created.
| In that diagnostics area, RETURNED_SQLSTATE is set to the SQLSTATE or
| condition name specified. If you specified message text as part of the SIGNAL
| statement, MESSAGE_TEXT in the diagnostics area is also set to the specified
| value.

| When you issue a RESIGNAL statement with a SQLSTATE value, condition name,
| or message text, the current diagnostics area is updated with the specified
| information.

552 Application Programming and SQL Guide

| Returning the procedure status as an integer value
| In an SQL procedure, you can set the status to be returned to the calling program.
| The status is an integer that indicates the success of the procedure. If you do not
| set the status, DB2 sets the status to 0 or -1 depending on the value of the
| SQLCODE.

| You can use the RETURN statement in an SQL procedure to return an integer
| status value. If a RETURN statement with a specified return value is used to return
| from a procedure, DB2 sets the SQLCODE in the SQLCA to 0, and the caller must
| retrieve the return status of the procedure in either of the following ways:
| v By using the DB2_RETURN_STATUS item of GET DIAGNOSTICS to retrieve the
| return value of the RETURN statement
| v By retrieving SQLERRD(1) of the SQLCA (SQLERRD[0] of the SQLCA in C
| applications), which contains the return value of the RETURN statement

| If a RETURN statement is not used to return from a procedure or if a value is not

| specified on the RETURN statement:
| v The specified target for DB2_RETURN_STATUS in a GET DIAGNOSTICS
| statement is set to a value of zero if the procedure returns with an SQLCODE
| that is greater or equal to zero.
| v The specified target for DB2_RETURN_STATUS in a GET DIAGNOSTICS
| statement is set to a value of -1 if the procedure returns with an SQLCODE that
| is less than zero.

| When the SQLCODE is not less than zero, the caller can access the value directly
| from the SQLCA returned from processing the CALL of an SQL procedure by
| retrieving the value of SQLERRD[0]. When the SQLCODE is less than zero, the
| SQLERRD[0] value is not set and the application should assume a return status
| value of -1.

| Example: Using GET DIAGNOSTICS to retrieve the return status: Suppose that
| you create an SQL procedure, named TESTIT, that calls another SQL procedure,
| named TRYIT. The TRYIT procedure returns a status value, and the TESTIT
| procedure retrieves that value with the DB2_RETURN_STATUS item of GET
| DIAGNOSTICS:
| CREATE PROCEDURE TESTIT ()
| LANGUAGE SQL
| A1:BEGIN
| DECLARE RETVAL INTEGER DEFAULT 0;
| ...
| CALL TRYIT;
| GET DIAGNOSTICS RETVAL = DB2_RETURN_STATUS;
| IF RETVAL <> 0 THEN
| ...
| LEAVE A1;
| ELSE
| ...
| END IF;
| END A1

| Making copies of a package for a native SQL procedure

| When you create a native SQL procedure, a package is implicitly bound with the
| options that you specified on the CREATE PROCEDURE statement. If the native
| SQL procedure performs certain actions, you need to explicitly make copies of that
| package.

Chapter 10. Creating and modifying DB2 objects 553

| If the native SQL procedure performs one or more of the following actions, you
| need to create copies of the package for that procedure:
| v Uses a CONNECT statement to connect to a database server.
| v Refers to a table with a three part name that includes a location other than the
| current server or refers to an alias that resolves to such a name.
| v Sets the CURRENT PACKAGESET special register to control which package is
| invoked for that version of the procedure.
| v Sets the CURRENT PACKAGE PATH special register to control which package is
| invoked for that version of the procedure.

| The package for a version of a procedure has the following name:

| location.collection-id.package-id.version-id where these variables have the following
| values:
| location
| Value of the CURRENT SERVER special register
| collection-id
| Schema qualifier of the procedure
| package-id
| Procedure name
| version-id
| Version identifier

| To make copies of a package for a native SQL procedure, specify the BIND
| PACKAGE command with the COPY option. For copies that are created on the
| current server, specify a different schema qualifier, which is the collection ID. For
| the first copy that is created on a remote server, you can specify the same schema
| qualifier. For other copies on that remote server, specify a different schema
| qualifier.

| If you later change the native SQL procedure, you might need to explicitly rebind
| any local or remote copies of the package that exist for that version of the
| procedure. For more information on the situations when this rebinding in
| necessary and how to rebind, see “Replacing copies of a package for a version of a
| native SQL procedure” on page 555 and “Regenerating an existing version of a
| native SQL procedure” on page 560.

| Example: Because the following native SQL procedure contains a CONNECT

| statement, you must create a copy of the package at the target server, which in this
| case is at location SAN_JOSE. The subsequent BIND command creates a copy of
| the package for version ABC of the procedure TEST.MYPROC. This package is
| created at location SAN_JOSE and is used by DB2 when this procedure is
| executed.
| CREATE PROCEDURE TEST.MYPROC VERSION ABC LANGUAGE SQL ...
| BEGIN
| ...
| CONNECT TO SAN_JOSE
| ...
| END
|
| BIND PACKAGE (SAN_JOSE.TEST) COPY(TEST.MYPROC) COPYVER(ABC) ACTION(ADD)

| Example: The following native SQL procedure sets the CURRENT PACKAGESET
| special register to ensure that DB2 uses the package with the collection ID COLL2
| for this version of the procedure. Consequently, you must create such a package.

554 Application Programming and SQL Guide

| The subsequent BIND command creates this package with collection ID COLL2.
| This package is a copy of the package for version ABC of the procedure
| TEST.MYPROC. DB2 uses this package to process the SQL statements in this
| procedure.
| CREATE PROCEDURE TEST.MYPROC VERSION ABC LANGUAGE SQL ...
| BEGIN
| ...
| SET CURRENT PACKAGESET = 'COLL2'
| ...
| END
|
| BIND PACKAGE(COLL2) COPY(TEST.MYPROC) COPYVER(ABC)
| ACTION(ADD) QUALIFIER(XYZ)

| For more information about the bind options that you can set when you create or
| alter a native SQL procedure, see the topic “ALTER PROCEDURE (SQL - native)”
| in DB2 SQL Reference.

| Replacing copies of a package for a version of a native SQL procedure:

| When you change a version of a native SQL procedure and the ALTER
| PROCEDURE REPLACE statement contains a certain option or options, you must
| replace any local or remote copies of the package that exist for that version of the
| procedure.

| If you specify any of the following ALTER PROCEDURE options, you must replace
| copies of the package:
| v REPLACE VERSION
| v REGENERATE
| v DISABLE DEBUG MODE
| v QUALIFIER
| v PACKAGE OWNER
| v DEFER PREPARE
| v NODEFER PREPARE
| v CURRENT DATA
| v DEGREE
| v DYNAMICRULES
| v APPLICATION ENCODING SCHEME
| v WITH EXPLAIN
| v WITHOUT EXPLAIN
| v WITH IMMEDIATE WRITE
| v WITHOUT IMMEDIATE WRITE
| v ISOLATION LEVEL
| v WITH KEEP DYNAMIC
| v WITHOUT KEEP DYNAMIC
| v OPTHINT
| v SQL PATH
| v RELEASE AT COMMIT
| v RELEASE AT DEALLOCATE
| v REOPT
| v VALIDATE RUN

Chapter 10. Creating and modifying DB2 objects 555

| v VALIDATE BIND
| v ROUNDING
| v DATE FORMAT
| v DECIMAL
| v FOR UPDATE CLAUSE OPTIONAL
| v FOR UPDATE CLAUSE REQUIRED
| v TIME FORMAT

| To replace copies of a package for a version of a native SQL procedure, specify the
| BIND COPY ACTION(REPLACE) command with the appropriate package name
| and version ID.

| Creating a new version of a native SQL procedure

| A new version of a native SQL procedure can change the parameter names,
| procedure options, or procedure body.

| Requirement: All versions of a procedure must have the same procedure

| signature. Therefore, each version of the procedure must have the same of the
| following items:
| v schema name
| v procedure name
| v number of parameters
| v data types for corresponding parameters

| To create a new version of a procedure, issue the ALTER PROCEDURE statement

| with the following items:
| v The name of the native SQL procedure for which you want to create a new
| version.
| v The ADD VERSION clause with a name for the new version.
| v The parameter list of the procedure that you want to alter. This parameter list
| must be the same as the original procedure.
| v Any procedure options. These options can be different than the options for other
| versions of this procedure. If you do not specify a value for a particular option,
| the default value is used, regardless of the value that is used by the current
| active version of this procedure.
| v A procedure body. This body can be different than the procedure body for other
| versions of this procedure.
| After you create a new version, if you want that version to be invoked by all
| subsequent calls to this procedure, you need to make that version the active
| version.

| Example: The following CREATE PROCEDURE statement defines a new native

| SQL procedure called UPDATE_BALANCE. The version of the procedure is V1,
| and it is the active version.
| CREATE PROCEDURE
| UPDATE_BALANCE
| (IN CUSTOMER_NO INTEGER,
| IN AMOUNT DECIMAL(9,2))
| VERSION V1
| LANGUAGE SQL
| READS SQL DATA
| BEGIN
| DECLARE CUSTOMER_NAME CHAR(20);
| SELECT CUSTNAME

556 Application Programming and SQL Guide

| INTO CUSTOMER_NAME
| FROM ACCOUNTS
| WHERE CUSTNO = CUSTOMER_NO;
| END

| The following ALTER PROCEDURE statement creates a new version of the

| UPDATE_BALANCE procedure. The version name of the new version is V2. This
| new version has a different procedure body.
| ALTER PROCEDURE
| UPDATE_BALANCE
| ADD VERSION V2
| (IN CUSTOMER_NO INTEGER,
| IN AMOUNT DECIMAL (9,2) )
| MODIFIES SQL DATA
| BEGIN
| UPDATE ACCOUNTS
| SET BAL = BAL + AMOUNT
| WHERE CUSTNO = CUSTOMER_NO;
| END

| Multiple versions of native SQL procedures:

| You can define multiple versions of a native SQL procedure. DB2 maintains this
| version information for you.

| One or more versions of a procedure can exist at any point in time at the current
| server, but only one version of a procedure is considered the active version. When
| you first create a procedure, that initial version is considered the active version of
| the procedure.

| Using multiple versions of a native SQL procedure has the following advantages:
| v You can keep the existing version of a procedure active while you create another
| version. When the other version is ready, you can make it the active one.
| v When you make another version of a procedure active, you do not need to
| change any existing calls to that procedure.
| v You can easily switch back to a previous version of a procedure if the version
| that you switched to does not work as planned.
| v You can drop an unneeded version of a procedure.

| A new version of a native SQL procedure can have different values for the
| following items:
| v parameter names
| v procedure options
| v procedure body

| Restriction: A new version of a native SQL procedure cannot have different values
| for the following items:
| v number of parameters
| v parameter data types
| v parameter attributes for character data
| v parameter CCSIDs
| v Whether a parameter is an input or output parameter, as defined by the IN,
| OUT, and INOUT options
| If you need to specify different values for any of the preceding items, create a new
| native SQL procedure.

Chapter 10. Creating and modifying DB2 objects 557

| Deploying a native SQL procedure to another DB2 for z/OS
| server
| When deploying a native SQL procedure to another DB2 for z/OS server, you can
| change the bind options to better match the deploying environment. The procedure
| logic remains the same. This deployment process is useful when you want to move
| a procedure from a test system to a production system.

| Requirements:
| v The remote server must be properly defined in the communications database of
| the DB2 subsystem from which you deploy the native SQL procedure.
| v The target DB2 subsystem must be operating at a PTF level that is compatible
| with the PTF level of the local DB2 subsystem.

| To deploy a native SQL procedure to another DB2 for z/OS server:

| Issue the BIND PACKAGE command with the following options:

| DEPLOY
| Specify the name of the procedure whose logic you want to use on the target
| server.

| Tip: When specifying the parameters for the DEPLOY option, consider the
| following naming rules for native SQL procedures:
| v The collection ID is the same as the schema name in the original CREATE
| PROCEDURE statement.
| v The package ID is the same as the procedure name in the original CREATE
| PROCEDURE statement.
| COPYVER
| Specify the version of the procedure whose logic you want to use on the target
| server.
| ACTION(ADD) or ACTION(REPLACE)
| Specify whether you want DB2 to create a new version of the native SQL
| procedure and its associated package or to replace the specified version.

| Optionally, you can also specify the bind options QUALIFIER or OWNER if want
| to change them.

| Example of deploying the same version of a procedure at another location: The

| following BIND command creates a native SQL procedure with the name
| PRODUCTION.MYPROC at the CHICAGO location. This procedure is created
| from the procedure TEST.MYPROC at the current site. Both native SQL procedures
| have the same content and version, ABC. However, the package for the procedure
| CHICAGO.PRODUCTION.MYPROC has XYZ as its qualifier.
| CREATE PROCEDURE TEST.MYPROC VERSION ABC LANGUAGE SQL ...
| BEGIN
| ...
| END
|
| BIND PACKAGE(CHICAGO.PRODUCTION) DEPLOY(TEST.MYPROC) COPYVER(ABC)
| ACTION(ADD) QUALIFIER(XYZ)

| Example of replacing a version of a procedure at another location: The following

| BIND command replaces version ABC of the procedure PRODUCTION.MYPROC
| at the CHICAGO location with version ABC of the procedure TEST.MYPROC at
| the current site.

558 Application Programming and SQL Guide

| BIND PACKAGE(CHICAGO.PRODUCTION) DEPLOY(TEST.MYPROC) COPYVER(ABC)
| ACTION(REPLACE) REPLVER(ABC)
| Related concepts
| Communications database for the server (DB2 Administration Guide)
| Related reference
| Scenario for deployment (DB2 9 for z/OS Stored Procedures: Through the
| CALL and Beyond)
| BIND and REBIND options (DB2 Command Reference)
| BIND PACKAGE (DSN) (DB2 Command Reference)

| Migrating an external SQL procedure to a native SQL

| procedure
| Native SQL procedures typically perform better, have more functionality, and are
| easier to maintain than external SQL procedures.

| If you created the external SQL procedure in a previous release of DB2, consider
| the release incompatibilities for applications that use stored procedures. Examine
| your external SQL procedure source code, and make any adjustments.

| To migrate an external SQL procedure to a native SQL procedure:

| 1. Find and save the existing CREATE PROCEDURE and GRANT EXECUTE
| statements for the existing external SQL procedure.
| 2. Drop the existing external SQL procedure by using the DROP PROCEDURE
| statement.
| 3. Re-create the procedure as a native SQL procedure by using the same CREATE
| PROCEDURE statement that you used to originally create the procedure, with
| both of the following changes:
| v If the procedure was defined with the options FENCED or EXTERNAL,
| remove these keywords.
| v Either remove the WLM ENVIRONMENT keyword, or add the FOR DEBUG
| MODE clause.
| v If the procedure body contains statements with unqualified names that could
| refer to either a column or an SQL variable or parameter, qualify these
| names. Otherwise, you might need to change the statement.
| DB2 resolves these names differently depending on whether the procedure is
| an external SQL procedure or a native SQL procedure. For external SQL
| procedures, DB2 first assumes that the name is a variable or parameter if one
| exists with that name. For native SQL procedures, DB2 first assumes that the
| name is a column if a column exists with that name. For example, consider
| the following statement:
| CREATE PROCEDURE P1 (INOUT C1 INT) ... SELECT C1 INTO xx FROM T1

| For external SQL procedures, DB2 assumes that C1 is a parameter. For native
| SQL procedures, DB2 assumes that C1 is a column in table T1. If such a
| column does not exist, DB2 then assumes that C1 is a parameter.
| 4. Issue the same GRANT EXECUTE statements that you used to originally grant
| privileges for this stored procedure.
| 5. Test your new native SQL procedure.

Chapter 10. Creating and modifying DB2 objects 559

| Related concepts
| Application and SQL release incompatibilities (DB2 Installation and Migration)
| Related tasks
| Implementing DB2 stored procedures (DB2 Administration Guide)
| Related reference
| CREATE PROCEDURE (SQL - external) (SQL Reference)
| CREATE PROCEDURE (SQL - native) (SQL Reference)
| DROP (SQL Reference)
| GRANT (function or procedure privileges) (SQL Reference)

Changing an existing version of a native SQL procedure

You can change an option or the procedure body for a particular version of a
native SQL procedure. If you want to keep a copy of that stored procedure,
consider creating a new version instead of changing the existing version.

To change an existing version of a native SQL procedure, issue the ALTER

PROCEDURE statement with the REPLACE VERSION clause. Any option that you
do not explicitly specify inherits the system default values even if those options
were explicitly specified for a prior version by using a CREATE PROCEDURE
statement, ALTER PROCEDURE statement, or REBIND command.

Example: The following ALTER PROCEDURE statement updates version V2 of the

UPDATE_BALANCE procedure.
ALTER PROCEDURE
TEST.UPDATE_BALANCE
REPLACE VERSION V2
(IN CUSTOMER_NO INTEGER,
IN AMOUNT DECIMAL(9,2))
MODIFIES SQL DATA
ASUTIME LIMIT 100
BEGIN
UPDATE ACCOUNTS
SET BAL = BAL + AMOUNT
WHERE CUSTNO = CUSTOMER_NO
AND CUSTSTAT = 'A';
END

Regenerating an existing version of a native SQL procedure

When you apply DB2 maintenance that changes how native SQL procedures are
generated, you need to regenerate any affected procedures. When you regenerate a
version of a native SQL procedure, DB2 rebinds the associated package for that
version of the procedure.

ALTER PROCEDURE REGENERATE is different than the REBIND PACKAGE

command. When you specify REBIND PACKAGE, DB2 rebinds only the
non-control SQL statements. Use this command when you think rebinding will
improve the access path. When you specify ALTER PROCEDURE REGENERATE,
DB2 rebinds the SQL control statements as well as the non-control statements.

To regenerate an existing version of a native SQL procedure:

1. Issue the ALTER PROCEDURE statement with the REGENERATE clause and
specify the version to be regenerated.

560 Application Programming and SQL Guide

2. If copies of the package for the specified version of the procedure exist at
remote sites, replace those packages. Issue the BIND PACKAGE command with
the COPY option and appropriate location for each remote package.
3. If copies of the package for the specified version of the procedure exist locally
with different schema names, replace those packages. Issue the BIND
PACKAGE command with the COPY option and appropriate schema for each
local package.

Example: The following ALTER PROCEDURE statement regenerates the active

version of the UPDATE_SALARY_1 procedure.
ALTER PROCEDURE UPDATE_SALARY_1
REGENERATE ACTIVE VERSION

Removing an existing version of a native SQL procedure

You can drop a particular version of a native SQL procedure without dropping the
other versions of the procedure.

Before you remove an existing version of a native SQL procedure, ensure that the
version is not active. If the version is the active version, designate a different active
version before proceeding.

To remove an existing version of a native SQL procedure:

| Issue the ALTER PROCEDURE statement with the DROP VERSION clause and the
| name of the version that you want to drop. If you instead want to drop all
| versions of the procedure, use the DROP statement.

| Example of dropping a version that is not active: The following statement drops
| the OLD_PRODUCTION version of the P1 procedure.
| ALTER PROCEDURE P1 DROP VERSION OLD_PRODUCTION

| Example of dropping an active version: Assume that the OLD_PRODUCTION

| version of the P1 procedure is the active version. The following example first
| switches the active version to NEW_PRODUCTION and then drops the
| OLD_PRODUCTION version.
| ALTER PROCEDURE P1 ACTIVATE VERSION NEW_PRODUCTION;
| ALTER PROCEDURE P1 DROP VERSION OLD_PRODUCTION;
| Related tasks
“Designating the active version of a native SQL procedure” on page 765

| Creating an external SQL procedure

| External SQL procedures are procedures whose body is written entirely in SQL, but
| DB2 supports them by generating an associated C program for each procedure. All
| SQL procedures that were created prior to Version 9 are external SQL procedures.

| Configure DB2 for running stored procedures and user-defined functions (DB2
| Installation Guide).

| To create an external SQL procedure:

| 1. Use one of the following methods to create the external SQL procedure:
| v IBM Optim Development Studio.
| v JCL
| v The DB2 for z/OS SQL procedure processor (DSNTPSMP)

Chapter 10. Creating and modifying DB2 objects 561

| Restriction: If you plan to use the DB2 stored procedure debugger or the
| Unified Debugger, do not use JCL. Use either DSNTPSMP or IBM Optim
| Development Studio.
| If you plan to use DSNTPSMP or IBM Optim Development Studio, you must
| set up the environment for the SQL procedure processor (DSNTPSMP).
| The preceding methods perform the following actions:
| v Convert the external SQL procedure source statements into a C language
| program by using the DB2 precompiler
| v Create an executable load module and a DB2 package from the C language
| program.
| v Define the external SQL procedure to DB2 by issuing a CREATE
| PROCEDURE statement either statically or dynamically.
| 2. Authorize the appropriate users to use the stored procedure by issuing the
| GRANT EXECUTE statement.
| Related tasks
| Implementing DB2 stored procedures (DB2 Administration Guide)
| Related reference
| Integrated Data Management Information Center
| CREATE PROCEDURE (SQL - external) (SQL Reference)
| GRANT (function or procedure privileges) (SQL Reference)

| Setting up the environment for the SQL procedure processor

| (DSNTPSMP)
| You can use the SQL procedure processor, DSNTPSMP, to prepare an external SQL
| procedure. You can invoke DSNTPSMP only through an SQL CALL statement in
| an application program or through IBM DB2 Data Studio Developer. Before you
| invoke DSNTPSMP, you need to perform several setup tasks.

| To set up the environment for the SQL procedure processor (DSNTPSMP):

| 1. If you plan to call DSNTPSMP directly, write and prepare an application
| program that executes an SQL CALL statement for DSNTPSMP.
| See “Creating an external SQL procedure by using DSNTPSMP” on page 565
| for more information.
| If you plan to invoke DSNTPSMP through the IBM DB2 Development Center,
| see the following URL for information about installing and using the IBM DB2
| Development Center.
| http://www.redbooks.ibm.com/abstracts/sg247604.html
| 2. Set up a WLM environment in which to run DSNTPSMP. For information about
| setting up a WLM environment for DSNTPSMP, see “Sample startup procedure
| for a WLM address space for DSNTPSMP” on page 563.

| DB2 for z/OS SQL procedure processor (DSNTPSMP):

| The SQL procedure processor, DSNTPSMP, is a REXX stored procedure that you
| can use to prepare an external SQL procedure for execution.

| You can also use DSNTPSMP to perform selected steps in the preparation process
| or delete an existing external SQL procedure. DSNTPSMP is the only preparation
| method for enabling external SQL procedures to be debugged with either the SQL
| Debugger or the Unified Debugger.

562 Application Programming and SQL Guide

| DSNTPSMP requires that the default EBCDIC CCSID that is used by DB2 also be
| compatible with the C compiler. Using an incompatible CCSID results in
| compile-time errors. Examples of incompatible CCSIDs include 290, 930, 1026, and
| 1155.

| Sample startup procedure for a WLM address space for DSNTPSMP:

| You must run DSNTPSMP in a WLM-established stored procedures address space.

| You should run only DSNTPSMP in that address space, and you must limit the
| address space to run only one task concurrently. This example shows how to set
| up a WLM address space for DSNTPSMP.

| The following example shows sample JCL for a startup procedure for the address
| space in which DSNTPSMP runs.
| //DSN8WLMP PROC DB2SSN=DSN,NUMTCB=1,APPLENV=WLMTPSMP
1
| //*
| //WLMTPSMP EXEC PGM=DSNX9WLM,TIME=1440,
2
| // PARM='&DB2SSN,&NUMTCB,&APPLENV',
| // REGION=0M,DYNAMNBR=10
| //STEPLIB DD DISP=SHR,DSN=DSN810.SDSNEXIT
3
| // DD DISP=SHR,DSN=DSN810.SDSNLOAD
| // DD DISP=SHR,DSN=CBC.SCCNCMP
| // DD DISP=SHR,DSN=CEE.SCEERUN
| //SYSEXEC DD DISP=SHR,DSN=DSN810.SDSNCLST
4
| //SYSTSPRT DD SYSOUT=A
| //CEEDUMP DD SYSOUT=A
| //SYSABEND DD DUMMY
| //*
| //SQLDBRM DD DISP=SHR,DSN=DSN910.DBRMLIB.DATA
5
| //SQLCSRC DD DISP=SHR,DSN=USER.PSMLIB.DATA
6
| //SQLLMOD DD DISP=SHR,DSN=DSN910.RUNLIB.LOAD
7
| //SQLLIBC DD DISP=SHR,DSN=CEE.SCEEH.H
8
| // DD DISP=SHR,DSN=CEE.SCEEH.SYS.H
| //SQLLIBL DD DISP=SHR,DSN=CEE.SCEELKED
9
| // DD DISP=SHR,DSN=DSN910.SDSNLOAD
| //SYSMSGS DD DISP=SHR,DSN=CEE.SCEEMSGP(EDCPMSGE)
10
| //*
| //* DSNTPSMP Configuration File - CFGTPSMP (optional)
11
| //* A site-provided sequential dataset or member, used to
| //* define customized operation of DSNTPSMP in this APPLENV
| //*
| //* CFGTPSMP DD DISP=SHR,DSN=
| //*
| //SQLSRC DD UNIT=SYSALLDA,SPACE=(800,(20,20)),
12
| // DCB=(RECFM=FB,LRECL=80,BLKSIZE=3200)
| //SQLPRINT DD UNIT=SYSALLDA,SPACE=(16000,(20,20)),
| // DCB=(RECFM=VB,LRECL=137,BLKSIZE=882)
| //SQLTERM DD UNIT=SYSALLDA,SPACE=(4000,(20,20)),
| // DCB=(RECFM=VB,LRECL=137,BLKSIZE=882)
| //SQLOUT DD UNIT=SYSALLDA,SPACE=(16000,(20,20)),
| // DCB=(RECFM=FB,LRECL=80,BLKSIZE=3200)
| //SQLCPRT DD UNIT=SYSALLDA,SPACE=(16000,(20,20)),
| // DCB=(RECFM=VB,LRECL=137,BLKSIZE=882)
| //SQLUT1 DD UNIT=SYSALLDA,SPACE=(16000,(20,20)),
| // DCB=(RECFM=FB,LRECL=80,BLKSIZE=3200)
| //SQLUT2 DD UNIT=SYSALLDA,SPACE=(16000,(20,20)),
| // DCB=(RECFM=FB,LRECL=80,BLKSIZE=3200)
| //SQLCIN DD UNIT=SYSALLDA,SPACE=(8000,(20,20))
| //SQLLIN DD UNIT=SYSALLDA,SPACE=(3200,(30,30)),
| // DCB=(RECFM=FB,LRECL=80,BLKSIZE=3200)
| //SYSMOD DD UNIT=SYSALLDA,SPACE=(8000,(20,20)),
| // DCB=(RECFM=FB,LRECL=80,BLKSIZE=3200)
| //SQLDUMMY DD DUMMY

Chapter 10. Creating and modifying DB2 objects 563

| Notes:
|
1 APPLENV specifies the application environment in which DSNTPSMP
| runs. To ensure that DSNTPSMP always uses the correct data sets and
| parameters for preparing each external SQL procedure, you can set up
| different application environments for preparing stored procedures with
| different program preparation requirements. For example, if all payroll
| applications use the same set of data sets during program preparation, you
| could set up an application environment called PAYROLL for preparing
| only payroll applications. The startup procedure for PAYROLL would point
| to the data sets that are used for payroll applications.
| DB2SSN specifies the DB2 subsystem name.
| NUMTCB specifies the number of programs that can run concurrently in
| the address space. You should always set NUMTCB to 1 to ensure that
| executions of DSNTPSMP occur serially.
|
2 WLMTPSMP specifies the address space in which DSNTPSMP runs.
| DYNAMNBR reserves space for dynamic allocation of data sets during the
| SQL procedure preparation process.
|
3 STEPLIB specifies the DB2 load libraries, the z/OS C/C++ compiler library,
| and the Language Environment run-time library that DSNTPSMP uses
| when it runs.
|
4 SYSEXEC specifies the library that contains the REXX exec DSNTPSMP.
|
5 SQLDBRM is an output data set that specifies the library into which
| DSNTPSMP puts the DBRM that it generates when it precompiles your
| external SQL procedure.
|
6 SQLCSRC is an output data set that specifies the library into which
| DSNTPSMP puts the C source code that it generates from the external SQL
| procedure source code. This data set should have a logical record length of
| 80.
|
7 SQLLMOD is an output data set that specifies the library into which
| DSNTPSMP puts the load module that it generates when it compiles and
| link-edits your external SQL procedure.
|
8 SQLLIBC specifies the library that contains standard C header files. This
| library is used during compilation of the generated C program.
|
9 SQLLIBL specifies the following libraries, which DSNTPSMP uses when it
| link-edits the external SQL procedure:
| v Language Environment link-edit library
| v DB2 load library
|
10 SYSMSGS specifies the library that contains messages that are used by the
| C prelink-edit utility.
|
11 CFGTPSMP specifies an optional data set that you can use to customize
| DSNTPSMP, including specifying the compiler level. For details on all of
| the options that you can set in this file and how to set them, see the
| DSNTPSMP CLIST comments.
|
12 The DD statements that follow describe work file data sets that are used by
| DSNTPSMP.

564 Application Programming and SQL Guide

| Creating an external SQL procedure by using DSNTPSMP
| The SQL procedure processor, DSNTPSMP, is one of several methods that you can
| use to create and prepare an external SQL procedure. DSNTPSMP is a REXX stored
| procedure that you can invoke from your application program.

| Set up the environment for DSNTPSMP.

| Also ensure that you have the required authorizations, as indicated in the
| following table, for invoking DSNTPSMP.
| Table 94. Required authorizations for invoking DSNTPSMP
| Required authorization Associated syntax for the authorization
| Procedure privilege to run application EXECUTE ON PROCEDURE
| programs that invoke the stored procedure. SYSPROC.DSNTPSMP
| Collection privilege to use BIND to create CREATE ON COLLECTION collection-id
| packages in the specified collection. You can
| use an asterisk (*) as the identifier for a
| collection.
| Package privilege to use BIND or REBIND to BIND ON PACKAGE collection-id.*
| bind packages in the specified collection.
| System privilege to use BIND with the ADD BINDADD
| option to create packages and plans.
| Schema privilege to create, alter, or drop CREATEIN, ALTERIN, DROPIN ON
| stored procedures in the specified schema. SCHEMA schema-name
| The BUILDOWNER authorization ID must
| have the CREATEIN privilege on the schema.
| You can use an asterisk (*) as the identifier
| for a schema.
|| Table privileges to select or delete from, SELECT ON TABLE
|| insert into, or update the specified catalog SYSIBM.SYSROUTINES
| tables.
| SELECT ON TABLE SYSIBM.SYSPARMS
| SELECT, INSERT, UPDATE, DELETE ON
| TABLE SYSIBM.SYSROUTINES_SRC
| SELECT, INSERT, UPDATE, DELETE ON
| TABLE SYSIBM.SYSROUTINES_OPTS
| ALL ON TABLE SYSIBM.SYSPSMOUT
| Any privileges that are required for the SQL Syntax varies depending on the SQL
| statements and that are contained within the procedure body
| SQL procedure body. These privileges must
| be associated with the OWNER
| authorization-id that is specified in your bind
| options. The default owner is the user that is
| invoking DSNTPSMP.
|

| To create an external SQL procedure by using DSNTPSMP:

| 1. Write an application program that calls DSNTPSMP. Include the following
| items in your program:
| v A CLOB host variable that contains a CREATE PROCEDURE statement for
| the external SQL procedure. That statement should include the FENCED
| keyword or the EXTERNAL keyword, and the procedure body, which is
| written in SQL.
| Alternatively, instead of defining a host variable for the CREATE
| PROCEDURE statement, you can store the statement in a data set member.

Chapter 10. Creating and modifying DB2 objects 565

| v An SQL CALL statement with the BUILD function. The CALL statement
| should use the proper syntax for invoking DSNTPSMP.
| Pass the SQL procedure source to DSNTPSMP as one of the following input
| parameters:
| SQL-procedure-source
| Use this parameter if you defined a host variable in your application to
| contain the CREATE PROCEDURE statement.
| source-data-set-name
| Use this parameter if you stored the CREATE PROCEDURE statement in
| a data set.
| v Based on the return value from the CALL statement, issue either an SQL
| COMMIT or a ROLLBACK statement. If the return value is 0 or 4, issue a
| COMMIT statement. Otherwise, issue a ROLLBACK statement.
| You must process the result set before issuing the COMMIT or ROLLBACK
| statement.
| A QUERYLEVEL request must be followed by the COMMIT statement.
| 2. Precompile, compile, and link-edit the application program.
| 3. Bind a package for the application program.
| 4. Run the application program.
| Related concepts
| “SQL procedure body” on page 527
| Related reference
| CREATE PROCEDURE (SQL - external) (SQL Reference)

| CALL statement syntax for invoking DSNTPSMP:

| You can invoke the SQL procedure processor, DSNTPSMP, from an application
| program by using an SQL CALL statement. DSNTPSMP prepares an external SQL
| procedure.

| The following diagrams show the syntax of invoking DSNTPSMP through the SQL
| CALL statement:
|

|

CALL SYSPROC.DSNTPSMP ( function , SQL-procedure-name , SQL-procedure-source ,

| empty-string

|
bind-options , compiler-options , precompiler-options ,

| empty-string empty-string empty-string

|
prelink-options , link-options , alter-statement ,

| empty-string empty-string empty-string

|
source-data-set-name , build-owner , build-utility , return-code )


| empty-string empty-string empty-string
|
||
| Figure 32. DSNTPSMP syntax
|

566 Application Programming and SQL Guide

| ,

’  option ’

|
||
| Figure 33. CALL DSNTPSMP bind-options, compiler-options, precompiler-options, prelink-options, link-options
|
| Note: You must specify:
| v The DSNTPSMP parameters in the order listed
| v The empty string if an optional parameter is not required for the function
| v The options in the order: bind, compiler, precompiler, prelink, and link

| The DSNTPSMP parameters are:

| function
| A VARCHAR(20) input parameter that identifies the task that you want
| DSNTPSMP to perform. The tasks are:
| BUILD
| Creates the following objects for an external SQL procedure:
| v A DBRM, in the data set that DD name SQLDBRM points to
| v A load module, in the data set that DD name SQLLMOD points to
| v The C language source code for the external SQL procedure, in the data
| set that DD name SQLCSRC points to
| v The stored procedure package
| v The stored procedure definition
| The following input parameters are required for the BUILD function:
| SQL-procedure name
| SQL-procedure-source or source-data-set-name
| If you choose the BUILD function, and an external SQL procedure with
| name SQL-procedure-name already exists, DSNTPSMP issues an error
| message and terminates.
| BUILD_DEBUG
| Creates the following objects for an external SQL procedure and includes
| the preparation necessary to debug the external SQL procedure with the
| SQL Debugger and the Unified Debugger:
| v A DBRM, in the data set that DD name SQLDBRM points to
| v A load module, in the data set that DD name SQLLMOD points to
| v The C language source code for theexternal SQL procedure, in the data
| set that DD name SQLCSRC points to
| v The stored procedure package
| v The stored procedure definition
| The following input parameters are required for the BUILD_DEBUG
| function:
| SQL-procedure name
| SQL-procedure-source or source-data-set-name
| If you choose the BUILD_DEBUG function, and an external SQL procedure
| with name SQL-procedure-name already exists, DSNTPSMP issues an error
| message and terminates.

Chapter 10. Creating and modifying DB2 objects 567

| REBUILD
| Replaces all objects that were created by the BUILD function for an
| external SQL procedure, if it exists, otherwise creates those objects.
| The following input parameters are required for the REBUILD function:
| SQL-procedure name
| SQL-procedure-source or source-data-set-name
| REBUILD_DEBUG
| Replaces all objects that were created by the BUILD_DEBUG function for
| an external SQL procedure, if it exists, otherwise creates those objects, and
| includes the preparation necessary to debug the external SQL procedure
| with the SQL Debugger and the Unified Debugger.
| The following input parameters are required for the REBUILD_DEBUG
| function:
| SQL-procedure name
| SQL-procedure-source or source-data-set-name
| REBIND
| Binds the external SQL procedure package for an existing external SQL
| procedure.
| The following input parameter is required for the REBIND function:
| SQL-procedure name
| DESTROY
| Deletes the following objects for an existing external SQL procedure:
| v The DBRM, from the data set that DD name SQLDBRM points to
| v The load module, from the data set that DD name SQLLMOD points to
| v The C language source code for the external SQL procedure, from the
| data set that DD name SQLCSRC points to
| v The stored procedure package
| v The stored procedure definition
| The following input parameter is required for the DESTROY function:
| SQL-procedure name
| ALTER
| Updates the registration for an existing external SQL procedure.
| The following input parameters are required for the ALTER function:
| SQL-procedure name
| alter-statement
| ALTER_REBUILD
| Updates an existing external SQL procedure.
| The following input parameters are required for the ALTER_REBUILD
| function:
| SQL-procedure name
| SQL-procedure-source or source-data-set-name
| ALTER_REBUILD_DEBUG
| Updates an existing external SQL procedure, and includes the preparation
| necessary to debug the external SQL procedure with the SQL Debugger
| and the Unified Debugger.
| The following input parameters are required for the
| ALTER_REBUILD_DEBUG function:
| SQL-procedure name

568 Application Programming and SQL Guide

| SQL-procedure-source or source-data-set-name
| ALTER_REBIND
| Updates the registration and binds the SQL package for an existing
| external SQL procedure.
| The following input parameters are required for the ALTER_REBIND
| function:
| SQL-procedure name
| alter-statement
| QUERYLEVEL
| Obtains the interface level of the build utility invoked. No other input is
| required.
| SQL-procedure-name
| A VARCHAR(261) input parameter that specifies the external SQL procedure
| name.
| The name can be qualified or unqualified. The name must match the procedure
| name that is specified within the CREATE PROCEDURE statement that is
| provided in SQL-procedure-source or that is obtained from source-data-set-name.
| In addition, the name must match the procedure name that is specified within
| the ALTER PROCEDURE statement that is provided in alter-statement. Do not
| mix qualified and unqualified references.
| SQL-procedure-source
| A CLOB(2M) input parameter that contains the CREATE PROCEDURE
| statement for the external SQL procedure. If you specify an empty string for
| this parameter, you need to specify the name source-data-set-name of a data set
| that contains the external SQL procedure source code.
| bind-options
| A VARCHAR(1024) input parameter that contains the options that you want to
| specify for binding the external SQL procedure package. Do not specify the
| MEMBER or LIBRARY option for the DB2 BIND PACKAGE command.
| compiler-options
| A VARCHAR(255) input parameter that contains the options that you want to
| specify for compiling the C language program that DB2 generates for the
| external SQL procedure.
| precompiler-options
| A VARCHAR(255) input parameter that contains the options that you want to
| specify for precompiling the C language program that DB2 generates for the
| external SQL procedure. Do not specify the HOST option.
| prelink-options
| A VARCHAR(255) input parameter that contains the options that you want to
| specify for prelinking the C language program that DB2 generates for the
| external SQL procedure.
| link-options
| A VARCHAR(255) input parameter that contains the options that you want to
| specify for linking the C language program that DB2 generates for the external
| SQL procedure. For a list of valid link options, see z/OS MVS: Program
| Management User’s Guide and Reference.
| alter-statement
| A VARCHAR(32672) input parameter that contains the SQL ALTER
| PROCEDURE statement to process with the ALTER or ALTER_REBIND
| function.

Chapter 10. Creating and modifying DB2 objects 569

| source-data-set-name
| A VARCHAR(80) input parameter that contains the name of a z/OS sequential
| data set or partitioned data set member that contains the source code for the
| external SQL procedure. If you specify an empty string for this parameter, you
| need to provide the external SQL procedure source code in
| SQL-procedure-source.
| build-owner
| A VARCHAR(130) input parameter that contains the SQL identifier to serve as
| the build owner for newly created SQL stored procedures.
| When this parameter is not specified, the value defaults to the value in the
| CURRENT SQLID special register when the build utility is invoked.
| build-utility
| A VARCHAR(255) input parameter that contains the name of the build utility
| that is invoked. The qualified form of the name is suggested, for example,
| SYSPROC.DSNTPSMP.
| return-code
| A VARCHAR(255) output parameter in which DB2 puts the return code from
| the DSNTPSMP invocation. The values are:
| 0 Successful invocation. The calling application can optionally retrieve the
| result set and then issue the required SQL COMMIT statement.
| 4 Successful invocation, but warnings occurred. The calling application
| should retrieve the warning messages in the result set and then issue the
| required SQL COMMIT statement.
| 8 Failed invocation. The calling application should retrieve the error
| messages in the result set and then issue the required SQL ROLLBACK
| statement.
| 99x
| Where x is a digit between 0 and 9. Failed invocation with severe errors.
| The calling application should retrieve the error messages in the result set
| and then issue the required SQL ROLLBACK statement. To view error
| messages that are not in the result set, see the job log of the address space
| for the DSNTPSMP execution.
| 999 Unknown Severe internal error
| 998 APF environment setup error
| 997 DSNREXX setup error
| 996 GLOBAL Temp Table setup error
| 995 Internal REXX programming error
| 1.2x
| Where x is a digit between 0 and 9. Level of DSNTPSMP when request is
| QUERYLEVEL. The calling application can retrieve the result set for
| additional information about the release and service level and then issue
| the required SQL COMMIT statement.

570 Application Programming and SQL Guide

| Related reference
| “Descriptions of SQL processing options” on page 904
| Compiler Options (XL C/C++ User’s Guide)
| BIND and REBIND options (DB2 Command Reference)

| Examples of invoking the SQL procedure processor (DSNTPSMP):

| These examples show how to invoke the BUILD, DESTROY, REBUILD, and
| REBIND functions of DSNTPSMP.

| DSNTPSMP BUILD function: Call DSNTPSMP to build an external SQL procedure.

| The information that DSNTPSMP needs is listed in the following table:
| Table 95. The functions DSNTPSMP needs to BUILD an SQL procedure
| Function BUILD
| External SQL procedure MYSCHEMA.SQLPROC
| name
| Source location String in CLOB host variable procsrc
| Bind options VALIDATE(BIND)
| Compiler options SOURCE, LIST, LONGNAME, RENT
| Precompiler options SOURCE, XREF, STDSQL(NO)
| Prelink options None specified
| Link options AMODE=31, RMODE=ANY, MAP, RENT
| Build utility SYSPROC.DSNTPSMP
| Return value String returned in varying-length host variable returnval
|

| The CALL statement is:

| EXEC SQL CALL SYSPROC.DSNTPSMP('BUILD','MYSCHEMA.SQLPROC',:procsrc,
| 'VALIDATE(BIND)',
| 'SOURCE,LIST,LONGNAME,RENT',
| 'SOURCE,XREF,STDSQL(NO)',
| '',
| 'AMODE=31,RMODE=ANY,MAP,RENT',
| '','','','SYSPROC.DSNTPSMP',
| :returnval);

| DSNTPSMP DESTROY function: Call DSNTPSMP to delete an external SQL

| procedure definition and the associated load module. The information that
| DSNTPMSP needs is listed in the following table:
| Table 96. The functions DSNTPSMP needs to DESTROY an SQL procedure
| Function DESTROY
| External SQL procedure name MYSCHEMA.OLDPROC
| Return value String returned in varying-length host
| variable returnval
|

| The CALL statement is:

| EXEC SQL CALL SYSPROC.DSNTPSMP('DESTROY','MYSCHEMA.OLDPROC','',
| '','','','','',
| '','','','',
| :returnval);

Chapter 10. Creating and modifying DB2 objects 571

| DSNTPSMP REBUILD function: Call DSNTPSMP to recreate an existing external
| SQL procedure. The information that DSNTPMSP needs is listed in the following
| table:
| Table 97. The functions DSNTPSMP needs to REBUILD an SQL procedure
| Function REBUILD
| External SQL procedure name MYSCHEMA.SQLPROC
| Bind options VALIDATE(BIND)
| Compiler options SOURCE, LIST, LONGNAME, RENT
| Precompiler options SOURCE, XREF, STDSQL(NO)
| Prelink options None specified
| Link options AMODE=31, RMODE=ANY, MAP, RENT
| Source data set name Member PROCSRC of partitioned data set
| DSN910.SDSNSAMP
| Return value String returned in varying-length host variable
| returnval
|

| The CALL statement is:

| EXEC SQL CALL SYSPROC.DSNTPSMP('REBUILD','MYSCHEMA.SQLPROC','',
| 'VALIDATE(BIND)',
| 'SOURCE,LIST,LONGNAME,RENT',
| 'SOURCE,XREF,STDSQL(NO)',
| '',
| 'AMODE=31,RMODE=ANY,MAP,RENT',
| '','DSN910.SDSNSAMP(PROCSRC)','','',
| :returnval);

| If you want to recreate an existing external SQL procedure for debugging with the
| SQL Debugger and the Unified Debugger, use the following CALL statement,
| which includes the REBUILD_DEBUG function:
| EXEC SQL CALL SYSPROC.DSNTPSMP('REBUILD_DEBUG','MYSCHEMA.SQLPROC','',
| 'VALIDATE(BIND)',
| 'SOURCE,LIST,LONGNAME,RENT',
| 'SOURCE,XREF,STDSQL(NO)',
| '',
| 'AMODE=31,RMODE=ANY,MAP,RENT',
| '','DSN910.SDSNSAMP(PROCSRC)','','',
| :returnval);

| DSNTPSMP REBIND function: Call DSNTPSMP to rebind the package for an

| existing external SQL procedure. The information that DSNTPMSP needs is listed
| in the following table:
| Table 98. The functions DSNTPSMP needs to REBIND an SQL procedure
| Function REBIND
| ExternalSQL procedure name MYSCHEMA.SQLPROC
| Bind options VALIDATE(RUN), ISOLATION(RR)
| Return value String returned in varying-length host variable returnval
|

| The CALL statement is:

572 Application Programming and SQL Guide

| EXEC SQL CALL SYSPROC.DSNTPSMP('REBIND','MYSCHEMA.SQLPROC','',
| 'VALIDATE(RUN),ISOLATION(RR)','','','','',
| '','','','',
| :returnval);

| Result set that the SQL procedure processor (DSNTPSMP) returns:

| DSNTPSMP returns one result set that contains messages and listings. You can
| write your client program to retrieve information from this result set.

| This technique is shown in “Writing a program or stored procedure to receive the

| result sets from a stored procedure” on page 600.

| Each row of the result set contains the following information:

| Processing step
| The step in the function process to which the message applies.
| ddname
| The ddname of the data set that contains the message.
| Sequence number
| The sequence number of a line of message text within a message.
| Message
| A line of message text.

| Rows in the message result set are ordered by processing step, ddname, and
| sequence number.

| Creating an external SQL procedure by using JCL

| Using JCL is one of several ways that you can create and prepare an external SQL
| procedure.

| Restriction: You cannot use JCL to prepare an external SQL procedure for
| debugging with the DB2 stored procedure debugger or the Unified Debugger. If
| you plan to use either of these debugging tools, use either DSNTPSMP or IBM
| Optim Development Studio to create the external SQL procedure.

| To create an external SQL procedure by using JCL, include the following job steps
| in your JCL job:
| 1. Issue a CREATE PROCEDURE statement that includes either the FENCED
| keyword or the EXTERNAL keyword and the procedure body, which is written
| in SQL.
| Alternatively, you can issue the CREATE PROCEDURE statement dynamically
| by using an application such as SPUFI, DSNTEP2, DSNTIAD, or the command
| line processor.

| Tip: If the routine body of the CREATE PROCEDURE statement contains

| embedded semicolons, change the default SQL terminator character from a
| semicolon to some other special character, such as the percent sign (%).
| This statement defines the stored procedure to DB2. DB2 stores the definition in
| the DB2 catalog.
| 2. Run program DSNHPC with the HOST(SQL) option.
| This program converts the external SQL procedure source statements into a C
| language program. DSNHPC also writes a new CREATE PROCEDURE
| statement in the data set that is specified in the SYSUT1 DD statement.

Chapter 10. Creating and modifying DB2 objects 573

| 3. Precompile, compile, and link-edit the generated C program by using one of
| the following techniques:
| v The DB2 precompiler and JCL instructions to compile and link-edit the
| program
| v The SQL statement coprocessor
| When you perform this step, specify the following settings:
| v Give the DBRM the same name as the name of the load module for the
| external SQL procedure.
| v Specify MARGINS(1,80) for the MARGINS SQL processing option.
| v Specify the NOSEQ compiler option.
| This process produces an executable C language program.
| 4. Bind the resulting DBRM into a package.

| Example: Suppose that you define an external SQL procedure by issuing the
| following CREATE PROCEDURE statement dynamically:
| CREATE PROCEDURE DEVL7083.EMPDTLSS
| (
| IN PEMPNO CHAR(6)
| ,OUT PFIRSTNME VARCHAR(12)
| ,OUT PMIDINIT CHAR(1)
| ,OUT PLASTNAME VARCHAR(15)
| ,OUT PWORKDEPT CHAR(3)
| ,OUT PHIREDATE DATE
| ,OUT PSALARY DEC(9,2)
| ,OUT PSQLCODE INTEGER
| )
| RESULT SETS 0
| MODIFIES SQL DATA
| FENCED
| NO DBINFO
| WLM ENVIRONMENT DB9AWLMR
| STAY RESIDENT NO
| COLLID DEVL7083
| PROGRAM TYPE MAIN
| RUN OPTIONS 'TRAP(OFF),RPTOPTS(OFF)'
| COMMIT ON RETURN NO
| LANGUAGE SQL
| BEGIN
| DECLARE SQLCODE INTEGER;
| DECLARE SQLSTATE CHAR(5);
| SELECT
| FIRSTNME
| , MIDINIT
| , LASTNAME
| , WORKDEPT
| , HIREDATE
| , SALARY
| INTO PFIRSTNME
| , PMIDINIT
| , PLASTNAME
| , PWORKDEPT
| , PHIREDATE
| , PSALARY
| FROM EMP
| WHERE EMPNO = PEMPNO
| ;
| DECLARE EXIT HANDLER FOR SQLEXCEPTION SET PSQLCODE = SQLCODE;
| END

| You can use JCL that is similar to the following JCL to prepare the procedure:

574 Application Programming and SQL Guide

| //ADMF001S JOB (999,POK),'SQL C/L/B/E',CLASS=A,MSGCLASS=T, 00000001
| // NOTIFY=ADMF001,TIME=1440,REGION=0M 00000002
| /*JOBPARM SYSAFF=SC63,L=9999 00000003
| // JCLLIB ORDER=(DB9AU.PROCLIB) 00000004
| //* 00250000
| //JOBLIB DD DSN=DB9A9.SDSNEXIT,DISP=SHR 00260000
| // DD DSN=DB9A9.SDSNLOAD,DISP=SHR 00270000
| // DD DSN=CEE.SCEERUN,DISP=SHR 00270001
| //*---------------------------------------------------------- 00900000
| //* STEP 01: PRECOMP, COMP, LKED AN SQL PROCEDURE 01080000
| //*---------------------------------------------------------- 00900000
| //SQL01 EXEC DSNHSQL,MEM=EMPDTLSS,
| // PARM.PC='HOST(SQL),SOURCE,XREF,MAR(1,80),STDSQL(NO)',
| // PARM.PCC='HOST(C),SOURCE,XREF,MAR(1,80),STDSQL(NO)',
| // PARM.C='SOURCE LIST MAR(1,80) NOSEQ LO RENT',
| // PARM.LKED='AMODE=31,RMODE=ANY,MAP,RENT'
| //PC.SYSLIB DD DUMMY
| //PC.SYSUT2 DD DSN=&&SPDML,DISP=(,PASS), &lt;=MAKE IT PERMANENT, IF YOU
| // UNIT=SYSDA,SPACE=(TRK,1), WANT TO USE IT LATER
| // DCB=(RECFM=FB,LRECL=80)
| //PC.SYSIN DD DISP=SHR,DSN=SG247083.PROD.DDL(&MEM.)
| //PC.SYSCIN DD DISP=SHR,DSN=SG247083.TEST.C.SOURCE(&MEM.)
| //PCC.SYSIN DD DISP=SHR,DSN=SG247083.TEST.C.SOURCE(&MEM.)
| //PCC.SYSLIB DD DUMMY
| //PCC.DBRMLIB DD DISP=SHR,DSN=SG247083.DEVL.DBRM(&MEM.)
| //LKED.SYSLMOD DD DISP=SHR,DSN=SG247083.DEVL.LOAD(&MEM.)
| //LKED.SYSIN DD * INCLUDE SYSLIB(DSNRLI) NAME EMPDTLSS(R)
| /*
| //*---------------------------------------------------------- 00900000
| //* STEP 02: BIND THE PROGRAM 01290000
| //*---------------------------------------------------------- 01280000
| //SQL02 EXEC PGM=IKJEFT01,DYNAMNBR=20,COND=(4,LT) 01300000
| //DBRMLIB DD DSN=SG247083.DEVL.DBRM,DISP=SHR 01310000
| //SYSTSPRT DD SYSOUT=* 01320000
| //SYSPRINT DD SYSOUT=* 01330000
| //SYSUDUMP DD SYSOUT=* 01340000
| //SYSOUT DD SYSOUT=* 01350000
| //REPORT DD SYSOUT=* 01360000
| //SYSIN DD * 01370000
| //SYSTSIN DD * 01390000
| DSN SYSTEM(DB9A) 01400000
| BIND PACKAGE(DEVL7083) MEMBER(EMPDTLSS) VALIDATE(BIND) - 01410000
| OWNER(DEVL7083)
| END 01460000
| //* 01550000

Chapter 10. Creating and modifying DB2 objects 575

| Related concepts
| “SQL procedure body” on page 527
| Command Line Processor (DB2 Command Reference)
| Related tasks
| “Changing SPUFI defaults” on page 1019
| “Creating an external SQL procedure by using DSNTPSMP” on page 565
| Related reference
| “Descriptions of SQL processing options” on page 904
| “DSNTEP2 and DSNTEP4” on page 1084
| “DSNTIAD” on page 1083
| Integrated Data Management Information Center
| BIND PACKAGE (DSN) (DB2 Command Reference)
| CREATE PROCEDURE (SQL - external) (SQL Reference)

| Sample programs to help you prepare and run external SQL

| procedures
| DB2 provides sample jobs to help you prepare and run external SQL procedures.
| All samples are in data set DSN910.SDSNSAMP. Before you can run the samples,
| you must customize them for your installation. See the prolog of each sample for
| specific instructions.

| The following table lists the sample jobs that DB2 provides for external SQL
| procedures.
| Table 99. External SQL procedure samples shipped with DB2
| Member that
| contains
| source code Contents Purpose
| DSNHSQL JCL procedure Precompiles, compiles, prelink-edits, and link-edits an
| external SQL procedure
| DSNTEJ63 JCL job Invokes JCL procedure DSNHSQL to prepare external
| SQL procedure DSN8ES1 for execution
| DSN8ES1 External SQL A stored procedure that accepts a department number
| procedure as input and returns a result set that contains salary
| information for each employee in that department
| DSNTEJ64 JCL job Prepares client program DSN8ED3 for execution
| DSN8ED3 C program Calls SQL procedure DSN8ES1
| DSN8ES2 External SQL A stored procedure that accepts one input parameter
| procedure and returns two output parameters. The input
| parameter specifies a bonus to be awarded to
| managers. The external SQL procedure updates the
| BONUS column of DSN910.SDSNSAMP. If no SQL
| error occurs when the external SQL procedure runs,
| the first output parameter contains the total of all
| bonuses awarded to managers and the second output
| parameter contains a null value. If an SQL error
| occurs, the second output parameter contains an
| SQLCODE.
| DSN8ED4 C program Calls the SQL procedure processor, DSNTPSMP, to
| prepare DSN8ES2 for execution

576 Application Programming and SQL Guide

| Table 99. External SQL procedure samples shipped with DB2 (continued)
| Member that
| contains
| source code Contents Purpose
| DSN8WLMP JCL procedure A sample startup procedure for the WLM-established
| stored procedures address space in which DSNTPSMP
| runs
| DSN8ED5 C program Calls external SQL procedure DSN8ES2
| DSNTEJ65 JCL job Prepares and executes programs DSN8ED4 and
| DSN8ED5.

| DSNTEJ65 uses DSNTPSMP, the SQL procedure

| processor, which requires that the default EBCDIC
| CCSID that is used by DB2 also be compatible with
| the C compiler. Do not run DSNTEJ65 if the default
| EBCDIC CCSID for DB2 is not compatible with the C
| compiler. Examples of incompatible CCSIDs include
| 290, 930, 1026, and 1155.
| DSNTIJSD JCL job Prepares a DB2 for z/OS server for operation with the
| SQL Debugger and the Unified Debugger
|

| Creating an external stored procedure

External stored procedures are procedures that are written in a host language and
that can also contain SQL statements. The source code for external procedures is
separate from the definition.

Configure DB2 for running stored procedures and user-defined functions (DB2
Installation Guide).

Restriction: These instructions do not apply to Java stored procedures. The process
for creating a Java stored procedure is different. The preparation process varies
depending on what the procedure contains.

To create an external stored procedure:

| 1. Write the external stored procedure body in assembler, C, C++, COBOL, REXX,
| or PL/I.
| Ensure that the procedure body that you write follows the guidelines for
| external stored procedures
| For REXX procedures, continue with step 3 on page 578.
| 2. For assembler, C, C++, COBOL, or PL/I stored procedures, prepare the external
| procedure by completing the following tasks:
| a. Precompile, compile, and link-edit the application by using one of the
| following techniques:
| v The DB2 precompiler and JCL instructions to compile and link-edit the
| program
| v The SQL statement coprocessor

| Recommendation: Compile and link-edit code as reentrant.

| Link-edit the application by using DSNRLI, the language interface module
| for the Resource Recovery Services attachment facility. You must specify the
| parameter AMODE(31) when you link-edit the application.

Chapter 10. Creating and modifying DB2 objects 577

| If you want to run your procedure as a z/OS authorized program, you
| must also perform the following tasks when you link-edit the application:
| v Indicate that the load module can use restricted system services by
| specifying the parameter value AC=1.
| v Put the load module for the stored procedure in an APF-authorized
| library.
| You can compile COBOL stored procedures with either the DYNAM or
| NODYNAM COBOL compiler options. If you use DYNAM, ensure that the
| correct DB2 language interface module is loaded dynamically by performing
| one of the following actions:
| v Specify the ATTACH(RRSAF) SQL processing option.
| v Copy the DSNRLI module into a load library that is concatenated in front
| of the DB2 libraries. Use the member name DSNHLI.
| b. Bind the DBRM into a DB2 package by issuing the BIND PACKAGE
| command.
| If you want to control access to a stored procedure package, specify the
| ENABLE bind option with the system connection type of the calling
| application.
| Stored procedures require only a package. You do not need to bind a plan
| for the stored procedure or bind the stored procedure package to the plan
| for the calling application. For remote scenarios, you need a package at both
| the requestor and server sites. The following example BIND PACKAGE
| command binds the DBRM EMPDTL1P to the collection DEVL7083.
| BIND PACKAGE(DEVL7083) -
| MEMBER(EMPDTL1P) ACT(REP) ISO(UR) ENCODING(EBCDIC) -
| OWNER(DEVL7083) LIBRARY('SG247083.DEVL.DBRM')
| 3. Define the stored procedure to DB2 by issuing the CREATE PROCEDURE
| statement with the EXTERNAL option. Use the EXTERNAL NAME clause to
| specify the name of the load module for the program that runs when this
| procedure is called.
| If you want to run your procedure as a z/OS authorized program, specify an
| appropriate environment with the WLM ENVIRONMENT option. The stored
| procedure must run in an address space with a startup procedure in which all
| libraries in the STEPLIB concatenation are APF-authorized.
| If you want environment information to be passed to the stored procedure
| when it is invoked, specify the DBINFO and PARAMETER STYLE SQL options
| in the CREATE PROCEDURE statement. When the procedure is invoked, DB2
| passes the DBINFO structure, which contains environment information, to the
| stored procedure.

| Example of defining a C stored procedure:

| Suppose that you have written and prepared a stored procedure that has the
| following characteristics:
| v The name of the stored procedure is B.
| v The stored procedure has the following two parameters:
| – An integer input parameter that is named V1
| – A character output parameter of length 9 that is named V2
| v The stored procedure is written in the C language.
| v The stored procedure contains no SQL statements.
| v The same input always produces the same output.
| v The load module name is SUMMOD.

578 Application Programming and SQL Guide

| v The package collection name is SUMCOLL.
| v The stored procedure should run for no more than 900 CPU service units.
| v The parameters can have null values.
| v The stored procedure should be deleted from memory when it completes.
| v The stored procedure needs the following Language Environment runtime
| options:
| MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)
| v The stored procedure is part of the WLM application environment that is
| named PAYROLL.
| v The stored procedure runs as a main program.
| v The stored procedure does not access non-DB2 resources, so it does not need
| a special RACF environment.
| v The stored procedure can return at most 10 result sets.
| v When control returns to the client program, DB2 does not commit updates
| automatically.

| The following CREATE PROCEDURE statement defines the stored procedure to

| DB2:
| CREATE PROCEDURE B(IN V1 INTEGER, OUT V2 CHAR(9))
| LANGUAGE C
| DETERMINISTIC
| NO SQL
| EXTERNAL NAME SUMMOD
| COLLID SUMCOLL
| ASUTIME LIMIT 900
| PARAMETER STYLE GENERAL WITH NULLS
| STAY RESIDENT NO
| RUN OPTIONS 'MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)'
| WLM ENVIRONMENT PAYROLL
| PROGRAM TYPE MAIN
| SECURITY DB2
| DYNAMIC RESULT SETS 10
| COMMIT ON RETURN NO;
| 4. Authorize the appropriate users to use the stored procedure by issuing the
| GRANT EXECUTE statement.

| Example: The following statement allows an application that runs under the
| authorization ID JONES to call stored procedure SPSCHEMA.STORPRCA:
| GRANT EXECUTE ON PROCEDURE SPSCHEMA.STORPRCA TO JONES;

You can now invoke the stored procedure from an application program.

Chapter 10. Creating and modifying DB2 objects 579

Related concepts
“Packages and plans for external stored procedures” on page 582
“External stored procedures” on page 531
“REXX stored procedures” on page 594
Java stored procedures and user-defined functions (Programming for Java)
Related tasks
“Invoking the Resource Recovery Services attachment facility” on page 77
Implementing DB2 stored procedures (DB2 Administration Guide)
Related reference
“Descriptions of SQL processing options” on page 904
COBOL programming (DB2 9 for z/OS Stored Procedures: Through the CALL
and Beyond)
C programming (DB2 9 for z/OS Stored Procedures: Through the CALL and
Beyond)
REXX programming (DB2 9 for z/OS Stored Procedures: Through the CALL
and Beyond)
BIND and REBIND options (DB2 Command Reference)
BIND PACKAGE (DSN) (DB2 Command Reference)
CREATE PROCEDURE (external) (SQL Reference)
GRANT (function or procedure privileges) (SQL Reference)

DBINFO structure
Use the DBINFO structure to pass environment information to user-defined
functions and stored procedures. Some fields in the structure are not used for
stored procedures.

DBINFO is a structure that contains information such as the name of the current
server, the application runtime authorization ID and identification of the version
and release of the database manager that invoked the procedure.

The DBINFO structure includes the following information:

Location name length
An unsigned 2-byte integer field. It contains the length of the location name in
the next field.
Location name
A 128-byte character field. It contains the name of the location to which the
invoker is currently connected.
Authorization ID length
An unsigned 2-byte integer field. It contains the length of the authorization ID
in the next field.
Authorization ID
A 128-byte character field. It contains the authorization ID of the application
from which the stored procedure is invoked, padded on the right with blanks.
If this stored procedure is nested within other routines (user-defined functions
or stored procedures), this value is the authorization ID of the application that
invoked the highest-level routine.

580 Application Programming and SQL Guide

Subsystem code page
A 48-byte structure that consists of 10 integer fields and an eight-byte reserved
area. These fields provide information about the CCSIDs of the subsystem from
which the stored procedure is invoked.
Table qualifier length
An unsigned 2-byte integer field. This field contains 0.
Table qualifier
A 128-byte character field. This field is not used for stored procedures.
Table name length
An unsigned 2-byte integer field. This field contains 0.
Table name
A 128-byte character field. This field is not used for stored procedures.
Column name length
An unsigned 2-byte integer field. This field contains 0.
Column name
A 128-byte character field. This field is not used for stored procedures.
Product information
An 8-byte character field that identifies the product on which the stored
procedure executes. This field has the form pppvvrrm, where:
v ppp is a 3-byte product code:
ARI DB2 Server for VSE & VM
DSN DB2 for z/OS
QSQ DB2 for i
SQL DB2 for Linux, UNIX, and Windows
v vv is a two-digit version identifier.
v rr is a two-digit release identifier.
v m is a one-digit maintenance level identifier.
Reserved area
2 bytes.
Operating system
A 4-byte integer field. It identifies the operating system on which the program
that invokes the user-defined function runs. The value is one of these:
0 Unknown
1 OS/2
3 Windows
4 AIX
5 Windows NT
6 HP-UX
7 Solaris
8 z/OS
13 Siemens Nixdorf
15 Windows 95
16 SCO UNIX

Chapter 10. Creating and modifying DB2 objects 581

18 Linux
19 DYNIX/ptx
24 Linux for S/390
25 Linux for System z
26 Linux/IA64
27 Linux/PPC
28 Linux/PPC64
29 Linux/AMD64
400 iSeries
Number of entries in table function column list
An unsigned 2-byte integer field. This field contains 0.
Reserved area
26 bytes.
Table function column list pointer
This field is not used for stored procedures.
Unique application identifier
This field is a pointer to a string that uniquely identifies the application’s
connection to DB2. The string is regenerated at for each connection to DB2.
The string is the LUWID, which consists of a fully-qualified LU network name
followed by a period and an LUW instance number. The LU network name
consists of a one- to eight-character network ID, a period, and a one- to
eight-character network LU name. The LUW instance number consists of 12
hexadecimal characters that uniquely identify the unit of work.
Reserved area
20 bytes.

Packages and plans for external stored procedures

An external stored procedure must have an associated package. The calling
application can use either a plan or a package.

As part of the process of creating an external stored procedure, you prepare the
procedure, which means that you precompile, compile, link-edit, and bind the
application. The result of this process is a DB2 package. You do not need to create
a DB2 plan for an external procedure. The procedure runs under the caller’s thread
and uses the plan from the client program that calls it.

The calling application can use a DB2 package or plan to execute the CALL
statement.

Both the stored procedure package and the calling application plan or package
must exist on the server before you run the calling application.

The following figure shows this relationship between a client program and a stored
procedure. In the figure, the client program, which was bound into package A,
issues a CALL statement to program B. Program B is an external stored procedure
in a WLM address space. This external stored procedure was bound into package
B.

582 Application Programming and SQL Guide

Client Program DB2 System Address Space
User ID=yyyy User ID=yyyy User ID=xxxx
Program A
..
. Package
EXEC SQL B
CALL B
Package Program
A B
CALL B

Figure 34. Stored procedure runtime environment

You can control access to the stored procedure package by specifying the ENABLE
bind option when you bind the package.

In the following situations, the stored procedure might use more than one package:
v You bind a DBRM several times into several versions of the same package, all of
which have the same package name but reside in different package collections.
Your stored procedure can switch from one version to another by using the SET
CURRENT PACKAGESET statement.
v The stored procedure calls another program that contains SQL statements. This
program has an associated package. This package must exist at the location
where the stored procedure is defined and at the location where the SQL
statements are executed.
Related reference
BIND and REBIND options (DB2 Command Reference)
BIND PACKAGE (DSN) (DB2 Command Reference)
SET CURRENT PACKAGESET (SQL Reference)

Accessing other sites in an external procedure

External procedures can access tables at other DB2 locations. You should use
DRDA access to access these tables.

Stored procedures can access tables at other DB2 locations by using three-part
object names or CONNECT statements. If you use CONNECT statements, you use
DRDA access to access tables. If you use three-part object names or aliases for
three-part object names, the distributed access method depends on the value of
DBPROTOCOL that you specified when you bound the stored procedure package.
A value of PRIVATE tells DB2 to use DB2 private protocol access to access remote
data for the stored procedure. A value of DRDA tells DB2 to use DRDA access.

| Recommendation: Do not use private protocol. Support for private protocol will be
| removed in a future release of DB2.

When a local DB2 application calls a stored procedure, the stored procedure cannot
have DB2 private protocol access to any DB2 sites already connected to the calling
program by DRDA access.

Chapter 10. Creating and modifying DB2 objects 583

The local DB2 application cannot use DRDA access to connect to any location that
the stored procedure has already accessed using DB2 private protocol access.
Before making the DB2 private protocol connection, the local DB2 application must
first execute the RELEASE statement to terminate the DB2 private protocol
connection, and then commit the unit of work.
Related tasks
“Accessing distributed data by using three-part table names” on page 835

Writing an external procedure to access IMS databases

IMS Open Database Access (ODBA) support lets a DB2 stored procedure connect
to an IMS DBCTL or IMS DB/DC system and issue DL/I calls to access IMS
databases.

ODBA support uses RRS for syncpoint control of DB2 and IMS resources.
Therefore, stored procedures that use ODBA can run only in WLM-established
stored procedures address spaces.

When you write a stored procedure that uses ODBA, follow the rules for writing
an IMS application program that issues DL/I calls. For information about writing
DL/I applications, see IMS Application Programming: Database Manager and IMS
Application Programming: Transaction Manager.

IMS work that is performed in a stored procedure is in the same commit scope as
the stored procedure. As with any other stored procedure, the calling application
commits work.

A stored procedure that uses ODBA must issue a DPSB PREP call to deallocate a
PSB when all IMS work under that PSB is complete. The PREP keyword tells IMS
to move inflight work to an indoubt state. When work is in the indoubt state, IMS
does not require activation of syncpoint processing when the DPSB call is executed.
IMS commits or backs out the work as part of RRS two-phase commit when the
stored procedure caller executes COMMIT or ROLLBACK.

A sample COBOL stored procedure and client program demonstrate accessing IMS
data using the ODBA interface. The stored procedure source code is in member
DSN8EC1 and is prepared by job DSNTEJ61. The calling program source code is in
member DSN8EC1 and is prepared and executed by job DSNTEJ62. All code is in
data set DSN910.SDSNSAMP.

The startup procedure for a stored procedures address space in which stored
procedures that use ODBA run must include a DFSRESLB DD statement and an
extra data set in the STEPLIB concatenation. See “Setting up the stored procedures
environment” on page 533 for more information.

Writing an external procedure to return result sets to a DRDA

client
An external procedure can return multiple query result sets to a DRDA client if the
client supports the DRDA code points used to return query result sets and the
value of DYNAMIC RESULT SETS in the stored procedure definition is greater
than 0.

For each result set you want returned, your stored procedure must:
v Declare a cursor with the option WITH RETURN.
v Open the cursor.
v If the cursor is scrollable, ensure that the cursor is positioned before the first row
of the result table.

584 Application Programming and SQL Guide

v Leave the cursor open.

When the stored procedure ends, DB2 returns the rows in the query result set to
the client.

DB2 does not return result sets for cursors that are closed before the stored
procedure terminates. The stored procedure must execute a CLOSE statement for
each cursor associated with a result set that should not be returned to the DRDA
client.

Example: Declaring a cursor to return a result set: Suppose you want to return a
result set that contains entries for all employees in department D11. First, declare a
cursor that describes this subset of employees:
EXEC SQL DECLARE C1 CURSOR WITH RETURN FOR
SELECT * FROM DSN8910.EMP
WHERE WORKDEPT='D11';

Then, open the cursor:

EXEC SQL OPEN C1;

DB2 returns the result set and the name of the SQL cursor for the stored procedure
to the client.

Use meaningful cursor names for returning result sets: The name of the cursor that
is used to return result sets is made available to the client application through
extensions to the DESCRIBE statement. See “Writing a program or stored
procedure to receive the result sets from a stored procedure” on page 600 for more
information.

Use cursor names that are meaningful to the DRDA client application, especially
when the stored procedure returns multiple result sets.

Objects from which you can return result sets: You can use any of these objects in
the SELECT statement that is associated with the cursor for a result set:
v Tables, synonyms, views, created temporary tables, declared temporary tables,
and aliases defined at the local DB2 subsystem
v Tables, synonyms, views, created temporary tables, and aliases defined at remote
DB2 for z/OS systems that are accessible through DB2 private protocol access

Returning a subset of rows to the client: If you execute FETCH statements with a
result set cursor, DB2 does not return the fetched rows to the client program. For
example, if you declare a cursor WITH RETURN and then execute the statements
OPEN, FETCH, and FETCH, the client receives data beginning with the third row
in the result set. If the result set cursor is scrollable and you fetch rows with it, you
need to position the cursor before the first row of the result table after you fetch
the rows and before the stored procedure ends.

Using a temporary table to return result sets: You can use a created temporary
table or declared temporary table to return result sets from a stored procedure.
This capability can be used to return nonrelational data to a DRDA client.

For example, you can access IMS data from a stored procedure in the following
way:
v Use APPC/MVS to issue an IMS transaction.

Chapter 10. Creating and modifying DB2 objects 585

v Receive the IMS reply message, which contains data that should be returned to
the client.
v Insert the data from the reply message into a temporary table.
v Open a cursor against the temporary table. When the stored procedure ends, the
rows from the temporary table are returned to the client.

Restrictions when calling other programs from an external

stored procedure
An external procedure can consist of more than one program, each with its own
package. Your stored procedure can call other programs, stored procedures, or
user-defined functions. Use the facilities of your programming language to call
other programs.

If the stored procedure calls other programs that contain SQL statements, each of
those called programs must have a DB2 package. The owner of the package or
plan that contains the CALL statement must have EXECUTE authority for all
packages that the other programs use.

When a stored procedure calls another program, DB2 determines which collection
the package of the called program belongs to in one of the following ways:
| v If the stored procedure definition contains PACKAGE PATH with a specified list
| of collection IDs, DB2 uses those collection IDs. If you also specify COLLID, DB2
| ignores that clause.
v If the stored procedure definition contains COLLID collection-id, DB2 uses
collection-id.
v If the stored procedure executes SET CURRENT PACKAGE PATH and contains
the NO COLLID option, DB2 uses the CURRENT PACKAGE PATH special
register. The package of the called program comes from the list of collections in
the CURRENT PACKAGE PATH special register. For example, assume that
CURRENT PACKAGE PATH contains the list COLL1, COLL2, COLL3, COLL4.
DB2 searches for the first package (in the order of the list) that exists in these
collections.
v If the stored procedure does not execute SET CURRENT PACKAGE PATH and
instead executes SET CURRENT PACKAGESET, DB2 uses the CURRENT
PACKAGESET special register. The package of the called program comes from
the collection that is specified in the CURRENT PACKAGESET special register.
v If both of the following conditions are true, DB2 uses the collection ID of the
package that contains the SQL statement CALL:
– the stored procedure does not execute SET CURRENT PACKAGE PATH or
SET CURRENT PACKAGESET
– the stored procedure definition contains the NO COLLID option
When control returns from the stored procedure, the value of the CURRENT
PACKAGESET special register is reset.DB2 restores the value of the CURRENT
PACKAGESET special register to the value that it contained before the client
program executed the SQL statement CALL.

Reentrant code in external stored procedures

Reentrant code is code for which a single copy can be used concurrently by two or
more processes. Whenever possible, prepare your stored procedures to be
reentrant.

Using reentrant stored procedures can lead to improved performance for the
following reasons:

586 Application Programming and SQL Guide

v A reentrant stored procedure does not have to be loaded into storage every time
it is called.
v A single copy of the stored procedure can be shared by multiple tasks in the
stored procedures address space. This decreases the amount of virtual storage
used for code in the stored procedures address space.

To prepare a stored procedure as reentrant, compile it as reentrant and link-edit it

as reentrant and reusable.

For instructions on compiling programs to be reentrant, see the appropriate

language manual. For information about using the binder to produce reentrant and
reusable load modules, see z/OS MVS: Program Management User’s Guide and
Reference.

To make a reentrant stored procedure remain resident in storage, specify STAY

RESIDENT YES in the CREATE PROCEDURE or ALTER PROCEDURE statement
for the stored procedure.

If your stored procedure cannot be reentrant, link-edit it as non-reentrant and

non-reusable. The non-reusable attribute prevents multiple tasks from using a
single copy of the stored procedure at the same time. A non-reentrant stored
procedure must not remain in storage. You therefore need to specify STAY
RESIDENT NO in the CREATE PROCEDURE or ALTER PROCEDURE statement
for the stored procedure.

External stored procedures as main programs and subprograms

A stored procedure that runs in a WLM-established address space and uses
Language Environment Release 1.7 or a subsequent release can be either a main
program or a subprogram. A stored procedure that runs as a subprogram can
perform better because Language Environment does less processing for it.

In general, a subprogram must do the following extra tasks that Language

Environment performs for a main program:
v Initialization and cleanup processing
v Allocating and freeing storage
v Closing all open files before exiting

When you code stored procedures as subprograms, follow these rules:

v Follow the language rules for a subprogram. For example, you cannot perform
I/O operations in a PL/I subprogram.
v Avoid using statements that terminate the Language Environment enclave when
the program ends. Examples of such statements are STOP or EXIT in a PL/I
subprogram, or STOP RUN in a COBOL subprogram. If the enclave terminates
when a stored procedure ends, and the client program calls another stored
procedure that runs as a subprogram, Language Environment must build a new
enclave. As a result, the benefits of coding a stored procedure as a subprogram
are lost.
v In COBOL stored procedures that are defined as PROGRAM TYPE SUB and
STAY RESIDENT YES, if you use stored procedure parameters as host variables,
set the SQL-INIT-FLAG variable to 0. This variable is generated by the DB2
precompiler. Setting it to 0 ensures that the SQLDA is updated with the current
addresses.

Chapter 10. Creating and modifying DB2 objects 587

The following table summarizes the characteristics that define a main program and
a subprogram.
Table 100. Characteristics of main programs and subprograms
Language Main program Subprogram
Assembler MAIN=YES is specified in the MAIN=NO is specified in the
invocation of the CEEENTRY invocation of the CEEENTRY
macro. macro.
C Contains a main() function. Pass A fetchable function. Pass
parameters to it through argc and parameters to it explicitly.
argv.
COBOL A COBOL program that ends with A dynamically loaded subprogram
GOBACK that ends with GOBACK
PL/I Contains a procedure declared with A procedure declared with
OPTIONS(MAIN) OPTIONS(FETCHABLE)

The following code shows an example of coding a C stored procedure as a

subprogram.
/******************************************************************/
/* This C subprogram is a stored procedure that uses linkage */
/* convention GENERAL and receives 3 parameters. */
/******************************************************************/
#pragma linkage(cfunc,fetchable)
#include <stdlib.h>
void cfunc(char p1[11],long *p2,short *p3)
{
/****************************************************************/
/* Declare variables used for SQL operations. These variables */
/* are local to the subprogram and must be copied to and from */
/* the parameter list for the stored procedure call. */
/****************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
char parm1[11];
long int parm2;
short int parm3;
EXEC SQL END DECLARE SECTION;
/*************************************************************/
/* Receive input parameter values into local variables. */
/*************************************************************/
strcpy(parm1,p1);
parm2 = *p2;
parm3 = *p3;
/*************************************************************/
/* Perform operations on local variables. */
/*************************************************************/
.
.
.
/*************************************************************/
/* Set values to be passed back to the caller. */
/*************************************************************/
strcpy(parm1,"SETBYSP");
parm2 = 100;
parm3 = 200;
/*************************************************************/
/* Copy values to output parameters. */
/*************************************************************/
strcpy(p1,parm1);
*p2 = parm2;
*p3 = parm3;
}

588 Application Programming and SQL Guide

The following code shows an example of coding a C++ stored procedure as a
subprogram.
/******************************************************************/
/* This C++ subprogram is a stored procedure that uses linkage */
/* convention GENERAL and receives 3 parameters. */
/* The extern statement is required. */
/******************************************************************/
extern "C" void cppfunc(char p1[11],long *p2,short *p3);
#pragma linkage(cppfunc,fetchable)
#include <stdlib.h>
EXEC SQL INCLUDE SQLCA;
void cppfunc(char p1[11],long *p2,short *p3)
{
/****************************************************************/
/* Declare variables used for SQL operations. These variables */
/* are local to the subprogram and must be copied to and from */
/* the parameter list for the stored procedure call. */
/****************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
char parm1[11];
long int parm2;
short int parm3;
EXEC SQL END DECLARE SECTION;
/*************************************************************/
/* Receive input parameter values into local variables. */
/*************************************************************/
strcpy(parm1,p1);
parm2 = *p2;
parm3 = *p3;
/*************************************************************/
/* Perform operations on local variables. */
/*************************************************************/
.
.
.
/*************************************************************/
/* Set values to be passed back to the caller. */
/*************************************************************/
strcpy(parm1,"SETBYSP");
parm2 = 100;
parm3 = 200;
/*************************************************************/
/* Copy values to output parameters. */
/*************************************************************/
strcpy(p1,parm1);
*p2 = parm2;
*p3 = parm3;
}

Data types in stored procedures

A stored procedure that is written in any language except REXX must declare each
parameter that is passed to it. The definition for that stored procedure must also
contain a compatible SQL data type declaration for each parameter.

For languages other than REXX

For all data types except LOBs, ROWIDs, locators, and VARCHARs (for C
language), see the tables listed in the following table for the host data types that
are compatible with the data types in the stored procedure definition.

For LOBs, ROWIDs, VARCHARs, and locators, the following table shows
compatible declarations for the assembler language.

Chapter 10. Creating and modifying DB2 objects 589

Table 101. Compatible assembler language declarations for LOBs, ROWIDs, and locators
SQL data type in definition Assembler declaration
TABLE LOCATOR DS FL4
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR
BLOB(n) If n <= 65535:
var DS 0FL4
var_length DS FL4
var_data DS CLn
If n > 65535:
var DS 0FL4
var_length DS FL4
var_data DS CL65535
ORG var_data+(n-65535)
CLOB(n) If n <= 65535:
var DS 0FL4
var_length DS FL4
var_data DS CLn
If n > 65535:
var DS 0FL4
var_length DS FL4
var_data DS CL65535
ORG var_data+(n-65535)
DBCLOB(n) If m (=2*n) <= 65534:
var DS 0FL4
var_length DS FL4
var_data DS CLm
If m > 65534:
var DS 0FL4
var_length DS FL4
var_data DS CL65534
ORG var_data+(m-65534)
ROWID DS HL2,CL40
VARCHAR(n) If PARAMETER VARCHAR NULTERM is
specified or implied:
char data[n+1];

If PARAMETER VARCHAR STRUCTURE is

specified:
struct
{short len;
char data[n];
} var;
Note:
1. This row does not apply to VARCHAR(n) FOR BIT DATA. BIT DATA is always passed
in a structured representation.

For LOBs, ROWIDs, and locators, the following table shows compatible
declarations for the C language.
Table 102. Compatible C language declarations for LOBs, ROWIDs, and locators
SQL data type in definition C declaration
TABLE LOCATOR unsigned long
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR

590 Application Programming and SQL Guide

Table 102. Compatible C language declarations for LOBs, ROWIDs, and locators (continued)
SQL data type in definition C declaration
BLOB(n) struct
{unsigned long length;
char data[n];
} var;
CLOB(n) struct
{unsigned long length;
char var_data[n];
} var;
DBCLOB(n) struct
{unsigned long length;
sqldbchar data[n];
} var;
ROWID struct
{short int length;
char data[40];
} var;

For LOBs, ROWIDs, and locators, the following table shows compatible
declarations for COBOL.
Table 103. Compatible COBOL declarations for LOBs, ROWIDs, and locators
SQL data type in definition COBOL declaration
TABLE LOCATOR 01 var PIC S9(9) USAGE IS BINARY.
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR
BLOB(n) If n <= 32767:
01 var.
49 var-LENGTH PIC 9(9)
USAGE COMP.
49 var-DATA PIC X(n).

If n > 32767:
01 var.
02var-LENGTH PIC S9(9)
USAGE COMP.
02 var-DATA.
49 FILLER
PIC X(32767).
49 FILLER
.. PIC X(32767).
.
49 FILLER
PIC X(mod(n,32767)).

Chapter 10. Creating and modifying DB2 objects 591

Table 103. Compatible COBOL declarations for LOBs, ROWIDs, and locators (continued)
SQL data type in definition COBOL declaration
CLOB(n) If n <= 32767:
01 var.
49 var-LENGTH PIC 9(9)
USAGE COMP.
49 var-DATA PIC X(n).

If n > 32767:
01 var.
02var-LENGTH PIC S9(9)
USAGE COMP.
02 var-DATA.
49 FILLER
PIC X(32767).
49 FILLER
.. PIC X(32767).
.
49 FILLER
PIC X(mod(n,32767)).
DBCLOB(n) If n <= 32767:
01 var.
49 var-LENGTH PIC 9(9)
USAGE COMP.
49 var-DATA PIC G(n)
USAGE DISPLAY-1.

If n > 32767:
01 var.
02 var-LENGTH PIC S9(9)
USAGE COMP.
02 var-DATA.
49 FILLER
PIC G(32767)
USAGE DISPLAY-1.
49 FILLER
PIC G(32767).
.. USAGE DISPLAY-1.
.
49 FILLER
PIC G(mod(n,32767))
USAGE DISPLAY-1.
ROWID 01 var.
49 var-LEN PIC 9(4)
USAGE COMP.
49 var-DATA PIC X(40).

For LOBs, ROWIDs, and locators, the following table shows compatible
declarations for PL/I.
Table 104. Compatible PL/I declarations for LOBs, ROWIDs, and locators
SQL data type in definition PL/I
TABLE LOCATOR BIN FIXED(31)
BLOB LOCATOR
CLOB LOCATOR
DBCLOB LOCATOR

592 Application Programming and SQL Guide

Table 104. Compatible PL/I declarations for LOBs, ROWIDs, and locators (continued)
SQL data type in definition PL/I
BLOB(n) If n <= 32767:
01 var,
03 var_LENGTH
BIN FIXED(31),
03 var_DATA
CHAR(n);

If n > 32767:
01 var,
02 var_LENGTH
BIN FIXED(31),
02 var_DATA,
03 var_DATA1(n)
CHAR(32767),
03 var_DATA2
CHAR(mod(n,32767));
CLOB(n) If n <= 32767:
01 var,
03 var_LENGTH
BIN FIXED(31),
03 var_DATA
CHAR(n);

If n > 32767:
01 var,
02 var_LENGTH
BIN FIXED(31),
02 var_DATA,
03 var_DATA1(n)
CHAR(32767),
03 var_DATA2
CHAR(mod(n,32767));
DBCLOB(n) If n <= 16383:
01 var,
03 var_LENGTH
BIN FIXED(31),
03 var_DATA
GRAPHIC(n);

If n > 16383:
01 var,
02 var_LENGTH
BIN FIXED(31),
02 var_DATA,
03 var_DATA1(n)
GRAPHIC(16383),
03 var_DATA2
GRAPHIC(mod(n,16383));
ROWID CHAR(40) VAR

Tables of results: Each high-level language definition for stored procedure

parameters supports only a single instance (a scalar value) of the parameter. There
is no support for structure, array, or vector parameters. Because of this, the SQL
statement CALL limits the ability of an application to return some kinds of tables.
For example, an application might need to return a table that represents multiple
occurrences of one or more of the parameters passed to the stored procedure.

Chapter 10. Creating and modifying DB2 objects 593

Because the SQL statement CALL cannot return more than one set of parameters,
use one of the following techniques to return such a table:
v Put the data that the application returns in a DB2 table. The calling program can
receive the data in one of these ways:
– The calling program can fetch the rows from the table directly. Specify FOR
FETCH ONLY or FOR READ ONLY on the SELECT statement that retrieves
data from the table. A block fetch can retrieve the required data efficiently.
– The stored procedure can return the contents of the table as a result set. See
“Writing an external procedure to return result sets to a DRDA client” on
page 584 and “Writing a program or stored procedure to receive the result
sets from a stored procedure” on page 600 for more information.
v Convert tabular data to string format and return it as a character string
parameter to the calling program. The calling program and the stored procedure
can establish a convention for interpreting the content of the character string. For
example, the SQL statement CALL can pass a 1920-byte character string
parameter to a stored procedure, which enables the stored procedure to return a
24x80 screen image to the calling program.
Related concepts
“Compatibility of SQL and language data types” on page 148
Related tasks
“Setting up the stored procedures environment” on page 533

REXX stored procedures

A REXX stored procedure is much like any other REXX procedure and follows the
same rules as stored procedures in other languages. It receives input parameters,
executes REXX commands, optionally executes SQL statements, and returns at
most one output parameter. However, a few differences exist.

A REXX stored procedure is different from other REXX procedures in the following
ways:
v A REXX stored procedure must not execute any of the following DSNREXX
commands that are used for the DB2 subsystem thread attachment:
ADDRESS DSNREXX CONNECT
ADDRESS DSNREXX DISCONNECT
CALL SQLDBS ATTACH TO
CALL SQLDBS DETACH
When you execute SQL statements in your stored procedure, DB2 establishes the
connection for you.
v A REXX stored procedure must run in a WLM-established stored procedures
address space.

Unlike other stored procedures, you do not prepare REXX stored procedures for
execution. REXX stored procedures run using one of four packages that are bound
during the installation of DB2 REXX Language Support. The current isolation level
at which the stored procedure runs depends on the package that DB2 uses when
the stored procedure runs:
Package name
Isolation level
DSNREXRR
Repeatable read (RR)

594 Application Programming and SQL Guide

DSNREXRS
Read stability (RS)
DSNREXCS
Cursor stability (CS)
DSNREXUR
Uncommitted read (UR)

This topic shows an example of a REXX stored procedure that executes DB2
commands. The stored procedure performs the following actions:
v Receives one input parameter, which contains a DB2 command.
v Calls the IFI COMMAND function to execute the command.
v Extracts the command result messages from the IFI return area and places the
messages in a created temporary table. Each row of the temporary table contains
a sequence number and the text of one message.
v Opens a cursor to return a result set that contains the command result messages.
v Returns the unformatted contents of the IFI return area in an output parameter.

The following example shows the definition of the stored procedure.

CREATE PROCEDURE COMMAND(IN CMDTEXT VARCHAR(254), OUT CMDRESULT VARCHAR(32704))
LANGUAGE REXX
EXTERNAL NAME COMMAND
NO COLLID
ASUTIME NO LIMIT
PARAMETER STYLE GENERAL
STAY RESIDENT NO
RUN OPTIONS 'TRAP(ON)'
WLM ENVIRONMENT WLMENV1
SECURITY DB2
DYNAMIC RESULT SETS 1
COMMIT ON RETURN NO;

The following example shows the COMMAND stored procedure that executes DB2
commands.
/* REXX */
PARSE UPPER ARG CMD /* Get the DB2 command text */
/* Remove enclosing quotation marks */
IF LEFT(CMD,2) = ""'" & RIGHT(CMD,2) = "'"" THEN
CMD = SUBSTR(CMD,2,LENGTH(CMD)-2)
ELSE
IF LEFT(CMD,2) = """'" & RIGHT(CMD,2) = "'""" THEN
CMD = SUBSTR(CMD,3,LENGTH(CMD)-4)
COMMAND = SUBSTR("COMMAND",1,18," ")
/****************************************************************/
/* Set up the IFCA, return area, and output area for the */
/* IFI COMMAND call. */
/****************************************************************/
IFCA = SUBSTR('00'X,1,180,'00'X)
IFCA = OVERLAY(D2C(LENGTH(IFCA),2),IFCA,1+0)
IFCA = OVERLAY("IFCA",IFCA,4+1)
RTRNAREASIZE = 262144 /*1048572*/
RTRNAREA = D2C(RTRNAREASIZE+4,4)LEFT(' ',RTRNAREASIZE,' ')
OUTPUT = D2C(LENGTH(CMD)+4,2)||'0000'X||CMD
BUFFER = SUBSTR(" ",1,16," ")
/****************************************************************/
/* Make the IFI COMMAND call. */
/****************************************************************/
ADDRESS LINKPGM "DSNWLIR COMMAND IFCA RTRNAREA OUTPUT"
WRC = RC
RTRN= SUBSTR(IFCA,12+1,4)
REAS= SUBSTR(IFCA,16+1,4)

Chapter 10. Creating and modifying DB2 objects 595

TOTLEN = C2D(SUBSTR(IFCA,20+1,4))
/****************************************************************/
/* Set up the host command environment for SQL calls. */
/****************************************************************/
"SUBCOM DSNREXX" /* Host cmd env available? */
IF RC THEN /* No--add host cmd env */
S_RC = RXSUBCOM('ADD','DSNREXX','DSNREXX')
/****************************************************************/
/* Set up SQL statements to insert command output messages */
/* into a temporary table. */
/****************************************************************/
SQLSTMT='INSERT INTO SYSIBM.SYSPRINT(SEQNO,TEXT) VALUES(?,?)'
ADDRESS DSNREXX "EXECSQL DECLARE C1 CURSOR FOR S1"
IF SQLCODE ¬= 0 THEN CALL SQLCA
ADDRESS DSNREXX "EXECSQL PREPARE S1 FROM :SQLSTMT"
IF SQLCODE ¬= 0 THEN CALL SQLCA
/****************************************************************/
/* Extract messages from the return area and insert them into */
/* the temporary table. */
/****************************************************************/
SEQNO = 0
OFFSET = 4+1
DO WHILE ( OFFSET < TOTLEN )
LEN = C2D(SUBSTR(RTRNAREA,OFFSET,2))
SEQNO = SEQNO + 1
TEXT = SUBSTR(RTRNAREA,OFFSET+4,LEN-4-1)
ADDRESS DSNREXX "EXECSQL EXECUTE S1 USING :SEQNO,:TEXT"
IF SQLCODE ¬= 0 THEN CALL SQLCA
OFFSET = OFFSET + LEN
END
/****************************************************************/
/* Set up a cursor for a result set that contains the command */
/* output messages from the temporary table. */
/****************************************************************/
SQLSTMT='SELECT SEQNO,TEXT FROM SYSIBM.SYSPRINT ORDER BY SEQNO'
ADDRESS DSNREXX "EXECSQL DECLARE C2 CURSOR FOR S2"
IF SQLCODE ¬= 0 THEN CALL SQLCA
ADDRESS DSNREXX "EXECSQL PREPARE S2 FROM :SQLSTMT"
IF SQLCODE ¬= 0 THEN CALL SQLCA
/****************************************************************/
/* Open the cursor to return the message output result set to */
/* the caller. */
/****************************************************************/
ADDRESS DSNREXX "EXECSQL OPEN C2"
IF SQLCODE ¬= 0 THEN CALL SQLCA
S_RC = RXSUBCOM('DELETE','DSNREXX','DSNREXX') /* REMOVE CMD ENV */
EXIT SUBSTR(RTRNAREA,1,TOTLEN+4)
/****************************************************************/
/* Routine to display the SQLCA */
/****************************************************************/
SQLCA:
SAY 'SQLCODE ='SQLCODE
SAY 'SQLERRMC ='SQLERRMC
SAY 'SQLERRP ='SQLERRP
SAY 'SQLERRD ='SQLERRD.1',',
|| SQLERRD.2',',
|| SQLERRD.3',',
|| SQLERRD.4',',
|| SQLERRD.5',',
|| SQLERRD.6
SAY 'SQLWARN ='SQLWARN.0',',
|| SQLWARN.1',',
|| SQLWARN.2',',
|| SQLWARN.3',',
|| SQLWARN.4',',
|| SQLWARN.5',',

596 Application Programming and SQL Guide

|| SQLWARN.6',',
|| SQLWARN.7',',
|| SQLWARN.8',',
|| SQLWARN.9',',
|| SQLWARN.10
SAY 'SQLSTATE='SQLSTATE
SAY 'SQLCODE ='SQLCODE
EXIT 'SQLERRMC ='SQLERRMC';' ,
|| 'SQLERRP ='SQLERRP';' ,
|| 'SQLERRD ='SQLERRD.1',',
|| SQLERRD.2',',
|| SQLERRD.3',',
|| SQLERRD.4',',
|| SQLERRD.5',',
|| SQLERRD.6';' ,
|| 'SQLWARN ='SQLWARN.0',',
|| SQLWARN.1',',
|| SQLWARN.2',',
|| SQLWARN.3',',
|| SQLWARN.4',',
|| SQLWARN.5',',
|| SQLWARN.6',',
|| SQLWARN.7',',
|| SQLWARN.8',',
|| SQLWARN.9',',
|| SQLWARN.10';' ,
|| 'SQLSTATE='SQLSTATE';'
Related reference
“Calling a stored procedure from a REXX procedure” on page 757
TSO/E services available under IKJTSOEV (TSO/E Programming Services)

| Modifying an external stored procedure definition

| You can modify the definition of an external stored procedure or the stored
| procedure source code. In either case, you need to prepare the stored procedure
| again.

| To modify an external stored procedure definition:

| 1. Issue the ALTER PROCEDURE statement with the appropriate options. This
| new definition replaces the existing definition.
| 2. Prepare the external stored procedure again, as you did when you originally
| created the external stored procedure.

| Suppose that an existing C stored procedure was defined with the following
| statement:
| CREATE PROCEDURE B(IN V1 INTEGER, OUT V2 CHAR(9))
| LANGUAGE C
| DETERMINISTIC
| NO SQL
| EXTERNAL NAME SUMMOD
| COLLID SUMCOLL
| ASUTIME LIMIT 900
| PARAMETER STYLE GENERAL WITH NULLS
| STAY RESIDENT NO
| RUN OPTIONS 'MSGFILE(OUTFILE),RPTSTG(ON),RPTOPTS(ON)'
| WLM ENVIRONMENT PAYROLL
| PROGRAM TYPE MAIN
| SECURITY DB2
| DYNAMIC RESULT SETS 10
| COMMIT ON RETURN NO;

Chapter 10. Creating and modifying DB2 objects 597

| Assume that you need to make the following changes to the stored procedure
| definition:
| v The stored procedure selects data from DB2 tables but does not modify DB2
| data.
| v The parameters can have null values, and the stored procedure can return a
| diagnostic string.
| v The length of time that the stored procedure runs is unlimited.
| v If the stored procedure is called by another stored procedure or a user-defined
| function, the stored procedure uses the WLM environment of the caller.

| The following ALTER PROCEDURE statement makes these changes:

| ALTER PROCEDURE B
| READS SQL DATA
| ASUTIME NO LIMIT
| PARAMETER STYLE SQL
| WLM ENVIRONMENT (PAYROLL,*);
| Related reference
| ALTER PROCEDURE (external) (SQL Reference)

Creating multiple versions of external procedures and external

SQL procedures
For native SQL procedures, you can use DB2 to create and maintain multiple
versions of the procedure. For external SQL procedures and external procedures,
you must manually maintain multiple versions of the procedures.

To create multiple versions of external procedures and external SQL procedures,

use one of the following techniques:
v Define multiple procedures with the same name in different schemas. You can
subsequently use the SQL path to determine which version of the procedure is
to be used by a calling program.
v Define multiple versions of the executable code. You can subsequently use a
particular version by specifying the name of the load module for the version
that you want to use on the EXTERNAL clause of the CREATE PROCEDURE
statement or ALTER PROCEDURE statement.
v Define multiple packages for a procedure. You can subsequently use the
COLLID option, the CURRENT PACKAGESET special register, or the CURRENT
PACKAGE PATH special register to specify which version of the procedure is to
be used by the calling application.
v Set up multiple WLM environments to use different versions of a procedure.

COMMIT and ROLLBACK statements in a stored procedure

When you execute COMMIT or ROLLBACK statements in your stored procedure,
DB2 commits or rolls back all changes within the unit of work. These changes
include changes that the client application made before it called the stored
procedure, as well as DB2 work that the stored procedure does.

A stored procedure that includes COMMIT or ROLLBACK statements must be

defined with the CONTAINS SQL, READS SQL DATA, or MODIFIES SQL DATA
clause. There is no interaction between the COMMIT ON RETURN clause in a
stored procedure definition and COMMIT or ROLLBACK statements in the stored
procedure code. If you specify COMMIT ON RETURN YES when you define the

598 Application Programming and SQL Guide

stored procedure, DB2 issues a COMMIT when control returns from the stored
procedure. This occurs regardless of whether the stored procedure contains
COMMIT or ROLLBACK statements.

A ROLLBACK statement has the same effect on cursors in a stored procedure as it

has on cursors in stand-alone programs. A ROLLBACK statement closes all open
cursors. A COMMIT statement in a stored procedure closes cursors that are not
declared WITH HOLD, and leaves cursors open that are declared WITH HOLD.
The effect of COMMIT or ROLLBACK on cursors applies to cursors that are
declared in the calling application, as well as cursors that are declared in the stored
procedure.

Under the following conditions, you cannot include COMMIT or ROLLBACK

statements in a stored procedure:
v The stored procedure is nested within a trigger or a user-defined function.
v The stored procedure is called by a client that uses two-phase commit
processing.
v The client program uses a type 2 connection to connect to the remote server that
contains the stored procedure.
v DB2 is not the commit coordinator.

If a COMMIT or ROLLBACK statement in a stored procedure violates any of the

previous conditions, DB2 puts the transaction in a must-rollback state, and the
CALL statement returns a -751 SQLCODE.

Special registers in a stored procedure

You can use all special registers in a stored procedure. However, you can modify
only some of those special registers. After a stored procedure completes, DB2
restores all special registers to the values they had before invocation.

Restrictions for stored procedures

When you work with stored procedures, make sure that you understand all of the
associated restrictions.

Stored procedures have the following restrictions:

v Do not include explicit attachment facility calls in an external stored procedure.
External stored procedures running in a WLM-established address space use
Resource Recovery Services attachment facility (RRSAF) calls implicitly. If an
external stored procedure makes an explicit attachment facility call, DB2 rejects
the call.
v Do not include SRRCMIT or SRRBACK service calls in an external stored
procedure. If an external stored procedure invokes either SRRCMIT or
SRRBACK, DB2 puts the transaction in a must roll back state and the CALL
statement returns SQLCODE -919.
| v Do not pass file reference variables as stored procedure parameters.
| v Do not pass parameters with the type XML to stored procedures. You can
| specify tables or views that contain XML columns as table locator parameters.
| However, you cannot reference the XML columns in the body of the stored
| procedure.

Chapter 10. Creating and modifying DB2 objects 599

Writing a program or stored procedure to receive the result
sets from a stored procedure
You can write a program to receive results sets from a stored procedure for either a
fixed number of result sets, for which you know the contents, or a variable number
of result sets, for which you do not know the contents.

The first alternative is simpler to write, but if you use the second alternative, you
do not need to make major modifications to your client program if the stored
procedure changes.

Writing for a fixed number of result sets is the only alternative in which you can
write an SQL procedure to return result sets.

The basic steps for receiving result sets are as follows:

1. Declare a locator variable for each result set that will be returned.
If you do not know how many result sets will be returned, declare enough
result set locators for the maximum number of result sets that might be
returned.
2. Call the stored procedure and check the SQL return code.
If the SQLCODE from the CALL statement is +466, the stored procedure has
returned result sets.
3. Determine how many result sets the stored procedure is returning.
If you already know how many result sets the stored procedure returns, you
can skip this step.
Use the SQL statement DESCRIBE PROCEDURE to determine the number of
result sets. DESCRIBE PROCEDURE places information about the result sets in
an SQLDA. Make this SQLDA large enough to hold the maximum number of
result sets that the stored procedure might return. When the DESCRIBE
PROCEDURE statement completes, the fields in the SQLDA contain the
following values:
v SQLD contains the number of result sets returned by the stored procedure.
v Each SQLVAR entry gives information about a result set. In an SQLVAR
entry:
– The SQLNAME field contains the name of the SQL cursor used by the
stored procedure to return the result set.
– The SQLIND field contains the value -1. This indicates that no estimate of
the number of rows in the result set is available.
– The SQLDATA field contains the value of the result set locator, which is
the address of the result set.
4. Link result set locators to result sets.
You can use the SQL statement ASSOCIATE LOCATORS to link result set
locators to result sets. The ASSOCIATE LOCATORS statement assigns values to
the result set locator variables. If you specify more locators than the number of
result sets returned, DB2 ignores the extra locators.
To use the ASSOCIATE LOCATORS statement, you must embed it in an
application or SQL procedure.
If you executed the DESCRIBE PROCEDURE statement previously, the result
set locator values are in the SQLDATA fields of the SQLDA. You can copy the
values from the SQLDATA fields to the result set locators manually, or you can
execute the ASSOCIATE LOCATORS statement to do it for you.

600 Application Programming and SQL Guide

The stored procedure name that you specify in an ASSOCIATE LOCATORS or
DESCRIBE PROCEDURE statement must match the stored procedure name in
the CALL statement that returns the result sets. That is:
v If the stored procedure name in ASSOCIATE LOCATORS or DESCRIBE
PROCEDURE is unqualified, the stored procedure name in the CALL
statement must be unqualified.
v If the stored procedure name in ASSOCIATE LOCATORS or DESCRIBE
PROCEDURE is qualified with a schema name, the stored procedure name in
the CALL statement must be qualified with a schema name.
v If the stored procedure name in ASSOCIATE LOCATORS or DESCRIBE
PROCEDURE is qualified with a location name and a schema name, the
stored procedure name in the CALL statement must be qualified with a
location name and a schema name.
5. Allocate cursors for fetching rows from the result sets.
Use the SQL statement ALLOCATE CURSOR to link each result set with a
cursor. Execute one ALLOCATE CURSOR statement for each result set. The
cursor names can be different from the cursor names in the stored procedure.
To use the ALLOCATE CURSOR statement, you must embed it in an
application or SQL procedure.
6. Determine the contents of the result sets.
If you already know the format of the result set, you can skip this step.
Use the SQL statement DESCRIBE CURSOR to determine the format of a result
set and put this information in an SQLDA. For each result set, you need an
SQLDA big enough to hold descriptions of all columns in the result set.
You can use DESCRIBE CURSOR only for cursors for which you executed
ALLOCATE CURSOR previously.
After you execute DESCRIBE CURSOR, if the cursor for the result set is
declared WITH HOLD, the high-order bit of the eighth byte of field SQLDAID
in the SQLDA is set to 1.
7. Fetch rows from the result sets into host variables by using the cursors that you
allocated with the ALLOCATE CURSOR statements.
If you executed the DESCRIBE CURSOR statement, perform these steps before
you fetch the rows:
a. Allocate storage for host variables and indicator variables. Use the contents
of the SQLDA from the DESCRIBE CURSOR statement to determine how
much storage you need for each host variable.
b. Put the address of the storage for each host variable in the appropriate
SQLDATA field of the SQLDA.
c. Put the address of the storage for each indicator variable in the appropriate
SQLIND field of the SQLDA.
Fetching rows from a result set is the same as fetching rows from a table.

You do not need to connect to the remote location when you execute these
statements:
v DESCRIBE PROCEDURE
v ASSOCIATE LOCATORS
v ALLOCATE CURSOR
v DESCRIBE CURSOR
v FETCH
v CLOSE

Chapter 10. Creating and modifying DB2 objects 601

The following examples show C language code that accomplishes each of these
steps. Coding for other languages is similar.

The following example demonstrates how you receive result sets when you know
how many result sets are returned and what is in each result set.
/*************************************************************/
/* Declare result set locators. For this example, */
/* assume you know that two result sets will be returned. */
/* Also, assume that you know the format of each result set. */
/*************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
static volatile SQL TYPE IS RESULT_SET_LOCATOR *loc1, *loc2;
EXEC SQL END DECLARE SECTION;
.
.
.
/*************************************************************/
/* Call stored procedure P1. */
/* Check for SQLCODE +466, which indicates that result sets */
/* were returned. */
/*************************************************************/
EXEC SQL CALL P1(:parm1, :parm2, ...);
if(SQLCODE==+466)
{
/*************************************************************/
/* Establish a link between each result set and its */
/* locator using the ASSOCIATE LOCATORS. */
/*************************************************************/
EXEC SQL ASSOCIATE LOCATORS (:loc1, :loc2) WITH PROCEDURE P1;
.
.
.
/*************************************************************/
/* Associate a cursor with each result set. */
/*************************************************************/
EXEC SQL ALLOCATE C1 CURSOR FOR RESULT SET :loc1;
EXEC SQL ALLOCATE C2 CURSOR FOR RESULT SET :loc2;
/*************************************************************/
/* Fetch the result set rows into host variables. */
/*************************************************************/
while(SQLCODE==0)
{
EXEC SQL FETCH C1 INTO :order_no, :cust_no;
.
.
.
}
while(SQLCODE==0)
{
EXEC SQL FETCH C2 :order_no, :item_no, :quantity;
.
.
.
}
}

The following example demonstrates how you receive result sets when you do not
know how many result sets are returned or what is in each result set.
/*************************************************************/
/* Declare result set locators. For this example, */
/* assume that no more than three result sets will be */
/* returned, so declare three locators. Also, assume */
/* that you do not know the format of the result sets. */
/*************************************************************/
EXEC SQL BEGIN DECLARE SECTION;
static volatile SQL TYPE IS RESULT_SET_LOCATOR *loc1, *loc2, *loc3;
EXEC SQL END DECLARE SECTION;

602 Application Programming and SQL Guide

.
.
.
/*************************************************************/
/* Call stored procedure P2. */
/* Check for SQLCODE +466, which indicates that result sets */
/* were returned. */
/*************************************************************/
EXEC SQL CALL P2(:parm1, :parm2, ...);
if(SQLCODE==+466)
{
/*************************************************************/
/* Determine how many result sets P2 returned, using the */
/* statement DESCRIBE PROCEDURE. :proc_da is an SQLDA */
/* with enough storage to accommodate up to three SQLVAR */
/* entries. */
/*************************************************************/
EXEC SQL DESCRIBE PROCEDURE P2 INTO :proc_da;
.
.
.
/*************************************************************/
/* Now that you know how many result sets were returned, */
/* establish a link between each result set and its */
/* locator using the ASSOCIATE LOCATORS. For this example, */
/* we assume that three result sets are returned. */
/*************************************************************/
EXEC SQL ASSOCIATE LOCATORS (:loc1, :loc2, :loc3) WITH PROCEDURE P2;
.
.
.
/*************************************************************/
/* Associate a cursor with each result set. */
/*************************************************************/
EXEC SQL ALLOCATE C1 CURSOR FOR RESULT SET :loc1;
EXEC SQL ALLOCATE C2 CURSOR FOR RESULT SET :loc2;
EXEC SQL ALLOCATE C3 CURSOR FOR RESULT SET :loc3;
/*************************************************************/
/* Use the statement DESCRIBE CURSOR to determine the */
/* format of each result set. */
/*************************************************************/
EXEC SQL DESCRIBE CURSOR C1 INTO :res_da1;
EXEC SQL DESCRIBE CURSOR C2 INTO :res_da2;
EXEC SQL DESCRIBE CURSOR C3 INTO :res_da3;
.
.
.
/*************************************************************/
/* Assign values to the SQLDATA and SQLIND fields of the */
/* SQLDAs that you used in the DESCRIBE CURSOR statements. */
/* These values are the addresses of the host variables and */
/* indicator variables into which DB2 will put result set */
/* rows. */
/*************************************************************/
.
.
.
/*************************************************************/
/* Fetch the result set rows into the storage areas */
/* that the SQLDAs point to. */
/*************************************************************/
while(SQLCODE==0)
{
EXEC SQL FETCH C1 USING :res_da1;
.
.
.
}
while(SQLCODE==0)
{
EXEC SQL FETCH C2 USING :res_da2;

Chapter 10. Creating and modifying DB2 objects 603

.
.
.
}
while(SQLCODE==0)
{
EXEC SQL FETCH C3 USING :res_da3;
.
.
.
}
}

| The following example demonstrates how you can use an SQL procedure to
| receive result sets. The logic assumes that no handler exists to intercept the +466
| SQLCODE, such as DECLARE CONTINUE HANDLER FOR SQLWARNING ..... Such a
| handler causes SQLCODE to be reset to zero. Then the test for IF SQLCODE = 466
| is never true and the statements in the IF body are never executed.
| DECLARE RESULT1 RESULT_SET_LOCATOR VARYING;
| DECLARE RESULT2 RESULT_SET_LOCATOR VARYING;
| DECLARE AT_END, VAR1, VAR2 INT DEFAULT 0;
| DECLARE SQLCODE INTEGER DEFAULT 0;
| DECLARE CONTINUE HANDLER FOR NOT FOUND SET AT_END = 99;
| SET TOTAL1 = 0;
| SET TOTAL2 = 0;
| CALL TARGETPROCEDURE();
| IF SQLCODE = 466 THEN
| ASSOCIATE RESULT SET LOCATORS(RESULT1,RESULT2)
| WITH PROCEDURE SPDG3091;
| ALLOCATE RSCUR1 CURSOR FOR RESULT1;
| ALLOCATE RSCUR2 CURSOR FOR RESULT2;
| WHILE AT_END = 0 DO
| FETCH RSCUR1 INTO VAR1;
| SET TOTAL1 = TOTAL1 + VAR1;
| SET VAR1 = 0; /* Reset so the last value fetched is not added after AT_END */
| END WHILE;
| SET AT_END = 0; /* Reset for next loop */
| WHILE AT_END = 0 DO
| FETCH RSCUR2 INTO VAR2;
| SET TOTAL2 = TOTAL2 + VAR2;
| SET VAR2 = 0; /* Reset so the last value fetched is not added after AT_END */
| END WHILE;
| END IF;
Related concepts
“Examples of programs that call stored procedures” on page 228

604 Application Programming and SQL Guide

Chapter 11. Adding and modifying data
Your application program can add, modify, or delete data in any DB2 table for
which you have the appropriate access.

Inserting data into tables

You can use several different methods to insert data into a table. Decide which
method to use based on the amount of data that you need to insert and the other
operations that your program needs to perform.

Besides using stand-alone INSERT statements, you can use the following ways to
insert data into a table:
| v You can user the MERGE statement to insert new data and update existing data
| in the same operation. For information about how to perform this operation, see
| “Inserting data and updating data in a single operation” on page 611.
v You can write an application program to prompt for and enter large amounts of
data into a table.
v You can also use the DB2 LOAD utility to enter data from other sources. For
information about the LOAD utility, see the topic “LOAD” in DB2 Utility Guide
and Reference.

Inserting rows by using the INSERT statement

One way to insert data into tables is to use the SQL INSERT statement. This
method is useful for inserting small amounts of data or data from another table or
view.

Use an INSERT statement to add new rows to a table or view. Using an INSERT
statement, you can do the following actions:
v Specify the column values to insert a single row. You can specify constants, host
variables, expressions, DEFAULT, or NULL by using the VALUES clause.
v In an application program, specify arrays of column values to insert multiple
rows into a table. “Inserting multiple rows of data from host variable arrays” on
page 160 explains how to use host variable arrays in the VALUES clause of the
INSERT FOR n ROWS statement to add multiple rows of column values to a
table.
v Include a SELECT statement in the INSERT statement to tell DB2 that another
table or view contains the data for the new row or rows. “Inserting rows into a
table from another table” on page 607 explains how to use the SELECT
statement within an INSERT statement to add multiple rows to a table.

In each case, for every row that you insert, you must provide a value for any
column that does not have a default value. For a column that meets one of the
following conditions, specify DEFAULT to tell DB2 to insert the default value for
that column:
v The column is nullable.
v The column is defined with a default value.
v The column has data type ROWID. ROWID columns always have default
values.
v The column is an identity column. Identity columns always have default values.
v The column is a row change timestamp column.

© Copyright IBM Corp. 1983, 2009 605

| The values that you can insert into a ROWID column, an identity column, or a row
| change timestamp column depend on whether the column is defined with
| GENERATED ALWAYS or GENERATED BY DEFAULT.

For more information about inserting data into ROWID columns, see “Rules for
inserting data into a ROWID column” on page 608.

For more information about inserting data into identity columns, see “Rules for
inserting data into an identity column” on page 608.

| Fore more information about row change timestamp columns, see the topic
| “CREATE TABLE” in DB2 SQL Reference.

Inserting a single row:

You can use the VALUES clause of the INSERT statement to insert a single row of
column values into a table. You can either name all of the columns for which you
are providing values, or you can omit the list of column names. If you omit the
column name list, you must specify values for all of the columns.

Recommendation: For static INSERT statements, name all of the columns for
which you are providing values for the following reasons:
v Your INSERT statement is independent of the table format. (For example, you do
not need to change the statement when a column is added to the table.)
v You can verify that you are specifying the values in order.
v Your source statements are more self-descriptive.

If you do not name the columns in a static INSERT statement, and a column is
added to the table, an error can occur if the INSERT statement is rebound. An
error will occur after any rebind of the INSERT statement unless you change the
INSERT statement to include a value for the new column. This is true even if the
new column has a default value.

When you list the column names, you must specify their corresponding values in
the same order as in the list of column names.

Example: The following statement inserts information about a new department

into the YDEPT table.
INSERT INTO YDEPT (DEPTNO, DEPTNAME, MGRNO, ADMRDEPT, LOCATION)
VALUES ('E31', 'DOCUMENTATION', '000010', 'E01', ' ');

After inserting a new department row into your YDEPT table, you can use a
SELECT statement to see what you have loaded into the table. The following SQL
statement shows you all of the new department rows that you have inserted:
SELECT *
FROM YDEPT
WHERE DEPTNO LIKE 'E%'
ORDER BY DEPTNO;

The result table looks similar to the following output:

DEPTNO DEPTNAME MGRNO ADMRDEPT LOCATION
====== ==================================== ====== ======== ===========
E01 SUPPORT SERVICES 000050 A00 -----------
E11 OPERATIONS 000090 E01 -----------
E21 SOFTWARE SUPPORT 000100 E01 -----------
E31 DOCUMENTATION 000010 E01 -----------

606 Application Programming and SQL Guide

Example: The following statement inserts information about a new employee into
the YEMP table. Because the WORKDEPT column is a foreign key, the value that is
inserted for that column (E31) must be a value in the primary key column, which
is DEPTNO in the YDEPT table.
INSERT INTO YEMP
VALUES ('000400', 'RUTHERFORD', 'B', 'HAYES', 'E31', '5678', '1998-01-01',
'MANAGER', 16, 'M', '1970-07-10', 24000, 500, 1900);

Example: The following statement also inserts a row into the YEMP table. Because
the unspecified columns allow null values, DB2 inserts null values into the
columns that you do not specify.
INSERT INTO YEMP
(EMPNO, FIRSTNME, MIDINIT, LASTNAME, WORKDEPT, PHONENO, JOB)
VALUES ('000410', 'MILLARD', 'K', 'FILLMORE', 'D11', '4888', 'MANAGER');

Inserting rows into a table from another table

You can copy one or more rows from one table into another table.

Use a fullselect within an INSERT statement to select rows from one table to insert
into another table.

Example: The following SQL statement creates a table named TELE:

CREATE TABLE TELE
(NAME2 VARCHAR(15) NOT NULL,
NAME1 VARCHAR(12) NOT NULL,
PHONE CHAR(4));

The following statement copies data from DSN8910.EMP into the newly created
table:
INSERT INTO TELE
SELECT LASTNAME, FIRSTNME, PHONENO
FROM DSN8910.EMP
WHERE WORKDEPT = 'D21';

The two previous statements create and fill a table, TELE, that looks similar to the
following table:
NAME2 NAME1 PHONE
=============== ============ =====
PULASKI EVA 7831
JEFFERSON JAMES 2094
MARINO SALVATORE 3780
SMITH DANIEL 0961
JOHNSON SYBIL 8953
PEREZ MARIA 9001
MONTEVERDE ROBERT 3780

The CREATE TABLE statement example creates a table which, at first, is empty.
The table has columns for last names, first names, and phone numbers, but does
not have any rows.

The INSERT statement fills the newly created table with data that is selected from
the DSN8910.EMP table: the names and phone numbers of employees in
department D21.

Example: The following CREATE statement creates a table that contains an

employee’s department name and phone number. The fullselect within the INSERT
statement fills the DLIST table with data from rows that are selected from two
existing tables, DSN8910.DEPT and DSN8910.EMP.

Chapter 11. Adding and modifying data 607

CREATE TABLE DLIST
(DEPT CHAR(3) NOT NULL,
DNAME VARCHAR(36) ,
LNAME VARCHAR(15) NOT NULL,
FNAME VARCHAR(12) NOT NULL,
INIT CHAR ,
PHONE CHAR(4) );
INSERT INTO DLIST
SELECT DEPTNO, DEPTNAME, LASTNAME, FIRSTNME, MIDINIT, PHONENO
FROM DSN8910.DEPT, DSN8910.EMP
WHERE DEPTNO = WORKDEPT;

Rules for inserting data into a ROWID column

A ROWID column contains unique values that identify each row in a table.
Whether you can insert data into a ROWID column and how that data gets
inserted depends on how the column is defined.

AROWID column is a column that is defined with a ROWID data type. You must
have a column with a ROWID data type in a table that contains a LOB column.
The ROWID column is stored in the base table and is used to look up the actual
LOB data in the LOB table space. In addition, a ROWID column enables you to
write queries that navigate directly to a row in a table. For information about using
ROWID columns for direct-row access, see “Specifying direct row access by using
row IDs” on page 702.

Before you insert data into a ROWID column, you must know how the ROWID
column is defined. ROWID columns can be defined as GENERATED ALWAYS or
GENERATED BY DEFAULT. GENERATED ALWAYS means that DB2 generates a
value for the column, and you cannot insert data into that column. If the column is
defined as GENERATED BY DEFAULT, you can insert a value, and DB2 provides a
default value if you do not supply one.

Example: Suppose that tables T1 and T2 have two columns: an integer column and
a ROWID column. For the following statement to run successfully, ROWIDCOL2
must be defined as GENERATED BY DEFAULT.
INSERT INTO T2 (INTCOL2,ROWIDCOL2)
SELECT * FROM T1;

If ROWIDCOL2 is defined as GENERATED ALWAYS, you cannot insert the

ROWID column data from T1 into T2, but you can insert the integer column data.
To insert only the integer data, use one of the following methods:
v Specify only the integer column in your INSERT statement, as in the following
statement:
INSERT INTO T2 (INTCOL2)
SELECT INTCOL1 FROM T1;
v Specify the OVERRIDING USER VALUE clause in your INSERT statement to tell
DB2 to ignore any values that you supply for system-generated columns, as in
the following statement:
INSERT INTO T2 (INTCOL2,ROWIDCOL2) OVERRIDING USER VALUE
SELECT * FROM T1;

Rules for inserting data into an identity column

An identity column contains a unique numeric value for each row in the table.
Whether you can insert data into an identity column and how that data gets
inserted depends on how the column is defined.

608 Application Programming and SQL Guide

An identity column is a numeric column, defined in a CREATE TABLE or ALTER
TABLE statement, that has ascending or descending values. For an identity column
to be as useful as possible, its values should also be unique. The column has a
SMALLINT, INTEGER, or DECIMAL(p,0) data type and is defined with the AS
IDENTITY clause. The AS IDENTITY clause specifies that the column is an identity
column. For information about using identity columns to uniquely identify rows,
see “Identity columns” on page 431

Before you insert data into an identity column, you must know how the column is
defined. Identity columns are defined with the GENERATED ALWAYS or
GENERATED BY DEFAULT clause. GENERATED ALWAYS means that DB2
generates a value for the column, and you cannot insert data into that column. If
the column is defined as GENERATED BY DEFAULT, you can insert a value, and
DB2 provides a default value if you do not supply one.

Example: Suppose that tables T1 and T2 have two columns: a character column
and an integer column that is defined as an identity column. For the following
statement to run successfully, IDENTCOL2 must be defined as GENERATED BY
DEFAULT.
INSERT INTO T2 (CHARCOL2,IDENTCOL2)
SELECT * FROM T1;

If IDENTCOL2 is defined as GENERATED ALWAYS, you cannot insert the identity

column data from T1 into T2, but you can insert the character column data. To
insert only the character data, use one of the following methods:
v Specify only the character column in your INSERT statement, as in the following
statement:
INSERT INTO T2 (CHARCOL2)
SELECT CHARCOL1 FROM T1;
v Specify the OVERRIDING USER VALUE clause in your INSERT statement to tell
DB2 to ignore any values that you supply for system-generated columns, as in
the following statement:
INSERT INTO T2 (CHARCOL2,IDENTCOL2) OVERRIDING USER VALUE
SELECT * FROM T1;

Restrictions when assigning values to columns with distinct

types
When assigning a column value to another column or a constant to a column of a
distinct type, the type of the value to be assigned must match the column type, or
you must be able to cast one type to the other. Otherwise, you cannot assign the
value.

If you need to assign a value of one distinct type to a column of another distinct
type, a function must exist that converts the value from one type to another.
Because DB2 provides cast functions only between distinct types and their source
types, you must write the function to convert from one distinct type to another.

Assigning column values to columns with different distinct types

Suppose tables JAPAN_SALES and JAPAN_SALES_03 are defined like this:

CREATE TABLE JAPAN_SALES
(PRODUCT_ITEM INTEGER,
MONTH INTEGER CHECK (MONTH BETWEEN 1 AND 12),
YEAR INTEGER CHECK (YEAR > 1990),
TOTAL JAPANESE_YEN);

Chapter 11. Adding and modifying data 609

CREATE TABLE JAPAN_SALES_03
(PRODUCT_ITEM INTEGER,
TOTAL US_DOLLAR);

You need to insert values from the TOTAL column in JAPAN_SALES into the
TOTAL column of JAPAN_SALES_03. Because INSERT statements follow
assignment rules, DB2 does not let you insert the values directly from one column
to the other because the columns are of different distinct types. Suppose that a
user-defined function called US_DOLLAR has been written that accepts values of
type JAPANESE_YEN as input and returns values of type US_DOLLAR. You can
then use this function to insert values into the JAPAN_SALES_03 table:
INSERT INTO JAPAN_SALES_03
SELECT PRODUCT_ITEM, US_DOLLAR(TOTAL)
FROM JAPAN_SALES
WHERE YEAR = 2003;

Assigning column values with distinct types to host variables

The rules for assigning distinct types to host variables or host variables to columns
of distinct types differ from the rules for constants and columns.

You can assign a column value of a distinct type to a host variable if you can
assign a column value of the distinct type’s source type to the host variable. In the
following example, you can assign SIZECOL1 and SIZECOL2, which has distinct
type SIZE, to host variables of type double and short because the source type of
SIZE, which is INTEGER, can be assigned to host variables of type double or short.
EXEC SQL BEGIN DECLARE SECTION;
double hv1;
short hv2;
EXEC SQL END DECLARE SECTION;
CREATE DISTINCT TYPE SIZE AS INTEGER;
CREATE
. TABLE TABLE1 (SIZECOL1 SIZE, SIZECOL2 SIZE);
.
.
SELECT SIZECOL1, SIZECOL2
INTO :hv1, :hv2
FROM TABLE1;

Assigning host variable values to columns with distinct types

When you assign a value in a host variable to a column with a distinct type, the
type of the host variable must be able to cast to the distinct type. For a table of
base data types and the base data types to which they can be cast, see the topic
“Promotion of data types” in DB2 SQL Reference.

In this example, values of host variable hv2 can be assigned to columns SIZECOL1
and SIZECOL2, because C data type short is equivalent to DB2 data type
SMALLINT, and SMALLINT is promotable to data type INTEGER. However,
values of hv1 cannot be assigned to SIZECOL1 and SIZECOL2, because C data
type double, which is equivalent to DB2 data type DOUBLE, is not promotable to
data type INTEGER.
EXEC SQL BEGIN DECLARE SECTION;
double hv1;
short hv2;
EXEC SQL END DECLARE SECTION;
CREATE DISTINCT TYPE SIZE AS INTEGER;
CREATE
. TABLE TABLE1 (SIZECOL1 SIZE, SIZECOL2 SIZE);
.
.
INSERT INTO TABLE1

610 Application Programming and SQL Guide

VALUES (:hv1,:hv1); /* Invalid statement */
INSERT INTO TABLE1
VALUES (:hv2,:hv2); /* Valid statement */

| Inserting data and updating data in a single operation

| You can update existing data and insert new data in a single operation. This
| operation is useful when you want to update a table with a set of rows, some of
| which are changes to existing rows and some of which are new rows.

| You can update existing data and insert new data in a single operation by using
| the MERGE statement.

| For example, an application might request a set of rows from a database, enable a
| user to modify the data through a GUI, and then store the modified data in the
| database. Some of this modified data is updates to existing rows, and some of this
| data is new rows. You can do these update and insert operations in one step.

| To update existing data and inserting new data, specify a MERGE statement with
| the WHEN MATCHED and WHEN NOT MATCHED clauses. These clauses
| specify how DB2 handles matched and unmatched data. If DB2 finds a matching
| row, that row is updated. If DB2 does not find a matching row, a new row is
| inserted.

| Example: Suppose that you need to update the inventory at a car dealership. You
| need to add new car models to the inventory and update information about car
| models that are already in the inventory.

| You could make these changes with the following series of statements:
| UPDATE INVENTORY
| SET QUANTITY = QUANTITY + :hv_delta
| WHERE MODEL = :hv_model;
|
| --begin pseudo code
| if sqlcode >= 0
| then do
| GD
| if rc = 0 then INSERT..
| end
| -- end pseudo code
|
| GET DIAGNOSTICS :rc = ROW_COUNT;
|
| IF rc = 0 THEN
| INSERT INTO INVENTORY VALUES (:hv_model, :hv_delta);
| END IF;

| The MERGE statement simplifies the update and the insert into a single statement:
| MERGE INTO INVENTORY
| USING ( VALUES (:hv_model, :hv_delta) ) AS SOURCE(MODEL, DELTA)
| ON INVENTORY.MODEL = SOURCE.MODEL
| WHEN MATCHED THEN UPDATE SET QUANTITY = QUANTITY + SOURCE.DELTA
| WHEN NOT MATCHED THEN INSERT VALUES (SOURCE.MODEL, SOURCE.DELTA)
| NOT ATOMIC CONTINUE ON SQLEXCEPTION;

| Selecting values while merging data

| When you update existing data and insert new data in a single merge operation,
| you can select values from those rows at the same time.

Chapter 11. Adding and modifying data 611

| You can select values from rows that are being merged by specifying the MERGE
| statement in the FROM clause of the SELECT statement. When you merge one or
| more rows into a table, you can retrieve:
| v The value of an automatically generated column such as a ROWID or identity
| column
| v Any default values for columns
| v All values for a merged row, without specifying individual column names
| v Calculated values based on the changes to merged rows
| Specify the FINAL TABLE clause with SELECT FROM MERGE statements. The
| FINAL TABLE consists of the rows of the table or view after the merge occurs.

| Example: Suppose that you need to input data into the STOCK table, which
| contains company stock symbols and stock prices from your stock portfolio. Some
| of your input data refers to companies that are already in the STOCK table; some
| of the data refers to companies that you are adding to your stock portfolio. If the
| stock symbol exists in the SYMBOL column of the STOCK table, you need to
| update the PRICE column. If the company stock symbol is not yet in the STOCK
| table, you need to insert a new row with the stock symbol and the stock price.
| Furthermore, you need to add a new value DELTA to your output to show the
| change in stock price.

| Suppose that the STOCK table contains the data that is shown in Table 105.
| Table 105. STOCK table before SELECT FROM MERGE statement
| SYMBOL PRICE
| XCOM 95.00
| YCOM 24.50
|

| Now, suppose that :hv_symbol and :hv_price are host variable arrays that contain
| updated data that corresponds to the data that is shown in Table 105. Table 106
| shows the host variable data for stock activity.
| Table 106. Host variable arrays of stock activity
| hv_symbol hv_price
| XCOM 97.00
| NEWC 30.00
| XCOM 107.00
|

| NEWC is new to the STOCK table, so its symbol and price need to be inserted into
| the STOCK table. The rows for XCOM in Table 106represent changed stock prices,
| so these values need to be updated in the STOCK table. Also, the output needs to
| show the change in stock prices as a DELTA value.

| The following SELECT FROM MERGE statement updates the price of XCOM,
| inserts the symbol and price for NEWC, and returns an output that includes a
| DELTA value for the change in stock price.
| SELECT SYMBOL, PRICE, DELTA FROM FINAL TABLE
| (MERGE INTO STOCK AS S INCLUDE (DELTA DECIMAL(5,20)
| USING ((:hv_symbol, :hv_price) FOR :hv_nrows ROWS) AS R (SYMBOL, PRICE)
| ON S.SYMBOL = R.SYMBOL
| WHEN MATCHED THEN UPDATE SET

612 Application Programming and SQL Guide

| DELTA = R.PRICE - S.PRICE, PRICE=R.PRICE
| WHEN NOT MATCHED THEN INSERT
| (SYMBOL, PRICE, DELTA) VALUES (R.SYMBOL, R.PRICE, R.PRICE)
| NOT ATOMIC CONTINUE ON SQLEXCEPTION);

| The INCLUDE clause specifies that an additional column, DELTA, can be returned
| in the output without adding a column to the STOCK table. The UPDATE portion
| of the MERGE statement sets the DELTA value to the differential of the previous
| stock price with the value set for the update operation. The INSERT portion of the
| MERGE statement sets the DELTA value to the same value as the PRICE column.

| After the SELECT FROM MERGE statement is processed, the STOCK table
| contains the data that is shown in Table 107.
| Table 107. STOCK table after SELECT FROM MERGE statement
| SYMBOL PRICE
| XCOM 107.00
| YCOM 24.50
| NEWC 30.00
|
| The following output of the SELECT FROM MERGE statement includes both
| updates to XCOM and a DELTA value for each output row.
| SYMBOL PRICE DELTA
| =============================
| XCOM 97.00 2.00
| NEWC 30.00 30.00
| XCOM 107.00 10.00

| Selecting values while inserting data

When you insert rows into a table, you can select values from those rows at the
same time.

You can select values from rows that are being inserted by specifying the INSERT
statement in the FROM clause of the SELECT statement. When you insert one or
more new rows into a table, you can retrieve:
v The value of an automatically generated column such as a ROWID or identity
column
v Any default values for columns
v All values for an inserted row, without specifying individual column names
v All values that are inserted by a multiple-row INSERT operation
v Values that are changed by a BEFORE INSERT trigger

Example: In addition to examples that use the DB2 sample tables, the examples in
this topic use an EMPSAMP table that has the following definition:
CREATE TABLE EMPSAMP
(EMPNO INTEGER GENERATED ALWAYS AS IDENTITY,
NAME CHAR(30),
SALARY DECIMAL(10,2),
DEPTNO SMALLINT,
LEVEL CHAR(30),
HIRETYPE VARCHAR(30) NOT NULL WITH DEFAULT 'New Hire',
HIREDATE DATE NOT NULL WITH DEFAULT);

Assume that you need to insert a row for a new employee into the EMPSAMP
table. To find out the values for the generated EMPNO, HIRETYPE, and
HIREDATE columns, use the following SELECT FROM INSERT statement:

Chapter 11. Adding and modifying data 613

SELECT EMPNO, HIRETYPE, HIREDATE
FROM FINAL TABLE (INSERT INTO EMPSAMP (NAME, SALARY, DEPTNO, LEVEL)
VALUES('Mary Smith', 35000.00, 11, 'Associate'));

The SELECT statement returns the DB2-generated identity value for the EMPNO
column, the default value ’New Hire’ for the HIRETYPE column, and the value of
the CURRENT DATE special register for the HIREDATE column.

Recommendation: Use the SELECT FROM INSERT statement to insert a row into a
parent table and retrieve the value of a primary key that was generated by DB2 (a
ROWID or identity column). In another INSERT statement, specify this generated
value as a value for a foreign key in a dependent table. For an example of this
method, see “Identity columns” on page 431.

Result table of the INSERT operation:

The rows that are inserted into the target table produce a result table whose
columns can be referenced in the SELECT list of the query. The columns of the
result table are affected by the columns, constraints, and triggers that are defined
for the target table:
v The result table includes DB2-generated values for identity columns, ROWID
columns, or row change timestamp columns.
v Before DB2 generates the result table, it enforces any constraints that affect the
insert operation (that is, check constraints, unique index constraints, and
referential integrity constraints).
v The result table includes any changes that result from a BEFORE trigger that is
activated by the insert operation. An AFTER trigger does not affect the values in
the result table. For information about triggers, see “Creating triggers” on page
457.

Example: Suppose that a BEFORE INSERT trigger is created on table EMPSAMP to

give all new employees at the Associate level a $5000 increase in salary. The trigger
has the following definition:
CREATE TRIGGER NEW_ASSOC
NO CASCADE BEFORE INSERT ON EMPSAMP
REFERENCING NEW AS NEWSALARY
FOR EACH ROW MODE DB2SQL
WHEN LEVEL = 'Associate'
BEGIN ATOMIC
SET NEWSALARY.SALARY = NEWSALARY.SALARY + 5000.00;
END;

The INSERT statement in the FROM clause of the following SELECT statement
inserts a new employee into the EMPSAMP table:
SELECT NAME, SALARY
FROM FINAL TABLE (INSERT INTO EMPSAMP (NAME, SALARY, LEVEL)
VALUES('Mary Smith', 35000.00, 'Associate'));

The SELECT statement returns a salary of 40000.00 for Mary Smith instead of the
initial salary of 35000.00 that was explicitly specified in the INSERT statement.

Selecting values when you insert a single row:

When you insert a new row into a table, you can retrieve any column in the result
table of the SELECT FROM INSERT statement. When you embed this statement in
an application, you retrieve the row into host variables by using the SELECT ...

614 Application Programming and SQL Guide

INTO form of the statement. For information about using host variables and
SELECT ... INTO, see “Rules for host variables in an SQL statement” on page 151.

Example: You can retrieve all the values for a row that is inserted into a structure:
EXEC SQL SELECT * INTO :empstruct
FROM FINAL TABLE (INSERT INTO EMPSAMP (NAME, SALARY, DEPTNO, LEVEL)
VALUES('Mary Smith', 35000.00, 11, 'Associate'));

For this example, :empstruct is a host variable structure that is declared with
variables for each of the columns in the EMPSAMP table.

Selecting values when you insert data into a view:

If the INSERT statement references a view that is defined with a search condition,
that view must be defined with the WITH CASCADED CHECK OPTION option.
When you insert data into the view, the result table of the SELECT FROM INSERT
statement includes only rows that satisfy the view definition.

Example: Because view V1 is defined with the WITH CASCADED CHECK

OPTION option, you can reference V1 in the INSERT statement:
CREATE VIEW V1 AS
SELECT C1, I1 FROM T1 WHERE I1 > 10
WITH CASCADED CHECK OPTION;

SELECT C1 FROM
FINAL TABLE (INSERT INTO V1 (I1) VALUES(12));

The value 12 satisfies the search condition of the view definition, and the result
table consists of the value for C1 in the inserted row.

If you use a value that does not satisfy the search condition of the view definition,
the insert operation fails, and DB2 returns an error.

Selecting values when you insert multiple rows:

In an application program, to retrieve values from the insertion of multiple rows,

declare a cursor so that the INSERT statement is in the FROM clause of the
SELECT statement of the cursor. For information about using cursors, see
“Retrieving a set of rows by using a cursor” on page 670.

Example: Inserting rows with ROWID values: To see the values of the ROWID
columns that are inserted into the employee photo and resume table, you can
declare the following cursor:
EXEC SQL DECLARE CS1 CURSOR FOR
SELECT EMP_ROWID
FROM FINAL TABLE (INSERT INTO DSN8910.EMP_PHOTO_RESUME (EMPNO)
SELECT EMPNO FROM DSN8910.EMP);

Example: Using the FETCH FIRST clause: To see only the first five rows that are
inserted into the employee photo and resume table, use the FETCH FIRST clause:
EXEC SQL DECLARE CS2 CURSOR FOR
SELECT EMP_ROWID
FROM FINAL TABLE (INSERT INTO DSN8910.EMP_PHOTO_RESUME (EMPNO)
SELECT EMPNO FROM DSN8910.EMP)
FETCH FIRST 5 ROWS ONLY;

Example: Using the INPUT SEQUENCE clause: To retrieve rows in the order in
which they are inserted, use the INPUT SEQUENCE clause:

Chapter 11. Adding and modifying data 615

EXEC SQL DECLARE CS3 CURSOR FOR
SELECT EMP_ROWID
FROM FINAL TABLE (INSERT INTO DSN8910.EMP_PHOTO_RESUME (EMPNO)
VALUES(:hva_empno)
FOR 5 ROWS)
ORDER BY INPUT SEQUENCE;

The INPUT SEQUENCE clause can be specified only if an INSERT statement is in

the FROM clause of the SELECT statement. In this example, the rows are inserted
from an array of employee numbers. For information about the multiple-row
INSERT statement, see “Inserting multiple rows of data from host variable arrays”
on page 160.

Example: Inserting rows with multiple encoding CCSIDs: Suppose that you want
to populate an ASCII table with values from an EBCDIC table and then see
selected values from the ASCII table. You can use the following cursor to select the
EBCDIC columns, populate the ASCII table, and then retrieve the ASCII values:
EXEC SQL DECLARE CS4 CURSOR FOR
SELECT C1, C2
FROM FINAL TABLE (INSERT INTO ASCII_TABLE
SELECT * FROM EBCDIC_TABLE);

Selecting an additional column when you insert data:

You can use the INCLUDE clause to introduce a new column to the result table but
not add a column to the target table.

Example: Suppose that you need to insert department number data into the project
table. Suppose also, that you want to retrieve the department number and the
corresponding manager number for each department. Because MGRNO is not a
column in the project table, you can use the INCLUDE clause to include the
manager number in your result but not in the insert operation. The following
SELECT FROM INSERT statement performs the insert operation and retrieves the
data.
DECLARE CS1 CURSOR FOR
SELECT manager_num, projname FROM FINAL TABLE
(INSERT INTO PROJ (DEPTNO) INCLUDE(manager_num CHAR(6))
SELECT DEPTNO, MGRNO FROM DEPT);

Result table of the cursor when you insert multiple rows:

In an application program, when you insert multiple rows into a table, you declare
a cursor so that the INSERT statement is in the FROM clause of the SELECT
statement of the cursor. The result table of the cursor is determined during OPEN
cursor processing. The result table may or may not be affected by other processes
in your application.

Effect on cursor sensitivity:

When you declare a scrollable cursor, the cursor must be declared with the
INSENSITIVE keyword if an INSERT statement is in the FROM clause of the
cursor specification. The result table is generated during OPEN cursor processing
and does not reflect any future changes. You cannot declare the cursor with the
SENSITIVE DYNAMIC or SENSITIVE STATIC keywords. For information about
cursor sensitivity, see “Types of cursors” on page 671.

Effect of searched updates and deletes:

616 Application Programming and SQL Guide

When you declare a non-scrollable cursor, any searched updates or deletes do not
affect the result table of the cursor. The rows of the result table are determined
during OPEN cursor processing.

Example: Assume that your application declares a cursor, opens the cursor,
performs a fetch, updates the table, and then fetches additional rows:
EXEC SQL DECLARE CS1 CURSOR FOR
SELECT SALARY
FROM FINAL TABLE (INSERT INTO EMPSAMP (NAME, SALARY, LEVEL)
SELECT NAME, INCOME, BAND FROM OLD_EMPLOYEE);
EXEC SQL OPEN CS1;
EXEC SQL FETCH CS1 INTO :hv_salary;
/* print fetch result */
...
EXEC SQL UPDATE EMPSAMP SET SALARY = SALARY + 500;
while (SQLCODE == 0) {
EXEC SQL FETCH CS1 INTO :hv_salary;
/* print fetch result */
...
}

The fetches that occur after the updates return the rows that were generated when
the cursor was opened. If you use a simple SELECT (with no INSERT statement in
the FROM clause), the fetches might return the updated values, depending on the
access path that DB2 uses.

Effect of WITH HOLD:

When you declare a cursor with the WITH HOLD option and open the cursor, all
of the rows are inserted into the target table. The WITH HOLD option has no
effect on the SELECT FROM INSERT statement of the cursor definition. After your
application performs a commit, you can continue to retrieve all of the inserted
rows. For information about held cursors, see “Held and non-held cursors” on
page 673.

Example: Assume that the employee table in the DB2 sample application has five
rows. Your application declares a WITH HOLD cursor, opens the cursor, fetches
two rows, performs a commit, and then fetches the third row successfully:
EXEC SQL DECLARE CS2 CURSOR WITH HOLD FOR
SELECT EMP_ROWID
FROM FINAL TABLE (INSERT INTO DSN8910.EMP_PHOTO_RESUME (EMPNO)
SELECT EMPNO FROM DSN8910.EMP);
EXEC SQL OPEN CS2; /* Inserts 5 rows */
EXEC SQL FETCH CS2 INTO :hv_rowid; /* Retrieves ROWID for 1st row */
EXEC SQL FETCH CS2 INTO :hv_rowid; /* Retrieves ROWID for 2nd row */
EXEC SQL COMMIT; /* Commits 5 rows */
EXEC SQL FETCH CS2 INTO :hv_rowid; /* Retrieves ROWID for 3rd row */

Effect of SAVEPOINT and ROLLBACK:

A savepoint is a point in time within a unit of recovery to which relational

database changes can be rolled back. You can set a savepoint with the SAVEPOINT
statement.

When you set a savepoint prior to opening the cursor and then roll back to that
savepoint, all of the insertions are undone. For information about savepoints and
ROLLBACK processing, see “Undoing selected changes within a unit of work by
using savepoints” on page 28.

Chapter 11. Adding and modifying data 617

Example: Assume that your application declares a cursor, sets a savepoint, opens
the cursor, sets another savepoint, rolls back to the second savepoint, and then rolls
back to the first savepoint:
EXEC SQL DECLARE CS3 CURSOR FOR
SELECT EMP_ROWID
FROM FINAL TABLE (INSERT INTO DSN8910.EMP_PHOTO_RESUME (EMPNO)
SELECT EMPNO FROM DSN8910.EMP);
EXEC SQL SAVEPOINT A ON ROLLBACK RETAIN CURSORS; /* Sets 1st savepoint */
EXEC SQL OPEN CS3;
EXEC SQL SAVEPOINT B ON ROLLBACK RETAIN CURSORS; /* Sets 2nd savepoint */
...
EXEC SQL ROLLBACK TO SAVEPOINT B; /* Rows still in DSN8910.EMP_PHOTO_RESUME */
...
EXEC SQL ROLLBACK TO SAVEPOINT A; /* All inserted rows are undone */

What happens if an error occurs: In an application program, when you insert one
or more rows into a table by using the SELECT FROM INSERT statement, the
result table of the insert operation may or may not be affected, depending on
where the error occurred in the application processing.

During SELECT INTO processing: If the insert processing or the select processing
fails during a SELECT INTO statement, no rows are inserted into the target table,
and no rows are returned from the result table of the insert operation.

Example: Assume that the employee table of the DB2 sample application has one
row, and that the SALARY column has a value of 9 999 000.00.
EXEC SQL SELECT EMPNO INTO :hv_empno
FROM FINAL TABLE (INSERT INTO EMPSAMP (NAME, SALARY)
SELECT FIRSTNAME || MIDINIT || LASTNAME,
SALARY + 10000.00
FROM DSN8910.EMP)

The addition of 10000.00 causes a decimal overflow to occur, and no rows are
inserted into the EMPSAMP table.

During OPEN cursor processing: If the insertion of any row fails during the
OPEN cursor processing, all previously successful insertions are undone. The result
table of the insert is empty.

During FETCH processing: If the FETCH statement fails while retrieving rows
from the result table of the insert operation, a negative SQLCODE is returned to
the application, but the result table still contains the original number of rows that
was determined during the OPEN cursor processing. At this point, you can undo
all of the inserts.

Example: Assume that the result table contains 100 rows and the 90th row that is
being fetched from the cursor returns a negative SQLCODE:
EXEC SQL DECLARE CS1 CURSOR FOR
SELECT EMPNO
FROM FINAL TABLE (INSERT INTO EMPSAMP (NAME, SALARY)
SELECT FIRSTNAME || MIDINIT || LASTNAME, SALARY + 10000.00
FROM DSN8910.EMP);
EXEC SQL OPEN CS1; /* Inserts 100 rows */
while (SQLCODE == 0)
EXEC SQL FETCH CS1 INTO :hv_empno;
if (SQLCODE == -904) /* If SQLCODE is -904, undo all inserts */
EXEC SQL ROLLBACK;
else /* Else, commit inserts */
EXEC SQL COMMIT;

618 Application Programming and SQL Guide

| Preserving the order of a derived table
| When you specify SELECT FROM INSERT, SELECT FROM UPDATE, SELECT
| FROM DELETE, or SELECT FROM MERGE, you can preserve the order of the
| derived table. This action ensures that the result rows of a fullselect follow the
| same order as the result table of a subquery within the fullselect.

| To preserve the order of the derived table specify the ORDER OF clause with the
| ORDER BY clause. These two clauses ensure that the result rows of a fullselect
| follow the same order as the result table of a subquery within the fullselect.

| You can use the ORDER OF clause in any query that uses an ORDER BY clause,
| but the ORDER OF clause is most useful with queries that contain a set operator,
| such as UNION.

| Example: The following example retrieves the following rows:

| v Rows of table T1 in no specified order
| v Rows of table T2 in the order of the first column in table T2
| The example query then performs a UNION ALL operation on the results of the
| two subqueries. The ORDER BY ORDER OF UTABLE clause in the query specifies
| that the fullselect result rows are to be returned in the same order as the result
| rows of the UNION ALL statement.
| SELECT * FROM
| (SELECT * FROM T1
| UNION ALL
| (SELECT * FROM T2 ORDER BY 1)
| ) AS UTABLE
| ORDER BY ORDER OF UTABLE;

| Example: The following example joins data from table T1 to the result table of a
| nested table expression. The nested table expression is ordered by the second
| column in table T2. The ORDER BY ORDER OF TEMP clause in the query specifies
| that the fullselect result rows are to be returned in the same order as the nested
| table expression.
| SELECT T1.C1, T1.C2, TEMP.Cy, TEMP.Cx
| FROM T1, (SELECT T2.C1, T2.C2 FROM T2 ORDER BY 2) as TEMP(Cx, Cy)
| WHERE Cy = T1.C1
| ORDER BY ORDER OF TEMP;

| Alternatively, you can produce the same result by explicitly stating the ORDER BY
| column TEMP.Cy in the fullselect instead of using the ORDER OF syntax.
| SELECT T1.C1, T1.C2, TEMP.Cy, TEMP.Cx
| FROM T1, (SELECT T2.C1, T2.C2 FROM T2 ORDER BY 2) as TEMP(Cx, Cy)
| WHERE Cy = T1.C1
| ORDER BY TEMP.Cy;
|
Adding data to the end of a table
In a relational database, the rows of a table are not ordered, and thus, the table has
no “end”. However, depending on your goal, you can perform several actions to
simulate adding data to the end of a table.

Question: How can I add data to the end of a table?

Answer: Though the question is often asked, it has no meaning in a relational

database. The rows of a base table are not ordered; hence, the table does not have
an “end”.

Chapter 11. Adding and modifying data 619

| However, depending on your goal, you can perform one of the following actions to
| simulate adding data to the end of a table:
| v If your goal is to get a result table that is ordered according to when the rows
| were inserted, define a unique index on a TIMESTAMP column in the table
| definition. Then, when you retrieve data from the table, use an ORDER BY
| clause that names that column. The newest insert appears last.
| v If your goal is for DB2 to insert rows in the next available free space, without
| preserving clustering order, specify the APPEND YES option when you create or
| alter the table. Specifying this option might reduce the time it takes to insert
| rows, because DB2 does not spend time searching for free space.

Storing data that does not have a tabular format

DB2 provides several options for you to store large volumes of data that is not
defined as a set of columns in a table.

Question: How can I store a large volume of data that is not defined as a set of
columns in a table?

| Answer: You can store the data in a table in a binary string, a LOB, or an XML
| column.

Updating table data

You can change a column value to another value or remove it altogether.

To change the data in a table, use the UPDATE statement. You can also use the
UPDATE statement to remove a value from a column (without removing the row)
by changing the column value to null.

Example: Suppose that an employee relocates. To update several items of the

employee’s data in the YEMP work table to reflect the move, you can execute the
following statement:
UPDATE YEMP
SET JOB = 'MANAGER ',
PHONENO ='5678'
WHERE EMPNO = '000400';

You cannot update rows in a created temporary table, but you can update rows in
a declared temporary table.

The SET clause names the columns that you want to update and provides the
values that you want to assign to those columns. You can replace a column value
in the SET clause with any of the following items:
v A null value
The column to which you assign the null value must not be defined as NOT
NULL.
v An expression, which can be any of the following items:
– A column
– A constant
– A scalar fullselect
– A host variable
– A special register
| v A default value

620 Application Programming and SQL Guide

| If you specify DEFAULT, DB2 determines the value based on how the
| corresponding column is defined in the table.

In addition, you can replace one or more column values in the SET clause with the
column values in a row that is returned by a fullselect.

Next, identify the rows to update:

v To update a single row, use a WHERE clause that locates one, and only one,
row.
v To update several rows, use a WHERE clause that locates only the rows that you
want to update.

If you omit the WHERE clause, DB2 updates every row in the table or view with
the values that you supply.

If DB2 finds an error while executing your UPDATE statement (for example, an
update value that is too large for the column), it stops updating and returns an
error. No rows in the table change. Rows that were already changed, if any, are
restored to their previous values. If the UPDATE statement is successful,
SQLERRD(3) is set to the number of rows that are updated.

Example: The following statement supplies a missing middle initial and changes
the job for employee 000200.
UPDATE YEMP
SET MIDINIT = 'H', JOB = 'FIELDREP'
WHERE EMPNO = '000200';

The following statement gives everyone in department D11 a raise of 400.00. The
statement can update several rows.
UPDATE YEMP
SET SALARY = SALARY + 400.00
WHERE WORKDEPT = 'D11';

The following statement sets the salary for employee 000190 to the average salary
and sets the bonus to the minimum bonus for all employees.
UPDATE YEMP
SET (SALARY, BONUS) =
(SELECT AVG(SALARY), MIN(BONUS)
FROM EMP)
WHERE EMPNO = '000190';

| Selecting values while updating data

| When you update rows in a table, you can select the updated values from those
| rows at the same time.

| You can select values from rows that are being updated by specifying the UPDATE
| statement in the FROM clause of the SELECT statement. When you update one or
| more rows in a table, you can retrieve:
| v The value of an automatically generated column such as a ROWID or identity
| column
| v Any default values for columns
| v All values for an updated row, without specifying individual column names
| In most cases, you want to use the FINAL TABLE clause with SELECT FROM
| UPDATE statements. The FINAL TABLE consists of the rows of the table or view
| after the update occurs.

Chapter 11. Adding and modifying data 621

| Example: Suppose that all clerks for a company are receiving 5 percent raises. You
| can use the following SELECT FROM UPDATE statement to increase the salary of
| each designer by 5 percent and to retrieve the total increase in salary for the
| company.
| SELECT SUM(SALARY) INTO :salary FROM FINAL TABLE
| (UPDATE EMP SET SALARY = SALARY * 1.05
| WHERE JOB = 'DESIGNER');

| To retrieve row-by-row output of updated data, use a cursor with a SELECT

| FROM UPDATE statement.

| Example: Suppose that all designers for a company are receiving a 30 percent
| increase in their bonus. You can use the following SELECT FROM UPDATE
| statement to increase the bonus of each clerk by 30 percent and to retrieve the
| bonus for each clerk.
| DECLARE CS1 CURSOR FOR
| SELECT LASTNAME, BONUS FROM FINAL TABLE
| (UPDATE EMP SET BONUS = BONUS * 1.3
| WHERE JOB = 'CLERK');
| FETCH CS1 INTO :lastname, :bonus;

| You can use the INCLUDE clause to introduce a new column to the result table but
| not add the column to the target table.

| Example: Suppose that sales representatives received a 20 percent increase in their

| commission. You need to update the commission (COMM) of sales representatives
| (SALESREP) in the EMP table and that you need to retrieve the old commission
| and the new commission for each sales representative. You can use the following
| SELECT FROM UPDATE statement to perform the update and to retrieve the
| required data.
| DECLARE CS2 CURSOR FOR
| SELECT LASTNAME, COMM, old_comm FROM FINAL TABLE
| (UPDATE EMP INCLUDE(old_comm DECIMAL (7,2))
| SET COMM = COMM * 1.2, old_comm = COMM
| WHERE JOB = 'SALESREP');

| Updating thousands of rows

When updating large volumes of data, consider the recommended actions to
increase concurrency.

Question: Are there any special techniques for updating large volumes of data?

Answer: Yes. When updating large volumes of data using a cursor, you can
minimize the amount of time that you hold locks on the data by declaring the
cursor with the HOLD option and by issuing commits frequently.

Deleting data from tables

You can delete one or more rows that meet a condition that you specify.

You can use the DELETE statement to remove entire rows from a table. The
DELETE statement removes zero or more rows of a table, depending on how many
rows satisfy the search condition that you specify in the WHERE clause. If you
omit a WHERE clause from a DELETE statement, DB2 removes all rows from the
table or view that you have named. The DELETE statement does not remove
specific columns from the row.

622 Application Programming and SQL Guide

You can use DELETE to remove all rows from a created temporary table or
declared temporary table. You can use DELETE with a WHERE clause to remove
only selected rows from a declared temporary table.

| An alternative to the DELETE statement is the TRUNCATE statement.

This DELETE statement deletes each row in the YEMP table that has an employee
number 000060.
DELETE FROM YEMP
WHERE EMPNO = '000060';

When this statement executes, DB2 deletes any row from the YEMP table that
meets the search condition.

If DB2 finds an error while executing your DELETE statement, it stops deleting
data and returns error codes in the SQLCODE and SQLSTATE host variables or
related fields in the SQLCA. The data in the table does not change.

If the DELETE is successful, SQLERRD(3) in the SQLCA contains the number of

deleted rows. This number includes only the number of deleted rows in the table
that is specified in the DELETE statement. Rows that are deleted (in other tables)
according to the CASCADE rule are not included in SQLERRD(3).

Deleting every row in a table:

The DELETE statement is a powerful statement that deletes all rows of a table
unless you specify a WHERE clause to limit it. (With segmented table spaces,
deleting all rows of a table is very fast.) For example, the following statement
deletes every row in the YDEPT table:
DELETE FROM YDEPT;

If the statement executes, the table continues to exist (that is, you can insert rows
into it), but it is empty. All existing views and authorizations on the table remain
intact when using DELETE. By comparison, using DROP TABLE drops all views
and authorizations, which can invalidate plans and packages. For information
about the DROP statement, see “Dropping tables” on page 449.

| Alternatively, you can use the TRUNCATE statement to delete all of the rows in a
| table. A TRUNCATE statement can provide the following advantages over a
| DELETE statement:
| v The TRUNCATE statement can ignore delete triggers
| v The TRUNCATE statement can perform an immediate commit
| v The TRUNCATE statement can keep storage allocated for the table

| The TRUNCATE statement does not, however, reset the count for an automatically
| generated value for an identity column on the table. If 14872 was the next identity
| column value to be generated before a TRUNCATE statement, 14872 would be the
| next value generated after the TRUNCATE statement.

| The following examples demonstrate how to use the TRUNCATE statement with
| various keywords.

| Example: Suppose that you need to empty the data from an old inventory table,
| regardless of any existing delete triggers, and that you need to make the space that
| is allocated for the table available for other uses. Use the following statement.

Chapter 11. Adding and modifying data 623

| TRUNCATE INVENTORY_TABLE
| IGNORE DELETE TRIGGERS
| DROP STORAGE;

| Example: Suppose that you need to empty the data from an old inventory table
| permanently, regardless of any existing delete triggers, and that you need to
| preserve the space that is allocated for the table. You need the emptied data to be
| completely unavailable, so that a ROLLBACK statement cannot return the data.
| Use the following statement.
| TRUNCATE INVENTORY_TABLE
| REUSE STORAGE
| IGNORE DELETE TRIGGERS
| IMMEDIATE;

| Selecting values while deleting data

| When you delete rows in a table, you can select the values from those rows at the
| same time.

| You can select values from rows that are being deleted by specifying the DELETE
| statement in the FROM clause of the SELECT statement. When you delete one or
| more rows in a table, you can retrieve:
| v Any default values for columns
| v All values for a deleted row, without specifying individual column names
| v Calculated values based on deleted rows
| When you use a SELECT FROM DELETE statement, you must use the FROM OLD
| TABLE clause to retrieve deleted values. The OLD TABLE consists of the rows of
| the table or view before the delete occurs.

| Example: Suppose that a company is eliminating all operator positions and that
| the company wants to know how much salary money it will save by eliminating
| these positions. You can use the following SELECT FROM DELETE statement to
| delete operators from the EMP table and to retrieve the sum of operator salaries.
| SELECT SUM(SALARY) INTO :salary FROM OLD TABLE
| (DELETE FROM EMP
| WHERE JOB = 'OPERATOR');

| To retrieve row-by-row output of deleted data, use a cursor with a SELECT FROM
| DELETE statement.

| Example: Suppose that a company is eliminating all analyst positions and that the
| company wants to know how many years of experience each analyst had with the
| company. You can use the following SELECT FROM DELETE statement to delete
| analysts from the EMP table and to retrieve the experience of each analyst.
| DECLARE CS1 CURSOR FOR
| SELECT YEAR(CURRENT DATE - HIREDATE) FROM OLD TABLE
| (DELETE FROM EMP
| WHERE JOB = 'ANALYST');
| FETCH CS1 INTO :years_of_service;

| If you need to retrieve calculated data based on the data that you delete but not
| add that column to the target table.

| Example: Suppose that you need to delete managers from the EMP table and that
| you need to retrieve the salary and the years of employment for each manager.
| You can use the following SELECT FROM DELETE statement to perform the delete
| operation and to retrieve the required data.

624 Application Programming and SQL Guide

| DECLARE CS2 CURSOR FOR
| SELECT LASTNAME, SALARY, years_employed FROM OLD TABLE
| (DELETE FROM EMP INCLUDE(years_employed INTEGER)
| SET years_employed = YEAR(CURRENT DATE - HIREDATE)
| WHERE JOB = 'MANAGER');

Chapter 11. Adding and modifying data 625

626 Application Programming and SQL Guide
Chapter 12. Accessing data
Your program can use a number of different techniques to read data from any DB2
tables for which you have read access. The simplest technique is to use basic SQL
SELECT statements. However, you should choose the technique that works best for
your situation and performs well.

Determining which tables you have access to

You can ask DB2 to list the tables that a specific authorization ID has access to.

The contents of the DB2 catalog tables can be a useful reference tool when you
begin to develop an SQL statement or an application program.

The catalog table, SYSIBM.SYSTABAUTH, lists table privileges that are granted to
authorization IDs. To display the tables that you have authority to access (by
privileges granted either to your authorization ID or to PUBLIC), you can execute
an SQL statement similar to the one shown in the following example. To do this,
you must have the SELECT privilege on SYSIBM.SYSTABAUTH.

Example: The following statement displays the tables that the current user has
authority to access:
SELECT DISTINCT TCREATOR, TTNAME
FROM SYSIBM.SYSTABAUTH
WHERE GRANTEE IN (USER, 'PUBLIC', 'PUBLIC*') AND GRANTEETYPE = ' ';

In this query, the predicate GRANTEETYPE = ' ' selects authorization IDs.

Exception: If your DB2 subsystem uses an exit routine for access control
authorization, you cannot rely on catalog queries to tell you the tables that you can
access. When such an exit routine is installed, both RACF and DB2 control table
access.

Displaying information about the columns for a given table

You can ask DB2 to list the columns in particular table and certain information
about those columns.

The catalog table, SYSIBM.SYSCOLUMNS, describes every column of every table.

Example: Suppose that you want to display information about table

DSN8910.DEPT. If you have the SELECT privilege on SYSIBM.SYSCOLUMNS, you
can use the following statement:
SELECT NAME, COLTYPE, SCALE, LENGTH
FROM SYSIBM.SYSCOLUMNS
WHERE TBNAME = 'DEPT'
AND TBCREATOR = 'DSN8910';

If you display column information about a table that includes LOB or ROWID
columns, the LENGTH field for those columns contains the number of bytes that
those column occupy in the base table. The LENGTH field does not contain the
length of the LOB or ROWID data.

© Copyright IBM Corp. 1983, 2009 627

Example: To determine the maximum length of data for a LOB or ROWID column,
include the LENGTH2 column in your query:
SELECT NAME, COLTYPE, LENGTH, LENGTH2
FROM SYSIBM.SYSCOLUMNS
WHERE TBNAME = 'EMP_PHOTO_RESUME'
AND TBCREATOR = 'DSN8910';

Retrieving data by using the SELECT statement

The simplest way to retrieve data is to use the SQL SELECT statement to specify a
result table. You can specify the columns and rows that you want to retrieve.

| Consider developing SQL statements similar to the examples in this section, and
| then running them dynamically using SPUFI, the command line processor, or DB2
| Query Management Facility (DB2 QMF).

For more advanced topics on using SELECT statements, see “Subqueries” on page
659, and “Remote servers and distributed data” on page 32.

| You do not need to know the column names to select DB2 data. Use an asterisk (*)
| in the SELECT clause to indicate that you want to retrieve all columns of each
| selected row of the named table. Implicitly hidden columns, such as ROWID
| columns and XML document ID columns, are not included in the result of the
| SELECT * statement. To view the values of these columns, you must specify the
| column name.

Example: SELECT *: The following SQL statement selects all columns from the
department table:
SELECT *
FROM DSN8910.DEPT;

The result table looks similar to the following output:

DEPTNO DEPTNAME MGRNO ADMRDEPT LOCATION
====== ============================== ====== ======== ========
A00 SPIFFY COMPUTER SERVICES DIV. 000010 A00 --------
B01 PLANNING 000020 A00 --------
C01 INFORMATION CENTER 000030 A00 --------
D01 DEVELOPMENT CENTER ------ A00 --------
D11 MANUFACTURING CENTER 000060 D01 --------
D21 ADMINISTRATION SYSTEMS 000070 D01 --------
E01 SUPPORT SERVICES 000050 A00 --------
E11 OPERATIONS 000090 E01 --------
E21 SOFTWARE SUPPORT 000100 E01 --------
F22 BRANCH OFFICE F2 ------ E01 --------
G22 BRANCH OFFICE G2 ------ E01 --------
H22 BRANCH OFFICE H2 ------ E01 --------
I22 BRANCH OFFICE I2 ------ E01 --------
J22 BRANCH OFFICE J2 ------ E01 --------

Because the example does not specify a WHERE clause, the statement retrieves
data from all rows.

The dashes for MGRNO and LOCATION in the result table indicate null values.

SELECT * is recommended mostly for use with dynamic SQL and view definitions.
You can use SELECT * in static SQL, but doing so is not recommended because of
host variable compatibility and performance reasons.

628 Application Programming and SQL Guide

Example: Suppose that you add a column to the table to which SELECT * refers. If
you have not defined a receiving host variable for that column, an error occurs.

If you list the column names in a static SELECT statement instead of using an
asterisk, you can avoid the problem that sometimes occurs with SELECT *. You can
also see the relationship between the receiving host variables and the columns in
the result table.

For more information about host variables, see “Host variables” on page 143.

Selecting some columns: SELECT column-name:

Select the column or columns you want to retrieve by naming each column. All
columns appear in the order you specify, not in their order in the table.

Example: SELECT column-name: The following SQL statement retrieves only the
MGRNO and DEPTNO columns from the department table:
SELECT MGRNO, DEPTNO
FROM DSN8910.DEPT;

The result table looks similar to the following output:

MGRNO DEPTNO
====== ======
000010 A00
000020 B01
000030 C01
------ D01
000050 E01
000060 D11
000070 D21
000090 E11
000100 E21
------ F22
------ G22
------ H22
------ I22
------ J22

With a single SELECT statement, you can select data from one column or as many
as 750 columns.

| To SELECT data from implicitly hidden columns, such as ROWID and XML
| document ID, look up the column names in SYSIBM.SYSCOLUMNS and specify
| these names in the SELECT list. For example, suppose that you create and
| populate the following table:
| CREATE TABLE MEMBERS (MEMBERID INTEGER,
| BIO XML,
| REPORT XML,
| RECOMMENDATIONS XML);

| DB2 generates one additional implicitly hidden XML document ID column. To

| retrieve data in all columns, including the generated XML document ID column,
| first look up the name of the generated column in SYSIBM.SYSCOLUMNS.
| Suppose the name is DB2_GENERATED_DOCID_FOR_XML. Then, specify the
| following statement:
| SELECT DB2_GENERATED_DOCID_FOR_XML, MEMBERID, BIO,
| REPORT, RECOMMENDATIONS FROM MEMBERS

| Selecting rows using search conditions: WHERE:

Chapter 12. Accessing data 629

Use a WHERE clause to select the rows that meet certain conditions. A WHERE
clause specifies a search condition. A search condition consists of one or more
predicates. A predicate specifies a test that you want DB2 to apply to each table
row.

DB2 evaluates a predicate for each row as true, false, or unknown. Results are
unknown only if an operand is null.

If a search condition contains a column of a distinct type, the value to which that
column is compared must be of the same distinct type, or you must cast the value
to the distinct type. See “Distinct types” on page 477 for more information about
distinct types.

The following table lists the type of comparison, the comparison operators, and an
example of each type of comparison that you can use in a predicate in a WHERE
clause.
Table 108. Comparison operators used in conditions
Type of comparison Comparison operator Example
Equal to = DEPTNO = ’X01’
Not equal to <> DEPTNO <> ’X01’
Less than < AVG(SALARY) < 30000
Less than or equal to <= AGE <= 25
Not less than >= AGE >= 21
Greater than > SALARY > 2000
Greater than or equal to >= SALARY >= 5000
Not greater than <= SALARY <= 5000
Equal to null IS NULL PHONENO IS NULL
Not equal to another IS DISTINCT FROM PHONENO IS DISTINCT FROM
value or one value is :PHONEHV
equal to null
Similar to another value LIKE NAME LIKE ’ or STATUS LIKE ’N_’
At least one of two OR HIREDATE < ’1965-01-01’ OR SALARY
conditions < 16000
Both of two conditions AND HIREDATE < ’1965-01-01’ AND
SALARY < 16000
Between two values BETWEEN SALARY BETWEEN 20000 AND 40000
Equals a value in a set IN (X, Y, Z) DEPTNO IN (’B01’, ’C01’, ’D01’)
Note: SALARY BETWEEN 20000 AND 40000 is equivalent to SALARY >= 20000 AND
SALARY <= 40000. For more information about predicates, see the topic “Predicates” in DB2
SQL Reference.

You can also search for rows that do not satisfy one of the preceding conditions by
using the NOT keyword before the specified condition.

You can search for rows that do not satisfy the IS DISTINCT FROM predicate by
using either of the following predicates:
v value 1 IS NOT DISTINCT FROM value 2
v NOT(value 1 IS DISTINCT FROM value 2)

630 Application Programming and SQL Guide

Both of these forms of the predicate create an expression for which one value is
equal to another value or both values are equal to null.

Selecting derived columns

In an SQL SELECT statement, you can select columns that are not actual columns
in a table. Instead, you can specify “columns” that are derived from a constant, an
expression, or a function.

Example: SELECT with an expression: This SQL statement generates a result table
in which the second column is a derived column that is generated by adding the
values of the SALARY, BONUS, and COMM columns.
SELECT EMPNO, (SALARY + BONUS + COMM)
FROM DSN8910.EMP;

Derived columns in a result table, such as (SALARY + BONUS + COMM), do not

have names. You can use the AS clause to give a name to an unnamed column of
the result table. For information about using the AS clause, see “Naming result
columns” on page 633.

To order the rows in a result table by the values in a derived column, specify a
name for the column by using the AS clause, and specify that name in the ORDER
BY clause. For information about using the ORDER BY clause, see “Ordering the
result table rows” on page 634.

| Selecting XML data

| You can select all XML data that is stored in a particular column or only a subset
| of data from an XML column.

| You can select all XML data that is stored in a particular column by specifying
| SELECT column name or SELECT *, just as you would for columns of any other
| data type. Alternatively, you can select only a subset of data from an XML column
| by using an XPath expression in a SELECT statement. XPath expressions identify
| specific nodes in an XML document. For more information about XPath, see the
| topic “DB2 XPath basics” in DB2 XML Guide.

| To select a subset of data in an XML column, specify the XMLQUERY function in

| your SELECT statement with the following parameters:
| v An XPath expression that is embedded in a character string constant. Specify an
| XPath expression that identifies which XML data to return.
| v Any additional values to pass to the XPath expression, including the XML
| column name. Specify these values after the PASSING keyword.
| For more information about the syntax of the XMLQUERY function, see the topic
| “XMLQUERY” in DB2 SQL Reference.

| Example: Suppose that you store purchase orders as XML documents in the
| POrder column in the PurchaseOrders table. You need to find in each purchase
| order the items whose product name is equal to a name in the Product table. You
| can use the following statement to find these values:
| SELECT XMLQUERY('//item[productName = $n]'
| PASSING PO.POrder,
| P.name AS "n")
| FROM PurchaseOrders PO, Product P;

Chapter 12. Accessing data 631

| This statement returns the item elements in the POrder column that satisfy the
| criteria in the XPath expression.

Formatting the result table

An SQL statement returns data in a table called a result table. You can specify
certain attributes of the result table, such as the column names, how the rows are
ordered, and whether the rows are numbered.

Result tables
The data that is retrieved by an SQL statement is always in the form of a table,
which is called a result table. Like the tables from which you retrieve the data, a
result table has rows and columns. A program fetches this data one row at a time.

Example result table: Assume that you issue the following SELECT statement,
which retrieves the last name, first name, and phone number of employees in
department D11 from the sample employee table:
SELECT LASTNAME, FIRSTNME, PHONENO
FROM DSN8910.EMP
WHERE WORKDEPT = 'D11'
ORDER BY LASTNAME;

The result table looks similar to the following output:

LASTNAME FIRSTNME PHONENO
================ ============== ==========
ADAMSON BRUCE 4510
BROWN DAVID 4501
JOHN REBA 0672
JONES WILLIAM 0942
LUTZ JENNIFER 0672
PIANKA ELIZABETH 3782
SCOUTTEN MARILYN 1682
STERN IRVING 6432
WALKER JAMES 2986
YAMAMOTO KIYOSHI 2890
YOSHIMURA MASATOSHI 2890

Eliminating redundant duplicate rows in the result table

If a query result table contains multiple identical rows, you can ask DB2 to remove
these redundant rows. For example, a query might return multiple rows for each
employee when one row per employee is sufficient for your program.

The DISTINCT keyword removes redundant duplicate rows from your result table,
so that each row contains unique data.

Example: SELECT DISTINCT: The following SELECT statement lists unique

department numbers for administrative departments:
SELECT DISTINCT ADMRDEPT
FROM DSN8910.DEPT;

The result table looks similar to the following output:

ADMRDEPT
========
A00
D01
E01

| Restriction: You cannot use the DISTINCT keyword with LOB columns or XML
| columns.

632 Application Programming and SQL Guide

Naming result columns
You can provide your own names for the result table columns for a SELECT
statement. This capability is particularly useful for a column that is derived from
an expression or a function.

With the AS clause, you can name result columns in a SELECT statement. For
more information about the syntax of the AS clause, see the topic “select-clause” in
DB2 SQL Reference.

The following examples show different ways to use the AS clause.

Example: SELECT with AS CLAUSE: The following example of the SELECT

statement gives the expression SALARY+BONUS+COMM the name TOTAL_SAL.
SELECT SALARY+BONUS+COMM AS TOTAL_SAL
FROM DSN8910.EMP
ORDER BY TOTAL_SAL;

Example: CREATE VIEW with AS clause: You can specify result column names in
the select-clause of a CREATE VIEW statement. You do not need to supply the
column list of CREATE VIEW, because the AS keyword names the derived column.
The columns in the view EMP_SAL are EMPNO and TOTAL_SAL.
CREATE VIEW EMP_SAL AS
SELECT EMPNO,SALARY+BONUS+COMM AS TOTAL_SAL
FROM DSN8910.EMP;

For more information about using the CREATE VIEW statement, see “Defining a
view” on page 449.

Example: set operator with AS clause: You can use the AS clause with set
operators, such as UNION. In this example, the AS clause is used to give the same
name to corresponding columns of tables in a UNION. The third result column
from the union of the two tables has the name TOTAL_VALUE, even though it
contains data that is derived from columns with different names:
SELECT 'On hand' AS STATUS, PARTNO, QOH * COST AS TOTAL_VALUE
FROM PART_ON_HAND
UNION ALL
SELECT 'Ordered' AS STATUS, PARTNO, QORDER * COST AS TOTAL_VALUE
FROM ORDER_PART
ORDER BY PARTNO, TOTAL_VALUE;

The column STATUS and the derived column TOTAL_VALUE have the same name
in the first and second result tables. They are combined in the union of the two
result tables, which is similar to the following partial output:
STATUS PARTNO TOTAL_VALUE
======= ====== ===========
On hand 00557 345.60
Ordered 00557 150.50
.
.
.

For information about unions, see “Combining result tables from multiple SELECT
statements” on page 637.

Example: GROUP BY derived column: You can use the AS clause in a FROM clause
to assign a name to a derived column that you want to refer to in a GROUP BY
clause. This SQL statement names HIREYEAR in the nested table expression,
which lets you use the name of that result column in the GROUP BY clause:

Chapter 12. Accessing data 633

SELECT HIREYEAR, AVG(SALARY)
FROM (SELECT YEAR(HIREDATE) AS HIREYEAR, SALARY
FROM DSN8910.EMP) AS NEWEMP
GROUP BY HIREYEAR;

You cannot use GROUP BY with a name that is defined with an AS clause for the
derived column YEAR(HIREDATE) in the outer SELECT, because that name does
not exist when the GROUP BY runs. However, you can use GROUP BY with a
name that is defined with an AS clause in the nested table expression, because the
nested table expression runs before the GROUP BY that references the name. For
more information about using the GROUP BY clause, see “Summarizing group
values” on page 642.

Ordering the result table rows

If you want to guarantee that the rows in your result table are ordered in a
particular way, you must specify the order in the SELECT statement. Otherwise,
DB2 can return the rows in any order.

To retrieve rows in a specific order, use the ORDER BY clause. Using ORDER BY is
the only way to guarantee that your rows are ordered as you want them. The
following topics show you how to use the ORDER BY clause.

Specifying the sort key in the ORDER BY clause:

The order of the selected rows depends on the sort keys that you identify in the
ORDER BY clause. A sort key can be a column name, an integer that represents the
number of a column in the result table, or an expression. DB2 orders the rows by
the first sort key, followed by the second sort key, and so on.

You can list the rows in ascending or descending order. Null values appear last in
an ascending sort and first in a descending sort.

| DB2 sorts strings in the collating sequence associated with the encoding scheme of
| the table. DB2 sorts numbers algebraically and sorts datetime values
| chronologically.

| Restriction: You cannot use the ORDER BY clause with LOB or XML columns.

Example: ORDER BY clause with a column name as the sort key: Retrieve the
employee numbers, last names, and hire dates of employees in department A00 in
ascending order of hire dates:
SELECT EMPNO, LASTNAME, HIREDATE
FROM DSN8910.EMP
WHERE WORKDEPT = 'A00'
ORDER BY HIREDATE ASC;

The result table looks similar to the following output:

EMPNO LASTNAME HIREDATE
===== ========= ==========
000110 LUCCHESI 1958-05-16
000120 O'CONNELL 1963-12-05
000010 HAAS 1965-01-01
200010 HEMMINGER 1965-01-01
200120 ORLANDO 1972-05-05

Example: ORDER BY clause with an expression as the sort key: The following
subselect retrieves the employee numbers, salaries, commissions, and total

634 Application Programming and SQL Guide

compensation (salary plus commission) for employees with a total compensation
greater than 40000. Order the results by total compensation:
SELECT EMPNO, SALARY, COMM, SALARY+COMM AS "TOTAL COMP"
FROM DSN8910.EMP
WHERE SALARY+COMM > 40000
ORDER BY SALARY+COMM;

The intermediate result table looks similar to the following output:

EMPNO SALARY COMM TOTAL COMP
====== ======== ======= ==========
000030 38250.00 3060.00 41310.00
000050 40175.00 3214.00 43389.00
000020 41250.00 3300.00 44550.00
000110 46500.00 3720.00 50220.00
200010 46500.00 4220.00 50720.00
000010 52750.00 4220.00 56970.00

Referencing derived columns in the ORDER BY clause:

If you use the AS clause to name an unnamed column in a SELECT statement, you
can use that name in the ORDER BY clause.

Example: ORDER BY clause that uses a derived column: The following SQL
statement orders the selected information by total salary:
SELECT EMPNO, (SALARY + BONUS + COMM) AS TOTAL_SAL
FROM DSN8910.EMP
ORDER BY TOTAL_SAL;

| Numbering the rows in a result table

| DB2 does not number the rows in the result table for a query unless you explicitly
| request that the rows be numbered.

| To number the rows in a result table, include the ROW_NUMBER specification in

| your query. If you want to ensure that the rows are in a particular order, include
| an ORDER BY clause after the OVER keyword. Otherwise, the rows are numbered
| in an arbitrary order.

| Example: Suppose that you want a list of employees and salaries from department
| D11 in the sample EMP table. You can return a numbered list that is ordered by
| last name by submitting the following query:
| SELECT ROW_NUMBER() OVER (ORDER BY LASTNAME) AS NUMBER,
| WORKDEPT, LASTNAME, SALARY
| FROM DSN8910.EMP
| WHERE WORKDEPT='D11'

| This query returns the following result:

| ---------+---------+---------+---------+---------+---------+-----
| NUMBER WORKDEPT LASTNAME SALARY
| ---------+---------+---------+---------+---------+---------+-----
| 1 D11 ADAMSON 25280.00
| 2 D11 BROWN 27740.00
| 3 D11 JOHN 29840.00
| 4 D11 JONES 18270.00
| 5 D11 LUTZ 29840.00
| 6 D11 PIANKA 22250.00
| 7 D11 SCOUTTEN 21340.00
| 8 D11 STERN 32250.00
| 9 D11 WALKER 20450.00
| 10 D11 YAMAMOTO 24680.00
| 11 D11 YOSHIMURA 24680.00

Chapter 12. Accessing data 635

| For more information bout the syntax of the ROW_NUMBER specification, see the
| topic “OLAP specification” in DB2 SQL Reference.

| Ranking the rows

| You can request that DB2 calculate the ordinal rank of each row in the result set
| based on a particular column. For example, you can rank finishing times for a
| marathon to determine the first, second, and third place finishers.

| To rank rows, use one of the following ranking specifications in an SQL statement:
| RANK
| Returns a rank number for each row value. Use this specification if you
| want rank numbers to be skipped when duplicate row values exist. For
| example, suppose the top five finishers in a marathon have the following
| times:
| v 2:31:57
| v 2:34:52
| v 2:34:52
| v 2:37:26
| v 2:38:01
| When you use the RANK specification, DB2 returns the following rank
| numbers:
| Table 109. Example of values returned when you specify RANK
| Value Rank number
| 2:31:57 1
| 2:34:52 2
| 2:34:52 2
| 2:37:26 4
| 2:38:01 5
|
| DENSE_RANK
| Returns a rank number for each row value. Use this specification if you do
| not want rank numbers to be skipped when duplicate row values exist. For
| example, when you specify DENSE_RANK with the same times that are
| listed in the description of RANK, DB2 returns the following rank
| numbers:
| Table 110. Example of values returned when you specify RANK
| Value Rank number
| 2:31:57 1
| 2:34:52 2
| 2:34:52 2
| 2:37:26 3
| 2:38:01 4
|

| Example: Suppose that you had the following values in the DATA column of table
| T1:
| DATA
| -------
| 100

636 Application Programming and SQL Guide

| 35
| 23
| 8
| 8
| 6

| Suppose that you use the following RANK specification:

| SELECT DATA,
| RANK() OVER (ORDER BY DATA DESC) AS RANK_DATA
| FROM T1
| ORDER BY RANK_DATA;

| DB2 returns the following ranked data:

| DATA RANK_DATA
| -------------------
| 100 1
| 35 2
| 23 3
| 8 4
| 8 4
| 6 6

| Suppose that you use the following DENSE_RANK specification on the same data:
| SELECT DATA,
| DENSE_RANK() OVER (ORDER BY DATA DESC) AS RANK_DATA
| FROM T1
| ORDER BY RANK_DATA;

| DB2 returns the following ranked data:

| DATA RANK_DATA
| -------------------
| 100 1
| 36 2
| 23 3
| 8 4
| 8 4
| 6 5

| In the example with the RANK specification, two equal values are both ranked as
| 4. The next rank number is 6. Number 5 is skipped.

| In the example with the DENSE_RANK option, those two equal values are also
| ranked as 4. However, the next rank number is 5. With DENSE_RANK, no gaps
| exist in the sequential rank numbering.

| For more information about the syntax of the RANK and DENSE_RANK
| specifications, see the topic “OLAP-specification” in DB2 SQL Reference.

| Combining result tables from multiple SELECT statements

| When you combine the results of multiple SELECT statements, you can choose
| whether you want the result table to include all rows, only rows that are in the
| result table of both SELECT statements, or only rows that are unique to the result
| table of the first SELECT statement.

| To combine two or more SELECT statements to form a single result table, use one
| of the following key words:
| UNION
| Returns all of the values from the result table of each SELECT statement. If

Chapter 12. Accessing data 637

| you want all duplicate rows to be repeated in the result table, specify
| UNION ALL. If you want redundant duplicate rows to be eliminated from
| the result table, specify UNION or UNION DISTINCT.
| EXCEPT
| Returns all rows from the first result table (R1) that are not also in the
| second result table (R2). If you want all duplicate rows from R1 to be
| contained in the result table, specify EXCEPT ALL. If you want redundant
| duplicate rows in R1 to be eliminated from the result table, specify
| EXCEPT or EXCEPT DISTINCT.
| INTERSECT
| Returns rows that are in the result table of both SELECT statements. If you
| want all duplicate rows to be contained in the result table, specify
| INTERSECT ALL. If you want redundant duplicate rows to be eliminated
| from the result table, specify INTERSECT or INTERSECT DISTINCT.

| When you specify one of the preceding set operators (UNION, EXCEPT, or
| INTERSECT), DB2 processes each SELECT statement to form an interim result
| table, and then combines the interim result table of each statement. If the nth
| column of the first result table (R1) and the nth column of the second result table
| (R2) have the same result column name, the nth column of the result table has that
| same result column name. If the nth column of R1 and the nth column of R2 do
| not have the same names, the result column is unnamed.

| Examples: Assume that you want to combine the results of two SELECT statements
| that return the following result tables:
| R1 result table
| COL1 COL2
| a a
| a b
| a c
| R2 result table
| COL1 COL2
| a b
| a c
| a d
| A UNION operation combines the two result tables and returns four rows:
| COL1 COL2
| a a
| a b
| a c
| a d
| An EXCEPT operation combines the two result tables and returns one row
| The result of the EXCEPT operation depends on the which SELECT
| statement is included before the EXCEPT keyword in the SQL statement. If
| the SELECT statement that returns the R1 result table is listed first, the
| result is a single row:
| COL1 COL2
| a a

| If the SELECT statement that returns the R2 result table is listed first, the
| final result is a different row:
| COL1 COL2
| a d
| An INTERSECT operation combines the two result tables and returns two rows:
|
638 Application Programming and SQL Guide
| COL1 COL2
| a b
| a c

| Eliminating redundant duplicate rows when combining result tables:

| To eliminate redundant duplicate rows when combining result tables, specify one
| of the following keywords:
| v UNION or UNION DISTINCT
| v EXCEPT or EXCEPT DISTINCT
| v INTERSECT or INTERSECT DISTINCT

| To order the entire result table, specify the ORDER BY clause at the end.

| Examples: Assume that you have the following tables to manage stock at two book
| stores.
| Table 111. STOCKA
| ISBN TITLE AUTHOR NOBEL PRIZE
| 8778997709 For Whom the Bell Tolls Hemmingway N
| 4599877699 The Good Earth Buck Y
| 9228736278 A Tale of Two Cities Dickens N
| 1002387872 Beloved Morrison Y
| 4599877699 The Good Earth Buck Y
| 0087873532 The Labyrinth of Solitude Paz Y
|
| Table 112. STOCKB
| ISBN TITLE AUTHOR NOBEL PRIZE
| 6689038367 The Grapes of Wrath Steinbeck Y
| 2909788445 The Silent Cry Oe Y
| 1182983745 Light in August Faulkner Y
| 9228736278 A Tale of Two Cities Dickens N
| 1002387872 Beloved Morrison Y
|

| Example 1: UNION clause: Suppose that you want a list of books whose authors
| have won the Nobel Prize and that are in stock at either store. The following SQL
| statement returns these books in order by author name without redundant
| duplicate rows:
| SELECT TITLE, AUTHOR
| FROM STOCKA
| WHERE NOBELPRIZE = 'Y'
| UNION
| SELECT TITLE, AUTHOR
| FROM STOCKB
| WHERE NOBELPRIZE = 'Y'
| ORDER BY AUTHOR

Chapter 12. Accessing data 639

| This statement returns the following final result table:
| Table 113. Result of UNION
| TITLE AUTHOR
| The Good Earth Buck
| Light in August Faulkner
| Beloved Morrison
| The Silent Cry Oe
| The Labyrinth of Solitude Paz
| The Grapes of Wrath Steinbeck
|

| Example 2: EXCEPT : Suppose that you want a list of books that are only in
| STOCKA. The following SQL statement returns the book names that are in
| STOCKA only without any redundant duplicate rows:
| SELECT TITLE
| FROM STOCKA
| EXCEPT
| SELECT TITLE
| FROM STOCKB
| ORDER BY TITLE;

| This statement returns the following result table:

| Table 114. Result of EXCEPT
| TITLE
| For Whom the Bell Tolls
| The Good Earth
| The Labyrinth of Solitude
|

| Example 3: INTERSECT: Suppose that you want a list of books that are in both
| STOCKA and in STOCKB. The following statement returns a list of all books from
| both of these tables with redundant duplicate rows are removed
| SELECT TITLE
| FROM STOCKA
| INTERSECT
| SELECT TITLE
| FROM STOCKB
| ORDER BY TITLE;

| This statement returns the following result table:

| Table 115. Result of INTERSECT
| TITLE
| A Tale of Two Cities
| Beloved
|

| Keeping all duplicate rows when combining result tables:

| To keep all duplicate rows when combining result tables, specify ALL with one of
| the following set operator keywords:
| v UNION ALL

640 Application Programming and SQL Guide

| v EXCEPT ALL
| v INTERSECT ALL

| To order the entire result table, specify the ORDER BY clause at the end.

| Examples: The following examples use the STOCKA and STOCK B tables.

| Example: UNION ALL: The following SQL statement returns a list of books that
| won Nobel prizes and are in stock at either store, with duplicates included
| SELECT TITLE, AUTHOR
| FROM STOCKA
| WHERE NOBELPRIZE = 'Y'
| UNION ALL
| SELECT TITLE, AUTHOR
| FROM STOCKB
| WHERE NOBELPRIZE = 'Y'
| ORDER BY AUTHOR

| This statement returns the following result table:

| Table 116. Result of UNION ALL
| TITLE AUTHOR
| The Good Earth Buck
| The Good Earth Buck
| Light in August Faulkner
| Beloved Morrison
| Beloved Morrison
| The Silent Cry Oe
| The Labyrinth of Solitude Paz
| The Grapes of Wrath Steinbeck
|

| Example: EXCEPT ALL: Suppose that you want a list of books that are only in
| STOCKA. The following SQL statement returns the book names that are in
| STOCKA only with all duplicate rows:
| SELECT TITLE
| FROM STOCKA
| EXCEPT ALL
| SELECT TITLE
| FROM STOCKB
| ORDER BY TITLE;

| This statement returns the following result table:

| Table 117. Result of EXCEPT ALL
| TITLE
| For Whom the Bell Tolls
| The Good Earth
| The Good Earth
| The Labyrinth of Solitude
|

| Example: INTERSECT ALL clause: Suppose that you want a list of books that are
| in both STOCKA and in STOCKB, including any duplicate matches. The following

Chapter 12. Accessing data 641

| statement returns a list of titles that are in both stocks, including duplicate
| matches. In this case, one match exists for ″A Tale of Two Cities″ and one match
| exists for ″Beloved.″
| SELECT TITLE
| FROM STOCKA
| INTERSECT ALL
| SELECT TITLE
| FROM STOCKB
| ORDER BY TITLE;

| This statement returns the following result table:

| Table 118. Result of INTERSECT ALL
| TITLE
| A Tale of Two Cities
| Beloved
|

| Summarizing group values

You can group rows in the result table by the values of one or more columns or by
the results of an expression. You can then apply aggregate functions to each group.

To summarize group values, use GROUP BY.

Except for the columns that are named in the GROUP BY clause, the SELECT
statement must specify any other selected columns as an operand of one of the
aggregate functions.

Example: GROUP BY clause using one column: The following SQL statement lists,
for each department, the lowest and highest education level within that
department:
SELECT WORKDEPT, MIN(EDLEVEL), MAX(EDLEVEL)
FROM DSN8910.EMP
GROUP BY WORKDEPT;

If a column that you specify in the GROUP BY clause contains null values, DB2
considers those null values to be equal. Thus, all nulls form a single group.

When it is used, the GROUP BY clause follows the FROM clause and any WHERE
clause, and it precedes the ORDER BY clause.

You can group the rows by the values of more than one column.

Example: GROUP BY clause using more than one column: The following statement
finds the average salary for men and women in departments A00 and C01:
SELECT WORKDEPT, SEX, AVG(SALARY) AS AVG_SALARY
FROM DSN8910.EMP
WHERE WORKDEPT IN ('A00', 'C01')
GROUP BY WORKDEPT, SEX;

The result table looks similar to the following output:

WORKDEPT SEX AVG_SALARY
======== === ==============
A00 F 49625.00000000
A00 M 35000.00000000
C01 F 29722.50000000

642 Application Programming and SQL Guide

DB2 groups the rows first by department number and then (within each
department) by sex before it derives the average SALARY value for each group.

You can also group the rows by the results of an expression

Example: GROUP BY clause using a expression: The following statement groups

departments by their leading characters, and lists the lowest and highest education
level for each group:
SELECT SUBSTR(WORKDEPT,1,1), MIN(EDLEVEL), MAX(EDLEVEL)
FROM DSN8910.EMP
GROUP BY SUBSTR(WORKDEPT,1,1);

Filtering groups
If you group rows in the result table, you can also specify a search condition that
each retrieved group must satisfy. The search condition tests properties of each
group rather than properties of individual rows in the group.

To filter groups, use the HAVING clause to specify a search condition. The
HAVING clause acts like a WHERE clause for groups, and it contains the same
kind of search conditions that you specify in a WHERE clause.

Example: HAVING clause: The following SQL statement includes a HAVING clause
that specifies a search condition for groups of work departments in the employee
table:
SELECT WORKDEPT, AVG(SALARY) AS AVG_SALARY
FROM DSN8910.EMP
GROUP BY WORKDEPT
HAVING COUNT(*) > 1
ORDER BY WORKDEPT;

The result table looks similar to the following output:

WORKDEPT AVG_SALARY
======== ==============
A00 40850.00000000
C01 29722.50000000
D11 25147.27272727
D21 25668.57142857
E11 21020.00000000
E21 24086.66666666

Compare the preceding example with the second example shown in “Summarizing
group values” on page 642. The clause, HAVING COUNT(*) > 1, ensures that only
departments with more than one member are displayed. In this case, departments
B01 and E01 do not display because the HAVING clause tests a property of the
group.

Example: HAVING clause used with a GROUP BY clause: Use the HAVING clause
to retrieve the average salary and minimum education level of women in each
department for which all female employees have an education level greater than or
equal to 16. Assuming that you want results from only departments A00 and D11,
the following SQL statement tests the group property, MIN(EDLEVEL):
SELECT WORKDEPT, AVG(SALARY) AS AVG_SALARY,
MIN(EDLEVEL) AS MIN_EDLEVEL
FROM DSN8910.EMP
WHERE SEX = 'F' AND WORKDEPT IN ('A00', 'D11')
GROUP BY WORKDEPT
HAVING MIN(EDLEVEL) >= 16;

Chapter 12. Accessing data 643

The result table looks similar to the following output:
WORKDEPT AVG_SALARY MIN_EDLEVEL
======== ============== ===========
A00 49625.00000000 18
D11 25817.50000000 17

When you specify both GROUP BY and HAVING, the HAVING clause must follow
the GROUP BY clause. A function in a HAVING clause can include DISTINCT if
you have not used DISTINCT anywhere else in the same SELECT statement. You
can also connect multiple predicates in a HAVING clause with AND or OR, and
you can use NOT for any predicate of a search condition.

| Finding rows that were changed within a specified period of

| time
| You can filter rows based on the time that they were updated. For example, you
| might want to find all rows in a particular table that have been changed in the last
| 7 days.

| To find the rows that were changed within a specified period of time, specify the
| ROW CHANGE TIMESTAMP expression in the predicate of your SQL statement.
| For more information about the syntax of ROW CHANGE TIMESTAMP
| expression, see the topic “ROW CHANGE expression” inDB2 SQL Reference.

| Recommendation: Ensure that the table has a ROW CHANGE TIMESTAMP

| column that was defined prior to the time period that you want to query. This
| column ensures that DB2 returns only those rows that were updated in the given
| time period. For more information about how to create a table with a ROW
| CHANGE TIMESTAMP column, see the topic “CREATE TABLE” inDB2 SQL
| Reference.

| If the table does not have a ROW CHANGE TIMESTAMP column, DB2 returns all
| rows on each page that has had any changes within the given time period. In this
| case, your result set can contain rows that have not been updated in the give time
| period, if other rows on that page have been updated or inserted.

| Example: Suppose that the TAB table has a ROW CHANGE TIMESTAMP column
| and that you want to return all of the records that have changed in the last 30
| days. The following query returns all of those rows.
| SELECT * FROM TAB
| WHERE ROW CHANGE TIMESTAMP FOR TAB <= CURRENT TIMESTAMP AND
| ROW CHANGE TIMESTAMP FOR TAB >= CURRENT TIMESTAMP - 30 days;

| Example: Suppose that you want to return all of the records that have changed
| since 9:00 AM January 1, 2004. The following query returns all of those rows.
| SELECT * FROM TAB
| WHERE ROW CHANGE TIMESTAMP FOR TAB >= '2004-01-01-09.00.00';

| Joining data from more than one table

Sometimes the information that you want to see is not in a single table. To form a
row of the result table, you might want to retrieve some column values from one
table and some column values from another table.

You can use a SELECT statement to retrieve and join column values from two or
more tables into a single row.

644 Application Programming and SQL Guide

A join operation typically matches a row of one table with a row of another on the
basis of a join condition. DB2 supports the following types of joins: inner join, left
outer join, right outer join, and full outer join. You can specify joins in the FROM
clause of a query.

Nested table expressions and user-defined table functions in joins:

An operand of a join can be more complex than the name of a single table. You
can specify one of the following items as a join operand:
nested table expression
A fullselect that is enclosed in parentheses and followed by a correlation name.
The correlation name lets you refer to the result of that expression.
Using a nested table expression in a join can be helpful when you want to
create a temporary table to use in a join. You can specify the nested table
expression as either the right or left operand of a join, depending on which
unmatched rows you want included.
user-defined table function
A user-defined function that returns a table.
Using a nested table expression in a join can be helpful when you want to
perform some operation on the values in a table before you join them to
another table.

Example of using correlated references: In the following SELECT statement, the

correlation name that is used for the nested table expression is CHEAP_PARTS.
You can use this correlation name to refer to the columns that are returned by the
expression. In this case, those correlated references are CHEAP_PARTS.PROD# and
CHEAP_PARTS.PRODUCT.
SELECT CHEAP_PARTS.PROD#, CHEAP_PARTS.PRODUCT
FROM (SELECT PROD#, PRODUCT
FROM PRODUCTS
WHERE PRICE < 10) AS CHEAP_PARTS;

The result table looks similar to the following output:

PROD# PRODUCT
===== ===========
505 SCREWDRIVER
30 RELAY

The correlated references are valid because they do not occur in the table
expression where CHEAP_PARTS is defined. The correlated references are from a
table specification at a higher level in the hierarchy of subqueries.

Example of using a nested table expression as the right operand of a join: The
following query contains a fullselect (in bold) as the right operand of a left outer
join with the PROJECTS table. The correlation name is TEMP. In this case the
unmatched rows from the PROJECTS table are included, but the unmatched rows
from the nested table expression are not.
SELECT PROJECT, COALESCE(PROJECTS.PROD#, PRODNUM) AS PRODNUM,
PRODUCT, PART, UNITS
FROM PROJECTS LEFT JOIN
(SELECT PART,
COALESCE(PARTS.PROD#, PRODUCTS.PROD#) AS PRODNUM,
PRODUCTS.PRODUCT
FROM PARTS FULL OUTER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#) AS TEMP ON PROJECTS.PROD# = PRODNUM;

Chapter 12. Accessing data 645

Example of using a nested table expression as the left operand of a join: The
following query contains a fullselect as the left operand of a left outer join with the
PRODUCTS table. The correlation name is PARTX. In this case the unmatched
rows from the nested table expression are included, but the unmatched rows from
the PRODUCTS table are not.
SELECT PART, SUPPLIER, PRODNUM, PRODUCT
FROM (SELECT PART, PROD# AS PRODNUM, SUPPLIER
FROM PARTS
WHERE PROD# < '200') AS PARTX
LEFT OUTER JOIN PRODUCTS
ON PRODNUM = PROD#;

The result table looks similar to the following output:

PART SUPPLIER PRODNUM PRODUCT
======= ============ ======= ==========
WIRE ACWF 10 GENERATOR
MAGNETS BATEMAN 10 GENERATOR
OIL WESTERN_CHEM 160 ----------

Because PROD# is a character field, DB2 does a character comparison to determine

the set of rows in the result. Therefore, because the characters ’30’ are greater than
’200’, the row in which PROD# is equal to ’30’ does not appear in the result.

Example: Using a table function as an operand of a join: Suppose that CVTPRICE

is a table function that converts the prices in the PRODUCTS table to the currency
that you specify and returns the PRODUCTS table with the prices in those units.
You can obtain a table of parts, suppliers, and product prices with the prices in
your choice of currency by executing a query similar to the following query:
SELECT PART, SUPPLIER, PARTS.PROD#, Z.PRODUCT, Z.PRICE
FROM PARTS, TABLE(CVTPRICE(:CURRENCY)) AS Z
WHERE PARTS.PROD# = Z.PROD#;

Correlated references in table specifications in joins:

Use correlation names to refer to the results of a nested table expression. After you
specify the correlation name for an expression, any subsequent reference to this
correlation name is called a correlated reference.

You can include correlated references in nested table expressions or as arguments

to table functions. The basic rule that applies for both of these cases is that the
correlated reference must be from a table specification at a higher level in the
hierarchy of subqueries. You can also use a correlated reference and the table
specification to which it refers in the same FROM clause if the table specification
appears to the left of the correlated reference and the correlated reference is in one
of the following clauses:
v A nested table expression that is preceded by the keyword TABLE
v The argument of a table function
For more information about correlated references, see “Correlation names in
references” on page 664.

A table function or a table expression that contains correlated references to other

tables in the same FROM clause cannot participate in a full outer join or a right
outer join. The following examples illustrate valid uses of correlated references in
table specifications.

Example: In this example, the correlated reference T.C2 is valid because the table
specification, to which it refers, T, is to its left.

646 Application Programming and SQL Guide

SELECT T.C1, Z.C5
FROM T, TABLE(TF3(T.C2)) AS Z
WHERE T.C3 = Z.C4;

If you specify the join in the opposite order, with T following TABLE(TF3(T.C2),
T.C2 is invalid.

Example: In this example, the correlated reference D.DEPTNO is valid because the
nested table expression within which it appears is preceded by TABLE, and the
table specification D appears to the left of the nested table expression in the FROM
clause.
SELECT D.DEPTNO, D.DEPTNAME,
EMPINFO.AVGSAL, EMPINFO.EMPCOUNT
FROM DEPT D,
TABLE(SELECT AVG(E.SALARY) AS AVGSAL,
COUNT(*) AS EMPCOUNT
FROM EMP E
WHERE E.WORKDEPT=D.DEPTNO) AS EMPINFO;

If you remove the keyword TABLE, D.DEPTNO is invalid.

Joining more than two tables

Joins are not limited to two tables. You can join more than two tables in a single
SQL statement.

To join more than two tables, specify join conditions that include columns from all
of the relevant tables.

Example: Suppose that you want a result table that shows employees who have
projects that they are responsible for, their projects, and their department names.
You need to join three tables to get all the information. You can use the following
SELECT statement:
SELECT EMPNO, LASTNAME, DEPTNAME, PROJNO
FROM DSN8910.EMP, DSN8910.PROJ, DSN8910.DEPT
WHERE EMPNO = RESPEMP
AND WORKDEPT = DSN8910.DEPT.DEPTNO;

The result table looks similar to the following output:

EMPNO LASTNAME DEPTNAME PROJNO
====== ========= =========================== ======
000010 HAAS SPIFFY COMPUTER SERVICE DIV AD3100
000010 HAAS SPIFFY COMPUTER SERVICE DIV MA2100
000020 THOMPSON PLANNING PL2100
000030 KWAN INFORMATION CENTER IF1000
000030 KWAN INFORMATION CENTER IF2000
000050 GEYER SUPPORT SERVICES OP1000
000050 GEYER SUPPORT SERVICES OP2000
000060 STERN MANUFACTURING SYSTEMS MA2110
000070 PULASKI ADMINISTRATION SYSTEMS AD3110
000090 HENDERSON OPERATIONS OP1010
000100 SPENSER SOFTWARE SUPPORT OP2010
000150 ADAMSON MANUFACTURING SYSTEMS MA2112
000160 PIANKA MANUFACTURING SYSTEMS MA2113
000220 LUTZ MANUFACTURING SYSTEMS MA2111
000230 JEFFERSON ADMINISTRATION SYSTEMS AD3111
000250 SMITH ADMINISTRATION SYSTEMS AD3112
000270 PEREZ ADMINISTRATION SYSTEMS AD3113
000320 MEHTA SOFTWARE SUPPORT OP2011
000330 LEE SOFTWARE SUPPORT OP2012
000340 GOUNOT SOFTWARE SUPPORT OP2013

Chapter 12. Accessing data 647

DB2 determines the intermediate and final results of the previous query by
performing the following logical steps:
1. Join the employee and project tables on the employee number, dropping the
rows with no matching employee number in the project table.
2. Join the intermediate result table with the department table on matching
department numbers.
3. Process the select list in the final result table, leaving only four columns.

Joining more than two tables by using more than one join type:

When joining more than two tables, you don’t have to use the same join type for
every join.

To join tables by using more than one join type, specify the join types in the FROM
clause.

Example: Suppose that you want a result table that shows the following items:
v employees whose last name begins with ’S’ or a letter that comes after ’S’ in the
alphabet
v the department names for the these employees
v any projects that these employees are responsible for
You can use the following SELECT statement:
SELECT EMPNO, LASTNAME, DEPTNAME, PROJNO
FROM DSN8910.EMP INNER JOIN DSN8910.DEPT
ON WORKDEPT = DSN8910.DEPT.DEPTNO
LEFT OUTER JOIN DSN8910.PROJ
ON EMPNO = RESPEMP
WHERE LASTNAME > 'S';

The result table looks like similar to the following output:

EMPNO LASTNAME DEPTNAME PROJNO
====== ========= ====================== ======
000020 THOMPSON PLANNING PL2100
000060 STERN MANUFACTURING SYSTEMS MA2110
000100 SPENSER SOFTWARE SUPPORT OP2010
000170 YOSHIMURA MANUFACTURING SYSTEMS ------
000180 SCOUTTEN MANUFACTURING SYSTEMS ------
000190 WALKER MANUFACTURING SYSTEMS ------
000250 SMITH ADMINISTRATION SYSTEMS AD3112
000280 SCHNEIDER OPERATIONS ------
000300 SMITH OPERATIONS ------
000310 SETRIGHT OPERATIONS ------
200170 YAMAMOTO MANUFACTURING SYSTEMS ------
200280 SCHWARTZ OPERATIONS ------
200310 SPRINGER OPERATIONS ------
200330 WONG SOFTWARE SUPPORT ------

DB2 determines the intermediate and final results of the previous query by
performing the following logical steps:
1. Join the employee and department tables on matching department numbers,
dropping the rows where the last name begins with a letter before ’S in the
alphabet’.
2. Join the intermediate result table with the project table on the employee
number, keeping the rows for which no matching employee number exists in
the project table.
3. Process the select list in the final result table, leaving only four columns.

648 Application Programming and SQL Guide

Inner joins
An inner join is a method of combining two tables that discards rows of either table
that do not match any row of the other table. The matching is based on the join
condition.

To request an inner join, execute a SELECT statement in which you specify the
tables that you want to join in the FROM clause, and specify a WHERE clause or
an ON clause to indicate the join condition. The join condition can be any simple
or compound search condition that does not contain a subquery reference. For the
complete syntax of a join condition, see the topic “from-clause” in DB2 SQL
Reference.

In the simplest type of inner join, the join condition is column1=column2.

Example: You can join the PARTS and PRODUCTS tables in “Sample data for
joins” on page 655 on the PROD# column to get a table of parts with their
suppliers and the products that use the parts.

To do this, you can use either one of the following SELECT statements:
SELECT PART, SUPPLIER, PARTS.PROD#, PRODUCT
FROM PARTS, PRODUCTS
WHERE PARTS.PROD# = PRODUCTS.PROD#;
SELECT PART, SUPPLIER, PARTS.PROD#, PRODUCT
FROM PARTS INNER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#;

The result table looks like the following output:

PART SUPPLIER PROD# PRODUCT
======= ============ ===== =========
WIRE ACWF 10 GENERATOR
MAGNETS BATEMAN 10 GENERATOR
PLASTIC PLASTIK_CORP 30 RELAY
BLADES ACE_STEEL 205 SAW

Three things about this example:

v A part in the parts table (OIL) has product (#160), which is not in the products
table. A product (SCREWDRIVER, #505) has no parts listed in the parts table.
Neither OIL nor SCREWDRIVER appears in the result of the join.
In contrast, an outer join includes rows in which the values in the joined columns
do not match.
v You can explicitly specify that this join is an inner join (not an outer join). Use
INNER JOIN in the FROM clause instead of the comma, and use ON to specify
the join condition (rather than WHERE) when you explicitly join tables in the
FROM clause.
v If you do not specify a WHERE clause in the first form of the query, the result
table contains all possible combinations of rows for the tables that are identified
in the FROM clause. You can obtain the same result by specifying a join
condition that is always true in the second form of the query, as in the following
statement:
SELECT PART, SUPPLIER, PARTS.PROD#, PRODUCT
FROM PARTS INNER JOIN PRODUCTS
ON 1=1;

Regardless of whether you omit the WHERE clause or specify a join condition
that is always true, the number of rows in the result table is the product of the
number of rows in each table.

Chapter 12. Accessing data 649

You can specify more complicated join conditions to obtain different sets of results.
For example, to eliminate the suppliers that begin with the letter A from the table
of parts, suppliers, product numbers, and products, write a query like the
following query:
SELECT PART, SUPPLIER, PARTS.PROD#, PRODUCT
FROM PARTS INNER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#
AND SUPPLIER NOT LIKE 'A%';

The result of the query is all rows that do not have a supplier that begins with A.
The result table looks like the following output:
PART SUPPLIER PROD# PRODUCT
======= ============ ===== ==========
MAGNETS BATEMAN 10 GENERATOR
PLASTIC PLASTIK_CORP 30 RELAY

Example of joining a table to itself by using an inner join:Joining a table to itself is

useful to show relationships between rows. The following example returns a list of
major projects from the PROJ table and the projects that are part of those major
projects.

In this example, A indicates the first instance of table DSN8910.PROJ, and B

indicates the second instance of this table. The join condition is such that the value
in column PROJNO in table DSN8910.PROJ A must be equal to a value in column
MAJPROJ in table DSN8910.PROJ B.

The following SQL statement joins table DSN8910.PROJ to itself and returns the
number and name of each major project followed by the number and name of the
project that is part of it:
SELECT A.PROJNO, A.PROJNAME, B.PROJNO, B.PROJNAME
FROM DSN8910.PROJ A, DSN8910.PROJ B
WHERE A.PROJNO = B.MAJPROJ;

The result table looks similar to the following output:

PROJNO PROJNAME PROJNO PROJNAME
====== ======================== ======= ========================
AD3100 ADMIN SERVICES AD3110 GENERAL AD SYSTEMS
AD3110 GENERAL AD SYSTEMS AD3111 PAYROLL PROGRAMMING
AD3110
. GENERAL AD SYSTEMS AD3112 PERSONNEL PROGRAMMG
.
.
OP2010 SYSTEMS SUPPORT OP2013 DB/DC SUPPORT

In this example, the comma in the FROM clause implicitly specifies an inner join,
and it acts the same as if the INNER JOIN keywords had been used. When you
use the comma for an inner join, you must specify the join condition on the
WHERE clause. When you use the INNER JOIN keywords, you must specify the
join condition on the ON clause.

Outer joins
An outer join is a method of combining two or more tables so that the result
includes unmatched rows of one or the other table, or of both. The matching is
based on the join condition.

DB2 supports three types of outer joins:

full outer join
Includes unmatched rows from both tables. If any column of the result table
does not have a value, that column has the null value in the result table.

650 Application Programming and SQL Guide

left outer join
Includes rows from the table that is specified before LEFT OUTER JOIN that
have no matching values in the table that is specified after LEFT OUTER JOIN.
right outer join
Includes rows from the table that is specified after RIGHT OUTER JOIN that
have no matching values in the table that is specified before RIGHT OUTER
JOIN.

The following table illustrates how the PARTS and PRODUCTS tables in “Sample
data for joins” on page 655 can be combined using the three outer join functions.

PARTS PRODUCTS
PART PROD# PROD# PRICE Unmatched
WIRE 10 row
MAGNETS 10 Matches 505 3.70
10 45.75
BLADES 205 205 18.90
Unmatched PLASTIC 30 30 7.55
row OIL 160

LEFT OUTER JOIN FULL OUTER JOIN RIGHT OUTER JOIN

PART PROD# PRICE PART PROD# PRICE PART PROD# PRICE
WIRE 10 45.75 WIRE 10 45.75 WIRE 10 45.75
MAGNETS 10 45.75 MAGNETS 10 45.75 MAGNETS 10 45.75
BLADES 205 18.90 BLADES 205 18.90 BLADES 205 18.90
PLASTIC 30 7.55 PLASTIC 30 7.55 PLASTIC 30 7.55
OIL 160 (null) OIL 160 (null) (null) 505 3.70
(null) 505 3.70

Figure 35. Three outer joins from the PARTS and PRODUCTS tables

The result table contains data that is joined from all of the tables, for rows that
satisfy the search conditions.

The result columns of a join have names if the outermost SELECT list refers to
base columns. However, if you use a function (such as COALESCE or VALUE) to
build a column of the result, that column does not have a name unless you use the
AS clause in the SELECT list.

Full outer join

An full outer join is a method of combining tables so that the result includes
unmatched rows of both tables.

If you are joining two tables and want the result set to include unmatched rows
from both tables, use a FULL OUTER JOIN clause. The matching is based on the
join condition. If any column of the result table does not have a value, that column
has the null value in the result table.

The join condition for a full outer join must be a simple search condition that
compares two columns or an invocation of a cast function that has a column name
as its argument.

Chapter 12. Accessing data 651

Example: The following query performs a full outer join of the PARTS and
PRODUCTS tables in “Sample data for joins” on page 655:
SELECT PART, SUPPLIER, PARTS.PROD#, PRODUCT
FROM PARTS FULL OUTER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#;

The result table from the query looks similar to the following output:
PART SUPPLIER PROD# PRODUCT
======= ============ ===== ==========
WIRE ACWF 10 GENERATOR
MAGNETS BATEMAN 10 GENERATOR
PLASTIC PLASTIK_CORP 30 RELAY
BLADES ACE_STEEL 205 SAW
OIL WESTERN_CHEM 160 -----------
------- ------------ --- SCREWDRIVER

Example of using COALESCE or VALUE: COALESCE is the keyword that is

specified by the SQL standard as a synonym for the VALUE function. This
function, by either name, can be particularly useful in full outer join operations
because it returns the first non-null value from the pair of join columns.

The product number in the result of the example for “Full outer join” on page 651
is null for SCREWDRIVER, even though the PRODUCTS table contains a product
number for SCREWDRIVER. If you select PRODUCTS.PROD# instead, PROD# is
null for OIL. If you select both PRODUCTS.PROD# and PARTS.PROD#, the result
contains two columns, both of which contain some null values. You can merge data
from both columns into a single column, eliminating the null values, by using the
COALESCE function.

With the same PARTS and PRODUCTS tables, the following example merges the
non-null data from the PROD# columns:
SELECT PART, SUPPLIER,
COALESCE(PARTS.PROD#, PRODUCTS.PROD#) AS PRODNUM, PRODUCT
FROM PARTS FULL OUTER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#;

The result table looks similar to the following output:

PART SUPPLIER PRODNUM PRODUCT
======= ============ ======= ===========
WIRE ACWF 10 GENERATOR
MAGNETS BATEMAN 10 GENERATOR
PLASTIC PLASTIK_CORP 30 RELAY
BLADES ACE_STEEL 205 SAW
OIL WESTERN_CHEM 160 -----------
------- ------------ 505 SCREWDRIVER

The AS clause (AS PRODNUM) provides a name for the result of the COALESCE
function.

Left outer join

A left outer join is a method of combining tables so that the result includes
unmatched rows from only the table that is specified before the LEFT OUTER
JOIN clause.

If you are joining two tables and want the result set to include unmatched rows
from only one table, use a LEFT OUTER JOIN clause or a RIGHT OUTER JOIN
clause. The matching is based on the join condition.

652 Application Programming and SQL Guide

The clause LEFT OUTER JOIN includes rows from the table that is specified before
LEFT OUTER JOIN that have no matching values in the table that is specified after
LEFT OUTER JOIN.

As in an inner join, the join condition can be any simple or compound search
condition that does not contain a subquery reference.

Example: The following example uses the tables in “Sample data for joins” on
page 655. To include rows from the PARTS table that have no matching values in
the PRODUCTS table, and to include prices that exceed 10.00, run the following
query:
SELECT PART, SUPPLIER, PARTS.PROD#, PRODUCT, PRICE
FROM PARTS LEFT OUTER JOIN PRODUCTS
ON PARTS.PROD#=PRODUCTS.PROD#
AND PRODUCTS.PRICE>10.00;

The result table looks similar to the following output:

PART SUPPLIER PROD# PRODUCT PRICE
======= ============ ===== ========== =====
WIRE ACWF 10 GENERATOR 45.75
MAGNETS BATEMAN 10 GENERATOR 45.75
PLASTIC PLASTIK_CORP 30 ----------- -------
BLADES ACE_STEEL 205 SAW 18.90
OIL WESTERN_CHEM 160 ----------- -------

A row from the PRODUCTS table is in the result table only if its product number
matches the product number of a row in the PARTS table and the price is greater
than 10.00 for that row. Rows in which the PRICE value does not exceed 10.00 are
included in the result of the join, but the PRICE value is set to null.

In this result table, the row for PROD# 30 has null values on the right two columns
because the price of PROD# 30 is less than 10.00. PROD# 160 has null values on
the right two columns because PROD# 160 does not match another product
number.

Right outer join

A right outer join is a method of combining tables so that the result includes
unmatched rows from only the table that is specified after the RIGHT OUTER
JOIN clause.

If you are joining two tables and want the result set to include unmatched rows
from only one table, use a LEFT OUTER JOIN clause or a RIGHT OUTER JOIN
clause. The matching is based on the join condition.

The clause RIGHT OUTER JOIN includes rows from the table that is specified after
RIGHT OUTER JOIN that have no matching values in the table that is specified
before RIGHT OUTER JOIN.

As in an inner join, the join condition can be any simple or compound search
condition that does not contain a subquery reference.

Example: The following example uses the tables in “Sample data for joins” on
page 655. To include rows from the PRODUCTS table that have no corresponding
rows in the PARTS table, execute this query:
SELECT PART, SUPPLIER, PRODUCTS.PROD#, PRODUCT, PRICE
FROM PARTS RIGHT OUTER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#
AND PRODUCTS.PRICE>10.00;

Chapter 12. Accessing data 653

The result table looks similar to the following output:
PART SUPPLIER PROD# PRODUCT PRICE
======= ============ ===== ========== =====
WIRE ACWF 10 GENERATOR 45.75
MAGNETS BATEMAN 10 GENERATOR 45.75
BLADES ACE_STEEL 205 SAW 18.90
---------- ------------ 30 RELAY 7.55
---------- ------------ 505 SCREWDRIVER 3.70

A row from the PARTS table is in the result table only if its product number
matches the product number of a row in the PRODUCTS table and the price is
greater than 10.00 for that row.

Because the PRODUCTS table can have rows with nonmatching product numbers
in the result table, and the PRICE column is in the PRODUCTS table, rows in
which PRICE is less than or equal to 10.00 are included in the result. The PARTS
columns contain null values for these rows in the result table.

SQL rules for statements that contain join operations

Typically, DB2 performs a join operation first, before it evaluates the other clauses
of the SELECT statement.

SQL rules dictate that the result of a SELECT statement look as if the clauses had
been evaluated in this order:
v FROM
v WHERE
v GROUP BY
v HAVING
v SELECT

A join operation is part of a FROM clause; therefore, for the purpose of predicting
which rows will be returned from a SELECT statement that contains a join
operation, assume that the join operation is performed first.

Example: Suppose that you want to obtain a list of part names, supplier names,
product numbers, and product names from the PARTS and PRODUCTS tables. You
want to include rows from either table where the PROD# value does not match a
PROD# value in the other table, which means that you need to do a full outer join.
You also want to exclude rows for product number 10. Consider the following
SELECT statement:
SELECT PART, SUPPLIER,
VALUE(PARTS.PROD#,PRODUCTS.PROD#) AS PRODNUM, PRODUCT
FROM PARTS FULL OUTER JOIN PRODUCTS
ON PARTS.PROD# = PRODUCTS.PROD#
WHERE PARTS.PROD# <> '10' AND PRODUCTS.PROD# <> '10';

The following result is not what you wanted:

PART SUPPLIER PRODNUM PRODUCT
======= ============ ======= ===========
PLASTIC PLASTIK_CORP 30 RELAY
BLADES ACE_STEEL 205 SAW

DB2 performs the join operation first. The result of the join operation includes
rows from one table that do not have corresponding rows from the other table.
However, the WHERE clause then excludes the rows from both tables that have
null values for the PROD# column.

The following statement is a correct SELECT statement to produce the list:

654 Application Programming and SQL Guide

SELECT PART, SUPPLIER,
VALUE(X.PROD#, Y.PROD#) AS PRODNUM, PRODUCT
FROM
(SELECT PART, SUPPLIER, PROD# FROM PARTS WHERE PROD# <> '10') X
FULL OUTER JOIN
(SELECT PROD#, PRODUCT FROM PRODUCTS WHERE PROD# <> '10') Y
ON X.PROD# = Y.PROD#;

For this statement, DB2 applies the WHERE clause to each table separately. DB2
then performs the full outer join operation, which includes rows in one table that
do not have a corresponding row in the other table. The final result includes rows
with the null value for the PROD# column and looks similar to the following
output:
PART SUPPLIER PRODNUM PRODUCT
======= ============ ======= ===========
OIL WESTERN_CHEM 160 -----------
BLADES ACE_STEEL 205 SAW
PLASTIC PLASTIK_CORP 30 RELAY
------- ------------ 505 SCREWDRIVER

Sample data for joins

These sample tables are used by many of the join examples in this information.

The examples in these topics use the following two tables to show various types of
joins:
The PARTS table The PRODUCTS table
PART PROD# SUPPLIER PROD# PRODUCT PRICE
======= ===== ============ ===== =========== =====
WIRE 10 ACWF 505 SCREWDRIVER 3.70
OIL 160 WESTERN_CHEM 30 RELAY 7.55
MAGNETS 10 BATEMAN 205 SAW 18.90
PLASTIC 30 PLASTIK_CORP 10 GENERATOR 45.75
BLADES 205 ACE_STEEL

Optimizing retrieval for a small set of rows

When you need only a few of the thousands of rows that satisfy a query, you can
tell DB2 to optimize its retrieval process to return only this small number of rows.

Question: How can I tell DB2 that I want only a few of the thousands of rows that
satisfy a query?

Answer: Use OPTIMIZE FOR n ROWS or FETCH FIRST n ROWS ONLY.

DB2 usually optimizes queries to retrieve all rows that qualify. But sometimes you
want to retrieve only the first few rows. For example, to retrieve the first row that
is greater than or equal to a known value, code:
SELECT column list FROM table
WHERE key >= value
ORDER BY key ASC

Even with the ORDER BY clause, DB2 might fetch all the data first and sort it
afterwards, which could be wasteful. Instead, you can write the query in one of the
following ways:
SELECT * FROM table
WHERE key >= value
ORDER BY key ASC
OPTIMIZE FOR 1 ROW

Chapter 12. Accessing data 655

SELECT * FROM table
WHERE key >= value
ORDER BY key ASC
FETCH FIRST n ROWS ONLY

Use OPTIMIZE FOR 1 ROW to influence the access path. OPTIMIZE FOR 1 ROW
tells DB2 to select an access path that returns the first qualifying row quickly.

Use FETCH FIRST n ROWS ONLY to limit the number of rows in the result table
to n rows. FETCH FIRST n ROWS ONLY has the following benefits:
v When you use FETCH statements to retrieve data from a result table, FETCH
FIRST n ROWS ONLY causes DB2 to retrieve only the number of rows that you
need. This can have performance benefits, especially in distributed applications.
If you try to execute a FETCH statement to retrieve the n+1st row, DB2 returns a
+100 SQLCODE.
v When you use FETCH FIRST ROW ONLY in a SELECT INTO statement, you
never retrieve more than one row. Using FETCH FIRST ROW ONLY in a
SELECT INTO statement can prevent SQL errors that are caused by
inadvertently selecting more than one value into a host variable.

When you specify FETCH FIRST n ROWS ONLY but not OPTIMIZE FOR n ROWS,
OPTIMIZE FOR n ROWS is implied. When you specify FETCH FIRST n ROWS
ONLY and OPTIMIZE FOR m ROWS, and m is less than n, DB2 optimizes the
query for m rows. If m is greater than n, DB2 optimizes the query for n rows.

Creating recursive SQL by using common table expressions

Queries that use recursion are useful in applications like bill-of-materials
applications, network planning applications, and reservation systems.

You can use common table expressions to create recursive SQL If a fullselect of a
common table expression contains a reference to itself in a FROM clause, the
common table expression is a recursive common table expression.

Recursive common table expressions must follow these rules:

v The first fullselect of the first union (the initialization fullselect) must not include
a reference to the common table expression.
v Each fullselect that is part of the recursion cycle must:
– Start with SELECT or SELECT ALL. SELECT DISTINCT is not allowed.
– Include only one reference to the common table expression that is part of the
recursion cycle in its FROM clause.
– Not include aggregate functions, a GROUP BY clause, or a HAVING clause.
v The column names must be specified after the table name of the common table
expression.
v The data type, length, and CCSID of each column from the common table
expression must match the data type, length, and CCSID of each corresponding
column in the iterative fullselect.
| v If you use the UNION keyword, specify UNION ALL instead of UNION.
| v You cannot specify INTERSECT or EXCEPT.
v Outer joins must not be part of any recursion cycle.
v A subquery must not be part of any recursion cycle.

656 Application Programming and SQL Guide

Important: You should be careful to avoid an infinite loop when you use a
recursive common table expression. DB2 issues a warning if one of the following
items is not found in the iterative fullselect of a recursive common table
expression:
v An integer column that increments by a constant
v A predicate in the WHERE clause in the form of counter_column < constant or
counter_column < :host variable

See “Examples of recursive common table expressions” on page 453 for examples
of bill-of-materials applications that use recursive common table expressions.

Updating data as it is retrieved from the database

As you retrieve rows, you can update them at the same time.

Question: How can I update rows of data as I retrieve them?

Answer: On the SELECT statement, use the FOR UPDATE clause without a column
list, or the FOR UPDATE OF clause with a column list. For a more efficient
program, specify a column list with only those columns that you intend to update.
Then use the positioned UPDATE statement. The clause WHERE CURRENT OF
identifies the cursor that points to the row you want to update.

Avoiding decimal arithmetic errors

When you request that DB2 perform a decimal operation, errors might occur if
DB2 does not use the appropriate precision and scale.

For static SQL statements, the simplest way to avoid a division error is to override
DEC31 rules by specifying the precompiler option DEC(15). In some cases you can
avoid a division error by specifying D31.s, where s is a number between 1 and 9
and represents the minimum scale to be used for division operations. This
specification reduces the probability of errors for statements that are embedded in
the program.

If the dynamic SQL statements have bind, define, or invoke behavior and the value
of the installation option for USE FOR DYNAMICRULES on panel DSNTIP4 is
NO, you can use the precompiler option DEC(15), DEC15, or D15.s to override
DEC31 rules, where s is a number between 1 and 9.

For a dynamic statement, or for a single static statement, use the scalar function
DECIMAL to specify values of the precision and scale for a result that causes no
errors.

Before you execute a dynamic statement, set the value of special register
CURRENT PRECISION to DEC15 or D15.s, where s is a number between 1 and 9.

Even if you use DEC31 rules, multiplication operations can sometimes cause
overflow because the precision of the product is greater than 31. To avoid overflow
from multiplication of large numbers, use the MULTIPLY_ALT built-in function
instead of the multiplication operator.

Precision for operations with decimal numbers

DB2 accepts two sets of rules for determining the precision and scale of the result
of an operation with decimal numbers.

Chapter 12. Accessing data 657

v DEC15 rules allow a maximum precision of 15 digits in the result of an
operation. DEC15 rules are in effect when both operands have a precision of 15
or less, or unless the DEC31 rules apply.
v DEC31 rules allow a maximum precision of 31 digits in the result. DEC31 rules
are in effect if any of the following conditions is true:
– Either operand of the operation has a precision greater than 15 digits.
– The operation is in a dynamic SQL statement, and any of the following
conditions is true:
- The current value of special register CURRENT PRECISION is DEC31 or
D31.s, where s is a number between 1 and 9 and represents the minimum
scale to be used for division operations.
- The installation option for DECIMAL ARITHMETIC on panel DSNTIP4 is
DEC31, 31, or D31.s, where s is a number between 1 and 9; the installation
option for USE FOR DYNAMICRULES on panel DSNTIP4 is YES; and the
value of CURRENT PRECISION has not been set by the application.
- The SQL statement has bind, define, or invoke behavior; the statement is in
an application that is precompiled with option DEC(31); the installation
option for USE FOR DYNAMICRULES on panel DSNTIP4 is NO; and the
value of CURRENT PRECISION has not been set by the application. See
“DYNAMICRULES bind option” on page 932 for an explanation of bind,
define, and invoke behavior.
– The operation is in an embedded (static) SQL statement that you precompiled
with the DEC(31), DEC31, or D31.s option, or with the default for that option
when the installation option DECIMAL ARITHMETIC is DEC31 or 31. s is a
number between 1 and 9 and represents the minimum scale to be used for
division operations. See “Processing SQL statements” on page 890 for
information about precompiling and for a list of all precompiler options.

Recommendation: To reduce the chance of overflow, or when dealing with a

precision greater than 15 digits, choose DEC31 or D31.s , wheres is a number
between 1 and 9 and represents the minimum scale to be used for division
operations.

| Controlling how DB2 rounds decimal floating point numbers

| You can specify a default rounding mode that DB2 is to use for all DECFLOAT
| values.

| To control how DB2 rounds decimal floating point numbers, set the CURRENT
| DECFLOAT ROUNDING MODE special register.
| Related concepts
| CURRENT DECFLOAT ROUNDING MODE (SQL Reference)
| Related reference
| SET CURRENT DECFLOAT ROUNDING MODE (SQL Reference)

Implications of using SELECT *

Generally, you should use SELECT * only when you want to select all columns,
except for hidden columns. Otherwise, specify the specific columns that you want
to view.

Question: What are the implications of using SELECT * ?

658 Application Programming and SQL Guide

| Answer: Generally, you should select only the columns you need because DB2 is
| sensitive to the number of columns selected. Use SELECT * only when you are
| sure you want to select all columns, except hidden columns. (Hidden columns are
| not returned when you specify SELECT *.) One alternative to selecting all columns
| is to use views defined with only the necessary columns, and use SELECT * to
| access the views. Avoid SELECT * if all the selected columns participate in a sort
| operation (SELECT DISTINCT and SELECT...UNION, for example).

Subqueries
When you need to narrow your search condition based on information in an
interim table, you can use a subquery. For example, you might want to find all
employee numbers in one table that also exist for a given project in a second table.

Conceptual overview of subqueries:

Suppose that you want a list of the employee numbers, names, and commissions of
all employees who work on a particular project, whose project number is MA2111.
The first part of the SELECT statement is easy to write:
SELECT EMPNO, LASTNAME, COMM
FROM DSN8910.EMP
WHERE EMPNO
.
.
.

However, you cannot proceed because the DSN8910.EMP table does not include
project number data. You do not know which employees are working on project
MA2111 without issuing another SELECT statement against the
DSN8910.EMPPROJACT table.

You can use a subquery to solve this problem. A subquery is a subselect or a

fullselect in a WHERE clause. The SELECT statement that surrounds the subquery
is called the outer SELECT.
SELECT EMPNO, LASTNAME, COMM
FROM DSN8910.EMP
WHERE EMPNO IN
(SELECT EMPNO
FROM DSN8910.EMPPROJACT
WHERE PROJNO = 'MA2111');

To better understand the results of this SQL statement, imagine that DB2 goes
through the following process:
1. DB2 evaluates the subquery to obtain a list of EMPNO values:
(SELECT EMPNO
FROM DSN8910.EMPPROJACT
WHERE PROJNO = 'MA2111');

The result is in an interim result table, similar to the one in the following
output:
from EMPNO
=====
200
200
220
2. The interim result table then serves as a list in the search condition of the outer
SELECT. Effectively, DB2 executes this statement:

Chapter 12. Accessing data 659

SELECT EMPNO, LASTNAME, COMM
FROM DSN8910.EMP
WHERE EMPNO IN
('000200', '000220');
As a consequence, the result table looks similar to the following output:
EMPNO LASTNAME COMM
====== ======== ====
000200 BROWN 2217
000220 LUTZ 2387

Correlated and uncorrelated subqueries:

Subqueries supply information that is needed to qualify a row (in a WHERE

clause) or a group of rows (in a HAVING clause). The subquery produces a result
table that is used to qualify the row or group of selected rows.

A subquery executes only once, if the subquery is the same for every row or
group. This kind of subquery is uncorrelated, which means that it executes only
once. For example, in the following statement, the content of the subquery is the
same for every row of the table DSN8910.EMP:
SELECT EMPNO, LASTNAME, COMM
FROM DSN8910.EMP
WHERE EMPNO IN
(SELECT EMPNO
FROM DSN8910.EMPPROJACT
WHERE PROJNO = 'MA2111');

Subqueries that vary in content from row to row or group to group are correlated
subqueries. For information about correlated subqueries, see “Correlated
subqueries” on page 663.

Subqueries and predicates:

A predicate is an element of a search condition that specifies a condition that is true,

false, or unknown about a given row or group. A subquery, which is a SELECT
statement within the WHERE or HAVING clause of another SQL statement, is
always part of a predicate. The predicate is of the form:
operand operator (subquery)

A WHERE or HAVING clause can include predicates that contain subqueries. A

predicate that contains a subquery, like any other search predicate, can be enclosed
in parentheses, can be preceded by the keyword NOT, and can be linked to other
predicates through the keywords AND and OR. For example, the WHERE clause
of a query can look something like the following clause:
WHERE X IN (subquery1) AND (Y > SOME (subquery2) OR Z IS NULL)

Subqueries can also appear in the predicates of other subqueries. Such subqueries
are nested subqueries at some level of nesting. For example, a subquery within a
subquery within an outer SELECT has a nesting level of 2. DB2 allows nesting
down to a level of 15, but few queries require a nesting level greater than 1.

The relationship of a subquery to its outer SELECT is the same as the relationship
of a nested subquery to a subquery, and the same rules apply, except where
otherwise noted.

The subquery result table:

660 Application Programming and SQL Guide

A subquery must produce a result table that has the same number of columns as
the number of columns on the left side of the comparison operator. For example,
both of the following SELECT statements are acceptable:
SELECT EMPNO, LASTNAME
FROM DSN8910.EMP
WHERE SALARY =
(SELECT AVG(SALARY)
FROM DSN8910.EMP);
SELECT EMPNO, LASTNAME
FROM DSN8910.EMP
WHERE (SALARY, BONUS) IN
(SELECT AVG(SALARY), AVG(BONUS)
FROM DSN8910.EMP);

Except for a subquery of a basic predicate, the result table can contain more than
one row. For more information, see “Places where you can include a subquery.”

Places where you can include a subquery

You can specify a subquery in either a WHERE or HAVING clause.

You can specify a subquery in either a WHERE or HAVING clause by using one of
the following items:

Basic predicate in a subquery:

You can use a subquery immediately after any of the comparison operators. If you
do, the subquery can return at most one value. DB2 compares that value with the
value to the left of the comparison operator.

Example: The following SQL statement returns the employee numbers, names, and
salaries for employees whose education level is higher than the average
company-wide education level.
SELECT EMPNO, LASTNAME, SALARY
FROM DSN8910.EMP
WHERE EDLEVEL >
(SELECT AVG(EDLEVEL)
FROM DSN8910.EMP);

Quantified predicate in a subquery: ALL, ANY, or SOME:

You can use a subquery after a comparison operator, followed by the keyword
ALL, ANY, or SOME. The number of columns and rows that the subquery can
return for a quantified predicate depends on the type of quantified predicate:
v For = SOME, = ANY, or <> ALL, the subquery can return one or many rows and
one or many columns. The number of columns in the result table must match
the number of columns on the left side of the operator.
v For all other quantified predicates, the subquery can return one or many rows,
but no more than one column.

For more information about quantified predicates, including what to do if a

subquery that returns one or more null values gives you unexpected results, see
the topic “Quantified predicate” in DB2 SQL Reference.

ALL predicate:

Chapter 12. Accessing data 661

Use ALL to indicate that the operands on the left side of the comparison must
compare in the same way with all of the values that the subquery returns. For
example, suppose that you use the greater-than comparison operator with ALL:
WHERE column > ALL (subquery)

To satisfy this WHERE clause, the column value must be greater than all of the
values that the subquery returns. A subquery that returns an empty result table
satisfies the predicate.

Now suppose that you use the <> operator with ALL in a WHERE clause like this:
WHERE (column1, column1, ... columnn) <> ALL (subquery)

To satisfy this WHERE clause, each column value must be unequal to all of the
values in the corresponding column of the result table that the subquery returns. A
subquery that returns an empty result table satisfies the predicate.

ANY or SOME predicate:

Use ANY or SOME to indicate that the values on the left side of the operator must
compare in the indicated way to at least one of the values that the subquery
returns. For example, suppose that you use the greater-than comparison operator
with ANY:
WHERE expression > ANY (subquery)

To satisfy this WHERE clause, the value in the expression must be greater than at
least one of the values (that is, greater than the lowest value) that the subquery
returns. A subquery that returns an empty result table does not satisfy the
predicate.

Now suppose that you use the = operator with SOME in a WHERE clause like
this:
WHERE (column1, column1, ... columnn) = SOME (subquery)

To satisfy this WHERE clause, each column value must be equal to at least one of
the values in the corresponding column of the result table that the subquery
returns. A subquery that returns an empty result table does not satisfy the
predicate.

IN predicate in a subquery:

You can use IN to say that the value or values on the left side of the IN operator
must be among the values that are returned by the subquery. Using IN is
equivalent to using = ANY or = SOME.

Example: The following query returns the names of department managers:

SELECT EMPNO,LASTNAME
FROM DSN8910.EMP
WHERE EMPNO IN
(SELECT DISTINCT MGRNO
FROM DSN8910.DEPT);

EXISTS predicate in a subquery:

When you use the keyword EXISTS, DB2 checks whether the subquery returns one
or more rows. Returning one or more rows satisfies the condition; returning no
rows does not satisfy the condition.

662 Application Programming and SQL Guide

Example: The search condition in the following query is satisfied if any project that
is represented in the project table has an estimated start date that is later than 1
January 2005:
SELECT EMPNO,LASTNAME
FROM DSN8910.EMP
WHERE EXISTS
(SELECT *
FROM DSN8910.PROJ
WHERE PRSTDATE > '2005-01-01');

The result of the subquery is always the same for every row that is examined for
the outer SELECT. Therefore, either every row appears in the result of the outer
SELECT or none appears. A correlated subquery is more powerful than the
uncorrelated subquery that is used in this example because the result of a
correlated subquery is evaluated for each row of the outer SELECT.

As shown in the example, you do not need to specify column names in the
subquery of an EXISTS clause. Instead, you can code SELECT *. You can also use
the EXISTS keyword with the NOT keyword in order to select rows when the data
or condition that you specify does not exist; that is, you can code the following
clause:
WHERE NOT EXISTS (SELECT ...);

Correlated subqueries
A correlated subquery is a subquery that DB2 reevaluates when it examines a new
row (in a WHERE clause) or a group of rows (in a HAVING clause) as it executes
the outer SELECT statement.

In an uncorrelated subquery, DB2 executes the subquery once, substitutes the result
of the subquery in the right side of the search condition, and evaluates the outer
SELECT based on the value of the search condition.

User-defined functions in correlated subqueries: Use care when you invoke a

user-defined function in a correlated subquery, and that user-defined function uses
a scratchpad. DB2 does not refresh the scratchpad between invocations of the
subquery. This can cause undesirable results because the scratchpad keeps values
across the invocations of the subquery.

An example of a correlated subquery

Suppose that you want a list of all the employees whose education levels are
higher than the average education levels in their respective departments. To get
this information, DB2 must search the DSN8910.EMP table. For each employee in
the table, DB2 needs to compare the employee’s education level to the average
education level for that employee’s department.

For this example, you need to use a correlated subquery, which differs from an
uncorrelated subquery. An uncorrelated subquery compares the employee’s
education level to the average of the entire company, which requires looking at the
entire table. A correlated subquery evaluates only the department that corresponds
to the particular employee.

In the subquery, you tell DB2 to compute the average education level for the
department number in the current row. The following query performs this action:

Chapter 12. Accessing data 663

SELECT EMPNO, LASTNAME, WORKDEPT, EDLEVEL
FROM DSN8910.EMP X
WHERE EDLEVEL >
(SELECT AVG(EDLEVEL)
FROM DSN8910.EMP
WHERE WORKDEPT = X.WORKDEPT);

A correlated subquery looks like an uncorrelated one, except for the presence of
one or more correlated references. In the example, the single correlated reference is
the occurrence of X.WORKDEPT in the WHERE clause of the subselect. In this
clause, the qualifier X is the correlation name that is defined in the FROM clause of
the outer SELECT statement. X designates rows of the first instance of
DSN8910.EMP. At any time during the execution of the query, X designates the
row of DSN8910.EMP to which the WHERE clause is being applied.

Consider what happens when the subquery executes for a given row of
DSN8910.EMP. Before it executes, X.WORKDEPT receives the value of the
WORKDEPT column for that row. Suppose, for example, that the row is for
Christine Haas. Her work department is A00, which is the value of WORKDEPT
for that row. Therefore, the following is the subquery that is executed for that row:
(SELECT AVG(EDLEVEL)
FROM DSN8910.EMP
WHERE WORKDEPT = 'A00');

The subquery produces the average education level of Christine’s department. The
outer SELECT then compares this average to Christine’s own education level. For
some other row for which WORKDEPT has a different value, that value appears in
the subquery in place of A00. For example, in the row for Michael L Thompson,
this value is B01, and the subquery for his row delivers the average education level
for department B01.

The result table that is produced by the query is similar to the following output:
EMPNO LASTNAME WORKDEPT EDLEVEL
====== ========= ======== =======
000010 HASS A00 18
000030 KWAN C01 20
000070 PULASKI D21 16
000090 HENDERSON E11 16

Correlation names in references

A correlation name is name that you specify for a table, view, nested table
expression or table function. This name is valid only within the context in which it
is defined. Use correlation names to avoid ambiguity, establish correlated
references, or use shorter names for tables or views.

A correlated reference can appear in a subquery, in a nested table expression, or as

an argument of a user-defined table function. For information about correlated
references in nested table expressions and table functions, see “Joining data from
more than one table” on page 644. In a subquery, the reference should be of the
form X.C, where X is a correlation name and C is the name of a column in the
table that X represents.

Any number of correlated references can appear in a subquery, with no restrictions

on variety. For example, you can use one correlated reference in the outer SELECT,
and another in a nested subquery.

When you use a correlated reference in a subquery, the correlation name can be
defined in the outer SELECT or in any of the subqueries that contain the reference.

664 Application Programming and SQL Guide

Suppose, for example, that a query contains subqueries A, B, and C, and that A
contains B and B contains C. The subquery C can use a correlation reference that is
defined in B, A, or the outer SELECT.

You can define a correlation name for each table name in a FROM clause. Specify
the correlation name after its table name. Leave one or more blanks between a
table name and its correlation name. You can include the word AS between the
table name and the correlation name to increase the readability of the SQL
statement.

The following example demonstrates the use of a correlated reference in the search
condition of a subquery:
SELECT EMPNO, LASTNAME, WORKDEPT, EDLEVEL
FROM DSN8910.EMP AS X
WHERE EDLEVEL >
(SELECT AVG(EDLEVEL)
FROM DSN8910.EMP
WHERE WORKDEPT = X.WORKDEPT);

The following example demonstrates the use of a correlated reference in the select
list of a subquery:
UPDATE BP1TBL T1
SET (KEY1, CHAR1, VCHAR1) =
(SELECT VALUE(T2.KEY1,T1.KEY1), VALUE(T2.CHAR1,T1.CHAR1),
VALUE(T2.VCHAR1,T1.VCHAR1)
FROM BP2TBL T2
WHERE (T2.KEY1 = T1.KEY1))
WHERE KEY1 IN
(SELECT KEY1
FROM BP2TBL T3
WHERE KEY2 > 0);

Using correlated subqueries in an UPDATE statement:

Use correlation names in an UPDATE statement to refer to the rows that you are
updating. The subquery for which you specified a correlation name is called a
correlated subquery.

For example, when all activities of a project must complete before September 2006,
your department considers that project to be a priority project. Assume that you
have added the PRIORITY column to DSN8910.PROJ. You can use the following
SQL statement to evaluate the projects in the DSN8910.PROJ table, and write a 1 (a
flag to indicate PRIORITY) in the PRIORITY column for each priority project:
UPDATE DSN8910.PROJ X
SET PRIORITY = 1
WHERE DATE('2006-09-01') >
(SELECT MAX(ACENDATE)
FROM DSN8910.PROJACT
WHERE PROJNO = X.PROJNO);

As DB2 examines each row in the DSN8910.PROJ table, it determines the

maximum activity end date (the ACENDATE column) for all activities of the
project (from the DSN8910.PROJACT table). If the end date of each activity that is
associated with the project is before September 2006, the current row in the
DSN8910.PROJ table qualifies, and DB2 updates it.

Using correlated subqueries in a DELETE statement:

Chapter 12. Accessing data 665

Use correlation names in a DELETE statement to refer to the rows that you are
deleting. The subquery for which you specified a correlation name is called a
correlated subquery. DB2 evaluates the correlated subquery once for each row in the
table that is named in the DELETE statement to decide whether to delete the row.

Using tables with no referential constraints:

Suppose that a department considers a project to be complete when the combined

amount of time currently spent on it is less than or equal to half of a person’s time.
The department then deletes the rows for that project from the DSN8910.PROJ
table. In the examples in this topic, PROJ and PROJACT are independent tables;
that is, they are separate tables with no referential constraints defined on them.
DELETE FROM DSN8910.PROJ X
WHERE .5 >
(SELECT SUM(ACSTAFF)
FROM DSN8910.PROJACT
WHERE PROJNO = X.PROJNO);

To process this statement, DB2 determines for each project (represented by a row in
the DSN8910.PROJ table) whether the combined staffing for that project is less than
0.5. If it is, DB2 deletes that row from the DSN8910.PROJ table.

To continue this example, suppose that DB2 deletes a row in the DSN8910.PROJ
table. You must also delete rows that are related to the deleted project in the
DSN8910.PROJACT table. To do this, use a statement similar to this statement:
DELETE FROM DSN8910.PROJACT X
WHERE NOT EXISTS
(SELECT *
FROM DSN8910.PROJ
WHERE PROJNO = X.PROJNO);

DB2 determines, for each row in the DSN8910.PROJACT table, whether a row with
the same project number exists in the DSN8910.PROJ table. If not, DB2 deletes the
row from DSN8910.PROJACT.

Using a single table:

A subquery of a searched DELETE statement (a DELETE statement that does not

use a cursor) can reference the same table from which rows are deleted. In the
following statement, which deletes the employee with the highest salary from each
department, the employee table appears in the outer DELETE and in the subselect:
DELETE FROM YEMP X
WHERE SALARY = (SELECT MAX(SALARY) FROM YEMP Y
WHERE X.WORKDEPT =Y.WORKDEPT);

This example uses a copy of the employee table for the subquery.

The following statement, without a correlated subquery, yields equivalent results:

DELETE FROM YEMP
WHERE (SALARY, WORKDEPT) IN (SELECT MAX(SALARY), WORKDEPT
FROM YEMP
GROUP BY WORKDEPT);

Using tables with referential constraints:

DB2 restricts delete operations for dependent tables that are involved in referential
constraints. If a DELETE statement has a subquery that references a table that is

666 Application Programming and SQL Guide

involved in the deletion, make the last delete rule in the path to that table
RESTRICT or NO ACTION. This action ensures that the result of the subquery is
not materialized before the deletion occurs. However, if the result of the subquery
is materialized before the deletion, the delete rule can also be CASCADE or SET
NULL.

Example: Without referential constraints, the following statement deletes

departments from the department table whose managers are not listed correctly in
the employee table:
DELETE FROM DSN8910.DEPT THIS
WHERE NOT DEPTNO =
(SELECT WORKDEPT
FROM DSN8910.EMP
WHERE EMPNO = THIS.MGRNO);

With the referential constraints that are defined for the sample tables, this
statement causes an error because the result table for the subquery is not
materialized before the deletion occurs. Because DSN8910.EMP is a dependent
table of DSN8910.DEPT, the deletion involves the table that is referred to in the
subquery, and the last delete rule in the path to EMP is SET NULL, not RESTRICT
or NO ACTION. If the statement could execute, its results would depend on the
order in which DB2 accesses the rows. Therefore, DB2 prohibits the deletion.

Restrictions when using distinct types with UNION, EXCEPT,

and INTERSECT
| DB2 enforces strong typing of distinct types with UNION, EXCEPT, and
| INTERSECT. When you use these keywords to combine column values from
| several tables, the combined columns must be of the same types. If a column is a
| distinct type, the corresponding column must be the same distinct type.

Example: Suppose that you create a view that combines the values of the
US_SALES, EUROPEAN_SALES, and JAPAN_SALES tables. The TOTAL columns
in the three tables are of different distinct types. Before you combine the table
values, you must convert the types of two of the TOTAL columns to the type of
the third TOTAL column. Assume that the US_DOLLAR type has been chosen as
the common distinct type. Because DB2 does not generate cast functions to convert
from one distinct type to another, two user-defined functions must exist:
v A function called EURO_TO_US that converts values of type EURO to type
US_DOLLAR
v A function called YEN_TO_US that converts values of type JAPANESE_YEN to
type US_DOLLAR
Then you can execute a query like this to display a table of combined sales:
SELECT PRODUCT_ITEM, MONTH, YEAR, TOTAL
FROM US_SALES
UNION
SELECT PRODUCT_ITEM, MONTH, YEAR, EURO_TO_US(TOTAL)
FROM EUROPEAN_SALES
UNION
SELECT PRODUCT_ITEM, MONTH, YEAR, YEN_TO_US(TOTAL)
FROM JAPAN_SALES;

Because the result type of both the YEN_TO_US function and the EURO_TO_US
function is US_DOLLAR, you have satisfied the requirement that the distinct types
of the combined columns are the same.

Chapter 12. Accessing data 667

Comparison of distinct types
You can compare an object with a distinct type only to an object with exactly the
same distinct type. You cannot compare data of a distinct type directly to data of
its source type. However, you can compare a distinct type to its source type by
using a cast function.

The basic rule for comparisons is that the data types of the operands must be
compatible. The compatibility rule defines, for example, that all numeric types
(SMALLINT, INTEGER, FLOAT, and DECIMAL) are compatible. That is, you can
compare an INTEGER value with a value of type FLOAT. However, you cannot
compare an object of a distinct type to an object of a different type. You can
compare an object with a distinct type only to an object with exactly the same
distinct type.

For example, suppose you want to know which products sold more than
$100 000.00 in the US in the month of July in 2003 (7/03). Because you cannot
compare data of type US_DOLLAR with instances of data of the source type of
US_DOLLAR (DECIMAL) directly, you must use a cast function to cast data from
DECIMAL to US_DOLLAR or from US_DOLLAR to DECIMAL. Whenever you
create a distinct type, DB2 creates two cast functions, one to cast from the source
type to the distinct type and the other to cast from the distinct type to the source
type. For distinct type US_DOLLAR, DB2 creates a cast function called DECIMAL
and a cast function called US_DOLLAR. When you compare an object of type
US_DOLLAR to an object of type DECIMAL, you can use one of those cast
functions to make the data types identical for the comparison. Suppose table
US_SALES is defined like this:
CREATE TABLE US_SALES
(PRODUCT_ITEM INTEGER,
MONTH INTEGER CHECK (MONTH BETWEEN 1 AND 12),
YEAR INTEGER CHECK (YEAR > 1990),
TOTAL US_DOLLAR);

Then you can cast DECIMAL data to US_DOLLAR like this:

SELECT PRODUCT_ITEM
FROM US_SALES
WHERE TOTAL > US_DOLLAR(100000.00)
AND MONTH = 7
AND YEAR = 2003;

The casting satisfies the requirement that the compared data types are identical.

You cannot use host variables in statements that you prepare for dynamic
execution. As explained in “Dynamically executing an SQL statement by using
PREPARE and EXECUTE” on page 189, you can substitute parameter markers for
host variables when you prepare a statement, and then use host variables when
you execute the statement.

If you use a parameter marker in a predicate of a query, and the column to which
you compare the value represented by the parameter marker is of a distinct type,
you must cast the parameter marker to the distinct type, or cast the column to its
source type.

For example, suppose that distinct type CNUM is defined like this:
CREATE DISTINCT TYPE CNUM AS INTEGER;

Table CUSTOMER is defined like this:

668 Application Programming and SQL Guide

CREATE TABLE CUSTOMER
(CUST_NUM CNUM NOT NULL,
FIRST_NAME CHAR(30) NOT NULL,
LAST_NAME CHAR(30) NOT NULL,
PHONE_NUM CHAR(20) WITH DEFAULT,
PRIMARY KEY (CUST_NUM));

In an application program, you prepare a SELECT statement that compares the

CUST_NUM column to a parameter marker. Because CUST_NUM is of a distinct
type, you must cast the distinct type to its source type:
SELECT FIRST_NAME, LAST_NAME, PHONE_NUM FROM CUSTOMER
WHERE CAST(CUST_NUM AS INTEGER) = ?

Alternatively, you can cast the parameter marker to the distinct type:
SELECT FIRST_NAME, LAST_NAME, PHONE_NUM FROM CUSTOMER
WHERE CUST_NUM = CAST (? AS CNUM)

Nested SQL statements

An SQL statement can explicitly invoke user-defined functions or stored
procedures or can implicitly activate triggers that invoke user-defined functions or
stored procedures. This situation is known as nesting of SQL statements. DB2
supports up to 16 levels of nesting.

The following example shows SQL statement nesting.

Trigger TR1 is defined on table T3:
CREATE TRIGGER TR1
AFTER UPDATE ON T3
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
CALL SP3(PARM1);
END
Program P1 (nesting level 1) contains:
SELECT UDF1(C1) FROM T1;
UDF1 (nesting level 2) contains:
CALL SP2(C2);
SP2 (nesting level 3) contains:
UPDATE T3 SET C3=1;
SP3 (nesting level 4) contains:
. SELECT UDF4(C4) FROM T4;
.
.
SP16 (nesting level 16) cannot invoke stored procedures
or user-defined functions

DB2 has the following restrictions on nested SQL statements:

v Restrictions for SELECT statements:
| When you execute a SELECT statement on a table, you cannot execute INSERT,
| UPDATE, MERGE, or DELETE statements on the same table at a lower level of
| nesting.
For example, suppose that you execute this SQL statement at level 1 of nesting:
SELECT UDF1(C1) FROM T1;

You cannot execute this SQL statement at a lower level of nesting:

INSERT INTO T1 VALUES(...);
| v Restrictions for INSERT, UPDATE, MERGE, and DELETE statements:
| When you execute an INSERT, UPDATE, MERGE, or DELETE statement on a
| table, you cannot access that table from a user-defined function or stored
| procedure that is at a lower level of nesting.

Chapter 12. Accessing data 669

| For example, suppose that you execute this SQL statement at level 1 of nesting:
| DELETE FROM T1 WHERE UDF3(T1.C1) = 3;

| You cannot execute this SELECT statement at a lower level of nesting:

| SELECT * FROM T1;

The preceding list of restrictions do not apply to SQL statements that are executed
at a lower level of nesting as a result of an after trigger. For example, suppose an
UPDATE statement at nesting level 1 activates an after update trigger, which calls
a stored procedure. The stored procedure executes two SQL statements that
reference the triggering table: one SELECT statement and one INSERT statement.
In this situation, both the SELECT and the INSERT statements can be executed
even though they are at nesting level 3.

Although trigger activations count in the levels of SQL statement nesting, the
previous restrictions on SQL statements do not apply to SQL statements that are
executed in the trigger body.

Example: Suppose that trigger TR1 is defined on table T1:

CREATE TRIGGER TR1
AFTER INSERT ON T1
FOR EACH STATEMENT MODE DB2SQL
BEGIN ATOMIC
UPDATE T1 SET C1=1;
END

Now suppose that you execute this SQL statement at level 1 of nesting:
INSERT INTO T1 VALUES(...);

Although the UPDATE statement in the trigger body is at level 2 of nesting and
modifies the same table that the triggering statement updates, DB2 can execute the
INSERT statement successfully.

Retrieving a set of rows by using a cursor

In an application program, you can retrieve a set of rows from a table or a result
table that is returned by a stored procedure. You can retrieve one or more rows at
a time.

Use either of the following types of cursors to retrieve rows from a result table:
v A row-positioned cursor retrieves at most a single row at a time from the result
table into host variables. At any point in time, the cursor is positioned on at
most a single row. For information about how to use a row-positioned cursor,
see “Accessing data by using a row-positioned cursor” on page 675.
v A rowset-positioned cursor retrieves zero, one, or more rows at a time, as a
rowset, from the result table into host variable arrays. At any point in time, the
cursor can be positioned on a rowset. You can reference all of the rows in the
rowset, or only one row in the rowset, when you use a positioned DELETE or
positioned UPDATE statement. For information about how to use a
rowset-positioned cursor, see “Accessing data by using a rowset-positioned
cursor” on page 680.

670 Application Programming and SQL Guide

Cursors
A cursor is a mechanism that points to one or more rows in a set of rows that are
retrieved from a table or in a result set that is returned by a stored procedure. Your
application program can use a cursor to retrieve rows from a table.

Cursors bound with cursor stability that are used in block fetch operations are
particularly vulnerable to reading data that has already changed. In a block fetch,
database access prefetches rows ahead of the row retrieval controlled by the
application. During that time the cursor might close, and the locks might be
released, before the application receives the data. Thus, it is possible for the
application to fetch a row of values that no longer exists, or to miss a recently
inserted row. In many cases, that is acceptable; a case for which it is not acceptable
is said to require data currency.

If your application requires data currency for a cursor, you need to prevent block
fetching for the data to which it points. To prevent block fetching for a distributed
cursor, declare the cursor with the FOR UPDATE clause.

Types of cursors
You can declare cursors, both row-positioned and rowset-positioned, as scrollable
or not scrollable, held or not held, and returnable or not returnable.

In addition, you can declare a returnable cursor in a stored procedure by including

the WITH RETURN clause; the cursor can return result sets to a caller of the stored
procedure.

Scrollable and non-scrollable cursors:

When you declare a cursor, you tell DB2 whether you want the cursor to be
scrollable or non-scrollable by including or omitting the SCROLL clause. This
clause determines whether the cursor moves sequentially forward through the
result table or can move randomly through the result table.

Using a non-scrollable cursor:

The simplest type of cursor is a non-scrollable cursor. A non-scrollable cursor can

be either row-positioned or rowset-positioned. A row-positioned non-scrollable
cursor moves forward through its result table one row at a time. Similarly, a
rowset-positioned non-scrollable cursor moves forward through its result table one
rowset at a time.

A non-scrollable cursor always moves sequentially forward in the result table.

When the application opens the cursor, the cursor is positioned before the first row
(or first rowset) in the result table. When the application executes the first FETCH,
the cursor is positioned on the first row (or first rowset). When the application
executes subsequent FETCH statements, the cursor moves one row ahead (or one
rowset ahead) for each FETCH. After each FETCH statement, the cursor is
positioned on the row (or rowset) that was fetched.

After the application executes a positioned UPDATE or positioned DELETE

statement, the cursor stays at the current row (or rowset) of the result table. You
cannot retrieve rows (or rowsets) backward or move to a specific position in a
result table with a non-scrollable cursor.

Using a scrollable cursor:

Chapter 12. Accessing data 671

To make a cursor scrollable, you declare it as scrollable. A scrollable cursor can be
either row-positioned or rowset-positioned. To use a scrollable cursor, you execute
FETCH statements that indicate where you want to position the cursor. For
examples of FETCH statements that position a cursor for both rows and rowsets,
see Table 121 on page 697.

If you want to order the rows of the cursor’s result set, and you also want the
cursor to be updatable, you need to declare the cursor as scrollable, even if you
use it only to retrieve rows (or rowsets) sequentially. You can use the ORDER BY
clause in the declaration of an updatable cursor only if you declare the cursor as
scrollable.

Declaring a scrollable cursor:

To indicate that a cursor is scrollable, you declare it with the SCROLL keyword.
The following examples show a characteristic of scrollable cursors: the sensitivity.

The following figure shows a declaration for an insensitive scrollable cursor.

EXEC SQL DECLARE C1 INSENSITIVE SCROLL CURSOR FOR
SELECT DEPTNO, DEPTNAME, MGRNO
FROM DSN8910.DEPT
ORDER BY DEPTNO
END-EXEC.

Declaring a scrollable cursor with the INSENSITIVE keyword has the following
effects:
v The size, the order of the rows, and the values for each row of the result table
do not change after the application opens the cursor.
v The result table is read-only. Therefore, you cannot declare the cursor with the
FOR UPDATE clause, and you cannot use the cursor for positioned update or
delete operations.

The following figure shows a declaration for a sensitive static scrollable cursor.
EXEC SQL DECLARE C2 SENSITIVE STATIC SCROLL CURSOR FOR
SELECT DEPTNO, DEPTNAME, MGRNO
FROM DSN8910.DEPT
ORDER BY DEPTNO
END-EXEC.

Declaring a cursor as SENSITIVE STATIC has the following effects:

v When the application executes positioned UPDATE and DELETE statements
with the cursor, those changes are visible in the result table.
v When the current value of a row no longer satisfies the SELECT statement that
was used in the cursor declaration, that row is no longer visible in the result
table.
v When a row of the result table is deleted from the underlying table, that row is
no longer visible in the result table.
v Changes that are made to the underlying table by other cursors or other
application processes can be visible in the result table, depending on whether
the FETCH statements that you use with the cursor are FETCH INSENSITIVE or
FETCH SENSITIVE statements.

The following figure shows a declaration for a sensitive dynamic scrollable cursor.

672 Application Programming and SQL Guide

EXEC SQL DECLARE C2 SENSITIVE DYNAMIC SCROLL CURSOR FOR
SELECT DEPTNO, DEPTNAME, MGRNO
FROM DSN8910.DEPT
ORDER BY DEPTNO
END-EXEC.

Declaring a cursor as SENSITIVE DYNAMIC has the following effects:

v When the application executes positioned UPDATE and DELETE statements
with the cursor, those changes are visible. In addition, when the application
executes insert, update, or delete operations (within the application but outside
the cursor), those changes are visible.
v All committed inserts, updates, and deletes by other application processes are
visible.
v Because the FETCH statement executes against the base table, the cursor needs
no temporary result table. When you define a cursor as SENSITIVE DYNAMIC,
you cannot specify the INSENSITIVE keyword in a FETCH statement for that
cursor.
v If you specify an ORDER BY clause for a SENSITIVE DYNAMIC cursor, DB2
might choose an index access path if the ORDER BY is fully satisfied by an
existing index. However, a dynamic scrollable cursor that is declared with an
ORDER BY clause is not updatable.

Static scrollable cursor:

Both the INSENSITIVE cursor and the SENSITIVE STATIC cursor follow the static
cursor model:
v The size of the result table does not grow after the application opens the cursor.
Rows that are inserted into the underlying table are not added to the result
table.
v The order of the rows does not change after the application opens the cursor.
If the cursor declaration contains an ORDER BY clause, and the columns that are
in the ORDER BY clause are updated after the cursor is opened, the order of the
rows in the result table does not change.

Dynamic scrollable cursor:

When you declare a cursor as SENSITIVE, you can declare it either STATIC or
DYNAMIC. The SENSITIVE DYNAMIC cursor follows the dynamic cursor model:
v The size and contents of the result table can change with every fetch.
The base table can change while the cursor is scrolling on it. If another
application process changes the data, the cursor sees the newly changed data
when it is committed. If the application process of the cursor changes the data,
the cursor sees the newly changed data immediately.
v The order of the rows can change after the application opens the cursor.
If the cursor declaration contains an ORDER BY clause, and columns that are in
the ORDER BY clause are updated after the cursor is opened, the order of the
rows in the result table changes.

Held and non-held cursors

A held cursor does not close after a commit operation. A cursor that is not held
closes after a commit operation. You specify whether you want a cursor to be held
or not held by including or omitting the WITH HOLD clause when you declare the
cursor.

Chapter 12. Accessing data 673

After a commit operation, the position of a held cursor depends on its type:
v A non-scrollable cursor that is held is positioned after the last retrieved row and
before the next logical row. The next row can be returned from the result table
with a FETCH NEXT statement.
v A static scrollable cursor that is held is positioned on the last retrieved row. The
last retrieved row can be returned from the result table with a FETCH
CURRENT statement.
v A dynamic scrollable cursor that is held is positioned after the last retrieved row
and before the next logical row. The next row can be returned from the result
table with a FETCH NEXT statement. DB2 returns SQLCODE +231 for a FETCH
CURRENT statement.

A held cursor can close when:

v You issue a CLOSE cursor, ROLLBACK, or CONNECT statement
v You issue a CAF CLOSE function call or an RRSAF TERMINATE THREAD
function call
v The application program terminates.

If the program abnormally terminates, the cursor position is lost. To prepare for
restart, your program must reposition the cursor.

The following restrictions apply to cursors that are declared WITH HOLD:
v Do not use DECLARE CURSOR WITH HOLD with the new user signon from a
DB2 attachment facility, because all open cursors are closed.
v Do not declare a WITH HOLD cursor in a thread that might become inactive. If
you do, its locks are held indefinitely.

IMS

You cannot use DECLARE CURSOR...WITH HOLD in message processing

programs (MPP) and message-driven batch message processing (BMP). Each
message is a new user for DB2; whether or not you declare them using WITH
HOLD, no cursors continue for new users. You can use WITH HOLD in
non-message-driven BMP and DL/I batch programs.

CICS

In CICS applications, you can use DECLARE CURSOR...WITH HOLD to indicate

that a cursor should not close at a commit or sync point. However, SYNCPOINT
ROLLBACK closes all cursors, and end-of-task (EOT) closes all cursors before DB2
reuses or terminates the thread. Because pseudo-conversational transactions usually
have multiple EXEC CICS RETURN statements and thus span multiple EOTs, the
scope of a held cursor is limited. Across EOTs, you must reopen and reposition a
cursor declared WITH HOLD, as if you had not specified WITH HOLD.

You should always close cursors that you no longer need. If you let DB2 close a
CICS attachment cursor, the cursor might not close until the CICS attachment
facility reuses or terminates the thread.

The following cursor declaration causes the cursor to maintain its position in the
DSN8910.EMP table after a commit point:
EXEC SQL
DECLARE EMPLUPDT CURSOR WITH HOLD FOR
SELECT EMPNO, LASTNAME, PHONENO, JOB, SALARY, WORKDEPT

674 Application Programming and SQL Guide

FROM DSN8910.EMP
WHERE WORKDEPT < 'D11'
ORDER BY EMPNO
END-EXEC.

Accessing data by using a row-positioned cursor

A row-positioned cursor is a cursor that points to a single row and retrieves at
most a single row at a time from the result table. You can specify a fetch request to
specify which rows to retrieve relative to the current cursor position.

The basic steps in using a row-positioned cursor are:

1. Execute a DECLARE CURSOR statement to define the result table on which the
cursor operates. See “Declaring a row cursor.”
2. Execute an OPEN CURSOR to make the cursor available to the application. See
“Opening a row cursor” on page 677.
3. Specify what the program is to do when all rows have been retrieved. See
“Specifying the action that the row cursor is to take when it reaches the end of
the data” on page 677.
4. Execute multiple SQL statements to retrieve data from the table or modify
selected rows of the table. See “Executing SQL statements by using a row
cursor” on page 678.
5. Execute a CLOSE CURSOR statement to make the cursor unavailable to the
application. See “Closing a row cursor” on page 679.

Your program can have several cursors, each of which performs the previous steps.

Declaring a row cursor

Before you can use a row-positioned cursor to retrieve rows, you must declare the
cursor. When you declare a cursor, you identify a set of rows to be accessed with
the cursor.

To declare a row cursor, issue a DECLARE CURSOR statement. The DECLARE

CURSOR statement names a cursor and specifies a SELECT statement. The
SELECT statement defines the criteria for the rows that are to make up the result
table. For a complete list of clauses that you can use in the SELECT statement, see
the topic “select-statement” in DB2 SQL Reference.

The following example shows a simple form of the DECLARE CURSOR statement:
EXEC SQL
DECLARE C1 CURSOR FOR
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY
FROM DSN8910.EMP
END-EXEC.

You can use this cursor to list select information about employees.

More complicated cursors might include WHERE clauses or joins of several tables.
For example, suppose that you want to use a cursor to list employees who work
on a certain project. Declare a cursor like this to identify those employees:
EXEC SQL
DECLARE C2 CURSOR FOR
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY
FROM DSN8910.EMP X
WHERE EXISTS

Chapter 12. Accessing data 675

(SELECT *
FROM DSN8910.PROJ Y
WHERE X.EMPNO=Y.RESPEMP
AND Y.PROJNO=:GOODPROJ);

Declaring cursors for tables that use multilevel security: You can declare a cursor
that retrieves rows from a table that uses multilevel security with row-level
granularity. However, the result table for the cursor contains only those rows that
have a security label value that is equivalent to or dominated by the security label
value of your ID. For more information about multilevel security with row-level
granularity, see the topic “Multilevel security” in DB2 Administration Guide.

Updating a column: You can update columns in the rows that you retrieve.
Updating a row after you use a cursor to retrieve it is called a positioned update. If
you intend to perform any positioned updates on the identified table, include the
FOR UPDATE clause. The FOR UPDATE clause has two forms:
v The first form is FOR UPDATE OF column-list. Use this form when you know in
advance which columns you need to update.
v The second form is FOR UPDATE, with no column list. Use this form when you
might use the cursor to update any of the columns of the table.

For example, you can use this cursor to update only the SALARY column of the
employee table:
EXEC SQL
DECLARE C1 CURSOR FOR
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY
FROM DSN8910.EMP X
WHERE EXISTS
(SELECT *
FROM DSN8910.PROJ Y
WHERE X.EMPNO=Y.RESPEMP
AND Y.PROJNO=:GOODPROJ)
FOR UPDATE OF SALARY;

If you might use the cursor to update any column of the employee table, define
the cursor like this:
EXEC SQL
DECLARE C1 CURSOR FOR
SELECT EMPNO, FIRSTNME, MIDINIT, LASTNAME, SALARY
FROM DSN8910.EMP X
WHERE EXISTS
(SELECT *
FROM DSN8910.PROJ Y
WHERE X.EMPNO=Y.RESPEMP
AND Y.PROJNO=:GOODPROJ)
FOR UPDATE;

DB2 must do more processing when you use the FOR UPDATE clause without a
column list than when you use the FOR UPDATE clause with a column list.
Therefore, if you intend to update only a few columns of a table, your program
can run more efficiently if you include a column list.

The precompiler options NOFOR and STDSQL affect the use of the FOR UPDATE
clause in static SQL statements. For information about these options, see Table 150
on page 904. If you do not specify the FOR UPDATE clause in a DECLARE
CURSOR statement, and you do not specify the STDSQL(YES) option or the
NOFOR precompiler options, you receive an error if you execute a positioned
UPDATE statement.

676 Application Programming and SQL Guide

You can update a column of the identified table even though it is not part of the
result table. In this case, you do not need to name the column in the SELECT
statement. When the cursor retrieves a row (using FETCH) that contains a column
value you want to update, you can use UPDATE ... WHERE CURRENT OF to
identify the row that is to be updated.

Read-only result table: Some result tables cannot be updated—for example, the
result of joining two or more tables. For information about the defining
characteristics of read-only result tables, see the topic “DECLARE CURSOR” in
DB2 SQL Reference.

Opening a row cursor

After you declare a row cursor, you need to tell DB2 that you are ready to process
the first row of the result table. This action is called opening the cursor.

To open a row cursor, execute the OPEN statement in your program. DB2 then
uses the SELECT statement within DECLARE CURSOR to identify a set of rows. If
you use host variables in the search condition of that SELECT statement, DB2 uses
the current value of the variables to select the rows. The result table that satisfies
the search condition might contain zero, one, or many rows. An example of an
OPEN statement is:
EXEC SQL
OPEN C1
END-EXEC.

If you use the CURRENT DATE, CURRENT TIME, or CURRENT TIMESTAMP

special registers in a cursor, DB2 determines the values in those special registers
only when it opens the cursor. DB2 uses the values that it obtained at OPEN time
for all subsequent FETCH statements.

Two factors that influence the amount of time that DB2 requires to process the
OPEN statement are:
v Whether DB2 must perform any sorts before it can retrieve rows
v Whether DB2 uses parallelism to process the SELECT statement of the cursor

Specifying the action that the row cursor is to take when it

reaches the end of the data
Your program must anticipate and handle an end-of-data whenever you use a row
cursor to fetch a row.

To determine whether the program has retrieved the last row of data, test the
SQLCODE field for a value of 100 or the SQLSTATE field for a value of ’02000’.
These codes occur when a FETCH statement has retrieved the last row in the result
table and your program issues a subsequent FETCH. For example:
IF SQLCODE = 100 GO TO DATA-NOT-FOUND.

An alternative to this technique is to code the WHENEVER NOT FOUND

statement. The WHENEVER NOT FOUND statement causes your program to
branch to another part that then issues a CLOSE statement. For example, to branch
to label DATA-NOT-FOUND when the FETCH statement does not return a row,
use this statement:
EXEC SQL
WHENEVER NOT FOUND GO TO DATA-NOT-FOUND
END-EXEC.

Chapter 12. Accessing data 677

For more information about the WHENEVER NOT FOUND statement, see
“Checking the execution of SQL statements” on page 202.

Executing SQL statements by using a row cursor

You can use row cursors to execute FETCH statements, positioned UPDATE
statements, and positioned DELETE statements.

Execute a FETCH statement for one of the following purposes:

v To copy data from a row of the result table into one or more host variables
v To position the cursor before you perform a positioned update or positioned
delete operation
The following example shows a FETCH statement that retrieves selected columns
from the employee table:
EXEC SQL
FETCH C1 INTO
:HV-EMPNO, :HV-FIRSTNME, :HV-MIDINIT, :HV-LASTNAME, :HV-SALARY :IND-SALARY
END-EXEC.

The SELECT statement within DECLARE CURSOR statement identifies the result
table from which you fetch rows, but DB2 does not retrieve any data until your
application program executes a FETCH statement.

When your program executes the FETCH statement, DB2 positions the cursor on a
row in the result table. That row is called the current row. DB2 then copies the
current row contents into the program host variables that you specify on the INTO
clause of FETCH. This sequence repeats each time you issue FETCH, until you
process all rows in the result table.

The row that DB2 points to when you execute a FETCH statement depends on
whether the cursor is declared as a scrollable or non-scrollable.

When you query a remote subsystem with FETCH, consider using block fetch for
better performance. Block fetch processes rows ahead of the current row. You
cannot use a block fetch when you perform a positioned update or delete
operation.

After your program has executed a FETCH statement to retrieve the current row,
you can use a positioned UPDATE statement to modify the data in that row. An
example of a positioned UPDATE statement is:
EXEC SQL
UPDATE DSN8910.EMP
SET SALARY = 50000
WHERE CURRENT OF C1
END-EXEC.

A positioned UPDATE statement updates the row on which the cursor is

positioned.

A positioned UPDATE statement is subject to these restrictions:

v You cannot update a row if your update violates any unique, check, or
referential constraints.
v You cannot use an UPDATE statement to modify the rows of a created
temporary table. However, you can use an UPDATE statement to modify the
rows of a declared temporary table.

678 Application Programming and SQL Guide

v If the right side of the SET clause in the UPDATE statement contains a fullselect,
that fullselect cannot include a correlated name for a table that is being updated.
| v You cannot use an SQL data change statement in the FROM clause of a SELECT
| statement that defines a cursor that is used in a positioned UPDATE statement.
v A positioned UPDATE statement will fail if the value of the security label
column of the row where the cursor is positioned is not equivalent to the
security label value of your user id. If your user id has write down privilege, a
positioned UPDATE statement will fail if the value of the security label column
of the row where the cursor is positioned does not dominate the security label
value of your user id.

After your program has executed a FETCH statement to retrieve the current row,
you can use a positioned DELETE statement to delete that row. A example of a
positioned DELETE statement looks like this:
EXEC SQL
DELETE FROM DSN8910.EMP
WHERE CURRENT OF C1
END-EXEC.

A positioned DELETE statement deletes the row on which the cursor is positioned.

A positioned DELETE statement is subject to these restrictions:

v You cannot use a DELETE statement with a cursor to delete rows from a created
temporary table. However, you can use a DELETE statement with a cursor to
delete rows from a declared temporary table.
v After you have deleted a row, you cannot update or delete another row using
that cursor until you execute a FETCH statement to position the cursor on
another row.
v You cannot delete a row if doing so violates any referential constraints.
| v You cannot use an SQL data change statement in the FROM clause of a SELECT
| statement that defines a cursor that is used in a positioned DELETE statement.
v A positioned DELETE statement will fail if the value of the security label column
of the row where the cursor is positioned is not equivalent to the security label
value of your user id. If your user id has write down privilege, a positioned
DELETE statement will fail if the value of the security label column of the row
where the cursor is positioned does not dominate the security label value of
your user id.

Closing a row cursor

Close a row cursor when it finishes processing rows if you want to free the
resources that are held by the cursor or if you want to use the cursor again.
Otherwise, you can let DB2 automatically close the cursor when the current
transaction terminates or when your program terminates.

Recommendation: To free the resources that are held by the cursor, close the
cursor explicitly by issuing the CLOSE statement.

To close a row cursor, issue a CLOSE statement An example of a CLOSE statement

looks like this:
EXEC SQL
CLOSE C1
END-EXEC.

If you want to use the rowset cursor again, reopen it.

Chapter 12. Accessing data 679

Accessing data by using a rowset-positioned cursor
A rowset-positioned cursor is a cursor that can return one or more rows for a
single fetch operation. The cursor is positioned on the set of rows to be fetched.

The basic steps in using a rowset cursor are:

1. Execute a DECLARE CURSOR statement to define the result table on which the
cursor operates. See “Declaring a rowset cursor.”
2. Execute an OPEN CURSOR to make the cursor available to the application. See
“Opening a rowset cursor.”
3. Specify what the program is to do when all rows have been retrieved. See
“Specifying the action that the rowset cursor is to take when it reaches the end
of the data.”
4. Execute multiple SQL statements to retrieve data from the table or modify
selected rows of the table. See “Executing SQL statements by using a rowset
cursor” on page 681.
5. Execute a CLOSE CURSOR statement to make the cursor unavailable to the
application. See “Closing a rowset cursor” on page 685.

Your program can have several cursors, each of which performs the previous steps.

Declaring a rowset cursor

Before you can use a rowset-positioned cursor to retrieve rows, you must declare a
cursor that is enabled to fetch rowsets. When you declare a cursor, you identify a
set of rows to be accessed with the cursor.

To declare a rowset cursor, use the WITH ROWSET POSITIONING clause in the
DECLARE CURSOR statement. The following example shows how to declare a
rowset cursor:
EXEC SQL
DECLARE C1 CURSOR WITH ROWSET POSITIONING FOR
SELECT EMPNO, LASTNAME, SALARY
FROM DSN8910.EMP
END-EXEC.

For restrictions that apply to rowset-positioned cursors and row-positioned cursors,

see “Declaring a row cursor” on page 675.

Opening a rowset cursor

After you declare a rowset cursor, you need to tell DB2 that you are ready to
process the first rowset of the result table. This action is called opening the cursor.

To open a rowset cursor, execute the OPEN statement in your program. DB2 then
uses the SELECT statement within DECLARE CURSOR to identify the rows in the
result table. For more information about the OPEN CURSOR process, see “Opening
a row cursor” on page 677.

Specifying the action that the rowset cursor is to take when it

reaches the end of the data
Your program must anticipate and handle an end-of-data whenever you use a
rowset cursor to fetch rows.

To determine whether the program has retrieved the last row of data in the result
table, test the SQLCODE field for a value of +100 or the SQLSTATE field for a
value of ’02000’. With a rowset cursor, these codes occur when a FETCH statement
retrieves the last row in the result table. However, when the last row has been

680 Application Programming and SQL Guide

retrieved, the program must still process the rows in the last rowset through that
last row. For an example of end-of-data processing for a rowset cursor, see
“Examples of fetching rows by using cursors” on page 697.

To determine the number of retrieved rows, use either of the following values:
v The contents of the SQLERRD(3) field in the SQLCA
v The contents of the ROW_COUNT item of GET DIAGNOSTICS

For information about GET DIAGNOSTICS, see “Checking the execution of SQL
statements by using the GET DIAGNOSTICS statement” on page 209.

If you declare the cursor as dynamic scrollable, and SQLCODE has the value +100,
you can continue with a FETCH statement until no more rows are retrieved.
Additional fetches might retrieve more rows because a dynamic scrollable cursor is
sensitive to updates by other application processes. For information about dynamic
cursors, see “Types of cursors” on page 671.

Executing SQL statements by using a rowset cursor

You can use rowset cursors to execute multiple-row FETCH statements, positioned
UPDATE statements, and positioned DELETE statements.

You can execute these static SQL statements when you use a rowset cursor:
v A multiple-row FETCH statement that copies a rowset of column values into
either of the following data areas:
– Host variable arrays that are declared in your program
– Dynamically-allocated arrays whose storage addresses are put into an SQL
descriptor area (SQLDA), along with the attributes of the columns that are to
be retrieved
v After either form of the multiple-row FETCH statement, you can issue:
– A positioned UPDATE statement on the current rowset
– A positioned DELETE statement on the current rowset

You must use the WITH ROWSET POSITIONING clause of the DECLARE
CURSOR statement if you plan to use a rowset-positioned FETCH statement.

The following example shows a FETCH statement that retrieves 20 rows into host
variable arrays that are declared in your program:
EXEC SQL
FETCH NEXT ROWSET FROM C1
FOR 20 ROWS
INTO :HVA-EMPNO, :HVA-LASTNAME, :HVA-SALARY :INDA-SALARY
END-EXEC.

When your program executes a FETCH statement with the ROWSET keyword, the
cursor is positioned on a rowset in the result table. That rowset is called the current
rowset. The dimension of each of the host variable arrays must be greater than or
equal to the number of rows to be retrieved.

Suppose that you want to dynamically allocate the storage needed for the arrays of
column values that are to be retrieved from the employee table. You must:
1. Declare an SQLDA structure and the variables that reference the SQLDA.
2. Dynamically allocate the SQLDA and the arrays needed for the column values.
3. Set the fields in the SQLDA for the column values to be retrieved.
4. Open the cursor.
5. Fetch the rows.

Chapter 12. Accessing data 681

You must first declare the SQLDA structure. The following SQL INCLUDE
statement requests a standard SQLDA declaration:
EXEC SQL INCLUDE SQLDA;

Your program must also declare variables that reference the SQLDA structure, the
SQLVAR structure within the SQLDA, and the DECLEN structure for the precision
and scale if you are retrieving a DECIMAL column. For C programs, the code
looks like this:
struct sqlda *sqldaptr;
struct sqlvar *varptr;
struct DECLEN {
unsigned char precision;
unsigned char scale;
};

Before you can set the fields in the SQLDA for the column values to be retrieved,
you must dynamically allocate storage for the SQLDA structure. For C programs,
the code looks like this:
sqldaptr = (struct sqlda *) malloc (3 * 44 + 16);

The size of the SQLDA is SQLN * 44 + 16, where the value of the SQLN field is the
number of output columns.

You must set the fields in the SQLDA structure for your FETCH statement.
Suppose you want to retrieve the columns EMPNO, LASTNAME, and SALARY.
The C code to set the SQLDA fields for these columns looks like this:
| strcpy(sqldaptr->sqldaid,"SQLDA");
| sqldaptr->sqldabc = 148; /* number bytes of storage allocated for the SQLDA */
| sqldaptr->sqln = 3; /* number of SQLVAR occurrences */
| sqldaptr->sqld = 3;
| varptr = (struct sqlvar *) (&(sqldaptr->sqlvar[0])); /* Point to first SQLVAR */
| varptr->sqltype = 452; /* data type CHAR(6) */
| varptr->sqllen = 6;
| varptr->sqldata = (char *) hva1;
| varptr->sqlind = (short *) inda1;
| varptr->sqlname.length = 8;
| memcpy(varptr->sqlname.data, "\x00\x00\x00\x00\x00\x01\x00\x14",varptr->sqlname.length);
| varptr = (struct sqlvar *) (&(sqldaptr->sqlvar[0]) + 1); /* Point to next SQLVAR */
| varptr->sqltype = 448; /* data type VARCHAR(15) */
| varptr->sqllen = 15;
| varptr->sqldata = (char *) hva2;
| varptr->sqlind = (short *) inda2;
| varptr->sqlname.length = 8;
| memcpy(varptr->sqlname.data, "\x00\x00\x00\x00\x00\x01\x00\x14",varptr->sqlname.length);
| varptr = (struct sqlvar *) (&(sqldaptr->sqlvar[0]) + 2); /* Point to next SQLVAR */
| varptr->sqltype = 485; /* data type DECIMAL(9,2) */
| ((struct DECLEN *) &(varptr->sqllen))->precision = 9;
| ((struct DECLEN *) &(varptr->sqllen))->scale = 2;
| varptr->sqldata = (char *) hva3;
| varptr->sqlind = (short *) inda3;
| varptr->sqlname.length = 8;
| memcpy(varptr->sqlname.data, "\x00\x00\x00\x00\x00\x01\x00\x14",varptr->sqlname.length);

The SQLDA structure has these fields:

v SQLDABC indicates the number of bytes of storage that are allocated for the
SQLDA. The storage includes a 16-byte header and 44 bytes for each SQLVAR
field. The value is SQLN x 44 + 16, or 148 for this example.
v SQLN is the number of SQLVAR occurrences (or the number of output columns).
v SQLD is the number of variables in the SQLDA that are used by DB2 when
processing the FETCH statement.
682 Application Programming and SQL Guide
v Each SQLVAR occurrence describes a host variable array or buffer into which the
values for a column in the result table are to be returned. Within each SQLVAR:
– SQLTYPE indicates the data type of the column.
– SQLLEN indicates the length of the column. If the data type is DECIMAL,
this field has two parts: the PRECISION and the SCALE.
– SQLDATA points to the first element of the array for the column values. For
this example, assume that your program allocates the dynamic variable arrays
hva1, hva2, and hva3, and their indicator arrays inda1, inda2, and inda3.
– SQLIND points to the first element of the array of indicator values for the
column. If SQLTYPE is an odd number, this attribute is required. (If SQLTYPE
is an odd number, null values are allowed for the column.)
| – SQLNAME has two parts: the LENGTH and the DATA. The LENGTH is 8.
| The first two bytes of the DATA field is X’0000’. Bytes 5 and 6 of the DATA
| field are a flag indicating whether the variable is an array or a FOR n ROWS
| value. Bytes 7 and 8 are a two-byte binary integer representation of the
| dimension of the array.

For information about using the SQLDA in dynamic SQL, see “Dynamic SQL” on
page 162.

For more information about the SQLDA, see the topic “SQL descriptor area
(SQLDA)” in DB2 SQL Reference.

You can open the cursor only after all of the fields have been set in the output
SQLDA:
EXEC SQL OPEN C1;

After the OPEN statement, the program fetches the next rowset:
EXEC SQL
FETCH NEXT ROWSET FROM C1
FOR 20 ROWS
USING DESCRIPTOR :*sqldaptr;

The USING clause of the FETCH statement names the SQLDA that describes the
columns that are to be retrieved.

After your program executes a FETCH statement to establish the current rowset,
you can use a positioned UPDATE statement with either of the following clauses:
v Use WHERE CURRENT OF to modify all of the rows in the current rowset
v Use FOR ROW n OF ROWSET to modify row n in the current rowset
For information about restrictions for a positioned UPDATE, see “Executing SQL
statements by using a row cursor” on page 678.

An example of a positioned UPDATE statement that uses the WHERE CURRENT

OF clause is:
EXEC SQL
UPDATE DSN8910.EMP
SET SALARY = 50000
WHERE CURRENT OF C1
END-EXEC.

When the UPDATE statement is executed, the cursor must be positioned on a row
or rowset of the result table. If the cursor is positioned on a row, that row is
updated. If the cursor is positioned on a rowset, all of the rows in the rowset are
updated.

Chapter 12. Accessing data 683

An example of a positioned UPDATE statement that uses the FOR ROW n OF
ROWSET clause is:
EXEC SQL
UPDATE DSN8910.EMP
SET SALARY = 50000
FOR CURSOR C1 FOR ROW 5 OF ROWSET
END-EXEC.

When the UPDATE statement is executed, the cursor must be positioned on a

rowset of the result table. The specified row (in the example, row 5) of the current
rowset is updated.

After your program executes a FETCH statement to establish the current rowset,
you can use a positioned DELETE statement with either of the following clauses:
v Use WHERE CURRENT OF to delete all of the rows in the current rowset
v Use FOR ROW n OF ROWSET to delete row n in the current rowset
For information about restrictions for a positioned DELETE, see “Executing SQL
statements by using a row cursor” on page 678.

An example of a positioned DELETE statement that uses the WHERE CURRENT

OF clause is:
EXEC SQL
DELETE FROM DSN8910.EMP
WHERE CURRENT OF C1
END-EXEC.

When the DELETE statement is executed, the cursor must be positioned on a row
or rowset of the result table. If the cursor is positioned on a row, that row is
deleted, and the cursor is positioned before the next row of its result table. If the
cursor is positioned on a rowset, all of the rows in the rowset are deleted, and the
cursor is positioned before the next rowset of its result table.

An example of a positioned DELETE statement that uses the FOR ROW n OF

ROWSET clause is:
EXEC SQL
DELETE FROM DSN8910.EMP
FOR CURSOR C1 FOR ROW 5 OF ROWSET
END-EXEC.

When the DELETE statement is executed, the cursor must be positioned on a

rowset of the result table. The specified row of the current rowset is deleted, and
the cursor remains positioned on that rowset. The deleted row (in the example,
row 5 of the rowset) cannot be retrieved or updated.

Specifying the number of rows in a rowset:

If you do not explicitly specify the number of rows in a rowset, DB2 implicitly
determines the number of rows based on the last fetch request.

To explicitly set the size of a rowset, use the FOR n ROWS clause in the FETCH
statement. If a FETCH statement specifies the ROWSET keyword, and not the FOR
n ROWS clause, the size of the rowset is implicitly set to the size of the rowset that
was most recently specified in a prior FETCH statement. If a prior FETCH
statement did not specify the FOR n ROWS clause or the ROWSET keyword, the
size of the current rowset is implicitly set to 1. For examples of rowset positioning,
see Table 121 on page 697.

684 Application Programming and SQL Guide

Closing a rowset cursor
Close a rowset cursor when it finishes processing rows if you want to free the
resources that are held by the cursor or if you want to use the cursor again.
Otherwise, you can let DB2 automatically close the cursor when the current
transaction terminates or when your program terminates.

Recommendation: To free the resources held by the cursor, close the cursor
explicitly by issuing the CLOSE statement.

To close a rowset cursor, issue a CLOSE statement.

If you want to use the rowset cursor again, reopen it.

Retrieving rows by using a scrollable cursor

A scrollable cursor is cursor that can be moved in both a forward and a backward
direction. Scrollable cursors can be either row-positioned or rowset-positioned.

When you open any cursor, the cursor is positioned before the first row of the
result table. You move a scrollable cursor around in the result table by specifying a
fetch orientation keyword in a FETCH statement. A fetch orientation keyword
indicates the absolute or relative position of the cursor when the FETCH statement
is executed. The following table lists the fetch orientation keywords that you can
specify and their meanings. These keywords apply to both row-positioned
scrollable cursors and rowset-positioned scrollable cursors.
Table 119. Positions for a scrollable cursor
Keyword in FETCH statement Cursor position when FETCH is executed1
BEFORE Before the first row
FIRST or ABSOLUTE +1 On the first row
LAST or ABSOLUTE -1 On the last row
AFTER After the last row
ABSOLUTE2 On an absolute row number, from before the first
row forward or from after the last row backward
RELATIVE2 On the row that is forward or backward a relative
number of rows from the current row
CURRENT On the current row
PRIOR or RELATIVE -1 On the previous row
NEXT On the next row (default)
Notes:
1. The cursor position applies to both row position and rowset position, for example, before
the first row or before the first rowset.
2. For more information about ABSOLUTE and RELATIVE, see the topic “FETCH” inDB2
SQL Reference.

Example: To use the cursor that is declared in “Types of cursors” on page 671 to
fetch the fifth row of the result table, use a FETCH statement like this:
EXEC SQL FETCH ABSOLUTE +5 C1 INTO :HVDEPTNO, :DEPTNAME, :MGRNO;

To fetch the fifth row from the end of the result table, use this FETCH statement:
EXEC SQL FETCH ABSOLUTE -5 C1 INTO :HVDEPTNO, :DEPTNAME, :MGRNO;

Chapter 12. Accessing data 685

Comparison of scrollable cursors
Whether a scrollable cursor can view the changes that are made to the data by
other processes or cursors depends on how the cursor is declared and the type of
fetch operation that is executed.

When you declare a cursor as SENSITIVE STATIC, changes that other processes or
cursors make to the underlying table can be visible to the result table of the cursor.
Whether those changes are visible depends on whether you specify SENSITIVE or
INSENSITIVE when you execute FETCH statements with the cursor. When you
specify FETCH INSENSITIVE, changes that other processes or other cursors make
to the underlying table are not visible in the result table. When you specify FETCH
SENSITIVE, changes that other processes or cursors make to the underlying table
are visible in the result table.

When you declare a cursor as SENSITIVE DYNAMIC, changes that other processes
or cursors make to the underlying table are visible to the result table after the
changes are committed.

The following table summarizes the sensitivity values and their effects on the
result table of a scrollable cursor.
Table 120. How sensitivity affects the result table for a scrollable cursor
DECLARE
sensitivity FETCH INSENSITIVE FETCH SENSITIVE
INSENSITIVE No changes to the underlying Not valid.
table are visible in the result
table. Positioned UPDATE and
DELETE statements using the
cursor are not allowed.
SENSITIVE STATIC Only positioned updates and All updates and deletes are visible
deletes that are made by the in the result table. Inserts made by
cursor are visible in the result other processes are not visible in
table. the result table.
SENSITIVE Not valid. All committed changes are visible
DYNAMIC in the result table, including
updates, deletes, inserts, and
changes in the order of the rows.

Scrolling through a table in any direction

Use a scrollable cursor to move through the table in both a forward and a
backward direction.

Question: How can I fetch rows from a table in any direction?

Answer: Declare your cursor as scrollable. When you select rows from the table,
you can use the various forms of the FETCH statement to move to an absolute row
number, move ahead or back a certain number of rows, to the first or last row,
before the first row or after the last row, forward, or backward. You can use any
combination of these FETCH statements to change direction repeatedly.

You can use code like the following example to move forward in the department
table by 10 records, backward five records, and forward again by three records:
/**************************/
/* Declare host variables */
/**************************/

686 Application Programming and SQL Guide

EXEC SQL BEGIN DECLARE SECTION;
char[37] hv_deptname;
EXEC SQL END DECLARE SECTION;
/**********************************************************/
/* Declare scrollable cursor to retrieve department names */
/**********************************************************/
EXEC SQL DECLARE C1 SCROLL CURSOR FOR
. SELECT DEPTNAME FROM DSN8910.DEPT;
.
.
/**********************************************************/
/* Open the cursor and position it before the start of */
/* the result table. */
/**********************************************************/
EXEC SQL OPEN C1;
EXEC SQL FETCH BEFORE FROM C1;
/**********************************************************/
/* Fetch first 10 rows */
/**********************************************************/
for(i=0;i<10;i++)
{
EXEC SQL FETCH NEXT FROM C1 INTO :hv_deptname;
}
/**********************************************************/
/* Save the value in the tenth row */
/**********************************************************/
tenth_row=hv_deptname;
/**********************************************************/
/* Fetch backward 5 rows */
/**********************************************************/
for(i=0;i<5;i++)
{
EXEC SQL FETCH PRIOR FROM C1 INTO :hv_deptname;
}
/**********************************************************/
/* Save the value in the fifth row */
/**********************************************************/
fifth_row=hv_deptname;
/**********************************************************/
/* Fetch forward 3 rows */
/**********************************************************/
for(i=0;i<3;i++)
{
EXEC SQL FETCH NEXT FROM C1 INTO :hv_deptname;
}
/**********************************************************/
/* Save the value in the eighth row */
/**********************************************************/
eighth_row=hv_deptname;
/**********************************************************/
/* Close the cursor */
/**********************************************************/
EXEC SQL CLOSE C1;

Determining the number of rows in the result table for a static

scrollable cursor
You can determine how many rows are in the result table of an INSENSITIVE or
SENSITIVE STATIC scrollable cursor.

To do that, execute a FETCH statement, such as FETCH AFTER, that positions the
cursor after the last row. You can then examine the fields SQLERRD(1) and
SQLERRD(2) in the SQLCA (fields sqlerrd[0] and sqlerrd[1] for C and C++) for the
number of rows in the result table. Alternatively, you can use the GET
DIAGNOSTICS statement to retrieve the number of rows in the ROW_COUNT
statement item.

Chapter 12. Accessing data 687

Removing a delete hole or update hole
If you try to fetch from a delete hole or an update hole, DB2 issues an SQL
warning. If you try to update or delete a delete hole or delete an update hole, DB2
issues an SQL error.

You can remove a delete hole only by opening the scrollable cursor, setting a
savepoint, executing a positioned DELETE statement with the scrollable cursor,
and rolling back to the savepoint.

You can convert an update hole back to a result table row by updating the row in
the base table, as shown in the following figure. You can update the base table
with a searched UPDATE statement in the same application process, or a searched
or positioned UPDATE statement in another application process. After you update
the base table, if the row qualifies for the result table, the update hole disappears.

Figure 36. Removing an update hole

A hole becomes visible to a cursor when a cursor operation returns a non-zero

SQLCODE. The point at which a hole becomes visible depends on the following
factors:
v Whether the scrollable cursor creates the hole
v Whether the FETCH statement is FETCH SENSITIVE or FETCH INSENSITIVE

If the scrollable cursor creates the hole, the hole is visible when you execute a
FETCH statement for the row that contains the hole. The FETCH statement can be
FETCH INSENSITIVE or FETCH SENSITIVE.

If an update or delete operation outside the scrollable cursor creates the hole, the
hole is visible at the following times:
v If you execute a FETCH SENSITIVE statement for the row that contains the hole,
the hole is visible when you execute the FETCH statement.
v If you execute a FETCH INSENSITIVE statement, the hole is not visible when
you execute the FETCH statement. DB2 returns the row as it was before the
update or delete operation occurred. However, if you follow the FETCH
INSENSITIVE statement with a positioned UPDATE or DELETE statement, the
hole becomes visible.

Holes in the result table of a scrollable cursor:

688 Application Programming and SQL Guide

A hole in the result table means that the result table does not shrink to fill the
space of deleted rows or rows that have been updated and no longer satisfy the
search condition. You cannot access a delete or update hole. However, you can
remove holes in specific situations.

In some situations, you might not be able to fetch a row from the result table of a
scrollable cursor, depending on how the cursor is declared:
v Scrollable cursors that are declared as INSENSITIVE or SENSITIVE STATIC
follow a static model, which means that DB2 determines the size of the result
table and the order of the rows when you open the cursor.
Deleting or updating rows after a static cursor is open can result in holes in the
result table. See “Removing a delete hole or update hole” on page 688.
v Scrollable cursors that are declared as SENSITIVE DYNAMIC follow a dynamic
model, which means that the size and contents of the result table, and the order
of the rows, can change after you open the cursor.
A dynamic cursor scrolls directly on the base table. If the current row of the
cursor is deleted or if it is updated so that it no longer satisfies the search
condition, and the next cursor operation is FETCH CURRENT, then DB2 issues
an SQL warning.

The following examples demonstrate how delete and update holes can occur when
you use a SENSITIVE STATIC scrollable cursor.

Creating a delete hole with a static scrollable cursor:

Suppose that table A consists of one integer column, COL1, which has the values
shown in the following figure.
Now suppose that you declare the following SENSITIVE STATIC scrollable cursor,

Figure 37. Values for COL1 of table A

which you use to delete rows from A:

EXEC SQL DECLARE C3 SENSITIVE STATIC SCROLL CURSOR FOR
SELECT COL1
FROM A
FOR UPDATE OF COL1;

Now you execute the following SQL statements:

EXEC SQL OPEN C3;
EXEC SQL FETCH ABSOLUTE +3 C3 INTO :HVCOL1;
EXEC SQL DELETE FROM A WHERE CURRENT OF C3;

The positioned delete statement creates a delete hole, as shown in the following
figure.

Chapter 12. Accessing data 689

Figure 38. Delete hole

After you execute the positioned delete statement, the third row is deleted from
the result table, but the result table does not shrink to fill the space that the deleted
row creates.

Creating an update hole with a static scrollable cursor

Suppose that you declare the following SENSITIVE STATIC scrollable cursor,
which you use to update rows in A:
EXEC SQL DECLARE C4 SENSITIVE STATIC SCROLL CURSOR FOR
SELECT COL1
FROM A
WHERE COL1<6;

Now you execute the following SQL statements:

EXEC SQL OPEN C4;
UPDATE A SET COL1=COL1+1;

The searched UPDATE statement creates an update hole, as shown in the following
figure.

Figure 39. Update hole

After you execute the searched UPDATE statement, the last row no longer qualifies
for the result table, but the result table does not shrink to fill the space that the
disqualified row creates.

| Accessing XML or LOB data quickly by using FETCH WITH

| CONTINUE
| You can improve the performance of some queries that reference XML and LOB
| columns with unknown or very large maximum lengths by using the FETCH
| WITH CONTINUE statement.

| FETCH WITH CONTINUE breaks XML and LOB values into manageable pieces
| and processes the pieces one at a time to avoid the following buffer allocation
| problems:
690 Application Programming and SQL Guide
| v Allocating overly large or unnecessary space for buffers. If some LOB values are
| shorter than the maximum length for values in a column, you can waste buffer
| space if you allocate enough space for the maximum length. The buffer
| allocation problem can be even worse for XML data because an XML column
| does not have a defined maximum length. If you use FETCH WITH
| CONTINUE, you can allocate more appropriate buffer space for the actual
| length of the XML and LOB values.
| v Truncating very large XML and LOB data. If a very large XML or LOB value
| does not fit in the host variable buffer space that is provided by the application
| program, DB2 truncates the value. If the application program retries this fetch
| with a larger buffer, two problems exist. First, when using a non-scrollable
| cursor, you cannot re-fetch the current row without closing, reopening, and
| repositioning the cursor to the row that was truncated. Second, if you do not use
| FETCH WITH CONTINUE, DB2 does not return the actual length of the entire
| value to the application program. Thus, DB2 does not know how large a buffer
| to reallocate. If you use FETCH WITH CONTINUE, DB2 preserves the truncated
| portion of the data for subsequent retrieval and returns the actual length of the
| entire data value so that the application can reallocate a buffer of the appropriate
| size.
| DB2 provides two methods for using FETCH WITH CONTINUE with LOB and
| XML data:
| v “Dynamically allocating buffers when fetching XML and LOB data”
| v “Moving data through fixed-size buffers when fetching XML and LOB data” on
| page 692

| Dynamically allocating buffers when fetching XML and LOB data

| If you specify FETCH WITH CONTINUE, DB2 returns information about which
| data does not fit in the buffer. Your application can then use the information about
| the truncated data to allocate an appropriate target buffer and execute a fetch
| operation with the CURRENT CONTINUE clause to retrieve the remaining data.

| To use dynamic buffer allocation for LOB and XML data, perform the following
| steps:
| 1. Use an initial FETCH WITH CONTINUE to fetch data into a pre-allocated
| buffer of a moderate size.
| 2. If the value is too large to fit in the buffer, use the length information that is
| returned by DB2 to allocate the appropriate amount of storage.
| 3. Use a single FETCH CURRENT CONTINUE statement to retrieve the
| remainder of the data.

| Example: Suppose that table T1 was created with the following statement:
| CREATE TABLE T1 (C1 INT, C2 CLOB(100M), C3 CLOB(32K), C4 XML);

| A row exists in T1 where C1 contains a valid integer, C2 contains 10MB of data, C3

| contains 32KB of data, and C4 contains 4MB of data.

| Now, suppose that you declare CURSOR1, prepare and describe statement
| DYNSQLSTMT1 with descriptor sqlda, and open CURSOR1 with the following
| statements:
| EXEC SQL DECLARE CURSOR1 CURSOR FOR DYNSQLSTMT1;
| EXEC SQL PREPARE DYNSQLSTMT1 FROM 'SELECT * FROM T1';
| EXEC SQL DESCRIBE DYNSQLSTMT1 INTO DESCRIPTOR :SQLDA;
| EXEC SQL OPEN CURSOR1;

Chapter 12. Accessing data 691

| Next, suppose that you allocate moderately sized buffers (32 KB for each CLOB or
| XML column) and set data pointers and lengths in SQLDA. Then, you use the
| following FETCH WITH CONTINUE statement:
| EXEC SQL FETCH WITH CONTINUE CURSOR1 INTO DESCRIPTOR :SQLDA;

| Because C2 and C4 contain data that do not fit in the buffer, some of the data is
| truncated. Your application can use the information that DB2 returns to allocate
| large enough buffers for the remaining data and reset the data pointers and length
| fields in SQLDA. At that point, you can resume the fetch and complete the process
| with the following FETCH CURRENT CONTINUE statement and CLOSE CURSOR
| statement:
| EXEC SQL FETCH CURRENT CONTINUE CURSOR1 INTO DESCRIPTOR :SQLDA;
| EXEC SQL CLOSE CURSOR1;

| The application needs to concatenate the two returned pieces of the data value.
| One technique is to move the first piece of data to the dynamically-allocated larger
| buffer before the FETCH CONTINUE. Set the SQLDATA pointer in the SQLDA
| structure to point immediately after the last byte of this truncated value. DB2 then
| writes the remaining data to this location and thus completes the concatenation.

| Moving data through fixed-size buffers when fetching XML and

| LOB data
| If you use the WITH CONTINUE clause, DB2 returns information about which
| data does not fit in the buffer. Your application can then use repeated FETCH
| CURRENT CONTINUE operations to effectively ″stream″ large XML and LOB data
| through a fixed-size buffer, one piece at a time.

| To use fixed buffer allocation for LOB and XML data, perform the following steps:
| 1. Use an initial FETCH WITH CONTINUE to fetch data into a pre-allocated
| buffer of a moderate size.
| 2. If the value is too large to fit in the buffer, use as many FETCH CONTINUE
| statements as necessary to process all of the data through a fixed buffer.
| After each FETCH operation, check whether a column was truncated by first
| examining the SQLWARN1 field in the returned SQLCA. If that field contains a
| ’W’ value, at least one column in the returned row has been truncated. To then
| determine if a particular LOB or XML column was truncated, your application
| must compare the value that is returned in the length field with the declared
| length of the host variable. If a column is truncated, continue to use FETCH
| CONTINUE statements until all of the data has been retrieved.
| After you fetch each piece of the data, move it out of the buffer to make way
| for the next fetch. Your application can write the pieces to an output file or
| reconstruct the entire data value in a buffer above the 2-GB bar.

| Example: Suppose that table T1 was created with the following statement:
| CREATE TABLE T1 (C1 INT, C2 CLOB(100M), C3 CLOB(32K), C4 XML);

| A row exists in T1 where C2 contains 10 MB of data.

| Now, suppose that you declare a 32 KB section CLOBHV:

| EXEC SQL BEGIN DECLARE SECTION
| DECLARE CLOBHV SQL TYPE IS CLOB(32767);
| EXEC SQL END DECLARE SECTION.

| Next, suppose that you use the following statements to declare and open
| CURSOR1 and to FETCH WITH CONTINUE:

692 Application Programming and SQL Guide

| EXEC SQL DECLARE CURSOR1 CURSOR FOR SELECT C2 FROM T1;
| EXEC SQL OPEN CURSOR1;
| EXEC SQL FETCH WITH CONTINUE CURSOR1 INTO :CLOBHV;

| As each piece of the data value is fetched, move it from the buffer to the output
| file.

| Because the 10 MB value in C2 does not fit into the 32 KB buffer, some of the data
| is truncated. Your application can loop through the following FETCH CURRENT
| CONTINUE:
| EXEC SQL FETCH CURRENT CONTINUE CURSOR1 INTO :CLOBHV;

| After each FETCH operation, you can determine if the data was truncated by first
| checking if the SQLWARN1 field in the returned SQLCA contains a ’W’ value. If
| so, then check if the length value, which is returned in CLOBHV_LENGTH, is
| greater than the declared length of 32767. (CLOBHV_LENGTH is declared as part
| of the precompiler expansion of the CLOBHV declaration.) If the value is greater,
| that value has been truncated and more data can be retrieved with the next
| FETCH CONTINUE operation.

| When all of the data has moved to the output file, you can close the cursor:
| EXEC SQL CLOSE CURSOR1;

| Determining the attributes of a cursor by using the SQLCA

An SQL communications area (SQLCA) is an area that is set apart for
communication with DB2 and consists of a collection of variables. Using the
SQLCA is one way to get information about any open cursors. Alternatively, you
can use the GET DIAGNOSTICS statement.

After you open a cursor, you can determine the following attributes of the cursor
by checking the following SQLWARN and SQLERRD fields of the SQLCA:
SQLWARN1
Indicates whether the cursor is scrollable or non-scrollable.
SQLWARN4
Indicates whether the cursor is insensitive (I), sensitive static (S), or sensitive
dynamic (D).
SQLWARN5
Indicates whether the cursor is read-only, readable and deletable, or readable,
deletable, and updatable.
SQLERRD(1) and SQLERRD(2)
| These two fields together contain a double byte integer that represents the
| number of rows in the result table of a cursor when the cursor is positioned
| after the last row. The cursor is positioned after the last row when the
| SQLCODE is 100. These fields are not set for dynamic scrollable cursors.
SQLERRD(3)
| The number of rows in the result table when the SELECT statement of the
| cursor contains a data change statement.

If the OPEN statement executes with no errors or warnings, DB2 does not set
SQLWARN0 when it sets SQLWARN1, SQLWARN4, or SQLWARN5.

For more information about the SQLCA fields, see the topic “Description of
SQLCA fields” in DB2 SQL Reference.

Chapter 12. Accessing data 693

Determining the attributes of a cursor by using the GET
DIAGNOSTICS statement
Using the GET DIAGNOSTICS statement is one way to get information about any
open cursors. Alternatively, you can use the SQLCA.

After you open a cursor, you can determine the following attributes of the cursor
by checking these GET DIAGNOSTICS items:
DB2_SQL_ATTR_CURSOR_HOLD
Indicates whether the cursor can be held open across commits (Y or N)
DB2_SQL_ATTR_CURSOR_ROWSET
Indicates whether the cursor can use rowset positioning (Y or N)
DB2_SQL_ATTR_CURSOR_SCROLLABLE
Indicates whether the cursor is scrollable (Y or N)
DB2_SQL_ATTR_CURSOR_SENSITIVITY
Indicates whether the cursor is insensitive or sensitive to changes that are
made by other processes (I or S)
DB2_SQL_ATTR_CURSOR_TYPE
Indicates whether the cursor is forward (F) declared static (S for INSENSITIVE
or SENSITIVE STATIC) or dynamic (D for SENSITIVE DYNAMIC)

For more information about the GET DIAGNOSTICS statement, see “Checking the
execution of SQL statements by using the GET DIAGNOSTICS statement” on page
209.

Scrolling through previously retrieved data

To scroll backward through data, use a scrollable cursor or use a ROWID column
or identity column retrieve data in reverse order.

Question: When a program retrieves data from the database, how can the program
scroll backward through the data?

Answer: Use one of the following techniques:

v Use a scrollable cursor.
v If the table contains a ROWID or an identity column, retrieve the values from
that column into an array. Then use the ROWID or identity column values to
retrieve the rows in reverse order.

Using a scrollable cursor: Using a scrollable cursor to fetch backward through data
involves these basic steps:
1. Declare the cursor with the SCROLL keyword.
2. Open the cursor.
3. Execute a FETCH statement to position the cursor at the end of the result table.
4. In a loop, execute FETCH statements that move the cursor backward and then
retrieve the data.
5. When you have retrieved all the data, close the cursor.
You can use code like the following example to retrieve department names in
reverse order from table DSN8910.DEPT:
/**************************/
/* Declare host variables */
/**************************/

694 Application Programming and SQL Guide

EXEC SQL BEGIN DECLARE SECTION;
char[37] hv_deptname;
EXEC SQL END DECLARE SECTION;
/**********************************************************/
/* Declare scrollable cursor to retrieve department names */
/**********************************************************/
EXEC SQL DECLARE C1 SCROLL CURSOR FOR
. SELECT DEPTNAME FROM DSN8910.DEPT;
.
.
/**********************************************************/
/* Open the cursor and position it after the end of the */
/* result table. */
/**********************************************************/
EXEC SQL OPEN C1;
EXEC SQL FETCH AFTER FROM C1;
/**********************************************************/
/* Fetch rows backward until all rows are fetched. */
/**********************************************************/
while(SQLCODE==0) {
EXEC SQL FETCH PRIOR FROM C1 INTO :hv_deptname;
.
.
.
}
EXEC SQL CLOSE C1;

Using a ROWID or identity column: If your table contains a ROWID column or

an identity column, you can use that column to rapidly retrieve the rows in reverse
order. When you perform the original SELECT, you can store the ROWID or
identity column value for each row you retrieve. Then, to retrieve the values in
reverse order, you can execute SELECT statements with a WHERE clause that
compares the ROWID or identity column value to each stored value.

For example, suppose you add ROWID column DEPTROWID to table

DSN8910.DEPT. You can use code like the following example to select all
department names, then retrieve the names in reverse order:
/**************************/
/* Declare host variables */
/**************************/
EXEC SQL BEGIN DECLARE SECTION;
SQL TYPE IS ROWID hv_dept_rowid;
char[37] hv_deptname;
EXEC SQL END DECLARE SECTION;
/***************************/
/* Declare other variables */
/***************************/
struct rowid_struct {
short int length;
char data[40]; /* ROWID variable structure */
}
struct rowid_struct rowid_array[200];
/* Array to hold retrieved */
/* ROWIDs. Assume no more */
/* than 200 rows will be */
/* retrieved. */
short int i,j,n;
/***********************************************/
/* Declare cursor to retrieve department names */
/***********************************************/
EXEC SQL DECLARE C1 CURSOR FOR
. SELECT DEPTNAME, DEPTROWID FROM DSN8910.DEPT;
.
.
/**********************************************************/
/* Retrieve the department name and ROWID from DEPT table */
/* and store the ROWID in an array. */

Chapter 12. Accessing data 695

/**********************************************************/
EXEC SQL OPEN C1;
i=0;
while(SQLCODE==0) {
EXEC SQL FETCH C1 INTO :hv_deptname, :hv_dept_rowid;
rowid_array[i].length=hv_dept_rowid.length;
for(j=0;j<hv_dept_rowid.length;j++)
rowid_array[i].data[j]=hv_dept_rowid.data[j];
i++;
}
EXEC SQL CLOSE C1;
n=i-1; /* Get the number of array elements */
/**********************************************************/
/* Use the ROWID values to retrieve the department names */
/* in reverse order. */
/**********************************************************/
for(i=n;i>=0;i--) {
hv_dept_rowid.length=rowid_array[i].length;
for(j=0;j<hv_dept_rowid.length;j++)
hv_dept_rowid.data[j]=rowid_array[i].data[j];
EXEC SQL SELECT DEPTNAME INTO :hv_deptname
FROM DSN8910.DEPT
WHERE DEPTROWID=:hv_dept_rowid;
}

Updating previously retrieved data

To scroll backward through data and update it, use a scrollable cursor that is
declared with the FOR UPDATE clause.

Question: How can you scroll backward and update data that was retrieved
previously?

Answer: Use a scrollable cursor that is declared with the FOR UPDATE clause.
Using a scrollable cursor to update backward involves these basic steps:
1. Declare the cursor with the SENSITIVE STATIC SCROLL keywords.
2. Open the cursor.
3. Execute a FETCH statement to position the cursor at the end of the result table.
4. FETCH statements that move the cursor backward, until you reach the row that
you want to update.
5. Execute the UPDATE WHERE CURRENT OF statement to update the current
row.
6. Repeat steps 4 and 5 until you have update all the rows that you need to.
7. When you have retrieved and updated all the data, close the cursor.

FETCH statement interaction between row and rowset

positioning
When you declare a cursor with the WITH ROWSET POSITIONING clause, you
can intermix row-positioned FETCH statements with rowset-positioned FETCH
statements.

For information about using a multiple-row FETCH statement, see “Executing SQL
statements by using a rowset cursor” on page 681.

The following table shows the interaction between row and rowset positioning for
a scrollable cursor. Assume that you declare the scrollable cursor on a table with 15
rows.

696 Application Programming and SQL Guide

Table 121. Interaction between row and rowset positioning for a scrollable cursor
Keywords in FETCH statement Cursor position when FETCH is executed
FIRST On row 1
FIRST ROWSET On a rowset of size 1, consisting of row 1
FIRST ROWSET FOR 5 ROWS On a rowset of size 5, consisting of rows 1, 2, 3, 4,
and 5
CURRENT ROWSET On a rowset of size 5, consisting of rows 1, 2, 3, 4,
and 5
CURRENT On row 1
NEXT (default) On row 2
NEXT ROWSET On a rowset of size 1, consisting of row 3
NEXT ROWSET FOR 3 ROWS On a rowset of size 3, consisting of rows 4, 5, and
6
NEXT ROWSET On a rowset of size 3, consisting of rows 7, 8, and
9
LAST On row 15
LAST ROWSET FOR 2 ROWS On a rowset of size 2, consisting of rows 14 and
15
PRIOR ROWSET On a rowset of size 2, consisting of rows 12 and
13
ABSOLUTE 2 On row 2
ROWSET STARTING AT ABSOLUTE 2 On a rowset of size 3, consisting of rows 2, 3, and
FOR 3 ROWS 4
RELATIVE 2 On row 4
ROWSET STARTING AT ABSOLUTE 2 On a rowset of size 4, consisting of rows 2, 3, 4,
FOR 4 ROWS and 5
RELATIVE -1 On row 1
ROWSET STARTING AT ABSOLUTE 3 On a rowset of size 2, consisting of rows 3 and 4
FOR 2 ROWS
ROWSET STARTING AT RELATIVE 4 On a rowset of size 2, consisting of rows 7 and 8
PRIOR On row 6
ROWSET STARTING AT ABSOLUTE 13 On a rowset of size 3, consisting of rows 13, 14,
FOR 5 ROWS and 15
FIRST ROWSET On a rowset of size 5, consisting of rows 1, 2, 3, 4,
and 5
Note: For more information about the FOR n ROWS clause and the ROWSET clause, see the
topic “FETCH” inDB2 SQL Reference.

Examples of fetching rows by using cursors

These examples show the SQL statements that you include in a COBOL program to
define and use non-scrollable cursor for row-positioned updates, scrollable cursors
to retrieve rows backward, non-scrollable cursors for rowset-positioned updates,
and scrollable cursors for rowset-positioned operations.

The following example shows how to update a row by using a cursor.

**************************************************
* Declare a cursor that will be used to update *
* the JOB column of the EMP table. *

Chapter 12. Accessing data 697

**************************************************
EXEC SQL
DECLARE THISEMP CURSOR FOR
SELECT EMPNO, LASTNAME,
WORKDEPT, JOB
FROM DSN8910.EMP
WHERE WORKDEPT = 'D11'
FOR UPDATE OF JOB
END-EXEC.
**************************************************
* Open the cursor *
**************************************************
EXEC SQL
OPEN THISEMP
END-EXEC.
**************************************************
* Indicate what action to take when all rows *
* in the result table have been fetched. *
**************************************************
EXEC SQL
WHENEVER NOT FOUND
GO TO CLOSE-THISEMP
END-EXEC.
**************************************************
* Fetch a row to position the cursor. *
**************************************************
EXEC SQL
FETCH FROM THISEMP
INTO :EMP-NUM, :NAME2,
:DEPT, :JOB-NAME
END-EXEC.
**************************************************
* Update the row where the cursor is positioned. *
**************************************************
EXEC SQL
UPDATE DSN8910.EMP
SET JOB = :NEW-JOB
WHERE CURRENT OF THISEMP
. END-EXEC.
.
.
**************************************************
* Branch back to fetch and process the next row. *
**************************************************
.
.
.
**************************************************
* Close the cursor *
**************************************************
CLOSE-THISEMP.
EXEC SQL
CLOSE THISEMP
END-EXEC.

The following example shows how to retrieve data backward with a cursor.
**************************************************
* Declare a cursor to retrieve the data backward *
* from the EMP table. The cursor has access to *
* changes by other processes. *
**************************************************
EXEC SQL
DECLARE THISEMP SENSITIVE STATIC SCROLL CURSOR FOR
SELECT EMPNO, LASTNAME, WORKDEPT, JOB
FROM DSN8910.EMP
END-EXEC.
**************************************************
* Open the cursor *
**************************************************

698 Application Programming and SQL Guide

EXEC SQL
OPEN THISEMP
END-EXEC.
**************************************************
* Indicate what action to take when all rows *
* in the result table have been fetched. *
**************************************************
EXEC SQL
WHENEVER NOT FOUND GO TO CLOSE-THISEMP
END-EXEC.
**************************************************
* Position the cursor after the last row of the *
* result table. This FETCH statement cannot *
* include the SENSITIVE or INSENSITIVE keyword *
* and cannot contain an INTO clause. *
**************************************************
EXEC SQL
FETCH AFTER FROM THISEMP
END-EXEC.
**************************************************
* Fetch the previous row in the table. *
**************************************************
EXEC SQL
FETCH SENSITIVE PRIOR FROM THISEMP
INTO :EMP-NUM, :NAME2, :DEPT, :JOB-NAME
END-EXEC.
**************************************************
* Check that the fetched row is not a hole *
* (SQLCODE +222). If not, print the contents. *
**************************************************
IF SQLCODE IS GREATER THAN OR EQUAL TO 0 AND
SQLCODE IS NOT EQUAL TO +100 AND
SQLCODE IS NOT EQUAL TO +222 THEN
. PERFORM PRINT-RESULTS.
.
.
**************************************************
* Branch back to fetch the previous row. *
**************************************************
.
.
.
**************************************************
* Close the cursor *
**************************************************
CLOSE-THISEMP.
EXEC SQL
CLOSE THISEMP
END-EXEC.

The following example shows how to update an entire rowset with a cursor.
**************************************************
* Declare a rowset cursor to update the JOB *
* column of the EMP table. *
**************************************************
EXEC SQL
DECLARE EMPSET CURSOR
WITH ROWSET POSITIONING FOR
SELECT EMPNO, LASTNAME, WORKDEPT, JOB
FROM DSN8910.EMP
WHERE WORKDEPT = 'D11'
FOR UPDATE OF JOB
END-EXEC.
**************************************************
* Open the cursor. *
**************************************************
EXEC SQL
OPEN EMPSET
END-EXEC.

Chapter 12. Accessing data 699

**************************************************
* Indicate what action to take when end-of-data *
* occurs in the rowset being fetched. *
**************************************************
EXEC SQL
WHENEVER NOT FOUND
GO TO CLOSE-EMPSET
END-EXEC.
**************************************************
* Fetch next rowset to position the cursor. *
**************************************************
EXEC SQL
FETCH NEXT ROWSET FROM EMPSET
FOR :SIZE-ROWSET ROWS
INTO :HVA-EMPNO, :HVA-LASTNAME,
:HVA-WORKDEPT, :HVA-JOB
END-EXEC.
**************************************************
* Update rowset where the cursor is positioned. *
**************************************************
UPDATE-ROWSET.
EXEC SQL
UPDATE DSN8910.EMP
SET JOB = :NEW-JOB
WHERE CURRENT OF EMPSET
END-EXEC.
. END-UPDATE-ROWSET.
.
.
**************************************************
* Branch back to fetch the next rowset. *
**************************************************
.
.
.
**************************************************
* Update the remaining rows in the current *
* rowset and close the cursor. *
**************************************************
CLOSE-EMPSET.
PERFORM UPDATE-ROWSET.
EXEC SQL
CLOSE EMPSET
END-EXEC.

The following example shows how to update specific rows with a rowset cursor.
*****************************************************
* Declare a static scrollable rowset cursor. *
*****************************************************
EXEC SQL
DECLARE EMPSET SENSITIVE STATIC SCROLL CURSOR
WITH ROWSET POSITIONING FOR
SELECT EMPNO, WORKDEPT, JOB
FROM DSN8910.EMP
FOR UPDATE OF JOB
END-EXEC.
*****************************************************
* Open the cursor. *
*****************************************************
EXEC SQL
OPEN EMPSET
END-EXEC.
*****************************************************
* Fetch next rowset to position the cursor. *
*****************************************************
EXEC SQL
FETCH SENSITIVE NEXT ROWSET FROM EMPSET
FOR :SIZE-ROWSET ROWS
INTO :HVA-EMPNO,

700 Application Programming and SQL Guide

:HVA-WORKDEPT :INDA-WORKDEPT,
:HVA-JOB :INDA-JOB
END-EXEC.
*****************************************************
* Process fetch results if no error and no hole. *
*****************************************************
IF SQLCODE >= 0
EXEC SQL GET DIAGNOSTICS
:HV-ROWCNT = ROW_COUNT
END-EXEC
PERFORM VARYING N FROM 1 BY 1 UNTIL N > HV-ROWCNT
IF INDA-WORKDEPT(N) NOT = -3
EVALUATE HVA-WORKDEPT(N)
WHEN ('D11')
PERFORM UPDATE-ROW
WHEN ('E11')
PERFORM DELETE-ROW
END-EVALUATE
END-IF
END-PERFORM
IF SQLCODE = 100
GO TO CLOSE-EMPSET
END-IF
ELSE
EXEC SQL GET DIAGNOSTICS
:HV-NUMCOND = NUMBER
END-EXEC
PERFORM VARYING N FROM 1 BY 1 UNTIL N > HV-NUMCOND
EXEC SQL GET DIAGNOSTICS CONDITION :N
:HV-SQLCODE = DB2_RETURNED_SQLCODE,
:HV-ROWNUM = DB2_ROW_NUMBER
END-EXEC
DISPLAY "SQLCODE = " HV-SQLCODE
DISPLAY "ROW NUMBER = " HV-ROWNUM
END-PERFORM
GO TO CLOSE-EMPSET
END-IF.
.
.
.
*****************************************************
* Branch back to fetch and process *
* the next rowset. *
*****************************************************
.
.
.
*****************************************************
* Update row N in current rowset. *
*****************************************************
UPDATE-ROW.
EXEC SQL
UPDATE DSN8910.EMP
SET JOB = :NEW-JOB
FOR CURSOR EMPSET FOR ROW :N OF ROWSET
END-EXEC.
END-UPDATE-ROW.
*****************************************************
* Delete row N in current rowset. *
*****************************************************
DELETE-ROW.
EXEC SQL
DELETE FROM DSN8910.EMP
FOR CURSOR EMPSET FOR ROW :N OF ROWSET
END-EXEC.
. END-DELETE-ROW.
.
.
*****************************************************
* Close the cursor. *
*****************************************************

Chapter 12. Accessing data 701

CLOSE-EMPSET.
EXEC SQL
CLOSE EMPSET
END-EXEC.

Specifying direct row access by using row IDs

For some applications, you can use the value of a ROWID column to navigate
directly to a row.

When you select a ROWID column, the value implicitly contains the location of the
retrieved row. If you use the value from the ROWID column in the search
condition of a subsequent query, DB2 can choose to navigate directly to that row.

Example: Suppose that an EMPLOYEE table is defined in the following way:

CREATE TABLE EMPLOYEE
(EMP_ROWID ROWID NOT NULL GENERATED ALWAYS,
EMPNO SMALLINT,
NAME CHAR(30),
SALARY DECIMAL(7,2),
WORKDEPT SMALLINT);

The following code uses the SELECT from INSERT statement to retrieve the value
of the ROWID column from a new row that is inserted into the EMPLOYEE table.
This value is then used to reference that row for the update of the SALARY
column.
EXEC SQL BEGIN DECLARE SECTION;
SQL TYPE IS ROWID hv_emp_rowid;
short hv_dept, hv_empno;
char hv_name[30];
decimal(7,2) hv_salary;
EXEC SQL END DECLARE SECTION;
...
EXEC SQL
SELECT EMP_ROWID INTO :hv_emp_rowid
FROM FINAL TABLE (INSERT INTO EMPLOYEE
VALUES (DEFAULT, :hv_empno, :hv_name, :hv_salary, :hv_dept));
EXEC SQL
UPDATE EMPLOYEE
SET SALARY = SALARY + 1200
WHERE EMP_ROWID = :hv_emp_rowid;

EXEC SQL COMMIT;

For DB2 to be able to use direct row access for the update operation, the SELECT
from INSERT statement and the UPDATE statement must execute within the same
unit of work. If these statements execute in different units of work, the ROWID
value for the inserted row might change due to a REORG of the table space before
| the update operation. Alternatively, you can use a SELECT from MERGE
| statement. The MERGE statement performs INSERT and UPDATE operations as
| one coordinated statement.

ROWID columns as keys:

If you define a column in a table to have the ROWID data type, DB2 provides a
unique value for each row in the table only if you define the column as
GENERATED ALWAYS. The purpose of the value in the ROWID column is to
uniquely identify rows in the table.

702 Application Programming and SQL Guide

You can use a ROWID column to write queries that navigate directly to a row,
which can be useful in situations where high performance is a requirement. This
direct navigation, without using an index or scanning the table space, is called
direct row access. In addition, a ROWID column is a requirement for tables that
contain LOB columns. This topic discusses the use of a ROWID column in direct
row access.

Requirement: To use direct row access, you must use a retrieved ROWID value
before you commit. When your application commits, it releases its claim on the
table space. After the commit, a REORG on your table space might execute and
change the physical location of the rows.

Restriction: In general, you cannot use a ROWID column as a key that is to be

used as a single column value across multiple tables. The ROWID value for a
particular row in a table might change over time due to a REORG of the table
space. In particular, you cannot use a ROWID column as part of a parent key or
foreign key.

The value that you retrieve from a ROWID column is a varying-length character
value that is not monotonically ascending or descending (the value is not always
increasing or not always decreasing). Therefore, a ROWID column does not
provide suitable values for many types of entity keys, such as order numbers or
employee numbers.

Specifying direct row access by using RIDs:

When you specify a particular row ID, or RID, DB2 can navigate directly to the
specified row for those queries that qualify for direct row access.

Before you begin this task, ensure that the query qualifies for direct row access. To
qualify, the search condition must be a Boolean term, stage 1 predicate that fits one
of the following criteria:
v A simple Boolean term predicate of the following form:
RID (table designator) = noncolumn expression

Where the noncolumn expression contains a result of a RID function.

v A compound Boolean term that combines several simple predicates by using the
AND operator, where one of the simple predicates fits the first criteria.

To specify direct row access by using RIDs, specify the RID function in the search
condition of a SELECT, DELETE, or UPDATE statement.

The RID function returns the RID of a row, which you can use to uniquely identify
a row.

| Restriction: Because DB2 might reuse RID numbers when the REORG utility is
| run, the RID function might return different values when invoked for a row
| multiple times.

| If you specify a RID and DB2 cannot locate the row through direct row access, DB2
| does not switch to another access method. Instead, DB2 returns no rows.

Chapter 12. Accessing data 703

ROWID columns
A ROWID column uniquely identifies each row in a table. This column enables
queries to be written that navigate directly to a row in the table, because the
column implicitly contains the location of the row.

You can define a ROWID column as either GENERATED BY DEFAULT or

GENERATED ALWAYS:
v If you define the column as GENERATED BY DEFAULT, you can insert a value.
DB2 provides a default value if you do not supply one. However, to be able to
insert an explicit value (by using the INSERT statement with the VALUES
clause), you must create a unique index on that column.
v If you define the column as GENERATED ALWAYS (which is the default), DB2
always generates a unique value for the column. You cannot insert data into that
column. In this case, DB2 does not require an index to guarantee unique values.
For more information, see “Rules for inserting data into a ROWID column” on
page 608.

Ways to manipulate LOB data

You can use SQL statements, LOB locators and LOB file reference variables in your
application programs to manipulate LOB data that is stored in DB2.

For example, you can use the following statements to extract information about an
employee’s department from the resume:
EXEC SQL BEGIN DECLARE SECTION;
char employeenum[6];
long deptInfoBeginLoc;
long deptInfoEndLoc;
SQL TYPE IS CLOB_LOCATOR resume;
SQL TYPE IS CLOB_LOCATOR deptBuffer;
EXEC
. SQL END DECLARE SECTION;
.
.
EXEC SQL DECLARE C1 CURSOR FOR
. SELECT EMPNO, EMP_RESUME FROM EMP;
.
.
EXEC
. SQL FETCH C1 INTO :employeenum, :resume;
.
.
EXEC SQL SET :deptInfoBeginLoc =
POSSTR(:resumedata, 'Department Information');

EXEC SQL SET :deptInfoEndLoc =

POSSTR(:resumedata, 'Education');

EXEC SQL SET :deptBuffer =

SUBSTR(:resume, :deptInfoBeginLoc,
:deptInfoEndLoc - :deptInfoBeginLoc);

These statements use host variables of data type large object locator (LOB locator).
LOB locators let you manipulate LOB data without moving the LOB data into host
variables. By using LOB locators, you need much smaller amounts of memory for
your programs. LOB locators are discussed in “Saving storage when manipulating
LOBs by using LOB locators” on page 711.

| You can also use LOB file reference variables when you are working with LOB
| data. You can use LOB file reference variables to insert LOB data from a file into a
| DB2 table or to retrieve LOB data from a DB2 table. LOB file reference variables
| are discussed in “LOB file reference variables” on page 715.

704 Application Programming and SQL Guide

Sample LOB applications: The following table lists the sample programs that DB2
provides to assist you in writing applications to manipulate LOB data. All
programs reside in data set DSN910.SDSNSAMP.
Table 122. LOB samples shipped with DB2
Member that
contains
source code Language Function
DSNTEJ7 JCL Demonstrates how to create a table with LOB columns, an
auxiliary table, and an auxiliary index. Also demonstrates
how to load LOB data that is 32 KB or less into a LOB table
space.
DSN8DLPL C Demonstrates the use of LOB locators and UPDATE
statements to move binary data into a column of type
BLOB.
DSN8DLRV C Demonstrates how to use a locator to manipulate data of
type CLOB.
DSNTEP2 PL/I Demonstrates how to allocate an SQLDA for rows that
include LOB data and use that SQLDA to describe an input
statement and fetch data from LOB columns.

For instructions on how to prepare and run the sample LOB applications, see the
topic “ Phase 7: Accessing LOB data” in DB2 Installation Guide.

LOB host variable, LOB locator, and LOB file reference

variable declarations
When you write applications to manipulate LOB data, you need to declare host
variables to hold the LOB data or LOB locator or LOB file reference variables to
point to the LOB data.

| You can declare LOB host variables and LOB locators in assembler, C, C++,
| COBOL, Fortran, and PL/I. Additionally, you can declare LOB file reference
| variables in assembler, C, C++, COBOL, and PL/I. For each host variable, locator,
| or file reference variable of SQL type BLOB, CLOB, or DBCLOB that you declare,
| DB2 generates an equivalent declaration that uses host language data types. When
| you refer to a LOB host variable, LOB locator, or LOB file reference variable in an
| SQL statement, you must use the variable that you specified in the SQL type
| declaration. When you refer to the host variable in a host language statement, you
| must use the variable that DB2 generates.

DB2 supports host variable declarations for LOBs with lengths of up to 2 GB - 1.

However, the size of a LOB host variable is limited by the restrictions of the host
language and the amount of storage available to the program.

| Declare LOB host variables that are referenced by the precompiler in SQL
| statements by using the SQL TYPE IS BLOB, SQL TYPE IS CLOB, or SQL TYPE IS
| DBCLOB keywords.

LOB host variables that are referenced only by an SQL statement that uses a
DESCRIPTOR should use the same form as declared by the precompiler. In this
form, the LOB host-variable-array consists of a 31-bit length, followed by the data,
followed by another 31-bit length, followed by the data, and so on. The 31-bit
length must be fullword aligned.

Chapter 12. Accessing data 705

Example: Suppose that you want to allocate a LOB array of 10 elements, each with
a length of 5 bytes. You need to allocate the following bytes for each element, for a
total of 120 bytes:
v 4 bytes for the 31-bit integer
v 5 bytes for the data
v 3 bytes to force fullword alignment

The following examples show you how to declare LOB host variables in each
supported language. In each table, the left column contains the declaration that
you code in your application program. The right column contains the declaration
that DB2 generates.

Declarations of LOB host variables in assembler

The following table shows assembler language declarations for some typical LOB
types.
Table 123. Example of assembler LOB variable declarations
You declare this variable DB2 generates this variable
clob_var SQL TYPE IS CLOB 40000K clob_var DS 0FL4
clob_var_length DS FL4
clob_var_data DS CL655351
ORG clob_var_data +(40960000-65535)
dbclob_var SQL TYPE IS DBCLOB 4000K dbclob_var DS 0FL4
dbclob_var_length DS FL4
dbclob_var_data DS GL655342
ORG dbclob_var_data+(8192000-65534)
blob_var SQL TYPE IS BLOB 1M blob_var DS 0FL4
blob_var_length DS FL4
blob_var_data DS CL655351
ORG blob_var_data+(1048476-65535)
clob_loc SQL TYPE IS CLOB_LOCATOR clob_loc DS FL4
dbclob_loc SQL TYPE IS DBCLOB_LOCATOR dbclob_loc DS FL4
blob_loc SQL TYPE IS BLOB_LOCATOR blob_loc DS FL4
| clob_file SQL TYPE IS CLOB_FILE clob_file DS FL4
| dbclob_file SQL TYPE IS DBCLOB_FILE dbclob_file DS FL4
| blob_file SQL TYPE IS BLOB_FILE blob_file DS FL4
Notes:
1. Because assembler language allows character declarations of no more than 65535 bytes,
DB2 separates the host language declarations for BLOB and CLOB host variables that are
longer than 65535 bytes into two parts.
2. Because assembler language allows graphic declarations of no more than 65534 bytes,
DB2 separates the host language declarations for DBCLOB host variables that are longer
than 65534 bytes into two parts.

Declarations of LOB host variables in C

The following table shows C and C++ language declarations for some typical LOB
types.

706 Application Programming and SQL Guide

| Table 124. Examples of C language variable declarations
| You declare this variable DB2 generates this variable
|| SQL TYPE IS BLOB (1M) blob_var; struct {
| unsigned long length;
| char data[1048576];
| } blob_var;
|| SQL TYPE IS CLOB(400K) clob_var; struct {
| unsigned long length;
| char data[409600];
| } clob_var;
|| SQL TYPE IS DBCLOB (4000K) dbclob_var; struct {
| unsigned long length;
| sqldbchar data[4096000];
| } dbclob_var;
| SQL TYPE IS BLOB_LOCATOR blob_loc; unsigned long blob_loc;
| SQL TYPE IS CLOB_LOCATOR clob_loc; unsigned long clob_loc;
| SQL TYPE IS DBCLOB_LOCATOR dbclob_loc; unsigned long dbclob_loc;
| SQL TYPE IS BLOB_FILE FBLOBhv; #pragma pack(full)
| struct {
| unsigned long name_length;
| unsigned long data_length;
| unsigned long file_options;
| char name??(255??);
| } FBLOBhv ;
| #pragma pack(reset)
| SQL TYPE IS CLOB_FILE FCLOBhv; #pragma pack(full)
| struct {
| unsigned long name_length;
| unsigned long data_length;
| unsigned long file_options;
| char name??(255??);
| } FCLOBhv ;
| #pragma pack(reset)
| SQL TYPE IS DBCLOB_FILE FDBCLOBhv; #pragma pack(full)
| struct {
| unsigned long name_length;
| unsigned long data_length;
| unsigned long file_options;
| char name??(255??);
| } FDBCLOBhv ;
| #pragma pack(reset)
|

Declarations of LOB host variables in COBOL

| The declarations that are generated for COBOL depend on whether you use the
| DB2 precompiler or the DB2 coprocessor. The following table shows COBOL
| declarations that the DB2 precompiler generates for some typical LOB types. The
| declarations that the DB2 coprocessor generates might be different.

Chapter 12. Accessing data 707

| Table 125. Examples of COBOL variable declarations by the DB2 precompiler
| You declare this variable DB2 precompiler generates this variable
|| 01 BLOB-VAR USAGE IS 01 BLOB-VAR.
|| SQL TYPE IS BLOB(1M). 02BLOB-VAR-LENGTH
| PIC 9(9) COMP.
| 02 BLOB-VAR-DATA.
| 49 FILLER PIC X(32767).1
| 49 FILLER PIC X(32767).
|| .. Repeat 30 times
|| .
| 49 FILLER
| PIC X(1048576-32*32767).

| 01 CLOB-VAR USAGE IS 01 CLOB-VAR.

| SQL TYPE IS CLOB(40000K). 02CLOB-VAR-LENGTH
| PIC 9(9) COMP.
| 02 CLOB-VAR-DATA.
| 49 FILLER PIC X(32767).1
| 49 FILLER PIC X(32767).
|| .. Repeat 1248 times
|| .
| 49 FILLER
| PIC X(40960000-1250*32767).

| 01 DBCLOB-VAR USAGE IS 01 DBCLOB-VAR.

| SQL TYPE IS DBCLOB(4000K). 02DBCLOB-VAR-LENGTH
| PIC 9(9) COMP.
| 02 DBCLOB-VAR-DATA.
| 49 FILLER PIC G(32767)
| USAGE DISPLAY-1.2
| 49 FILLER PIC G(32767)
| USAGE DISPLAY-1.
|| .. Repeat 123 times
|| .
| 49 FILLER
| PIC G(20480000-125*32767)
| USAGE DISPLAY-1.

| 01 BLOB-LOC USAGE IS SQL 01 BLOB-LOC PIC S9(9) COMP.

| TYPE IS BLOB-LOCATOR.

| 01 CLOB-LOC USAGE IS SQL 01 CLOB-LOC PIC S9(9) COMP.

| TYPE IS CLOB-LOCATOR.

| 01 DBCLOB-LOC USAGE IS SQL 01 DBCLOB-LOC PIC S9(9) COMP.

| TYPE IS DBCLOB-LOCATOR.

| 01 BLOB-FILE USAGE IS SQL 01 BLOB-FILE.

| TYPE IS BLOB-FILE. 49 BLOB-NAME-LENGTH PIC S9(9) COMP-5 SYNC.
| 49 BLOB-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 BLOB-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 BLOB-FILE-NAME PIC X(255) .

| 01 CLOB-FILE USAGE IS SQL 01 CLOB-FILE.

| TYPE IS CLOB-FILE. 49 CLOB-NAME-LENGTH PIC S9(9) COMP-5 SYNC.
| 49 CLOB-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 CLOB-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 CLOB-FILE-NAME PIC X(255) .

| 01 DBCLOB-FILE USAGE IS SQL 01 DBCLOB-FILE.

| TYPE IS DBCLOB-FILE. 49 DBCLOB-NAME-LENGTH PIC S9(9) COMP-5 SYNC.
| 49 DBCLOB-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 DBCLOB-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 DBCLOB-FILE-NAME PIC X(255) .

708 Application Programming and SQL Guide

| Table 125. Examples of COBOL variable declarations by the DB2 precompiler (continued)
| You declare this variable DB2 precompiler generates this variable
| Notes:
| 1. Because the COBOL language allows character declarations of no more than 32767 bytes,
| for BLOB or CLOB host variables that are greater than 32767 bytes in length, DB2 creates
| multiple host language declarations of 32767 or fewer bytes.
| 2. Because the COBOL language allows graphic declarations of no more than 32767
| double-byte characters, for DBCLOB host variables that are greater than 32767
| double-byte characters in length, DB2 creates multiple host language declarations of
| 32767 or fewer double-byte characters.
|

Declarations of LOB host variables in Fortran

The following table shows Fortran declarations for some typical LOB types.
Table 126. Examples of Fortran variable declarations
You declare this variable DB2 generates this variable

SQL TYPE IS BLOB(1M) blob_var CHARACTER blob_var(1048580)

INTEGER*4 blob_var_LENGTH
CHARACTER blob_var_DATA
EQUIVALENCE( blob_var(1),
+ blob_var_LENGTH )
EQUIVALENCE( blob_var(5),
+ blob_var_DATA )

SQL TYPE IS CLOB(40000K) clob_var CHARACTER clob_var(4096004)

INTEGER*4 clob_var_length
CHARACTER clob_var_data
EQUIVALENCE( clob_var(1),
+ clob_var_length )
EQUIVALENCE( clob_var(5),
+ clob_var_data )

SQL TYPE IS BLOB_LOCATOR blob_loc INTEGER*4 blob_loc

SQL TYPE IS CLOB_LOCATOR clob_loc INTEGER*4 clob_loc

Declarations of LOB host variables in PL/I

| The declarations that are generated for PL/I depend on whether you use the DB2
| precompiler or the DB2 coprocessor. The following table shows PL/I declarations
| that the DB2 precompiler generates for some typical LOB types. The declarations
| that the DB2 coprocessor generates might be different.
| Table 127. Examples of PL/I variable declarations by the DB2 precompiler
| You declare this variable DB2 precompiler generates this variable

| DCL BLOB_VAR DCL 1 BLOB_VAR,

| SQL TYPE IS BLOB (1M); 2 BLOB_VAR_LENGTH FIXED BINARY(31),
| 2 BLOB_VAR_DATA,1
| 3 BLOB_VAR_DATA1(32)
| CHARACTER(32767),
| 3 BLOB_VAR_DATA2
| CHARACTER(1048576-32*32767);

Chapter 12. Accessing data 709

| Table 127. Examples of PL/I variable declarations by the DB2 precompiler (continued)
| You declare this variable DB2 precompiler generates this variable

| DCL CLOB_VAR DCL 1 CLOB_VAR,

| SQL TYPE IS CLOB (40000K); 2 CLOB_VAR_LENGTH FIXED BINARY(31),
| 2 CLOB_VAR_DATA,1
| 3 CLOB_VAR_DATA1(1250)
| CHARACTER(32767),
| 3 CLOB_VAR_DATA2
| CHARACTER(40960000-1250*32767);

| DCL DBCLOB_VAR DCL 1 DBCLOB_VAR,

| SQL TYPE IS DBCLOB (4000K); 2 DBCLOB_VAR_LENGTH FIXED BINARY(31),
| 2 DBCLOB_VAR_DATA,2
| 3 DBCLOB_VAR_DATA1(250)
| GRAPHIC(16383),
| 3 DBCLOB_VAR_DATA2
| GRAPHIC(4096000-250*16383);

| DCL blob_loc DCL blob_loc FIXED BINARY(31);

| SQL TYPE IS BLOB_LOCATOR;

| DCL clob_loc DCL clob_loc FIXED BINARY(31);

| SQL TYPE IS CLOB_LOCATOR;

| DCL dbclob_loc SQL TYPE IS DCL dbclob_loc FIXED BINARY(31);

| DBCLOB_LOCATOR;

| DCL blob_file DCL 1 blob_file,

| SQL TYPE IS BLOB_FILE; 2 blob_file_NAME_LENGTH BIN FIXED(31)
| ALIGNED,
| 2 blob_file_DATA_LENGTH BIN FIXED(31),
| 2 blob_file_FILE_OPTIONS BIN FIXED(31),
| 2 blob_file_NAME CHAR(255) ;

| DCL clob_file DCL 1 clob_file,

| SQL TYPE IS CLOB_FILE; 2 clob_file_NAME_LENGTH BIN FIXED(31)
| ALIGNED,
| 2 clob_file_DATA_LENGTH BIN FIXED(31),
| 2 clob_file_FILE_OPTIONS BIN FIXED(31),
| 2 clob_file_NAME CHAR(255) ;

| DCL dbclob_file SQL TYPE IS DCL 1 dbclob_file,

| DBCLOB_FILE; 2 dbclob_file_NAME_LENGTH BIN FIXED(31)
| ALIGNED,
| 2 dbclob_file_DATA_LENGTH BIN FIXED(31),
| 2 dbclob_file_FILE_OPTIONS BIN FIXED(31),
| 2 dbclob_file_NAME CHAR(255) ;
| Notes:
| 1. For BLOB or CLOB host variables that are greater than 32767 bytes in length, DB2 creates PL/I host language
| declarations in the following way:
| v If the length of the LOB is greater than 32767 bytes and evenly divisible by 32767, DB2 creates an array of
| 32767-byte strings. The dimension of the array is length/32767.
| v If the length of the LOB is greater than 32767 bytes but not evenly divisible by 32767, DB2 creates two
| declarations: The first is an array of 32767 byte strings, where the dimension of the array, n, is length/32767.
| The second is a character string of length length-n*32767.
| 2. For DBCLOB host variables that are greater than 16383 double-byte characters in length, DB2 creates PL/I host
| language declarations in the following way:
| v If the length of the LOB is greater than 16383 characters and evenly divisible by 16383, DB2 creates an array of
| 16383-character strings. The dimension of the array is length/16383.
| v If the length of the LOB is greater than 16383 characters but not evenly divisible by 16383, DB2 creates two
| declarations: The first is an array of 16383 byte strings, where the dimension of the array, m, is length/16383.
| The second is a character string of length length-m*16383.

710 Application Programming and SQL Guide

|
Related concepts
“LOB file reference variables” on page 715
Related tasks
“Saving storage when manipulating LOBs by using LOB locators”

LOB materialization
Materialization means that DB2 puts the data that is selected into a work file. This
action can slow performance. Because LOB values can be very large, DB2 avoids
materializing LOB data until absolutely necessary.

DB2 stores LOB values in contiguous storage. DB2 must materialize LOBs when
your application program performs the following actions:
v Calls a user-defined function with a LOB as an argument
v Moves a LOB into or out of a stored procedure
v Assigns a LOB host variable to a LOB locator host variable
v Converts a LOB from one CCSID to another

The amount of storage that is used for LOB materialization depends on a number
of factors including:
v The size of the LOBs
v The number of LOBs that need to be materialized in a statement

DB2 loads LOBs into virtual pools above the bar. If insufficient space is available
for LOB materialization, your application receives SQLCODE -904.

Although you cannot completely avoid LOB materialization, you can minimize it
by using LOB locators, rather than LOB host variables in your application
programs. See “Saving storage when manipulating LOBs by using LOB locators”
for information on how to use LOB locators.

Saving storage when manipulating LOBs by using LOB

locators
LOB locators let you to manipulate LOB data without retrieving the data from the
DB2 table. By using locators, you avoid having to allocate the large amounts of
storage that are needed for host variables to hold LOB data.

To retrieve LOB data from a DB2 table, you can define host variables that are large
enough to hold all of the LOB data. This requires your application to allocate large
amounts of storage, and requires DB2 to move large amounts of data, which can
be inefficient or impractical. Instead, you can use LOB locators. LOB locators let
you manipulate LOB data without retrieving the data from the DB2 table. Using
LOB locators for LOB data retrieval is a good choice in the following situations:
v When you move only a small part of a LOB to a client program
v When the entire LOB does not fit in the application’s memory
v When the program needs a temporary LOB value from a LOB expression but
does not need to save the result
v When performance is important

A LOB locator is associated with a LOB value or expression, not with a row in a
DB2 table or a physical storage location in a table space. Therefore, after you select

Chapter 12. Accessing data 711

a LOB value using a locator, the value in the locator normally does not change
until the current unit of work ends. However the value of the LOB itself can
change.

If you want to remove the association between a LOB locator and its value before a
unit of work ends, execute the FREE LOCATOR statement. To keep the association
between a LOB locator and its value after the unit of work ends, execute the
HOLD LOCATOR statement. After you execute a HOLD LOCATOR statement, the
locator keeps the association with the corresponding value until you execute a
FREE LOCATOR statement or the program ends.

If you execute HOLD LOCATOR or FREE LOCATOR dynamically, you cannot use
EXECUTE IMMEDIATE. For more information about the HOLD LOCATOR
statement, see the topic “HOLD LOCATOR” in DB2 SQL Reference. For more
information about the FREE LOCATOR statement, see the topic “FREE LOCATOR”
in DB2 SQL Reference.

Indicator variables and LOB locators

DB2 uses indicator variables for LOB locators differently that it uses indicator
variables for host variables.

For host variables other than LOB locators, when you select a null value into a
host variable, DB2 assigns a negative value to the associated indicator variable.
However, for LOB locators, DB2 uses indicator variables differently. A LOB locator
is never null. When you select a LOB column using a LOB locator and the LOB
column contains a null value, DB2 assigns a null value to the associated indicator
variable. The value in the LOB locator does not change. In a client/server
environment, this null information is recorded only at the client.

When you use LOB locators to retrieve data from columns that can contain null
values, define indicator variables for the LOB locators, and check the indicator
variables after you fetch data into the LOB locators. If an indicator variable is null
after a fetch operation, you cannot use the value in the LOB locator.

Valid assignments for LOB locators

Although you usually use LOB locators to assign data to and retrieve data from
LOB columns, you can also use LOB locators to assign data to non-LOB columns.

| You can use LOB locators to make the following assignments:

| v A CLOB or DBCLOB locator can be assigned to a CHAR, VARCHAR,
| GRAPHIC, or VARGRAPHIC column. However, you cannot fetch data from
| CHAR, VARCHAR, GRAPHIC, or VARGRAPHIC columns into a CLOB or
| DBCLOB locators.
| v A BLOB locator can be assigned to a BINARY or VARBINARY column.
| However, you cannot fetch data from a BINARY or VARBINARY column into a
| BLOB locator.

Avoiding character conversion for LOB locators

In certain situations, DB2 materializes the entire LOB value and converts it to the
encoding scheme of a particular SQL statement. This extra processing can slow
performance and should be avoided.

You can use a VALUES INTO or SET statement to obtain the results of functions
that operate on LOB locators, such as LENGTH or SUBSTR. VALUES INTO and
SET statements are processed in the application encoding scheme for the plan or
package that contains the statement. If that encoding scheme is different from the

712 Application Programming and SQL Guide

encoding scheme of the LOB data, the entire LOB value is materialized and
converted to the encoding scheme of the statement. This materialization and
conversion processing can cause performance degradation.

To avoid the character conversion, SELECT from the SYSIBM.SYSDUMMYA,

SYSIBM.SYSDUMMYE, or SYSIBM.SYSDUMMYU sample table. These dummy
tables perform functions similar to SYSIBM.SYSDUMMY1, and are each associated
with an encoding scheme:
SYSIBM.SYSDUMMYA
ASCII
SYSIBM.SYSDUMMYE
EBCDIC
SYSIBM.SYSDUMMYU
Unicode

By using these tables, you can obtain the same result as you would with a
VALUES INTO or SET statement.

Example: Suppose that the encoding scheme of the following statement is EBCDIC:
SET : unicode_hv = SUBSTR(:Unicode_lob_locator,X,Y);

DB2 must materialize the LOB that is specified by :Unicode_lob_locator and

convert that entire LOB to EBCDIC before executing the statement. To avoid
materialization and conversion, you can execute the following statement, which
produces the same result but is processed by the Unicode encoding scheme of the
table:
SELECT SUBSTR(:Unicode_lob_locator,X,Y) INTO :unicode_hv
FROM SYSIBM.SYSDUMMYU;

Deferring evaluation of a LOB expression to improve

performance
DB2 does not move any bytes of a LOB value until a program assigns a LOB
expression to a target destination. When you use a LOB locator with string
functions and operators, DB2 does not evaluate the expression until the time of
assignment. This deferring evaluation can improve performance.

The following example is a C language program that defers evaluation of a LOB

expression. The program runs on a client and modifies LOB data at a server. The
program searches for a particular resume (EMPNO = ’000130’) in the
EMP_RESUME table. It then uses LOB locators to rearrange a copy of the resume
(with EMPNO = ’A00130’). In the copy, the Department Information Section
appears at the end of the resume. The program then inserts the copy into
EMP_RESUME without modifying the original resume.

Because the program in the following figure uses LOB locators, rather than placing
the LOB data into host variables, no LOB data is moved until the INSERT
statement executes. In addition, no LOB data moves between the client and the
server.
EXEC SQL INCLUDE SQLCA;

/**************************/
/* Declare host variables */
1
/**************************/
EXEC SQL BEGIN DECLARE SECTION;

Chapter 12. Accessing data 713

char userid[9];
char passwd[19];
long HV_START_DEPTINFO;
long HV_START_EDUC;
long HV_RETURN_CODE;
SQL TYPE IS CLOB_LOCATOR HV_NEW_SECTION_LOCATOR;
SQL TYPE IS CLOB_LOCATOR HV_DOC_LOCATOR1;
SQL TYPE IS CLOB_LOCATOR HV_DOC_LOCATOR2;
SQL TYPE IS CLOB_LOCATOR HV_DOC_LOCATOR3;
EXEC SQL END DECLARE SECTION;

/*************************************************/
/* Delete any instance of "A00130" from previous */
/* executions of this sample */
/*************************************************/
EXEC SQL DELETE FROM EMP_RESUME WHERE EMPNO = 'A00130';

/*************************************************/
/* Use a single row select to get the document */
2
/*************************************************/
EXEC SQL SELECT RESUME
INTO :HV_DOC_LOCATOR1
FROM EMP_RESUME
WHERE EMPNO = '000130'
AND RESUME_FORMAT = 'ascii';
/*****************************************************/
/* Use the POSSTR function to locate the start of */
/* sections "Department Information" and "Education" */
3
/*****************************************************/
EXEC SQL SET :HV_START_DEPTINFO =
POSSTR(:HV_DOC_LOCATOR1, 'Department Information');

EXEC SQL SET :HV_START_EDUC =

POSSTR(:HV_DOC_LOCATOR1, 'Education');
/*******************************************************/
/* Replace Department Information section with nothing */
/*******************************************************/
EXEC SQL SET :HV_DOC_LOCATOR2 =
SUBSTR(:HV_DOC_LOCATOR1, 1, :HV_START_DEPTINFO -1)
|| SUBSTR (:HV_DOC_LOCATOR1, :HV_START_EDUC);
/*******************************************************/
/* Associate a new locator with the Department */
/* Information section */
/*******************************************************/
EXEC SQL SET :HV_NEW_SECTION_LOCATOR =
SUBSTR(:HV_DOC_LOCATOR1, :HV_START_DEPTINFO,
:HV_START_EDUC -:HV_START_DEPTINFO);

/*******************************************************/
/* Append the Department Information to the end */
/* of the resume */
/*******************************************************/
EXEC SQL SET :HV_DOC_LOCATOR3 =
:HV_DOC_LOCATOR2 || :HV_NEW_SECTION_LOCATOR;
/*******************************************************/
/* Store the modified resume in the table. This is */
4
/* where the LOB data really moves. */
/*******************************************************/
EXEC SQL INSERT INTO EMP_RESUME VALUES ('A00130', 'ascii',
:HV_DOC_LOCATOR3, DEFAULT);

/*********************/
/* Free the locators */
5
/*********************/
EXEC SQL FREE LOCATOR :HV_DOC_LOCATOR1, :HV_DOC_LOCATOR2, :HV_DOC_LOCATOR3;

714 Application Programming and SQL Guide

Notes:

1 Declare the LOB locators here.

2 This SELECT statement associates LOB locator HV_DOC_LOCATOR1 with
the value of column RESUME for employee number 000130.

3 The next five SQL statements use LOB locators to manipulate the resume
data without moving the data.

4 Evaluation of the LOB expressions in the previous statements has been
deferred until execution of this INSERT statement.

5 Free all LOB locators to release them from their associated values.

| LOB file reference variables

| In a host application, you can use a file reference variable of type BLOB_FILE,
| CLOB_FILE, or DBCLOB_FILE to insert a LOB or XML value from a file into a
| DB2 table or to select a LOB or XML value from a DB2 table into a file.

| When you use a file reference variable, you can select or insert an entire LOB or
| XML value without contiguous application storage to contain the entire LOB or
| XML value. LOB file reference variables move LOB or XML values from the
| database server to an application or from an application to the database server
| without going through the application’s memory. Furthermore, LOB file reference
| variables bypass the host language limitation on the maximum size allowed for
| dynamic storage to contain a LOB value.

| You can declare LOB or XML values as LOB file reference variables or LOB file
| reference arrays for applications that are written in C, COBOL, PL/I, and
| assembler. The LOB file reference variables do not contain LOB data; they
| represent a file that contains LOB data. Database queries, updates, and inserts can
| use file reference variables to store or retrieve column values. As with other host
| variables, a LOB file reference variable can have an associated indicator variable.

| DB2-generated LOB file reference variable constructs

| For each LOB file reference variable that an application declares for a LOB or XML
| value, DB2 generates an equivalent construct that uses the host language data
| types. When an application references a LOB file reference variable, it must use the
| equivalent construct that DB2 generates or the DB2 precompiler issues an error.

| The construct describes the following properties of the file:

| Data type
| BLOB, CLOB, or DBCLOB. This property is specified when the variable is
| declared by using the BLOB_FILE, CLOB_FILE, or DBCLOB_FILE data
| type.
| Direction
| This property must be specified by the application program at run time as
| part of the file option property. The direction property can have the
| following values:
| Input Used as a data source on an EXECUTE, OPEN, UPDATE, INSERT,
| DELETE, SET, or MERGE statement.
| Output
| Used as the target of data on a FETCH statement or a SELECT
| INTO statement.

Chapter 12. Accessing data 715

| File name
| This property must be specified by the application program at run time.
| The file name property can have the following values:
| v The complete path name of the file. This is recommended.
| v A relative file name. If a relative file name is provided, it is appended to
| the current path of the client process. A file should be referenced only
| once in a file reference variable.
| File name length
| This property must be specified by the application program at run time.
| File options
| An application must assign one of the file options to a file reference
| variable before the application can use that variable. File options are set by
| the INTEGER value in a field in the file reference variable construct. One
| of the following values must be specified for each file reference variable:
| v Input (from application to database):
| SQL_FILE_READ
| A regular file that can be opened, read, and closed.
| v Output (from database to application):
| SQL_FILE_CREATE
| If the file does not exists, a new file is created. If the file already
| exists, an error is returned.
| SQL_FILE_OVERWRITE
| If the file does not exists, a new file is created. If the file already
| exists, it is overwritten.
| SQL_FILE_APPEND
| If the file does not exists, a new file is created. If the file already
| exists, the output is appended to the existing file.
| Data length
| The length, in bytes, of the new data written to the file

| Examples of declaring file reference variables

| These examples show how to declare a file reference variable in C, COBOL, and
| PL/I, and the file reference variable construct that DB2 generates.

| C Example: Consider the following C declaration:

| EXEC SQL BEGIN DECLARE SECTION
| SQL TYPE IS CLOB_FILE hv_text_file;
| CHAR hv_thesis_title[64];
| EXEC SQL END DECLARE SECTION

| That declaration results in the following DB2-generated construct:

| EXEC SQL BEGIN DECLARE SECTION
| /* SQL TYPE IS CLOB_FILE hv_text_file; */
| struct {
| unsigned long name_length; // File name length
| unsigned long data_length; // Data length
| unsigned long file_options; // File options
| char name [255]; // File name
| } hv_text_file;
| char hv_thesis_title[64]

| With the DB2-generated construct, you can use the following code to select from a
| CLOB column in the database into a new file that is referenced by :hv_text_file.

716 Application Programming and SQL Guide

| strcopy(hv_text_file.name, "/u/gainer/papers/sigmod.94");
| hv_text_file.name_length = strlen("/u/gainer/papers/sigmod.94");
| hv_text_file.file_options = SQL_FILE_CREATE;
| EXEC SQL SELECT CONTENT INTO :hv_text_file FROM PAPERS
| WHERE TITLE = 'The Relational Theory Behind Juggling';

| Similarly, you can use the following code to insert the data from a from a file that
| is referenced by :hv_text_file into a CLOB column.
| strcopy(hv_text_file.name, "/u/gainer/patents/chips.13");
| hv_text_file.name_length = strlen("/u/gainer/patents/chips.13");
| hv_text_file.file_options = SQL_FILE_READ;
| strcopy(:hv_patent_title, "A Method for Pipelining Chip Consumption");
| EXEC SQL INSERT INTO PATENTS(TITLE, TEXT)
| VALUES(:hv_patent_title, :hv_text_file);

| COBOL Example: Consider the following COBOL declaration:

| 01 MY-FILE SQL TYPE IS BLOB-FILE

| That declaration results in the following DB2-generated construct:

| 01 MY-FILE.
| 49 MY-FILE-NAME-LENGTH PIC S9(9) COMP-5.
| 49 MY-FILE-DATA-LENGTH PIC S9(9) COMP-5.
| 49 MY-FILE-FILE-OPTION PIC S9(9) COMP-5.
| 49 MY-FILE-NAME PIC(255);

| PL/I Example: Consider the following PL/I declaration:

| DCL MY_FILE SQL TYPE IS CLOB_FILE

| That declaration results in the following DB2-generated construct:

| DCL 1 MY_FILE,
| 3 MY_FILE_NAME_LENGTH BINARY FIXED (31) UNALIGNED,
| 3 MY_FILE_DATA_LENGTH BINARY FIXED (31) UNALIGNED,
| 3 MY_FILE_FILE_OPTIONS BINARY FIXED (31) UNALIGNED,
| 3 MY_FILE_NAME CHAR(255);

| For examples of how to declare file reference variables for XML data in C, COBOL,
| and PL/I, see “Host variable data types for XML data in embedded SQL
| applications” on page 217.

Referencing a sequence object

A sequence object is a user-defined object that generates a sequence of numeric
values according to the specification with which the sequence was created. You can
retrieve the next or previous value in the sequence.

You reference a sequence by using the NEXT VALUE expression or the PREVIOUS
VALUE expression, specifying the name of the sequence:
v A NEXT VALUE expression generates and returns the next value for the
specified sequence. If a query contains multiple instances of a NEXT VALUE
expression with the same sequence name, the sequence value increments only
once for that query. The ROLLBACK statement has no effect on values already
generated.
v A PREVIOUS VALUE expression returns the most recently generated value for
the specified sequence for a previous NEXT VALUE expression that specified the
same sequence within the current application process. The value of the
PREVIOUS VALUE expression persists until the next value is generated for the

Chapter 12. Accessing data 717

sequence, the sequence is dropped, or the application session ends. The
COMMIT statement and the ROLLBACK statement have no effect on this value.

You can specify a NEXT VALUE or PREVIOUS VALUE expression in a SELECT

clause, within a VALUES clause of an insert operation, within the SET clause of an
update operation (with certain restrictions), or within a SET host-variable statement.

Retrieving thousands of rows

When retrieving large numbers of rows, consider the possibilities for lock
escalation and other locking issues.

Question: Are there any special techniques for fetching and displaying large
volumes of data?

Answer: There are no special techniques; but for large numbers of rows, efficiency
can become very important. In particular, you need to be aware of locking
considerations, including the possibilities of lock escalation.

If your program allows input from a terminal before it commits the data and
thereby releases locks, it is possible that a significant loss of concurrency results.

| Determining when a row was changed

| If a table has a ROW CHANGE TIMESTAMP column, you can determine when a
| row was changed.

| For information about how to create a table with a ROW CHANGE TIMESTAMP
| column, see the topic “CREATE TABLE” inDB2 SQL Reference.

| To determine when a row was changed, issue a SELECT statement with the ROW
| CHANGE TIMESTAMP column in the column list.

| If a qualifying row does not have a value for the ROW CHANGE TIMESTAMP
| column, DB2 returns the time that the page in which that row resides was
| updated.

| Example: Suppose that you issue the following statements to create, populate, and
| alter a table:
| CREATE TABLE T1 (C1 INTEGER NOT NULL);
| INSERT INTO T1 VALUES (1);
| ALTER TABLE T1 ADD COLUMN C2 NOT NULL GENERATED ALWAYS
| FOR EACH ROW ON UPDATE AS ROW CHANGE TIMESTAMP;
| SELECT T1.C2 FROM T1 WHERE T1.C1 = 1;

| Because the ROW CHANGE TIMESTAMP column was added after the data was
| inserted, the following statement returns the time that the page was last modified:
| SELECT T1.C2 FROM T1 WHERE T1.C1 = 1;

| Assume that you then issue the following statement:

| INSERT INTO T1(C1) VALUES (2);

| Assume that this row is added to the same page as the first row. The following
| statement returns the time that value ″2″ was inserted into the table:
| SELECT T1.C2 FROM T1 WHERE T1.C1 = 2;

718 Application Programming and SQL Guide

| Because the row with value ″1″ still does not have a value for the ROW CHANGE
| TIMESTAMP column, the following statement still returns the time that the page
| was last modified, which in this case is the time that value ″2″ was inserted:
| SELECT T1.C2 FROM T1 WHERE T1.C1 = 1;
|
| Checking whether an XML column contains a certain value
| You can determine which rows contain any fragment of XML data that you specify.

| To check whether an XML column contains a certain value, specify the XMLEXISTS
| predicate in the WHERE clause of your SQL statement. Include the following
| parameters for the XMLEXISTS predicate:
| v An XPath expression that is embedded in a character string literal. Specify an
| XPath expression that identifies the XML data that you are looking for. If the
| result of the XPath expression is an empty sequence, XMLEXISTS returns false.
| If the result is not empty, XMLEXISTS returns true. If the evaluation of the
| XPath expression returns an error, XMLEXISTS returns an error.
| v The XML column name. Specify this value after the PASSING keyword.

| Example: Suppose that you want to return only purchase orders that have a billing
| address. Assume that column XMLPO stores the XML purchase order documents
| and that the billTo nodes within these documents contain any billing addresses.
| You can use the following SELECT statement with the XMLEXISTS predicate:
| SELECT XMLPO FROM T1
| WHERE XMLEXISTS ('declare namespace ipo="http://www.example.com/IPO";
| /ipo:purchaseOrder[billTo]'
| PASSING XMLPO);
| Related reference
| XMLEXISTS predicate (SQL Reference)

Accessing DB2 data that is not in a table

You can access DB2 data that is not in a table by returning the value of an SQL
expression in a host variable.

The expression does not include a column of a table. The three ways to return a
value in a host variable are shown in the following examples.

Example: To set the contents of a host variable to the value of an expression, use
the SET host-variable assignment statement:
EXEC SQL SET :hvrandval = RAND(:hvrand);

Example: To return the value of an expression in a host variable, use the VALUES
INTO statement:
EXEC SQL VALUES RAND(:hvrand)
INTO :hvrandval;

Example: To select the expression from the DB2-provided EBCDIC table, named
SYSIBM.SYSDUMMY1, which consists of one row, use the following statement:
EXEC SQL SELECT RAND(:hvrand)
INTO :hvrandval
FROM SYSIBM.SYSDUMMY1;

Chapter 12. Accessing data 719

Ensuring that queries perform sufficiently
Part of ensuring that your application program performs sufficiently is making
sure that any individual queries that are included in your program are not slowing
down the performance of your program.

To ensure that queries perform sufficiently:

1. Tune each query in your program by following the general tuning guidelines
for how to write efficient queries.
2. If you suspect that a query is not as efficient as it could be, monitor its
performance. You can use a number of different functions and techniques to
monitor SQL performance, including the SQL EXPLAIN statement and the
Optimization Service Center for DB2 for z/OS.
Related concepts
Tuning your queries (DB2 Performance)
Related tasks
Monitoring SQL performance (DB2 Performance)

Items to include in a batch DL/I program

When you use a batch DL/I program with DB2, you must include certain items in
your application.

A batch DL/I program can issue:

v Any IMS batch call, except ROLS, SETS, and SYNC calls. ROLS and SETS calls
provide intermediate backout point processing, which DB2 does not support.
The SYNC call provides commit point processing without identifying the
commit point with a value. IMS does not allow a SYNC call in batch, and
neither does the DB2 DL/I batch support.
Issuing a ROLS, SETS, or SYNC call in an application program causes a system
abend X’04E’ with the reason code X’00D44057’ in register 15.
v GSAM calls.
v IMS system services calls.
v Any SQL statements, except COMMIT and ROLLBACK. IMS and CICS
environments do not allow those SQL statements; however, IMS and CICS do
allow ROLLBACK TO SAVEPOINT. You can use the IMS CHKP call to commit
data and the IMS ROLL or ROLB to roll back changes.
Issuing a COMMIT statement causes SQLCODE -925; issuing a ROLLBACK
statement causes SQLCODE -926. Those statements also return SQLSTATE
’2D521’.
v Any call to a standard or traditional access method (for example, QSAM, VSAM,
and so on).

The restart capabilities for DB2 and IMS databases, as well as for sequential data
sets that are accessed through GSAM, are available through the IMS Checkpoint
and Restart facility.

DB2 allows access to both DB2 and DL/I data through the use of the following
DB2 and IMS facilities:
v IMS synchronization calls, which commit and abnormally terminate units of
recovery

720 Application Programming and SQL Guide

v The DB2 IMS attachment facility, which handles the two-phase commit protocol
and enables both systems to synchronize a unit of recovery during a restart after
a failure
v The IMS log, which is used to record the instant of commit

In a data sharing environment, DL/I batch supports group attachment. You can
specify a group attachment name instead of a subsystem name in the SSN
parameter of the DDITV02 data set for the DL/I batch job. For information about
the SSN parameter and the DDITV02 data set, see “Input and output data sets for
DL/I batch jobs” on page 949.

Requirements for using DB2 in a DL/I batch job: Using DB2 in a DL/I batch job
requires the following changes to the application program and the job step JCL:
v Add SQL statements to your application program to gain access to DB2 data.
You must then precompile the application program and bind the resulting
DBRM into a plan or package, as described in Chapter 17, “Preparing an
application to run on DB2 for z/OS,” on page 887.
v Before you run the application program, use JOBLIB, STEPLIB, or link book to
access the DB2 load library, so that DB2 modules can be loaded.
v In a data set that is specified by a DDITV02 DD statement, specify the program
name and plan name for the application, and the connection name for the DL/I
batch job.
In an input data set or in a subsystem member, specify information about the
connection between DB2 and IMS. The input data set name is specified with a
DDITV02 DD statement. The subsystem member name is specified by the
parameter SSM= on the DL/I batch invocation procedure. For detailed
information about the contents of the subsystem member and the DDITV02 data
set, see “Input and output data sets for DL/I batch jobs” on page 949.
v Optionally specify an output data set using the DDOTV02 DD statement. You
might need this data set to receive messages from the IMS attachment facility
about indoubt threads and diagnostic information.

Program design considerations for using DL/I batch:

Address spaces in DL/I batch: A DL/I batch region is independent of both the
IMS control region and the CICS address space. The DL/I batch region loads the
DL/I code into the application region along with the application program.

Commits in DL/I batch: Commit IMS batch applications frequently so that you do
not use resources for an extended time. For more information about coordinated
commits for recovery, see the topic “Multiple system consistency” in DB2
Administration Guide.

SQL statements and IMS calls in DL/I batch: DL/I batch applications cannot use
the SQL COMMIT and ROLLBACK statements; otherwise, you get an SQL error
code. DLI/I batch applications also cannot use ROLS, SETS, and SYNC calls;
otherwise the application program abnormally terminates.

Checkpoint calls in DL/I batch: Write your program with SQL statements and
DL/I calls, and use checkpoint calls. The frequency of checkpoints depends on the
application design. All checkpoints that are issued by a batch application program
must be unique. At a checkpoint, DL/I positioning is lost, DB2 cursors are closed
(with the possible exception of cursors that are defined as WITH HOLD), commit

Chapter 12. Accessing data 721

duration locks are freed (again with some exceptions), and database changes are
considered permanent to both IMS and DB2.

Application program synchronization in DL/I batch: You can design an

application program without using IMS checkpoints. In that case, if the program
abnormally terminates before completing, DB2 backs out any updates, and you can
use the IMS batch backout utility to back out the DL/I changes.

You can also have IMS dynamically back out the updates within the same job. You
must specify the BKO parameter as ’Y’ and allocate the IMS log to DASD.

You could have a problem if the system on which the job is run fails after the
program terminates but before the job step ends. If you do not have a checkpoint
call before the program ends, DB2 commits the unit of work without involving
IMS. If the system fails before DL/I commits the data, the DB2 data is out of
synchronization with the DL/I changes. If the system fails during DB2 commit
processing, the DB2 data could be indoubt. When you restart the application
program, use the XRST call to obtain checkpoint information and resolve any DB2
indoubt work units.

Recommendation: Always issue a symbolic checkpoint at the end of any update

job to coordinate the commit of the outstanding unit of work for IMS and DB2.

Checkpoint and XRST considerations in DL/I batch: If you use an XRST call, DB2
assumes that any checkpoint that is issued is a symbolic checkpoint. The options of
the symbolic checkpoint call differ from the options of a basic checkpoint call.
Using the incorrect form of the checkpoint call can cause problems.

If you do not use an XRST call, DB2 assumes that any checkpoint call that is issued
is a basic checkpoint.

To make restart easier, use EBCDIC characters for checkpoint IDs.

When an application program needs to be restartable, you must use symbolic

checkpoint and XRST calls. If you use an XRST call, it must be the first IMS call
that is issued, and it must occur before any SQL statement. Also, you must use
only one XRST call.

Synchronization call abends in DL/I batch: If the application program contains an

incorrect IMS synchronization call (CHKP, ROLB, ROLL, or XRST), causing IMS to
issue a bad status code in the PCB, DB2 abends the application program. Be sure
to test these calls before placing the programs in production.

722 Application Programming and SQL Guide

Chapter 13. Invoking a user-defined function
You can use a user-defined functions wherever you can use a built-in function.

You can invoke a sourced or external user-defined scalar function in an SQL

statement wherever you use an expression. For a table function, you can invoke
the user-defined function only in the FROM clause of a SELECT statement. The
invoking SQL statement can be in a stand alone program, a stored procedure, a
trigger body, or another user-defined function.

See the following topics for details you that should know before you invoke a
user-defined function:
v “How DB2 resolves functions” on page 726
v “Cases when DB2 casts arguments for a user-defined function” on page 733
v “Abnormal termination of an external user-defined function” on page 517

For information about the syntax for invoking a table function, see the topic
“from-clause” in DB2 SQL Reference.

For information about the syntax for invoking a user-defined scalar function, see
the topic “Function invocation” in DB2 SQL Reference.

Recommendations for invoking user-defined functions:

Invoke user-defined functions with external actions and nondeterministic

user-defined functions from select lists: Invoking user-defined functions with
external action from a select list and nondeterministic user-defined functions from
a select list is preferred to invoking these user-defined functions from a predicate.

The access path that DB2 chooses for a predicate determines whether a
user-defined function in that predicate is executed. To ensure that DB2 executes the
external action for each row of the result table, put the user-defined function
invocation in the SELECT list.

Invoking a nondeterministic user-defined function from a predicate can yield

undesirable results. The following example demonstrates this idea.

Suppose that you execute this query:

SELECT COUNTER(), C1, C2 FROM T1 WHERE COUNTER() = 2;

Table T1 looks like this:

C1 C2
-- --
1 b
2 c
3 a

COUNTER is a user-defined function that increments a variable in the scratchpad

each time it is invoked.

DB2 invokes an instance of COUNTER in the predicate 3 times. Assume that

COUNTER is invoked for row 1 first, for row 2 second, and for row 3 third. Then
COUNTER returns 1 for row 1, 2 for row 2, and 3 for row 3. Therefore, row 2

© Copyright IBM Corp. 1983, 2009 723

satisfies the predicate WHERE COUNTER()=2, so DB2 evaluates the SELECT list
for row 2. DB2 uses a different instance of COUNTER in the select list from the
instance in the predicate. Because the instance of COUNTER in the select list is
invoked only once, it returns a value of 1. Therefore, the result of the query is:
COUNTER() C1 C2
--------- -- --
1 2 c

This is not the result you might expect.

The results can differ even more, depending on the order in which DB2 retrieves
the rows from the table. Suppose that an ascending index is defined on column C2.
Then DB2 retrieves row 3 first, row 1 second, and row 2 third. This means that
row 1 satisfies the predicate WHERE COUNTER()=2. The value of COUNTER in
the select list is again 1, so the result of the query in this case is:
COUNTER() C1 C2
--------- -- --
1 1 b

Understand the interaction between scrollable cursors and nondeterministic

user-defined functions or user-defined functions with external actions: When you
use a scrollable cursor, you might retrieve the same row multiple times while the
cursor is open. If the select list of the cursor’s SELECT statement contains a
user-defined function, that user-defined function is executed each time you retrieve
a row. Therefore, if the user-defined function has an external action, and you
retrieve the same row multiple times, the external action is executed multiple times
for that row.

A similar situation occurs with scrollable cursors and nondeterministic functions.

The result of a nondeterministic user-defined function can be different each time
you execute the user-defined function. If the select list of a scrollable cursor
contains a nondeterministic user-defined function, and you use that cursor to
retrieve the same row multiple times, the results can differ each time you retrieve
the row.

A nondeterministic user-defined function in the predicate of a scrollable cursor’s

SELECT statement does not change the result of the predicate while the cursor is
open. DB2 evaluates a user-defined function in the predicate only once while the
cursor is open.

Determining the authorization ID for invoking user-defined functions

The authorization ID under which a user-defined function is invoked depends on
whether the function was invoked statically or dynamically.

If your user-defined function is invoked statically, the authorization ID under

which the user-defined function is invoked is the owner of the package that
contains the user-defined function invocation.

If the user-defined function is invoked dynamically, the authorization ID under

which the user-defined function is invoked depends on the value of bind
parameter DYNAMICRULES for the package that contains the function invocation.

While a user-defined function is executing, the authorization ID under which static

SQL statements in the user-defined function package execute is the owner of the
user-defined function package. The authorization ID under which dynamic SQL

724 Application Programming and SQL Guide

statements in the user-defined function package execute depends on the value of
DYNAMICRULES with which the user-defined function package was bound.

DYNAMICRULES influences a number of features of an application program. For

information about how DYNAMICRULES works, see “DYNAMICRULES bind
option” on page 932.

Ensuring that DB2 executes the intended user-defined function

Because multiple functions with the same name can exist in the same schema or
different schemas, you should take certain actions to ensure that DB2 chooses the
correct function to execute.

When you use the following techniques, you can simplify function resolution:
v When you invoke a function, use the qualified name. This causes DB2 to search
for functions only in the schema you specify. This has two advantages:
– DB2 is less likely to choose a function that you did not intend to use. Several
functions might fit the invocation equally well. DB2 picks the function whose
schema name is earliest in the SQL path, which might not be the function you
want.
– The number of candidate functions is smaller, so DB2 takes less time for
function resolution.
v Cast parameters in a user-defined function invocation to the types in the
user-defined function definition. For example, if an input parameter for
user-defined function FUNC is defined as DECIMAL(13,2), and the value you
want to pass to the user-defined function is an integer value, cast the integer
value to DECIMAL(13,2):
SELECT FUNC(CAST (INTCOL AS DECIMAL(13,2))) FROM T1;
| v Use the data type BIGINT for numeric parameters in a user-defined function. If
| you use BIGINT as the parameter type, when you invoke the function, you can
| pass in SMALLINT, INTEGER, or BIGINT values. If you use SMALLINT or
| REAL as the parameter type, you must pass parameters of the same types. For
| example, if user-defined function FUNC is defined with a parameter of type
| SMALLINT, only an invocation with a parameter of type SMALLINT resolves
| correctly. The following call does not resolve to FUNC because the constant 123
| is of type INTEGER, not SMALLINT:
| SELECT FUNC(123) FROM T1;
| v Avoid defining user-defined function string parameters with fixed-length string
| types. If you define a parameter with a fixed-length string type (CHAR,
| GRAPHIC, or BINARY), you can invoke the user-defined function only with a
| fixed-length string parameter. However, if you define the parameter with a
| varying-length string type (VARCHAR, VARGRAPHIC, or VARBINARY), you
| can invoke the user-defined function with either a fixed-length string parameter
| or a varying-length string parameter.
| If you must define parameters for a user-defined function as CHAR or BINARY,
| and you call the user-defined function from a C program or SQL procedure, you
| need to cast the corresponding parameter values in the user-defined function
| invocation to CHAR or BINARY to ensure that DB2 invokes the correct function.
| For example, suppose that a C program calls user-defined function CVRTNUM,
| which takes one input parameter of type CHAR(6). Also suppose that you
| declare host variable empnumbr as char empnumbr[6]. When you invoke
| CVRTNUM, cast empnumbr to CHAR:

Chapter 13. Invoking a user-defined function 725

| UPDATE EMP
| SET EMPNO=CVRTNUM(CHAR(:empnumbr))
| WHERE EMPNO = :empnumbr;

How DB2 resolves functions

Function resolution is the process by which DB2 determines which user-defined
function or built-in function to execute. You need to understand the function
resolution process that DB2 uses to ensure that you invoke the user-defined
function that you want to invoke.

Several user-defined functions with the same name but different numbers or types
of parameters can exist in a DB2 subsystem. Several user-defined functions with
the same name can have the same number of parameters, as long as the data types
of any of the first 30 parameters are different. In addition, several user-defined
functions might have the same name as a built-in function. When you invoke a
function, DB2 must determine which user-defined function or built-in function to
execute.

DB2 performs these steps for function resolution:

1. Determines if any function instances are candidates for execution. If no
candidates exist, DB2 issues an SQL error message.
2. Compares the data types of the input parameters to determine which
candidates fit the invocation best.
DB2 does not compare data types for input parameters that are untyped
parameter markers.
For a qualified function invocation, if there are no parameter markers in the
invocation, the result of the data type comparison is one best fit. That best fit is
the choice for execution. If there are parameter markers in the invocation, there
might be more than one best fit. DB2 issues an error if there is more than one
best fit.
For an unqualified function invocation, DB2 might find multiple best fits
because the same function name with the same input parameters can exist in
different schemas, or because there are parameter markers in the invocation.
3. If two or more candidates fit the unqualified function invocation equally well
because the same function name with the same input parameters exists in
different schemas, DB2 chooses the user-defined function whose schema name
is earliest in the SQL path.
For example, suppose functions SCHEMA1.X and SCHEMA2.X fit a function
invocation equally well. Assume that the SQL path is:
"SCHEMA2", "SYSPROC", "SYSIBM", "SCHEMA1", "SYSFUN"

Then DB2 chooses function SCHEMA2.X.

If two or more candidates fit the unqualified function invocation equally well
because the function invocation contains parameter markers, DB2 issues an
error.

The remainder of this section discusses details of the function resolution process
and gives suggestions on how you can ensure that DB2 picks the right function.

How DB2 chooses candidate functions:

An instance of a user-defined function is a candidate for execution only if it meets

all of the following criteria:

726 Application Programming and SQL Guide

v If the function name is qualified in the invocation, the schema of the function
instance matches the schema in the function invocation.
If the function name is unqualified in the invocation, the schema of the function
instance matches a schema in the invoker’s SQL path.
v The name of the function instance matches the name in the function invocation.
v The number of input parameters in the function instance matches the number of
input parameters in the function invocation.
v The function invoker is authorized to execute the function instance.
v The type of each of the input parameters in the function invocation matches or
is promotable to the type of the corresponding parameter in the function instance.
If an input parameter in the function invocation is an untyped parameter
marker, DB2 considers that parameter to be a match or promotable.
For a function invocation that passes a transition table, the data type, length,
precision, and scale of each column in the transition table must match exactly
the data type, length, precision, and scale of each column of the table that is
named in the function instance definition. For information about transition
tables, see “Creating triggers” on page 457.
v The create timestamp for a user-defined function must be older than the BIND
or REBIND timestamp for the package or plan in which the user-defined
function is invoked.
If DB2 authorization checking is in effect, and DB2 performs an automatic rebind
on a plan or package that contains a user-defined function invocation, any
user-defined functions that were created after the original BIND or REBIND of
the invoking plan or package are not candidates for execution.
If you use an access control authorization exit routine, some user-defined
functions that were not candidates for execution before the original BIND or
REBIND of the invoking plan or package might become candidates for execution
during the automatic rebind of the invoking plan or package. For information
about function resolution with access control authorization exit routines, see the
topic “Writing exit routines” in DB2 Administration Guide.
If a user-defined function is invoked during an automatic rebind, and that
user-defined function is invoked from a trigger body and receives a transition
table, then the form of the invoked function that DB2 uses for function selection
includes only the columns of the transition table that existed at the time of the
original BIND or REBIND of the package or plan for the invoking program.
During an automatic rebind, DB2 does not consider built-in functions for
function resolution if those built-in functions were introduced in a later release
of DB2 than the release in which the BIND or REBIND of the invoking plan or
package occurred.
When you explicitly bind or rebind a plan or package, the plan or package
receives a release dependency marker. When DB2 performs an automatic rebind
of a query that contains a function invocation, a built-in function is a candidate
for function resolution only if the release dependency marker of the built-in
function is the same as or lower than the release dependency marker of the plan
or package that contains the function invocation.

To determine whether a data type is promotable to another data type, see the topic
“Promotion of data types” in DB2 SQL Reference.

Example: Suppose that in this statement, the data type of A is SMALLINT:

SELECT USER1.ADDTWO(A) FROM TABLEA;

Chapter 13. Invoking a user-defined function 727

Two instances of USER1.ADDTWO are defined: one with an input parameter of
type INTEGER and one with an input parameter of type DECIMAL. Both function
instances are candidates for execution because the SMALLINT type is promotable
to either INTEGER or DECIMAL. However, the instance with the INTEGER type is
a better fit because INTEGER is higher in the list than DECIMAL.

How DB2 chooses the best fit among candidate functions:

More than one function instance might be a candidate for execution. In that case,
DB2 determines which function instances are the best fit for the invocation by
comparing parameter data types.

If the data types of all parameters in a function instance are the same as those in
the function invocation, that function instance is a best fit. If no exact match exists,
DB2 compares data types in the parameter lists from left to right, using this
method:
1. DB2 compares the data types of the first parameter in the function invocation
to the data type of the first parameter in each function instance.
If the first parameter in the invocation is an untyped parameter marker, DB2
does not do the comparison.
2. For the first parameter, if one function instance has a data type that fits the
function invocation better than the data types in the other instances, that
function is a best fit. For information about the possible fits for each data type,
in best-to-worst order, see the topic “Promotion of data types” in DB2 SQL
Reference.
3. If the data types of the first parameter are the same for all function instances,
or if the first parameter in the function invocation is an untyped parameter
marker, DB2 repeats this process for the next parameter. DB2 continues this
process for each parameter until it finds a best fit.

Example of function resolution: Suppose that a program contains the following

statement:
SELECT FUNC(VCHARCOL,SMINTCOL,DECCOL) FROM T1;

In user-defined function FUNC, VCHARCOL has data type VARCHAR,

SMINTCOL has data type SMALLINT, and DECCOL has data type DECIMAL.
Also suppose that two function instances with the following definitions meet the
appropriate criteria and are therefore candidates for execution.
Candidate 1:
CREATE FUNCTION FUNC(VARCHAR(20),INTEGER,DOUBLE)
RETURNS DECIMAL(9,2)
EXTERNAL NAME 'FUNC1'
PARAMETER STYLE SQL
LANGUAGE COBOL;

Candidate 2:
CREATE FUNCTION FUNC(VARCHAR(20),REAL,DOUBLE)
RETURNS DECIMAL(9,2)
EXTERNAL NAME 'FUNC2'
PARAMETER STYLE SQL
LANGUAGE COBOL;

DB2 compares the data type of the first parameter in the user-defined function
invocation to the data types of the first parameters in the candidate functions.
Because the first parameter in the invocation has data type VARCHAR, and both

728 Application Programming and SQL Guide

candidate functions also have data type VARCHAR, DB2 cannot determine the
better candidate based on the first parameter. Therefore, DB2 compares the data
types of the second parameters.

The data type of the second parameter in the invocation is SMALLINT. INTEGER,
which is the data type of candidate 1, is a better fit to SMALLINT than REAL,
which is the data type of candidate 2. Therefore, candidate 1 is the DB2 choice for
execution.

Checking how DB2 resolves functions by using

DSN_FUNCTION_TABLE
Because user-defined functions can have the same name, you should ensure that
DB2 invokes the function that you intended invoke. One way to check that the
correct function was invoked is to use a function table called
DSN_FUNCTION_TABLE.

To check how DB2 resolves a function by using DSN_FUNCTION_TABLE:

1. If your_userID.DSN_FUNCTION_TABLE does not already exist, create this table
by following the instructions in .
2. Populate your_userID.DSN_FUNCTION_TABLE with information about which
functions are invoked by a particular SQL statement by performing one of the
following actions:
v Execute the EXPLAIN statement on the SQL statement.
v Ensure that the program that contains the SQL statement is bound with
EXPLAIN(YES) and run the program.
DB2 puts a row in your_userID.DSN_FUNCTION_TABLE for each function that
is referenced in each SQL statement.
3. Check the rows that were added to your_userID.DSN_FUNCTION_TABLE to
ensure that the appropriate function was invoked. Use the following columns
to help you find applicable rows: QUERYNO, APPLNAME, PROGNAM,
COLLID, and EXPLAIN_TIME.
Related reference
BIND and REBIND options (DB2 Command Reference)
EXPLAIN (SQL Reference)

DSN_FUNCTION_TABLE
The function table, DSN_FUNCTION_TABLE, contains descriptions of functions
that are used in specified SQL statements.

Recommendation: Do not manually insert data into or delete data from EXPLAIN
tables. The data is intended to be manipulated only by the DB2 EXPLAIN function
and optimization tools.

| Important: If mixed data strings are allowed on a DB2 subsystem, EXPLAIN tables
| must be created with CCSID UNICODE. This includes, but is not limited to, mixed
| data strings that are used for tokens, SQL statements, application names, program
| names, correlation names, and collection IDs.

Chapter 13. Invoking a user-defined function 729

Qualifiers

Your subsystem or data sharing group can contain more than one of these tables,
including a table with the qualifier SYSIBM, a table with the qualifier DB2OSCA,
and additional tables that are qualified by user IDs.
SYSIBM
One instance of each EXPLAIN table can be created with the SYSIBM
qualifier. SQL optimization tools use these tables. You can find the SQL
statement for creating these tables in member DSNTESC of the
SDSNSAMP library.
userID You can create additional instances of EXPLAIN tables that are qualified by
user ID. These tables are populated with statement cost information when
you issue the EXPLAIN statement or bind, or rebind, a plan or package
with the EXPLAIN(YES) option. SQL optimization tools might also create
EXPLAIN tables that are qualified by a user ID. You can find the SQL
statement for creating an instance of these tables in member DSNTESC of
the SDSNSAMP library.
DB2OSC
SQL optimization tools, such as Optimization Service Center for DB2 for
z/OS, create EXPLAIN tables to collect information about SQL statements
and workloads to enable analysis and tuning processes. You can find the
SQL statements for creating EXPLAIN tables in member DSNTIJOS of the
SDSNSAMP library. You can also create this table from the Optimization
Service Center interface on your workstation.

Create table statement

The following statement creates a function table:

CREATE TABLE user-id.DSN_FUNCTION_TABLE
(QUERYNO INTEGER NOT NULL WITH DEFAULT,
QBLOCKNO INTEGER NOT NULL WITH DEFAULT,
| APPLNAME VARCHAR(24) NOT NULL WITH DEFAULT,
PROGNAME VARCHAR(128) NOT NULL WITH DEFAULT,
COLLID VARCHAR(128) NOT NULL WITH DEFAULT,
| GROUP_MEMBER VARCHAR(24) NOT NULL WITH DEFAULT,
EXPLAIN_TIME TIMESTAMP NOT NULL WITH DEFAULT,
SCHEMA_NAME VARCHAR(128) NOT NULL WITH DEFAULT,
FUNCTION_NAME VARCHAR(128) NOT NULL WITH DEFAULT,
SPEC_FUNC_NAME VARCHAR(128) NOT NULL WITH DEFAULT,
FUNCTION_TYPE CHAR(2) NOT NULL WITH DEFAULT,
VIEW_CREATOR VARCHAR(128) NOT NULL WITH DEFAULT,
VIEW_NAME VARCHAR(128) NOT NULL WITH DEFAULT,
PATH VARCHAR(2048) NOT NULL WITH DEFAULT,
FUNCTION_TEXT VARCHAR(1500) NOT NULL WITH DEFAULT)
IN database-name.table-space-name
| CCSID UNICODE;

Column descriptions

PSPI

The following table describes the columns of DSN_FUNCTION_TABLE.

730 Application Programming and SQL Guide

Table 128. Descriptions of columns in DSN_FUNCTION_TABLE
Column name Data type Description
QUERYNO INTEGER NOT NULL A number that identifies the statement that is being explained. The
origin of the value depends on the context of the row:
For rows produced by EXPLAIN statements
The number specified in the QUERYNO clause, which is an
optional part of the SELECT, INSERT, UPDATE, MERGE,
and DELETE statement syntax.
For rows not produced by EXPLAIN statements
DB2 assigns a number that is based on the line number of
the SQL statement in the source program.

When the values of QUERYNO are based on the statement number

in the source program, values that exceed 32767 are reported as 0.
However, in a very long program, the value is not guaranteed to be
unique. If QUERYNO is not unique, the value of EXPLAIN_TIME is
unique.
QBLOCKNO INTEGER NOT NULL A number that identifies each query block within a query.
APPLNAME VARCHAR(24) NOT The name of the application plan for the row, or blank.
NULL
PROGNAME VARCHAR(128) NOT The name of the program or package containing the statement being
NULL explained. Applies only to embedded EXPLAIN statements and to
statements explained as the result of binding a plan or package. A
blank indicates that the column is not applicable.
COLLID VARCHAR(128) NOT The collection ID for the package. Applies only to an embedded
NULL EXPLAIN statement that is executed from a package or to a
statement that is explained when binding a package. A blank
indicates that the column is not applicable. The value
DSNDYNAMICSQLCACHE indicates that the row is for a cached
statement.
GROUP_MEMBER VARCHAR(24) NOT The member name of the DB2 that executed EXPLAIN, or blank.
NULL For more information about the GROUP_MEMBER column, see
EXPLAIN_TIME TIMESTAMP NOT The time at which the statement is processed. This time is the same
NULL as the BIND_TIME column in PLAN_TABLE.
SCHEMA_NAME VARCHAR(128) NOT The schema name of the function invoked in the explained
NULL statement.
FUNCTION_NAME VARCHAR(128) NOT The name of the function invoked in the explained statement.
NULL
| SPEC_FUNC_NAME VARCHAR(128) NOT The specific name of the function invoked in the explained
NULL statement.
FUNCTION_TYPE CHAR(2) NOT NULL The type of function invoked in the explained statement. Possible
values are:
| CU Column function
| SU Scalar function
| TU Table function
VIEW_CREATOR VARCHAR(128) NOT If the function specified in the FUNCTION_NAME column is
NULL referenced in a view definition, the creator of the view. Otherwise,
blank.
VIEW_NAME VARCHAR(128) NOT If the function specified in the FUNCTION_NAME column is
NULL referenced in a view definition, the name of the view. Otherwise,
blank.
PATH VARCHAR(2048) NOT The value of the SQL path that was used to resolve the schema
NULL name of the function.

Chapter 13. Invoking a user-defined function 731

Table 128. Descriptions of columns in DSN_FUNCTION_TABLE (continued)
Column name Data type Description
FUNCTION_TEXT VARCHAR(1500) NOT The text of the function reference (the function name and
NULL parameters). If the function reference is over 100 bytes, this column
contains the first 100 bytes. For functions specified in infix notation,
FUNCTION_TEXT contains only the function name. For example,
for a function named /, which overloads the SQL divide operator, if
the function reference is A/B, FUNCTION_TEXT contains only /.

PSPI

Restrictions when passing arguments with distinct types to functions

Because DB2 enforces strong typing when you pass arguments to a function, you
must follow certain rules when passing arguments with distinct types to functions.

Adhere to the following rules:

v You can pass arguments that have distinct types to a function if either of the
following conditions is true:
– A version of the function that accepts those distinct types is defined.
This also applies to infix operators. If you want to use one of the five built-in
infix operators (||, /, *, +, -) with your distinct types, you must define a
version of that operator that accepts the distinct types.
– You can cast your distinct types to the argument types of the function.
v If you pass arguments to a function that accepts only distinct types, the
arguments you pass must have the same distinct types as in the function
definition. If the types are different, you must cast your arguments to the
distinct types in the function definition.
If you pass constants or host variables to a function that accepts only distinct
types, you must cast the constants or host variables to the distinct types that the
function accepts.

The following examples demonstrate how to use distinct types as arguments in

function invocations.

Example: Defining a function with distinct types as arguments: Suppose that you
want to invoke the built-in function HOUR with a distinct type that is defined like
this:
CREATE DISTINCT TYPE FLIGHT_TIME AS TIME;

The HOUR function takes only the TIME or TIMESTAMP data type as an
argument, so you need a sourced function that is based on the HOUR function that
accepts the FLIGHT_TIME data type. You might declare a function like this:
CREATE FUNCTION HOUR(FLIGHT_TIME)
RETURNS INTEGER
SOURCE SYSIBM.HOUR(TIME);

Example: Casting function arguments to acceptable types: Another way you can
invoke the HOUR function is to cast the argument of type FLIGHT_TIME to the
TIME data type before you invoke the HOUR function. Suppose table
FLIGHT_INFO contains column DEPARTURE_TIME, which has data type
FLIGHT_TIME, and you want to use the HOUR function to extract the hour of

732 Application Programming and SQL Guide

departure from the departure time. You can cast DEPARTURE_TIME to the TIME
data type, and then invoke the HOUR function:
SELECT HOUR(CAST(DEPARTURE_TIME AS TIME)) FROM FLIGHT_INFO;

Example: Using an infix operator with distinct type arguments: Suppose you want
to add two values of type US_DOLLAR. Before you can do this, you must define a
version of the + function that accepts values of type US_DOLLAR as operands:
CREATE FUNCTION "+"(US_DOLLAR,US_DOLLAR)
RETURNS US_DOLLAR
SOURCE SYSIBM."+"(DECIMAL(9,2),DECIMAL(9,2));

Because the US_DOLLAR type is based on the DECIMAL(9,2) type, the source
function must be the version of + with arguments of type DECIMAL(9,2).

Example: Casting constants and host variables to distinct types to invoke a

user-defined function: Suppose function CDN_TO_US is defined like this:
CREATE FUNCTION EURO_TO_US(EURO)
RETURNS US_DOLLAR
EXTERNAL NAME 'CDNCVT'
PARAMETER STYLE SQL
LANGUAGE C;

This means that EURO_TO_US accepts only the EURO type as input. Therefore, if
you want to call CDN_TO_US with a constant or host variable argument, you
must cast that argument to distinct type EURO:
SELECT * FROM US_SALES
WHERE TOTAL = EURO_TO_US(EURO(:H1));
SELECT * FROM US_SALES
WHERE TOTAL = EURO_TO_US(EURO(10000));

Cases when DB2 casts arguments for a user-defined function

In certain situations, when you invoke a user-defined function, DB2 casts your
input argument values to different data types and lengths.

Whenever you invoke a user-defined function, DB2 assigns your input argument
values to parameters with the data types and lengths in the user-defined function
definition.

When you invoke a user-defined function that is sourced on another function, DB2
casts your arguments to the data types and lengths of the sourced function.

The following example demonstrates what happens when the parameter

definitions of a sourced function differ from those of the function on which it is
sourced.

Suppose that external user-defined function TAXFN1 is defined like this:

CREATE FUNCTION TAXFN1(DEC(6,0))
RETURNS DEC(5,2)
PARAMETER STYLE SQL
LANGUAGE C
EXTERNAL NAME TAXPROG;

Sourced user-defined function TAXFN2, which is sourced on TAXFN1, is defined

like this:

Chapter 13. Invoking a user-defined function 733

CREATE FUNCTION TAXFN2(DEC(8,2))
RETURNS DEC(5,0)
SOURCE TAXFN1;

You invoke TAXFN2 using this SQL statement:

UPDATE TB1
SET SALESTAX2 = TAXFN2(PRICE2);

TB1 is defined like this:

CREATE TABLE TB1
(PRICE1 DEC(6,0),
SALESTAX1 DEC(5,2),
PRICE2 DEC(9,2),
SALESTAX2 DEC(7,2));

Now suppose that PRICE2 has the DECIMAL(9,2) value 0001234.56. DB2 must first
assign this value to the data type of the input parameter in the definition of
TAXFN2, which is DECIMAL(8,2). The input parameter value then becomes
001234.56. Next, DB2 casts the parameter value to a source function parameter,
which is DECIMAL(6,0). The parameter value then becomes 001234. (When you
cast a value, that value is truncated, rather than rounded.)

Now, if TAXFN1 returns the DECIMAL(5,2) value 123.45, DB2 casts the value to
DECIMAL(5,0), which is the result type for TAXFN2, and the value becomes 00123.
This is the value that DB2 assigns to column SALESTAX2 in the UPDATE
statement.

Casting of parameter markers

You can use untyped parameter markers in a function invocation. However, DB2
cannot compare the data types of untyped parameter markers to the data types of
candidate functions. Therefore, DB2 might find more than one function that
qualifies for invocation. If this happens, an SQL error occurs. To ensure that DB2
picks the right function to execute, cast the parameter markers in your function
invocation to the data types of the parameters in the function that you want to
execute. For example, suppose that two versions of function FX exist. One version
of FX is defined with a parameter of type of DECIMAL(9,2), and the other is
defined with a parameter of type INTEGER. You want to invoke FX with a
parameter marker, and you want DB2 to execute the version of FX that has a
DECIMAL(9,2) parameter. You need to cast the parameter marker to a
DECIMAL(9,2) type by using a CAST specification:
SELECT FX(CAST(? AS DECIMAL(9,2))) FROM T1;
Related concepts
Assignment and comparison (SQL Reference)

734 Application Programming and SQL Guide

Chapter 14. Calling a stored procedure from your application
| To run a stored procedure, you can either call it from a client program or invoke it
| from the command line processor.

| Before you call a stored procedure, ensure that you have all of the following
| authorizations that are required to run the stored procedure:
| v Authorization to execute the stored procedure that is referenced in the CALL
| statement.
| The authorizations that you need depend on whether the form of the CALL
| statement is CALL procedure-name or CALL :host-variable.
| v Authorization to execute any triggers or user-defined functions that the stored
| procedure invokes.
| v Authorization to execute the stored procedure package and any packages under
| the stored procedure package.
| For example, if the stored procedure invokes any user-defined functions, you
| need authorization to execute the packages for those user-defined functions.

| An application program that calls a stored procedure can perform one or more of
| the following actions:
| v Call more than one stored procedure.
| v Call a single stored procedure more than once at the same or at different levels
| of nesting. However, do not assume that the variables for the stored procedures
| persist between calls.
| If a stored procedure runs as a main program, before each call, Language
| Environment reinitializes the storage that is used by the stored procedure.
| Program variables for the stored procedure do not persist between calls.
| If a stored procedure runs as a subprogram, Language Environment does not
| initialize the storage between calls. Program variables for the stored procedure
| can persist between calls. However, you should not assume that your program
| variables are available from one stored procedure call to another call for the
| following reasons:
| – Stored procedures from other users can run in an instance of Language
| Environment between two executions of your stored procedure.
| – Consecutive executions of a stored procedure might run in different stored
| procedure address spaces.
| – The z/OS operator might refresh Language Environment between two
| executions of your stored procedure.
| v Call a local or remote stored procedure.
| If both the client and server application environments support two-phase
| commit, the coordinator controls updates between the application, the server,
| and the stored procedures. If either side does not support two-phase commit,
| updates fail.
| v Mix CALL statements with other SQL statements.
| v Use any of the DB2 attachment facilities.

| DB2 runs stored procedures under the DB2 thread of the calling application, which
| means that the stored procedures are part of the caller’s unit of work.

© Copyright IBM Corp. 1983, 2009 735

| To call a stored procedure from your application:
| 1. Assign values to the IN and INOUT parameters.
| 2. Optional: Initialize the length of LOB output parameters to zero. Doing so can
| improve application performance.
| 3. If the stored procedure exists at a remote location, perform the following
| actions:
| a. Assign values to the OUT parameters.
| For a stored procedure that runs locally, you do not need to initialize the
| values of output parameters before you call the stored procedure.
| However, when you call a stored procedure at a remote location, the local
| DB2 server cannot determine whether the parameters are input (IN) or
| output (OUT or INOUT) parameters. Therefore, you must initialize the
| values of all output parameters before you call a stored procedure at a
| remote location.
| b. Optional: Issue an explicit CONNECT statement to connect to the remote
| server.
| If you do not issue this statement explicitly, you can implicitly connect to
| the server by using a three-part name to identify the stored procedure in
| the next step.
| The advantage of issuing an explicit CONNECT statement is that your
| CALL statement, which is described in the next step, is portable to other
| operating systems. The advantage of implicitly connecting is that you do
| not need to issue this extra CONNECT statement.

| Requirement: When deciding whether to implicitly or explicitly connect to

| the remote server, consider the requirement for programs that execute the
| ASSOCIATE LOCATORS or DESCRIBE PROCEDURE statements. You
| must use the same form of the procedure name on the CALL statement
| and on the ASSOCIATE LOCATORS or DESCRIBE PROCEDURE
| statement.
| 4. For programs other than JDBC or ODBC programs, invoke the stored
| procedure with the SQL CALL statement. Make sure that you pass parameter
| data types that are compatible.
| If the stored procedure exists on a remote server and you did not issue an
| explicit CONNECT statement, specify a three-part name to identify the stored
| procedure, and implicitly connect to the server where the stored procedure is
| located.
| For native SQL procedures, the active version of the stored procedure is
| invoked by default. Optionally, you can specify a version of the stored
| procedure other than the active version. For instructions on how to specify a
| version other than the active version, see the information about temporarily
| overriding the active version of a native SQL procedure.
| To allow null values for parameters, use indicator variables.
| For ODBC programs, call several APIs, as described in the ODBC information
| about stored procedure calls.
| For JDBC, invoke a series of methods, to one of which you pass a CALL
| statement, as described in the information about calling stored procedures in
| JDBC applications.

| Example of simple CALL statement: The following example shows a simple

| CALL statement that you might use to invoke stored procedure A:
| EXEC SQL CALL A (:EMP, :PRJ, :ACT, :EMT, :EMS, :EME, :TYPE, :CODE);

736 Application Programming and SQL Guide

| In this example, :EMP, :PRJ, :ACT, :EMT, :EMS, :EME, :TYPE, and :CODE are
| host variables that you have declared earlier in your application program.

| Example of using a host structure for multiple parameter values: Instead of

| passing each parameter separately, as shown in the preceding example, you
| could pass them together as a host structure. For example, assume that you
| defined the following host structure in your application:
| struct {
| char EMP[7];
| char PRJ[7];
| short ACT;
| short EMT;
| char EMS[11];
| char EME[11];
| } empstruc;

| You can then issue the following CALL statement:

| EXEC SQL CALL A (:empstruc, :TYPE, :CODE);

| Example of calling a remote stored procedure: Suppose that stored procedure

| A is in schema SCHEMAA at remote location LOCA. To invoke stored
| procedure A, you can explicitly or implicitly connect to the server, as shown
| in the following examples:
| v The following example shows how to explicitly connect to LOCA and then
| issue a CALL statement:
| EXEC SQL CONNECT TO LOCA;
| EXEC SQL CALL SCHEMAA.A (:EMP, :PRJ, :ACT, :EMT, :EMS, :EME,
| :TYPE, :CODE);
| v The following example shows how to implicitly connect to LOCA by
| specifying the three-part name for stored procedure A in the CALL
| statement:
| EXEC SQL CALL LOCA.SCHEMAA.A (:EMP, :PRJ, :ACT, :EMT, :EMS,
| :EME, :TYPE, :CODE);

| Example of passing parameters that can have null values: The preceding
| examples assume that none of the input parameters can have null values. The
| following example shows how to allow for null values for the parameters by
| passing indicator variables in the parameter list:
| EXEC SQL CALL A (:EMP :IEMP, :PRJ :IPRJ, :ACT :IACT,
| :EMT :IEMT, :EMS :IEMS, :EME :IEME,
| :TYPE :ITYPE, :CODE :ICODE);

| In this example, :IEMP, :IPRJ, :IACT, :IEMT, :IEMS, :IEME, :ITYPE, and
| :ICODE are indicator variables for the parameters.

| Example of passing string constants and null values: The following example
| CALL statement passes integer and character string constants, a null value,
| and several host variables:
| EXEC SQL CALL A ('000130', 'IF1000', 90, 1.0, NULL, '2009-10-01',
| :TYPE, :CODE);

| Example of using a host variable for the stored procedure name: The
| following example CALL statement uses a host variable for the name of the
| stored procedure:
| EXEC SQL CALL :procnm (:EMP, :PRJ, :ACT, :EMT, :EMS, :EME,
| :TYPE, :CODE);

Chapter 14. Calling a stored procedure from your application 737

| Assume that the stored procedure name is A. The host variable procnm is a
| character variable of length 255 or less that contains the value ’A’. You should
| use this technique if you do not know in advance the name of the stored
| procedure, but you do know the parameter list convention.

| Example of using an SQLDA to pass parameters in a single structure: The

| following example CALL statement shows how to pass parameters in a single
| structure, the SQLDA, rather than as separate host variables:
| EXEC SQL CALL A USING DESCRIPTOR :sqlda;

| sqlda is the name of an SQLDA.

| One advantage of using this form is that you can change the encoding scheme
| of the stored procedure parameter values. For example, if the subsystem on
| which the stored procedure runs has an EBCDIC encoding scheme, and you
| want to retrieve data in ASCII CCSID 437, you can specify the desired CCSIDs
| for the output parameters in the SQLVAR fields of the SQLDA.

| This technique for overriding the CCSIDs of parameters is the same as the
| technique for overriding the CCSIDs of variables, which is described in the
| information about including dynamic SQL for varying-list SELECT statements
| in your program. When you use this technique, the defined encoding scheme
| of the parameter must be different from the encoding scheme that you specify
| in the SQLDA. Otherwise, no conversion occurs.

| The defined encoding scheme for the parameter is the encoding scheme that
| you specify in the CREATE PROCEDURE statement, or if you do not specify
| an encoding scheme in this statement, the default encoding scheme for the
| subsystem.

| Example of a reusable CALL statement:

| Because the following example CALL statement uses a host variable name for
| the stored procedure and an SQLDA for the parameter list, it can be reused to
| call different stored procedures with different parameter lists:
| EXEC SQL CALL :procnm USING DESCRIPTOR :sqlda;

| Your client program must assign a stored procedure name to the host variable
| procnm and load the SQLDA with the parameter information before issuing
| the SQL CALL statement.
| 5. Process any output, including the OUT and INOUT parameters.
| 6. If the stored procedure returns multiple result sets, retrieve those result sets.

| Recommendation: Close the result sets after you retrieve them, and issue
| commits often to prevent DB2 storage shortages and EDM POOL FULL
| conditions.
| 7. For PL/I applications, also perform the following actions:
| a. Include the runtime option NOEXECOPS in your source code.
| b. Specify the compile-time option SYSTEM(MVS).
| These additional steps ensure that the linkage conventions work correctly on
| z/OS.
| 8. For C applications, include the following line in your source code:
| #pragma runopts(PLIST(OS))

738 Application Programming and SQL Guide

| This code ensures that the linkage conventions work correctly on z/OS.
| This option is not applicable to other operating systems. If you plan to use a
| C stored procedure on other platforms besides z/OS, use conditional
| compilation, as shown in the following example, to include this option only
| when you compile on z/OS.
| #ifdef MVS
| #pragma runopts(PLIST(OS))
| #endif
|
| -- or --
|
| #ifndef WKSTN
| #pragma runopts(PLIST(OS))
| #endif
| 9. Prepare the application as you would any other application by precompiling,
| compiling, and link-editing the application and binding the DBRM.
| If the application calls a remote stored procedure, perform the following
| additional steps when you bind the DBRM:
| v Bind the DBRM into a package at the local DB2 server. Use the bind option
| DBPROTOCOL(DRDA). If the stored procedure name cannot be resolved
| until run time, also specify the bind option VALIDATE(RUN). The stored
| procedure name might not be resolved at run time if you use a variable for
| the stored procedure name or the stored procedure exists on a remote
| server.
| v Bind the DBRM into a package at the remote DB2 server. If your client
| program accesses multiple servers, bind the program at each server.
| v Bind all packages into a plan at the local DB2 server. Use the bind option
| DBPROTOCOL(DRDA).
| 10. Ensure that stored procedure completed successfully.
| If a stored procedure abnormally terminates, DB2 performs the following
| actions:
| v The calling program receives an SQL error as notification that the stored
| procedure failed.
| v DB2 places the calling program’s unit of work in a must-rollback state.
| v DB2 stops the stored procedure, and subsequent calls fail, in either of the
| following conditions:
| – The number of abnormal terminations equals the STOP AFTER n
| FAILURES value for the stored procedure.
| – The number of abnormal terminations equals the default MAX ABEND
| COUNT value for the subsystem.
| v The stored procedure does not handle the abend condition, and DB2
| refreshes the environment for Language Environment to recover the storage
| that the application uses. In most cases, the environment does not need to
| restart.
| v A data set is allocated in the DD statement CEEDUMP in the JCL procedure
| that starts the stored procedures address space. In this case, Language
| Environment writes a small diagnostic dump to this data set. Use this
| information to debug the stored procedure.
| v In a data sharing environment, the stored procedure is placed in STOPABN
| status only on the member where the abends occurred. A calling program
| can invoke the stored procedure from other members of the data sharing
| group. The status on all other members is STARTED.

Chapter 14. Calling a stored procedure from your application 739

Related concepts
“External stored procedures as main programs and subprograms” on page 587
“Examples of programs that call stored procedures” on page 228
Stored procedure calls in a DB2 ODBC application (Programming for ODBC)
Related tasks
“Debugging stored procedures” on page 1030
“Including dynamic SQL for varying-list SELECT statements in your program” on
page 169
Chapter 17, “Preparing an application to run on DB2 for z/OS,” on page 887
“Running stored procedures from the command line processor” on page 1006
Calling stored procedures in JDBC applications (Programming for Java)
Related reference
BIND and REBIND options (DB2 Command Reference)
ASSOCIATE LOCATORS (SQL Reference)
CALL (SQL Reference)
CONNECT (SQL Reference)
DESCRIBE PROCEDURE (SQL Reference)
SQL descriptor area (SQLDA) (SQL Reference)
Related information
z/OS Internet Library
Sample scenarios of program preparations

Parameter list for stored procedures

Application programs that call stored procedures must pass the required
parameters in the SQL CALL statement. Optionally, you can also include an
indicator variable with each parameter to allow for null values or to pass large
output parameter values. DB2 builds a parameter list based on these parameter
values.

Parameters are defined as part of the stored procedure definition in the CREATE
PROCEDURE statement. They can be one of the following types:
IN Input-only parameters, which provide values to the stored procedure
OUT Output-only parameters, which return values from the stored procedure to
the calling program
INOUT
Input/output parameters, which provide values to or return values from
the stored procedure

If a stored procedure fails to set one or more of the output-only parameters, DB2
does not return an error. Instead, DB2 returns the output parameters to the calling
program, with the values that were established on entry to the stored procedure.

740 Application Programming and SQL Guide

Related reference
CREATE PROCEDURE (SQL Reference)

Linkage conventions for stored procedures

A linkage convention specifies the rules for the parameter list that can be passed
by the program that calls the stored procedure. For example, the convention can
specify whether the calling program can pass null values for input parameters. The
linkage convention is declared in the stored procedure definition.

DB2 supports three parameter list conventions. DB2 chooses the parameter list
convention based on the value of the PARAMETER STYLE parameter in the stored
procedure definition: GENERAL, GENERAL WITH NULLS, or SQL.
v Use GENERAL when you do not want the calling program to pass null values
for input parameters (IN or INOUT) to the stored procedure. The stored
procedure must contain a variable declaration for each parameter passed in the
CALL statement.
The following figure shows the structure of the parameter list for PARAMETER
STYLE GENERAL.

Figure 40. Parameter convention GENERAL for a stored procedure

v Use GENERAL WITH NULLS to allow the calling program to supply a null
value for any parameter passed to the stored procedure. For the GENERAL
WITH NULLS linkage convention, the stored procedure must do the following
tasks:
– Declare a variable for each parameter passed in the CALL statement.
– Declare a null indicator structure containing an indicator variable for each
parameter.
– On entry, examine all indicator variables associated with input parameters to
determine which parameters contain null values.
– On exit, assign values to all indicator variables associated with output
variables. An indicator variable for an output variable that returns a null
value to the caller must be assigned a negative number. Otherwise, the
indicator variable must be assigned the value 0.
In the CALL statement, follow each parameter with its indicator variable, using
one of the following forms:
host-variable :indicator-variable
or
host-variable INDICATOR :indicator-variable.
The following figure shows the structure of the parameter list for PARAMETER
STYLE GENERAL WITH NULLS.

Chapter 14. Calling a stored procedure from your application 741

Figure 41. Parameter convention GENERAL WITH NULLS for a stored procedure

v Like GENERAL WITH NULLS, option SQL lets you supply a null value for any
parameter that is passed to the stored procedure. In addition, DB2 passes input
and output parameters to the stored procedure that contain this information:
– The SQLSTATE that is to be returned to DB2. This is a CHAR(5) parameter
that represents the SQLSTATE that is passed in to the program from the
database manager. The initial value is set to ‘00000’. Although the SQLSTATE
is usually not set by the program, it can be set as the result SQLSTATE that is
used to return an error or a warning. Returned values that start with
anything other than ‘00’, ‘01’, or ‘02’ are error conditions.
– The qualified name of the stored procedure. This is a VARCHAR(128) value.
– The specific name of the stored procedure. The specific name is a
VARCHAR(128) value that is the same as the unqualified name.
| – The SQL diagnostic string that is to be returned to DB2. This is a
| VARCHAR(1000) value. Use this area to pass descriptive information about
| an error or warning to the caller.
SQL is not a valid linkage convention for a REXX language stored procedure.
The following figure shows the structure of the parameter list for PARAMETER
STYLE SQL.

742 Application Programming and SQL Guide

Figure 42. Parameter convention SQL for a stored procedure

Example of stored procedure linkage convention GENERAL:

The following examples demonstrate how an assembler, C, COBOL, or PL/I stored

procedure uses the GENERAL linkage convention to receive parameters.

For these examples, assume that a COBOL application has the following parameter
declarations and CALL statement:
************************************************************
* PARAMETERS FOR THE SQL STATEMENT CALL *
************************************************************
01 V1 PIC S9(9) USAGE COMP.
01
. V2 PIC X(9).
.
.
EXEC SQL CALL A (:V1, :V2) END-EXEC.

In the CREATE PROCEDURE statement, the parameters are defined like this:
IN V1 INT, OUT V2 CHAR(9)

The following figures show how an assembler, C, COBOL, and PL/I stored
procedure uses the GENERAL linkage convention to receive parameters.

The following example shows how a stored procedure in assembler language

receives these parameters.

Chapter 14. Calling a stored procedure from your application 743

*******************************************************************
* CODE FOR AN ASSEMBLER LANGUAGE STORED PROCEDURE THAT USES *
* THE GENERAL LINKAGE CONVENTION. *
*******************************************************************
A CEEENTRY AUTO=PROGSIZE,MAIN=YES,PLIST=OS
USING PROGAREA,R13
*******************************************************************
* BRING UP THE LANGUAGE ENVIRONMENT. *
*******************************************************************
.
.
.
*******************************************************************
* GET THE PASSED PARAMETER VALUES. THE GENERAL LINKAGE CONVENTION*
* FOLLOWS THE STANDARD ASSEMBLER LINKAGE CONVENTION: *
* ON ENTRY, REGISTER 1 POINTS TO A LIST OF POINTERS TO THE *
* PARAMETERS. *
*******************************************************************
L R7,0(R1) GET POINTER TO V1
MVC LOCV1(4),0(R7) MOVE VALUE INTO LOCAL COPY OF V1
.
.
.
L R7,4(R1) GET POINTER TO V2
MVC 0(9,R7),LOCV2 MOVE A VALUE INTO OUTPUT VAR V2
.
.
.
CEETERM RC=0
*******************************************************************
* VARIABLE DECLARATIONS AND EQUATES *
*******************************************************************
R1 EQU 1 REGISTER 1
R7 EQU 7 REGISTER 7
PPA CEEPPA , CONSTANTS DESCRIBING THE CODE BLOCK
LTORG , PLACE LITERAL POOL HERE
PROGAREA DSECT
ORG *+CEEDSASZ LEAVE SPACE FOR DSA FIXED PART
LOCV1 DS F LOCAL COPY OF PARAMETER V1
LOCV2 DS CL9 LOCAL COPY OF PARAMETER V2
.
.
.
PROGSIZE EQU *-PROGAREA
CEEDSA , MAPPING OF THE DYNAMIC SAVE AREA
CEECAA , MAPPING OF THE COMMON ANCHOR AREA
END A

The following figure shows how a stored procedure in the C language receives
these parameters.
#pragma runopts(PLIST(OS))
#pragma options(RENT)
#include <stdlib.h>
#include <stdio.h>
/*****************************************************************/
/* Code for a C language stored procedure that uses the */
/* GENERAL linkage convention. */
/*****************************************************************/
main(argc,argv)
int argc; /* Number of parameters passed */
char *argv[]; /* Array of strings containing */
/* the parameter values */
{
long int locv1; /* Local copy of V1 */
char locv2[10]; /* Local copy of V2 */
/* (null-terminated) */
.
.
.
/***************************************************************/

744 Application Programming and SQL Guide

/* Get the passed parameters. The GENERAL linkage convention */
/* follows the standard C language parameter passing */
/* conventions: */
/* - argc contains the number of parameters passed */
/* - argv[0] is a pointer to the stored procedure name */
/* - argv[1] to argv[n] are pointers to the n parameters */
/* in the SQL statement CALL. */
/***************************************************************/
if(argc==3) /* Should get 3 parameters: */
{ /* procname, V1, V2 */
locv1 = *(int *) argv[1];
/* Get local copy of V1 */
.
.
.
strcpy(argv[2],locv2);
/* Assign a value to V2 */
.
.
.
}
}

The following figure shows how a stored procedure in the COBOL language
receives these parameters.
CBL RENT
IDENTIFICATION DIVISION.
************************************************************
* CODE FOR A COBOL LANGUAGE STORED PROCEDURE THAT USES THE *
* GENERAL LINKAGE CONVENTION. *
************************************************************
PROGRAM-ID. A.
.
.
.
DATA DIVISION.
.
.
.
LINKAGE SECTION.
************************************************************
* DECLARE THE PARAMETERS PASSED BY THE SQL STATEMENT *
* CALL HERE. *
************************************************************
01 V1 PIC S9(9) USAGE COMP.
01 V2 PIC X(9).
.
.
.
PROCEDURE DIVISION USING V1, V2.
************************************************************
* THE USING PHRASE INDICATES THAT VARIABLES V1 AND V2 *
* WERE PASSED BY THE CALLING PROGRAM. *
************************************************************
.
.
.
****************************************
* ASSIGN A VALUE TO OUTPUT VARIABLE V2 *
****************************************
MOVE '123456789' TO V2.

The following figure shows how a stored procedure in the PL/I language receives
these parameters.
*PROCESS SYSTEM(MVS);
A: PROC(V1, V2) OPTIONS(MAIN NOEXECOPS REENTRANT);
/***************************************************************/
/* Code for a PL/I language stored procedure that uses the */
/* GENERAL linkage convention. */
/***************************************************************/

Chapter 14. Calling a stored procedure from your application 745

/***************************************************************/
/* Indicate on the PROCEDURE statement that two parameters */
/* were passed by the SQL statement CALL. Then declare the */
/* parameters in the following section. */
/***************************************************************/
DCL V1 BIN FIXED(31),
V2 CHAR(9);
.
.
.
V2 = '123456789'; /* Assign a value to output variable V2 */

Example of stored procedure linkage convention GENERAL WITH NULLS:

The following examples demonstrate how an assembler, C, COBOL, or PL/I stored

procedure uses the GENERAL WITH NULLS linkage convention to receive
parameters.

For these examples, assume that a C application has the following parameter
declarations and CALL statement:
/************************************************************/
/* Parameters for the SQL statement CALL */
/************************************************************/
long int v1;
char v2[10]; /* Allow an extra byte for */
/* the null terminator */
/************************************************************/
/* Indicator structure */
/************************************************************/
struct indicators {
short int ind1;
short int ind2;
} indstruc;
.
.
.
indstruc.ind1 = 0; /* Remember to initialize the */
/* input parameter's indicator*/
/* variable before executing */
/* the CALL statement */
EXEC SQL CALL B (:v1 :indstruc.ind1, :v2 :indstruc.ind2);
.
.
.

In the CREATE PROCEDURE statement, the parameters are defined like this:
IN V1 INT, OUT V2 CHAR(9)

The following figures show how an assembler, C, COBOL, or PL/I stored

procedure uses the GENERAL WITH NULLS linkage convention to receive
parameters.

The following figure shows how a stored procedure in assembler language receives
these parameters.
*******************************************************************
* CODE FOR AN ASSEMBLER LANGUAGE STORED PROCEDURE THAT USES *
* THE GENERAL WITH NULLS LINKAGE CONVENTION. *
*******************************************************************
B CEEENTRY AUTO=PROGSIZE,MAIN=YES,PLIST=OS
USING PROGAREA,R13
*******************************************************************
* BRING UP THE LANGUAGE ENVIRONMENT. *
*******************************************************************

746 Application Programming and SQL Guide

.
.
.
*******************************************************************
* GET THE PASSED PARAMETER VALUES. THE GENERAL WITH NULLS LINKAGE*
* CONVENTION IS AS FOLLOWS: *
* ON ENTRY, REGISTER 1 POINTS TO A LIST OF POINTERS. IF N *
* PARAMETERS ARE PASSED, THERE ARE N+1 POINTERS. THE FIRST *
* N POINTERS ARE THE ADDRESSES OF THE N PARAMETERS, JUST AS *
* WITH THE GENERAL LINKAGE CONVENTION. THE N+1ST POINTER IS *
* THE ADDRESS OF A LIST CONTAINING THE N INDICATOR VARIABLE *
* VALUES. *
*******************************************************************
L R7,0(R1) GET POINTER TO V1
MVC LOCV1(4),0(R7) MOVE VALUE INTO LOCAL COPY OF V1
L R7,8(R1) GET POINTER TO INDICATOR ARRAY
MVC LOCIND(2*2),0(R7) MOVE VALUES INTO LOCAL STORAGE
LH R7,LOCIND GET INDICATOR VARIABLE FOR V1
LTR R7,R7 CHECK IF IT IS NEGATIVE
BM NULLIN IF SO, V1 IS NULL
.
.
.
L R7,4(R1) GET POINTER TO V2
MVC 0(9,R7),LOCV2 MOVE A VALUE INTO OUTPUT VAR V2
L R7,8(R1) GET POINTER TO INDICATOR ARRAY
MVC 2(2,R7),=H(0) MOVE ZERO TO V2'S INDICATOR VAR
.
.
.
CEETERM RC=0
*******************************************************************
* VARIABLE DECLARATIONS AND EQUATES *
*******************************************************************
R1 EQU 1 REGISTER 1
R7 EQU 7 REGISTER 7
PPA CEEPPA , CONSTANTS DESCRIBING THE CODE BLOCK
LTORG , PLACE LITERAL POOL HERE
PROGAREA DSECT
ORG *+CEEDSASZ LEAVE SPACE FOR DSA FIXED PART
LOCV1 DS F LOCAL COPY OF PARAMETER V1
LOCV2 DS CL9 LOCAL COPY OF PARAMETER V2
LOCIND DS 2H LOCAL COPY OF INDICATOR ARRAY
.
.
.
PROGSIZE EQU *-PROGAREA
CEEDSA , MAPPING OF THE DYNAMIC SAVE AREA
CEECAA , MAPPING OF THE COMMON ANCHOR AREA
END B

The following figure shows how a stored procedure in the C language receives
these parameters.
#pragma options(RENT)
#pragma runopts(PLIST(OS))
#include <stdlib.h>
#include <stdio.h>
/*****************************************************************/
/* Code for a C language stored procedure that uses the */
/* GENERAL WITH NULLS linkage convention. */
/*****************************************************************/
main(argc,argv)
int argc; /* Number of parameters passed */
char *argv[]; /* Array of strings containing */
/* the parameter values */
{
long int locv1; /* Local copy of V1 */
char locv2[10]; /* Local copy of V2 */
/* (null-terminated) */

Chapter 14. Calling a stored procedure from your application 747

short int locind[2]; /* Local copy of indicator */
/* variable array */
short int *tempint; /* Used for receiving the */
/* indicator variable array */
.
.
.
/***************************************************************/
/* Get the passed parameters. The GENERAL WITH NULLS linkage */
/* convention is as follows: */
/* - argc contains the number of parameters passed */
/* - argv[0] is a pointer to the stored procedure name */
/* - argv[1] to argv[n] are pointers to the n parameters */
/* in the SQL statement CALL. */
/* - argv[n+1] is a pointer to the indicator variable array */
/***************************************************************/
if(argc==4) /* Should get 4 parameters: */
{ /* procname, V1, V2, */
/* indicator variable array */
locv1 = *(int *) argv[1];
/* Get local copy of V1 */
tempint = argv[3]; /* Get pointer to indicator */
/* variable array */
locind[0] = *tempint;
/* Get 1st indicator variable */
locind[1] = *(++tempint);
/* Get 2nd indicator variable */
if(locind[0]<0) /* If 1st indicator variable */
{ /* is negative, V1 is null */
.
.
.
}
.
.
.
strcpy(argv[2],locv2);
/* Assign a value to V2 */
*(++tempint) = 0; /* Assign 0 to V2's indicator */
/* variable */
}
}

The following figure shows how a stored procedure in the COBOL language
receives these parameters.
CBL RENT
IDENTIFICATION DIVISION.
************************************************************
* CODE FOR A COBOL LANGUAGE STORED PROCEDURE THAT USES THE *
* GENERAL WITH NULLS LINKAGE CONVENTION. *
************************************************************
PROGRAM-ID. B.
.
.
.
DATA DIVISION.
.
.
.
LINKAGE SECTION.
************************************************************
* DECLARE THE PARAMETERS AND THE INDICATOR ARRAY THAT *
* WERE PASSED BY THE SQL STATEMENT CALL HERE. *
************************************************************
01 V1 PIC S9(9) USAGE COMP.
01 V2 PIC X(9).
*
01 INDARRAY.
10 INDVAR PIC S9(4) USAGE COMP OCCURS 2 TIMES.

748 Application Programming and SQL Guide

.
.
.
PROCEDURE DIVISION USING V1, V2, INDARRAY.
************************************************************
* THE USING PHRASE INDICATES THAT VARIABLES V1, V2, AND *
* INDARRAY WERE PASSED BY THE CALLING PROGRAM. *
************************************************************
.
.
.
***************************
* TEST WHETHER V1 IS NULL *
***************************
IF INDARRAY(1) < 0
PERFORM NULL-PROCESSING.
.
.
.
****************************************
* ASSIGN A VALUE TO OUTPUT VARIABLE V2 *
* AND ITS INDICATOR VARIABLE *
****************************************
MOVE '123456789' TO V2.
MOVE ZERO TO INDARRAY(2).

The following figure shows how a stored procedure in the PL/I language receives
these parameters.
*PROCESS SYSTEM(MVS);
A: PROC(V1, V2, INDSTRUC) OPTIONS(MAIN NOEXECOPS REENTRANT);
/***************************************************************/
/* Code for a PL/I language stored procedure that uses the */
/* GENERAL WITH NULLS linkage convention. */
/***************************************************************/
/***************************************************************/
/* Indicate on the PROCEDURE statement that two parameters */
/* and an indicator variable structure were passed by the SQL */
/* statement CALL. Then declare them in the following section.*/
/* For PL/I, you must declare an indicator variable structure, */
/* not an array. */
/***************************************************************/
DCL V1 BIN FIXED(31),
V2 CHAR(9);
DCL
01 INDSTRUC,
02 IND1 BIN FIXED(15),
02 IND2 BIN FIXED(15);
.
.
.
IF IND1 < 0 THEN
CALL NULLVAL; /* If indicator variable is negative */
/* then V1 is null */
.
.
.
V2 = '123456789'; /* Assign a value to output variable V2 */
IND2 = 0; /* Assign 0 to V2's indicator variable */

Example of stored procedure linkage convention SQL

The following examples demonstrate how an assembler, C, COBOL, or PL/I stored

procedure uses the SQL linkage convention to receive parameters. These examples
also show how a stored procedure receives the DBINFO structure.

For these examples, assume that a C application has the following parameter
declarations and CALL statement:

Chapter 14. Calling a stored procedure from your application 749

/************************************************************/
/* Parameters for the SQL statement CALL */
/************************************************************/
long int v1;
char v2[10]; /* Allow an extra byte for */
/* the null terminator */
/************************************************************/
/* Indicator variables */
/************************************************************/
short int ind1;
short int ind2;
.
.
.
ind1 = 0; /* Remember to initialize the */
/* input parameter's indicator*/
/* variable before executing */
/* the CALL statement */
EXEC SQL CALL B (:v1 :ind1, :v2 :ind2);
.
.
.

In the CREATE PROCEDURE statement, the parameters are defined like this:
IN V1 INT, OUT V2 CHAR(9)

The following figures show how an assembler, C, COBOL, or PL/I stored

procedure uses the SQL linkage convention to receive parameters.

The following figure shows how a stored procedure in assembler language receives
these parameters.
*******************************************************************
* CODE FOR AN ASSEMBLER LANGUAGE STORED PROCEDURE THAT USES *
* THE SQL LINKAGE CONVENTION. *
*******************************************************************
B CEEENTRY AUTO=PROGSIZE,MAIN=YES,PLIST=OS
USING PROGAREA,R13
*******************************************************************
* BRING UP THE LANGUAGE ENVIRONMENT. *
*******************************************************************
.
.
.
*******************************************************************
* GET THE PASSED PARAMETER VALUES. THE SQL LINKAGE *
* CONVENTION IS AS FOLLOWS: *
* ON ENTRY, REGISTER 1 POINTS TO A LIST OF POINTERS. IF N *
* PARAMETERS ARE PASSED, THERE ARE 2N+4 POINTERS. THE FIRST *
* N POINTERS ARE THE ADDRESSES OF THE N PARAMETERS, JUST AS *
* WITH THE GENERAL LINKAGE CONVENTION. THE NEXT N POINTERS ARE *
* THE ADDRESSES OF THE INDICATOR VARIABLE VALUES. THE LAST *
* 4 POINTERS (5, IF DBINFO IS PASSED) ARE THE ADDRESSES OF *
* INFORMATION ABOUT THE STORED PROCEDURE ENVIRONMENT AND *
* EXECUTION RESULTS. *
*******************************************************************
L R7,0(R1) GET POINTER TO V1
MVC LOCV1(4),0(R7) MOVE VALUE INTO LOCAL COPY OF V1
L R7,8(R1) GET POINTER TO 1ST INDICATOR VARIABLE
MVC LOCI1(2),0(R7) MOVE VALUE INTO LOCAL STORAGE
L R7,20(R1) GET POINTER TO STORED PROCEDURE NAME
MVC LOCSPNM(20),0(R7) MOVE VALUE INTO LOCAL STORAGE
L R7,24(R1) GET POINTER TO DBINFO
MVC LOCDBINF(DBINFLN),0(R7)
* MOVE VALUE INTO LOCAL STORAGE
LH R7,LOCI1 GET INDICATOR VARIABLE FOR V1
LTR R7,R7 CHECK IF IT IS NEGATIVE
BM NULLIN IF SO, V1 IS NULL

750 Application Programming and SQL Guide

.
.
.
L R7,4(R1) GET POINTER TO V2
MVC 0(9,R7),LOCV2 MOVE A VALUE INTO OUTPUT VAR V2
L R7,12(R1) GET POINTER TO INDICATOR VAR 2
MVC 0(2,R7),=H'0' MOVE ZERO TO V2'S INDICATOR VAR
L R7,16(R1) GET POINTER TO SQLSTATE
MVC 0(5,R7),=CL5'xxxxx' MOVE xxxxx TO SQLSTATE
.
.
.
CEETERM RC=0
| *******************************************************************
| * VARIABLE DECLARATIONS AND EQUATES *
| *******************************************************************
| R1 EQU 1 REGISTER 1
| R7 EQU 7 REGISTER 7
| PPA CEEPPA , CONSTANTS DESCRIBING THE CODE BLOCK
| LTORG , PLACE LITERAL POOL HERE
| PROGAREA DSECT
| ORG *+CEEDSASZ LEAVE SPACE FOR DSA FIXED PART
| LOCV1 DS F LOCAL COPY OF PARAMETER V1
| LOCV2 DS CL9 LOCAL COPY OF PARAMETER V2
| LOCI1 DS H LOCAL COPY OF INDICATOR 1
| LOCI2 DS H LOCAL COPY OF INDICATOR 2
| LOCSQST DS CL5 LOCAL COPY OF SQLSTATE
| LOCSPNM DS H,CL27 LOCAL COPY OF STORED PROC NAME
| LOCSPSNM DS H,CL18 LOCAL COPY OF SPECIFIC NAME
| LOCDIAG DS H,CL1000 LOCAL COPY OF DIAGNOSTIC DATA
| LOCDBINF DS 0H LOCAL COPY OF DBINFO DATA
| DBNAMELN DS H DATABASE NAME LENGTH
| DBNAME DS CL128 DATABASE NAME
| AUTHIDLN DS H APPL AUTH ID LENGTH
| AUTHID DS CL128 APPL AUTH ID
| ASC_SBCS DS F ASCII SBCS CCSID
| ASC_DBCS DS F ASCII DBCS CCSID
| ASC_MIXD DS F ASCII MIXED CCSID
| EBC_SBCS DS F EBCDIC SBCS CCSID
| EBC_DBCS DS F EBCDIC DBCS CCSID
| EBC_MIXD DS F EBCDIC MIXED CCSID
| UNI_SBCS DS F UNICODE SBCS CCSID
| UNI_DBCS DS F UNICODE DBCS CCSID
| UNI_MIXD DS F UNICODE MIXED CCSID
| ENCODE DS F PROCEDURE ENCODING SCHEME
| RESERV0 DS CL20 RESERVED
| TBQUALLN DS H TABLE QUALIFIER LENGTH
| TBQUAL DS CL128 TABLE QUALIFIER
| TBNAMELN DS H TABLE NAME LENGTH
| TBNAME DS CL128 TABLE NAME
| CLNAMELN DS H COLUMN NAME LENGTH
| COLNAME DS CL128 COLUMN NAME
| RELVER DS CL8 DBMS RELEASE AND VERSION
| RESERV1 DS CL2 RESERVED
| PLATFORM DS F DBMS OPERATING SYSTEM
| NUMTFCOL DS H NUMBER OF TABLE FUNCTION COLS USED
| RESERV2 DS CL26 RESERVED
| TFCOLNUM DS A POINTER TO TABLE FUNCTION COL LIST
| APPLID DS A POINTER TO APPLICATION ID
| RESERV3 DS CL20 RESERVED
| DBINFLN EQU *-LOCDBINF LENGTH OF DBINFO
|| .
|| .
.
| PROGSIZE EQU *-PROGAREA
| CEEDSA , MAPPING OF THE DYNAMIC SAVE AREA
| CEECAA , MAPPING OF THE COMMON ANCHOR AREA
| END B

Chapter 14. Calling a stored procedure from your application 751

The following figure shows how a stored procedure written as a main program in
the C language receives these parameters.
#pragma runopts(plist(os))
#include <;stdlib.h>
#include <;stdio.h>

main(argc,argv)
int argc;
char *argv[];
{
int parm1;
short int ind1;
char p_proc[28];
char p_spec[19];
/***************************************************/
/* Assume that the SQL CALL statement included */
/* 3 input/output parameters in the parameter list.*/
/* The argv vector will contain these entries: */
/* argv[0] 1 contains load module */
/* argv[1-3] 3 input/output parms */
/* argv[4-6] 3 null indicators */
/* argv[7] 1 SQLSTATE variable */
/* argv[8] 1 qualified proc name */
/* argv[9] 1 specific proc name */
/* argv[10] 1 diagnostic string */
/* argv[11] + 1 dbinfo */
/* ------ */
/* 12 for the argc variable */
/***************************************************/
if argc<>12 {
.
.
.
/* We end up here when invoked with wrong number of parms */
}
/***************************************************/
/* Assume the first parameter is an integer. */
/* The following code shows how to copy the integer*/
/* parameter into the application storage. */
/***************************************************/
parm1 = *(int *) argv[1];
/***************************************************/
/* We can access the null indicator for the first */
/* parameter on the SQL CALL as follows: */
/***************************************************/
ind1 = *(short int *) argv[4];
/***************************************************/
/* We can use the following expression */
/* to assign 'xxxxx' to the SQLSTATE returned to */
/* caller on the SQL CALL statement. */
/***************************************************/
strcpy(argv[7],"xxxxx/0");
/***************************************************/
/* We obtain the value of the qualified procedure */
/* name with this expression. */
/***************************************************/
strcpy(p_proc,argv[8]);
/***************************************************/
/* We obtain the value of the specific procedure */
/* name with this expression. */
/***************************************************/
strcpy(p_spec,argv[9]);
/***************************************************/
/* We can use the following expression to assign */
/* 'yyyyyyyy' to the diagnostic string returned */
/* in the SQLDA associated with the CALL statement.*/
/***************************************************/

752 Application Programming and SQL Guide

. strcpy(argv[10],"yyyyyyyy/0");
.
.
}

The following figure shows how a stored procedure written as a subprogram in

the C language receives these parameters.
| #pragma linkage(myproc,fetchable)
| #include <stdlib.h>
| #include <stdio.h>
| #include <sqludf.h>
|
| void myproc(*parm1 int, /* assume INT for PARM1 */
|| . parm2 char[11], /* assume CHAR(10) parm2 */
|| .
.
| *p_ind1 short int, /* null indicator for parm1 */
|| . *p_ind2 short int, /* null indicator for parm2 */
|| .
.
| p_sqlstate char[6], /* SQLSTATE returned to DB2 */
| p_proc char[28], /* Qualified stored proc name */
| p_spec char[19], /* Specific stored proc name */
| p_diag char[1001], /* Diagnostic string */
| struct sqludf_dbinfo *udf_dbinfo); /* DBINFO */
| {
| int l_p1;
| char[11] l_p2;
| short int l_ind1;
| short int l_ind2;
| char[6] l_sqlstate;
| char[28] l_proc;
| char[19] l_spec;
| char[71] l_diag;
|| . sqludf_dbinfo *ludf_dbinfo;
|| .
.
| /***************************************************/
| /* Copy each of the parameters in the parameter */
| /* list into a local variable, just to demonstrate */
| /* how the parameters can be referenced. */
| /***************************************************/
| l_p1 = *parm1;
|
| strcpy(l_p2,parm2);
|
| l_ind1 = *p_ind1;
|
| l_ind1 = *p_ind2;
|
| strcpy(l_sqlstate,p_sqlstate);
|
| strcpy(l_proc,p_proc);
|
| strcpy(l_spec,p_spec);
|
| strcpy(l_diag,p_diag);
|| . memcpy(&ludf_dbinfo,udf_dbinfo,sizeof(ludf_dbinfo));
|| .
.
| }

The following figure shows how a stored procedure in the COBOL language
receives these parameters.
| CBL RENT
|| . IDENTIFICATION DIVISION.
|| .
.
| DATA DIVISION.

Chapter 14. Calling a stored procedure from your application 753

|| .
.
| .
| LINKAGE SECTION.
| * Declare each of the parameters
| 01 PARM1 ...
|| . 01 PARM2 ...
|| .
.
| * Declare a null indicator for each parameter
| 01 P-IND1 PIC S9(4) USAGE COMP.
|| . 01 P-IND2 PIC S9(4) USAGE COMP.
|| .
.
| * Declare the SQLSTATE that can be set by stored proc
| 01 P-SQLSTATE PIC X(5).
| * Declare the qualified procedure name
| 01 P-PROC.
| 49 P-PROC-LEN PIC 9(4) USAGE BINARY.
| 49 P-PROC-TEXT PIC X(27).
| * Declare the specific procedure name
| 01 P-SPEC.
| 49 P-SPEC-LEN PIC 9(4) USAGE BINARY.
| 49 P-SPEC-TEXT PIC X(18).
| * Declare SQL diagnostic message token
| 01 P-DIAG.
| 49 P-DIAG-LEN PIC 9(4) USAGE BINARY.
| 49 P-DIAG-TEXT PIC X(1000).
| *********************************************************
| * Structure used for DBINFO *
| *********************************************************
| 01 SQLUDF-DBINFO.
| * Location name length
| 05 DBNAMELEN PIC 9(4) USAGE BINARY.
| * Location name
| 05 DBNAME PIC X(128).
| * authorization ID length
| 05 AUTHIDLEN PIC 9(4) USAGE BINARY.
| * authorization ID
| 05 AUTHID PIC X(128).
| * environment CCSID information
| 05 CODEPG PIC X(48).
| 05 CDPG-DB2 REDEFINES CODEPG.
| 10 DB2-CCSIDS OCCURS 3 TIMES.
| 15 DB2-SBCS PIC 9(9) USAGE BINARY.
| 15 DB2-DBCS PIC 9(9) USAGE BINARY.
| 15 DB2-MIXED PIC 9(9) USAGE BINARY.
| 10 ENCODING-SCHEME PIC 9(9) USAGE BINARY.
| 10 RESERVED PIC X(20).
* other platform-specific deprecated CCSID structures not included here
* schema name length
05 TBSCHEMALEN PIC 9(4) USAGE BINARY.
* schema name
05 TBSCHEMA PIC X(128).
* table name length
05 TBNAMELEN PIC 9(4) USAGE BINARY.
* table name
05 TBNAME PIC X(128).
* column name length
05 COLNAMELEN PIC 9(4) USAGE BINARY.
* column name
05 COLNAME PIC X(128).
* product information
05 VER-REL PIC X(8).
* reserved
05 RESD0 PIC X(2).
* platform type
05 PLATFORM PIC 9(9) USAGE BINARY.
* number of entries in the TF column list array (tfcolumn, below)
05 NUMTFCOL PIC 9(4) USAGE BINARY.

754 Application Programming and SQL Guide

* reserved
05 RESD1 PIC X(26).
* tfcolumn will be allocated dynamically of it is defined
* otherwise this will be a null pointer
05 TFCOLUMN USAGE IS POINTER.
* application identifier
05 APPL-ID USAGE IS POINTER.
* reserved
05 RESD2 PIC X(20).
*
.
.
.
PROCEDURE DIVISION USING PARM1, PARM2,
P-IND1, P-IND2,
P-SQLSTATE, P-PROC, P-SPEC, P-DIAG,
. SQLUDF-DBINFO.
.
.

The following figure shows how a stored procedure in the PL/I language receives
these parameters.
| *PROCESS SYSTEM(MVS);
| MYMAIN: PROC(PARM1, PARM2, ...,
| P_IND1, P_IND2, ...,
| P_SQLSTATE, P_PROC, P_SPEC, P_DIAG, DBINFO)
| OPTIONS(MAIN NOEXECOPS REENTRANT);
|
| DCL PARM1 ... /* first parameter */
|| . DCLPARM2 ... /* second parameter */
|| .
.
| DCL P_IND1 BIN FIXED(15);/* indicator for 1st parm */
|| . DCL P_IND2 BIN FIXED(15);/* indicator for 2nd parm */
|| .
.
| DCLP_SQLSTATE CHAR(5); /* SQLSTATE to return to DB2 */
| DCL01 P_PROC CHAR(27) /* Qualified procedure name */
| VARYING;
| DCL 01 P_SPEC CHAR(18) /* Specific stored proc */
| VARYING;
| DCL 01 P_DIAG CHAR(1000) /* Diagnostic string */
| VARYING;
| DCL DBINFO PTR;
DCL 01 SP_DBINFO BASED(DBINFO), /* Dbinfo */
03 UDF_DBINFO_LLEN BIN FIXED(15), /* location length */
03 UDF_DBINFO_LOC CHAR(128), /* location name */
03 UDF_DBINFO_ALEN BIN FIXED(15), /* auth ID length */
03 UDF_DBINFO_AUTH CHAR(128), /* authorization ID */
03 UDF_DBINFO_CCSID, /* CCSIDs for DB2 for z/OSDB2 for z/OS */
05 R1 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_ASBCS BIN FIXED(15), /* ASCII SBCS CCSID */
05 R2 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_ADBCS BIN FIXED(15), /* ASCII DBCS CCSID */
05 R3 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_AMIXED BIN FIXED(15), /* ASCII MIXED CCSID */
05 R4 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_ESBCS BIN FIXED(15), /* EBCDIC SBCS CCSID */
05 R5 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_EDBCS BIN FIXED(15), /* EBCDIC DBCS CCSID */
05 R6 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_EMIXED BIN FIXED(15), /* EBCDIC MIXED CCSID*/
05 R7 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_USBCS BIN FIXED(15), /* Unicode SBCS CCSID */
05 R8 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_UDBCS BIN FIXED(15), /* Unicode DBCS CCSID */
05 R9 BIN FIXED(15), /* Reserved */
05 UDF_DBINFO_UMIXED BIN FIXED(15), /* Unicode MIXED CCSID*/
05 UDF_DBINFO_ENCODE BIN FIXED(31), /* SP encode scheme */
05 UDF_DBINFO_RESERV0 CHAR(20), /* reserved */

Chapter 14. Calling a stored procedure from your application 755

03 UDF_DBINFO_SLEN BIN FIXED(15), /* schema length */
03 UDF_DBINFO_SCHEMA CHAR(128), /* schema name */
03 UDF_DBINFO_TLEN BIN FIXED(15), /* table length */
03 UDF_DBINFO_TABLE CHAR(128), /* table name */
03 UDF_DBINFO_CLEN BIN FIXED(15), /* column length */
03 UDF_DBINFO_COLUMN CHAR(128), /* column name */
03 UDF_DBINFO_RELVER CHAR(8), /* DB2 release level */
03 UDF_DBINFO_RESERV0 CHAR(2), /* reserved */
03 UDF_DBINFO_PLATFORM BIN FIXED(31), /* database platform*/
03 UDF_DBINFO_NUMTFCOL BIN FIXED(15), /* # of TF cols used*/
03 UDF_DBINFO_RESERV1 CHAR(26), /* reserved */
03 UDF_DBINFO_TFCOLUMN PTR, /* -> table fun col list */
03 UDF_DBINFO_APPLID PTR, /* -> application id */
. 03 UDF_DBINFO_RESERV2 CHAR(20); /* reserved */
.
.
Related concepts
“Examples of programs that call stored procedures” on page 228
Related reference
SQLSTATE values and common error codes (DB2 Codes)

Passing large output parameters to stored procedures by using

indicator variables
If any output parameters occupy a large amount of storage, passing the entire
storage area to a stored procedure can degrade performance. Instead, consider
using indicator variables in the calling program to pass only a 2-byte area to the
stored procedure and receive the entire area from the stored procedure.

You can use the following procedure regardless of whether the linkage convention
for the stored procedure is GENERAL, GENERAL WITH NULLS, or SQL.

To pass large output parameters to stored procedures by using indicator variables:

1. Declare an indicator variable for every large output parameter in the stored
procedure. If you are using the GENERAL WITH NULLS or SQL linkage
convention, you must declare indicator variables for all of your parameters. In
this case, you do not need to declare another indicator variable.
2. Assign a negative value to each indicator variable that is associated with a
large output variable.
3. Include the indicator variables in the CALL statement.

For example, suppose that a stored procedure that is defined with the GENERAL
linkage convention takes one integer input parameter and one character output
parameter of length 6000. You do not want to pass the 6000 byte storage area to
the stored procedure. The following example PL/I program passes only 2 bytes to
the stored procedure for the output variable and receives all 6000 bytes from the
stored procedure:
DCL INTVAR BIN FIXED(31); /* This is the input variable */
DCL BIGVAR(6000); /* This is the output variable */
DCL
. I1 BIN FIXED(15); /* This is an indicator variable */
.
.
I1 = -1; /* Setting I1 to -1 causes only */
/* a two byte area representing */
/* I1 to be passed to the */
/* stored procedure, instead of */
/* the 6000 byte area for BIGVAR*/
EXEC SQL CALL PROCX(:INTVAR, :BIGVAR INDICATOR :I1);

756 Application Programming and SQL Guide

Related concepts
“Linkage conventions for stored procedures” on page 741

Data types for calling stored procedures

The data types that are available for calling applications are the same as the data
types used when retrieving or updating stored procedures.

The format of the parameters that you pass in the CALL statement in an
application must be compatible with the data types of the parameters in the
CREATE PROCEDURE statement.

For languages other than REXX

For all data types except LOBs, ROWIDs, locators, and VARCHARs (for C
language), see the tables listed in the following table for the host data types that
are compatible with the data types in the stored procedure definition.
Table 129. Listing of tables of compatible data types
Language Compatible data types table
Assembler “Equivalent SQL and assembler data types” on
page 236
C “Equivalent SQL and C data types” on page 275
COBOL “Equivalent SQL and COBOL data types” on
page 322
PL/I “Equivalent SQL and PL/I data types” on page
389

Calling a stored procedure from a REXX procedure

The format of the parameters that you pass in the CALL statement in a REXX
procedure must be compatible with the data types of the parameters in the
CREATE PROCEDURE statement.

The following table lists each SQL data type that you can specify for the
parameters in the CREATE PROCEDURE statement and the corresponding format
for a REXX parameter that represents that data type.
Table 130. Parameter formats for a CALL statement in a REXX procedure
SQL data type REXX format
SMALLINT A string of numerics that does not contain a decimal point or exponent identifier.
INTEGER The first character can be a plus or minus sign. This format also applies to
| BIGINT indicator variables that are passed as parameters.
DECIMAL(p,s) A string of numerics that has a decimal point but no exponent identifier. The first
NUMERIC(p,s) character can be a plus or minus sign.
REAL A string that represents a number in scientific notation. The string consists of a
FLOAT(n) series of numerics followed by an exponent identifier (an E or e followed by an
DOUBLE optional plus or minus sign and a series of numerics).
| DECFLOAT
CHARACTER(n) A string of length n, enclosed in single quotation marks.
VARCHAR(n)
VARCHAR(n) FOR BIT DATA

Chapter 14. Calling a stored procedure from your application 757

Table 130. Parameter formats for a CALL statement in a REXX procedure (continued)
SQL data type REXX format
GRAPHIC(n) The character G followed by a string enclosed in single quotation marks. The
VARGRAPHIC(n) string within the quotation marks begins with a shift-out character (X’0E’) and
ends with a shift-in character (X’0F’). Between the shift-out character and shift-in
character are n double-byte characters.
| BINARY Recommendation: Pass BINARY and VARBINARY values by using the SQLDA.
| VARBINARY
| If you specify an SQLDA when you call the stored procedure, set the SQLTYPE in
| the SQLDA. SQLDATA is a string of characters.

| If you use host variables, the REXX format of BINARY and VARBINARY data is
| BX followed by a string that is enclosed in a single quotation mark.
DATE A string of length 10, enclosed in single quotation marks. The format of the string
depends on the value of field DATE FORMAT that you specify when you install
DB2.
TIME A string of length 8, enclosed in single quotation marks. The format of the string
depends on the value of field TIME FORMAT that you specify when you install
DB2.
TIMESTAMP A string of length 26, enclosed in single quotation marks. The string has the
format yyyy-mm-dd-hh.mm.ss.nnnnnn.
| XML No equivalent.

The following figure demonstrates how a REXX procedure calls the stored
procedure in “REXX stored procedures” on page 594. The REXX procedure
performs the following actions:
v Connects to the DB2 subsystem that was specified by the REXX procedure
invoker.
v Calls the stored procedure to execute a DB2 command that was specified by the
REXX procedure invoker.
v Retrieves rows from a result set that contains the command output messages.
/* REXX */
PARSE ARG SSID COMMAND /* Get the SSID to connect to */
/* and the DB2 command to be */
/* executed */
/****************************************************************/
/* Set up the host command environment for SQL calls. */
/****************************************************************/
"SUBCOM DSNREXX" /* Host cmd env available? */
IF RC THEN /* No--make one */
S_RC = RXSUBCOM('ADD','DSNREXX','DSNREXX')
/****************************************************************/
/* Connect to the DB2 subsystem. */
/****************************************************************/
ADDRESS DSNREXX "CONNECT" SSID
IF SQLCODE ¬= 0 THEN CALL SQLCA
PROC = 'COMMAND'
RESULTSIZE = 32703
RESULT = LEFT(' ',RESULTSIZE,' ')
/****************************************************************/
/* Call the stored procedure that executes the DB2 command. */
/* The input variable (COMMAND) contains the DB2 command. */
/* The output variable (RESULT) will contain the return area */
/* from the IFI COMMAND call after the stored procedure */
/* executes. */
/****************************************************************/
ADDRESS DSNREXX "EXECSQL" ,
"CALL" PROC "(:COMMAND, :RESULT)"

758 Application Programming and SQL Guide

IF SQLCODE < 0 THEN CALL SQLCA
SAY 'RETCODE ='RETCODE
SAY 'SQLCODE ='SQLCODE
SAY 'SQLERRMC ='SQLERRMC
SAY 'SQLERRP ='SQLERRP
SAY 'SQLERRD ='SQLERRD.1',',
|| SQLERRD.2',',
|| SQLERRD.3',',
|| SQLERRD.4',',
|| SQLERRD.5',',
|| SQLERRD.6
SAY 'SQLWARN ='SQLWARN.0',',
|| SQLWARN.1',',
|| SQLWARN.2',',
|| SQLWARN.3',',
|| SQLWARN.4',',
|| SQLWARN.5',',
|| SQLWARN.6',',
|| SQLWARN.7',',
|| SQLWARN.8',',
|| SQLWARN.9',',
|| SQLWARN.10
SAY 'SQLSTATE='SQLSTATE
SAY C2X(RESULT) "'"||RESULT||"'"
/****************************************************************/
/* Display the IFI return area in hexadecimal. */
/****************************************************************/
OFFSET = 4+1
TOTLEN = LENGTH(RESULT)
DO WHILE ( OFFSET < TOTLEN )
LEN = C2D(SUBSTR(RESULT,OFFSET,2))
SAY SUBSTR(RESULT,OFFSET+4,LEN-4-1)
OFFSET = OFFSET + LEN
END
/****************************************************************/
/* Get information about result sets returned by the */
/* stored procedure. */
/****************************************************************/
ADDRESS DSNREXX "EXECSQL DESCRIBE PROCEDURE :PROC INTO :SQLDA"
IF SQLCODE ¬= 0 THEN CALL SQLCA
DO I = 1 TO SQLDA.SQLD
SAY "SQLDA."I".SQLNAME ="SQLDA.I.SQLNAME";"
SAY "SQLDA."I".SQLTYPE ="SQLDA.I.SQLTYPE";"
SAY "SQLDA."I".SQLLOCATOR ="SQLDA.I.SQLLOCATOR";"
SAY "SQLDA."I".SQLESTIMATE="SQLDA.I.SQLESTIMATE";"
END I
/****************************************************************/
/* Set up a cursor to retrieve the rows from the result */
/* set. */
/****************************************************************/
ADDRESS DSNREXX "EXECSQL ASSOCIATE LOCATOR (:RESULT) WITH PROCEDURE :PROC"
IF SQLCODE ¬= 0 THEN CALL SQLCA
SAY RESULT
ADDRESS DSNREXX "EXECSQL ALLOCATE C101 CURSOR FOR RESULT SET :RESULT"
IF SQLCODE ¬= 0 THEN CALL SQLCA
CURSOR = 'C101'
ADDRESS DSNREXX "EXECSQL DESCRIBE CURSOR :CURSOR INTO :SQLDA"
IF SQLCODE ¬= 0 THEN CALL SQLCA
/****************************************************************/
/* Retrieve and display the rows from the result set, which */
/* contain the command output message text. */
/****************************************************************/
DO UNTIL(SQLCODE ¬= 0)
ADDRESS DSNREXX "EXECSQL FETCH C101 INTO :SEQNO, :TEXT"
IF SQLCODE = 0 THEN
DO
SAY TEXT

Chapter 14. Calling a stored procedure from your application 759

END
END
IF SQLCODE ¬= 0 THEN CALL SQLCA
ADDRESS DSNREXX "EXECSQL CLOSE C101"
IF SQLCODE ¬= 0 THEN CALL SQLCA
ADDRESS DSNREXX "EXECSQL COMMIT"
IF SQLCODE ¬= 0 THEN CALL SQLCA
/****************************************************************/
/* Disconnect from the DB2 subsystem. */
/****************************************************************/
ADDRESS DSNREXX "DISCONNECT"
IF SQLCODE ¬= 0 THEN CALL SQLCA
/****************************************************************/
/* Delete the host command environment for SQL. */
/****************************************************************/
S_RC = RXSUBCOM('DELETE','DSNREXX','DSNREXX') /* REMOVE CMD ENV */
RETURN
/****************************************************************/
/* Routine to display the SQLCA */
/****************************************************************/
SQLCA:
TRACE O
SAY 'SQLCODE ='SQLCODE
SAY 'SQLERRMC ='SQLERRMC
SAY 'SQLERRP ='SQLERRP
SAY 'SQLERRD ='SQLERRD.1',',
|| SQLERRD.2',',
|| SQLERRD.3',',
|| SQLERRD.4',',
|| SQLERRD.5',',
|| SQLERRD.6
SAY 'SQLWARN ='SQLWARN.0',',
|| SQLWARN.1',',
|| SQLWARN.2',',
|| SQLWARN.3',',
|| SQLWARN.4',',
|| SQLWARN.5',',
|| SQLWARN.6',',
|| SQLWARN.7',',
|| SQLWARN.8',',
|| SQLWARN.9',',
|| SQLWARN.10
SAY 'SQLSTATE='SQLSTATE
EXIT
Related concepts
“REXX stored procedures” on page 594

Preparing a client program for a stored procedure

You must prepare the program that calls a store procedure by precompiling,
compiling, and link-editing it on the client system.

Before you can call a stored procedure from your embedded SQL application, you
must bind a package for the client program on the remote system. You can use the
remote DRDA bind capability on your DRDA client system to bind the package to
the remote system.

If you have packages that contain SQL CALL statements that you bound before
DB2 Version 6, you can get better performance from those packages if you rebind
them in DB2 Version 6 or later. Rebinding lets DB2 obtain some information from

760 Application Programming and SQL Guide

the catalog at bind time that it obtained at run time before Version 6. Therefore,
after you rebind your packages, they run more efficiently because DB2 can do
fewer catalog searches at run time.

For an ODBC or CLI application, the DB2 packages and plan associated with the
ODBC driver must be bound to DB2 before you can run your application. A stored
procedure that runs under DB2 ODBC on a remote DB2 database server does not
need to be bound into the DB2 ODBC plan. It can be bound as a package at the
remote site.

A z/OS client can bind the DBRM to a remote server by specifying a location
name on the command BIND PACKAGE. For example, suppose you want a client
program to call a stored procedure at location LOCA. You precompile the program
to produce DBRM A. Then you can use the following command to bind DBRM A
into package collection COLLA at location LOCA:
BIND PACKAGE (LOCA.COLLA) MEMBER(A)

The plan for the package resides only at the client system.

How DB2 determines which stored procedure to run

A procedure is uniquely identified by its name and its qualifying schema name.
You can tell DB2 exactly which stored procedure to run by qualifying it with its
schema name when you call it. Otherwise, DB2 determines which stored procedure
to run.

However, if you do not qualify the stored procedure name, DB2 uses the following
method to determine which stored procedure to run:
1. DB2 searches the list of schema names from the PATH bind option or the
CURRENT PATH special register from left to right until it finds a schema name
for which a stored procedure definition exists with the name in the CALL
statement.
DB2 uses schema names from the PATH bind option for CALL statements of
the following form:
CALL procedure-name

DB2 uses schema names from the CURRENT PATH special register for CALL
statements of the following form:
CALL host-variable
2. When DB2 finds a stored procedure definition, DB2 executes that stored
procedure if the following conditions are true:
v The caller is authorized to execute the stored procedure.
v The stored procedure has the same number of parameters as in the CALL
statement.
If both conditions are not true, DB2 continues to go through the list of schemas
until it finds a stored procedure that meets both conditions or reaches the end
of the list.
3. If DB2 cannot find a suitable stored procedure, it returns an SQL error code for
the CALL statement.

Chapter 14. Calling a stored procedure from your application 761

Calling different versions of a stored procedure from a single
application
You can call different versions of a stored procedure from the same application
program, even though those versions all have the same load module name.

To call different versions of a stored procedure from a single application:

1. When you define each version of the stored procedure, use the same stored
procedure name but different schema names, different COLLID values, and
different WLM environments.
2. In the program that invokes the stored procedure, specify the unqualified
stored procedure name in the CALL statement.
3. Use the SQL path to indicate which version of the stored procedure that the
client program should call. You can choose the SQL path in several ways:
v If the client program is not an ODBC or JDBC application, use one of the
following methods:
– Use the CALL procedure-name form of the CALL statement. When you bind
plans or packages for the program that calls the stored procedure, bind
one plan or package for each version of the stored procedure that you
want to call. In the PATH bind option for each plan or package, specify
the schema name of the stored procedure that you want to call.
– Use the CALL host-variable form of the CALL statement. In the client
program, use the SET PATH statement to specify the schema name of the
stored procedure that you want to call.
v If the client program is an ODBC or JDBC application, choose one of the
following methods:
– Use the SET PATH statement to specify the schema name of the stored
procedure that you want to call.
– When you bind the stored procedure packages, specify a different
collection for each stored procedure package. Use the COLLID value that
you specified when defining the stored procedure to DB2.
4. When you run the client program, specify the plan or package with the PATH
value that matches the schema name of the stored procedure that you want to
call.

For example, suppose that you want to write one program, PROGY, that calls one
of two versions of a stored procedure named PROCX. The load module for both
stored procedures is named SUMMOD. Each version of SUMMOD is in a different
load library. The stored procedures run in different WLM environments, and the
startup JCL for each WLM environment includes a STEPLIB concatenation that
specifies the correct load library for the stored procedure module.

First, define the two stored procedures in different schemas and different WLM
environments:
CREATE PROCEDURE TEST.PROCX(IN V1 INTEGER, OUT V2 CHAR(9))
LANGUAGE C
EXTERNAL NAME SUMMOD
WLM ENVIRONMENT TESTENV;
CREATE PROCEDURE PROD.PROCX(IN V1 INTEGER, OUT V2 CHAR(9))
LANGUAGE C
EXTERNAL NAME SUMMOD
WLM ENVIRONMENT PRODENV;

762 Application Programming and SQL Guide

When you write CALL statements for PROCX in program PROGY, use the
unqualified form of the stored procedure name:
CALL PROCX(V1,V2);

Bind two plans for PROGY. In one BIND statement, specify PATH(TEST). In the
other BIND statement, specify PATH(PROD).

To call TEST.PROCX, execute PROGY with the plan that you bound with
PATH(TEST). To call PROD.PROCX, execute PROGY with the plan that you bound
with PATH(PROD).

Invoking multiple instances of a stored procedure

Your application program can issue multiple CALL statements to the same local or
remote stored procedure. If that stored procedure returns result sets and the calling
application leaves those result sets open before the next call to that same stored
procedure, each CALL statement invokes a unique instance of the stored
procedure.

Each instance of the stored procedure runs serially within the same DB2 thread
and opens its own result sets. These multiple calls invoke multiple instances of any
packages that are invoked while running the stored procedure. These instances are
invoked at either the same or different level of nesting under one DB2 connection
or thread.

To invoke multiple instances of remote stored procedures or local stored

procedures that have SQL to access a remote site, both the client and server must
be in DB2 Version 8 new-function mode or later. For local stored procedures that
issue remote SQL, instances of the applications are created at the remote server site
regardless of whether result sets exist or are left open between calls.

DB2 storage shortages and EDM POOL FULL conditions can occur if you call too
many instances of a stored procedure or if you open too many cursors. If the
stored procedure issues remote SQL statements to another DB2 server, these
conditions can occur at both the DB2 client and at the DB2 server.

To optimize storage usage, two subsystem parameters control the maximum

number of stored procedures instances and the maximum number of open cursors
for a thread. MAX_ST_PROC controls the maximum number of stored procedure
instances that you can call within the same thread. MAX_NUM_CUR controls the
maximum number of cursors that can be open by the same thread. When either of
the values from these subsystem parameters is exceeded while an application is
running, the CALL statement or the OPEN statement receives SQLCODE -904.

The calling application for the stored procedure should close the result sets and
issue commits often. Even read-only applications should perform these actions.
Applications that fail to do so terminate abnormally with DB2 storage shortage
and EDM POOL FULL conditions.

You can set the maximum number of stored procedure instances and the maximum
number of open cursors on installation panel DSNTIPX. For more information
about setting the maximum number of stored procedure instances and the
maximum number of open cursors per DB2 thread or connection, see the topic
“Routine parameters panel: DSNTIPX”in DB2 Installation Guide.

Chapter 14. Calling a stored procedure from your application 763

Stored procedures that access non-DB2 resources
Applications that run in a stored procedures address space can access any
resources available to z/OS address spaces, such as VSAM files, flat files,
APPC/MVS conversations, and IMS or CICS transactions.

Consider the following when you develop stored procedures that access non-DB2
resources:
| v When a stored procedure runs, the stored procedure uses the Recoverable
| Resource Manager Services for commitment control. When DB2 commits or rolls
| back work in this environment, DB2 coordinates all updates made to recoverable
| resources by other RRS compliant resource managers in the z/OS system.
| v When a stored procedure runs, DB2 can establish a RACF environment for
| accessing non-DB2 resources. The authority used when the stored procedure
| accesses protected z/OS resources depends on the value of SECURITY in the
| stored procedure definition:
| – If the value of SECURITY is DB2, the authorization ID associated with the
| stored procedures address space is used.
| – If the value of SECURITY is USER, the authorization ID under which the
| CALL statement is executed is used.
| – If the value of SECURITY is DEFINER, the authorization ID under which the
| CREATE PROCEDURE statement was executed is used.
v Not all non-DB2 resources can tolerate concurrent access by multiple TCBs in the
same address space. You might need to serialize the access within your
application.

CICS

Stored procedure applications can access CICS by one of these methods:

v Stored procedure DSNACICS
DSNACICS gives workstation applications a way to invoke CICS server
programs while using TCP/IP or SNA as their communication protocol. The
workstation applications use DB2 CONNECT to connect to a DB2 for z/OS
subsystem, and then call DSNACICS to invoke the CICS server programs.
v Message Queue Interface (MQI) for asynchronous execution of CICS transactions
v External CICS interface (EXCI) for synchronous execution of CICS transactions
v Advanced Program-to-Program Communication (APPC), using the Common
Programming Interface Communications (CPI Communications) application
programming interface

| If your system is running a release of CICS that uses z/OS RRS, then z/OS RRS
| controls commitment of all resources.

IMS

If your system is not running a release of IMS that uses z/OS RRS, you can use
one of the following methods to access DL/I data from your stored procedure:
v Use the CICS EXCI interface to run a CICS transaction synchronously. That CICS
transaction can, in turn, access DL/I data.
v Invoke IMS transactions asynchronously using the MQI.
v Use APPC through the CPI Communications application programming interface

764 Application Programming and SQL Guide

Designating the active version of a native SQL procedure
When a native SQL procedure is called, DB2 uses the version that is designated as
the active version. When you create a native SQL procedure, that first version is by
default the active version. If you create additional versions of a stored procedure,
you can designate another version to be the active version.

Exception: If an existing active version is still being used by a process, the new
active version is not used until the next call to that procedure.

To designate the active version of a native SQL procedure, issue an ALTER

PROCEDURE statement with the following items:
v The name of the native SQL procedure for which you want to change the active
version.
v The ACTIVATE VERSION clause with the name of the version that you want to
be active.
When the ALTER statement is committed, the new version of the procedure
becomes the active version and is used by the next call for that procedure.

Example: The following ALTER PROCEDURE statement makes version V2 of the

UPDATE_BALANCE procedure the active version.
ALTER PROCEDURE UPDATE_BALANCE
ACTIVATE VERSION V2;

Temporarily overriding the active version of a native SQL procedure

If you want a particular call to a native SQL procedure to use a version other than
the active version, you can temporarily override the active version. Such an
override might be helpful when you are testing a new version of a native SQL
procedure.

Recommendation: If you want all calls to a native SQL procedure to use a

particular version, do not temporarily override the active version in every call.
Instead, make that version the active version. Otherwise, performance might be
slower.

To temporarily override the active version of a native SQL procedure, specify the
following statements in your program in the following order:
1. The SET CURRENT ROUTINE VERSION statement with the name of the
version of the procedure that you want to use. If the specified version does not
exist, the active version is used.
2. The CALL statement with the name of the procedure.

Example: The following CALL statement invokes version V1 of the

UPDATE_BALANCE procedure, regardless of what the current active version of
that procedure is.
SET CURRENT ROUTINE VERSION = V1;
SET procname = 'UPDATE_BALANCE';
CALL :procname USING DESCRIPTOR :x;

Chapter 14. Calling a stored procedure from your application 765

Specifying the number of stored procedures that can run concurrently
Multiple stored procedures can run concurrently, each under its own z/OS task
(TCB). The z/OS Workload Manager (WLM) manages how many concurrent stored
procedures can run in an address space. The number of concurrent stored
procedures in an address space cannot exceed the value of the NUMTCB field that
was specified on the DSNTIPX installation panel, during DB2 installation.

You can override that value in the following ways:

| v Edit the JCL procedures that start stored procedures address spaces, and modify
| the value of the NUMTCB parameter.
| v Specify the following parameter in the Start Parameters field of the Create An
| Application Environment panel when you set up a WLM application
| environment:
NUMTCB=number-of-TCBs

Special cases:
– For REXX stored procedures, you must set the NUMTCB parameter to 1.
| – Stored procedures that invoke utilities can invoke only one utility at a time in
| a single address space. Consequently, the value of the NUMTCB parameter is
| forced to 1 for those procedures.
Related tasks
“Setting up the stored procedures environment” on page 533
Maximizing the number of procedures or functions that run in an address
space (DB2 Performance)

DB2-supplied stored procedures

DB2 provides some stored procedures that you can call in your application
programs to perform a number of utility and application programming functions.
Typically, these procedures are created during installation or migration.

The following table lists all of the DB2-supplied stored procedures.

Table 131. DB2-supplied stored procedures
Stored procedure name Description
ADMIN_COMMAND_DB2 The ADMIN_COMMAND_DB2 stored procedure is an
administrative enablement routine. It executes one or more DB2
commands on a connected DB2 subsystem or on a DB2 data sharing
group member and returns the command output messages.
ADMIN_COMMAND_DSN The ADMIN_COMMAND_DSN stored procedure is an
administrative enablement routine. It executes a BIND, REBIND, or
FREE DSN subcommand and then returns the output from the
subcommand.
ADMIN_COMMAND_UNIX The ADMIN_COMMAND_UNIX stored procedure is an
administrative enablement routine. It executes a USS command and
returns the output from the command.

766 Application Programming and SQL Guide

Table 131. DB2-supplied stored procedures (continued)
Stored procedure name Description
ADMIN_DS_BROWSE The ADMIN_DS_BROWSE stored procedure is an administrative
enablement routine. It returns either text or binary records from one
of the following entities:
v a physical sequential (PS) data set
v a generation data set (GDS)
v a partitioned data set (PDS)
v a partitioned data set extended (PDSE) member.
This stored procedure supports only data sets with LRECL=80 and
RECFM=FB.
ADMIN_DS_DELETE The ADMIN_DS_DELETE stored procedure is an administrative
enablement routine. It deletes one of the following entities:
v a physical sequential (PS) data set
v a partitioned data set (PDS)
v a partitioned data set extended (PDSE)
v a generation data set (GDS)
v a member of a PDS or PDSE
ADMIN_DS_LIST The ADMIN_DS_LIST stored procedure is an administrative
enablement routine. It returns a list of one of the following items:
v data set names
v generation data groups (GDG)
v partitioned data set (PDS) members
v partitioned data set extended (PDSE) members
v generation data sets of a GDG
ADMIN_DS_RENAME The ADMIN_DS_RENAME stored procedure is an administrative
enablement routine. It renames one of the following entities:
v a physical sequential (PS) data set
v a partitioned data set (PDS)
v a partitioned data set extended (PDSE)
v a member of a PDS or PDSE
ADMIN_DS_SEARCH The ADMIN_DS_SEARCH stored procedure is an administrative
enablement routine. It determines if one of the following items is
cataloged:
v a physical sequential (PS) data set
v a partitioned data set (PDS)
v a partitioned data set extended (PDSE)
v a generation data group (GDG)
v a generation data set (GDS)
Alternatively, ADMIN_DS_SEARCH determines if a library member
of a cataloged PDS or PDSE exists.

Chapter 14. Calling a stored procedure from your application 767

Table 131. DB2-supplied stored procedures (continued)
Stored procedure name Description
ADMIN_DS_WRIT The ADMIN_DS_WRITE stored procedure is an administrative
enablement routine. It writes either text or binary records that are
passed in a global temporary table to one of the following entities:
v a physical sequential (PS) data set
v partitioned data set (PDS) member
v partitioned data set extended (PDSE) member
v generation data set (GDS)
ADMIN_DS_WRITE can either append or replace an existing PS
data set, PDS member, PDSE member, or GDS. ADMIN_DS_WRITE
can create one of the following entities:
v a PS data set
v PDS data set or member
v PDSE data set or member
v GDS for an existing generation data group (GDG) as needed
This stored procedure supports only data sets with LRECL=80 and
RECFM=FB.
ADMIN_INFO_HOST The ADMIN_INFO_HOST stored procedure is an administrative
enablement routine. It returns the host name of a connected DB2
subsystem or the host name of every member of a data sharing
group.
ADMIN_INFO_SSID The ADMIN_INFO_SSID stored procedure is an administrative
enablement routine. It returns the subsystem ID of the connected
DB2 subsystem.
ADMIN_JOB_CANCEL The ADMIN_JOB_CANCEL stored procedure is an administrative
enablement routine. It purges or cancels a job.
ADMIN_JOB_FETCH The ADMIN_JOB_FETCH stored procedure is an administrative
enablement routine. It retrieves the output from the JES spool.
ADMIN_JOB_QUERY The ADMIN_JOB_QUERY stored procedure is an administrative
enablement routine. It displays the status and completion
information of a job.
ADMIN_JOB_SUBMIT The ADMIN_JOB_SUBMIT stored procedure is an administrative
enablement routine. It submits a job to a JES2 or JES3 system.
ADMIN_TASK_ADD The ADMIN_TASK_ADD stored procedure is an administrative task
scheduler routine. It adds a task to the task list of the administrative
task scheduler.
ADMIN_TASK_REMOVE The ADMIN_TASK_REMOVE stored procedure is an administrative
task scheduler routine. It removes a task from the task list of the
administrative task scheduler.
ADMIN_UTL_SCHEDULE The ADMIN_UTL_SCHEDULE stored procedure is an
administrative enablement routine. It executes utilities in parallel.
ADMIN_UTL_SORT The ADMIN_UTL_SORT stored procedure is an administrative
enablement routine. It sorts database objects for parallel utility
execution using JCL or the ADMIN_UTL_SCHEDULE stored
procedure.
DSNACCOR The real-time statistics stored procedure, DSNACCOR, queries the
DB2 real-time statistics tables. This information helps you determine
when you should run COPY, REORG, or RUNSTATS utility jobs, or
enlarge your DB2 data sets.

768 Application Programming and SQL Guide

Table 131. DB2-supplied stored procedures (continued)
Stored procedure name Description
DSNACCOX The enhanced DB2 real-time statistics stored procedure,
DSNACCOX, makes recommendations to help you maintain your
DB2 databases.

The DSNACCOX stored procedure replaces the previous

DSNACCOR stored procedure, beginning in Version 9.
DSNACICS The CICS transaction invocation stored procedure, DSNACICS,
invokes CICS transactions from a remote workstation.
DSNAEXP The DB2 EXPLAIN stored procedure, DSN8EXP, invokes the
EXPLAIN function on an SQL statement without requiring you to
have the authorization to execute that SQL statement.

The DSNAEXP stored procedure replaces the previous DSN8EXP

stored procedure, beginning in Version 8. DSN8EXP handles SQL
statements of up to 32,700 bytes in length. DSNAEXP can handle
longer statements.
DSNAHVPM The DSNAHVPM stored procedure is used by Optimization Service
Center for DB2 for z/OS to convert host variables in a static SQL
statement to typed parameter markers.
DSNAIMS The IMS transactions stored procedure, DSNAIMS, invokes IMS
transactions and commands, without requiring a DB2 subsystem to
maintain its own connection to IMS.
DSNAIMS2 The IMS transactions stored procedure 2, DSNAIMS2, performs the
same function as DSNAIMS, except that DSNAIMS2 also includes
multi-segment input support for IMS transactions.
DSNLEUSR The SYSIBM.USERNAMES encryption stored procedure,
DSNLEUSR, stores encrypted values in the NEWAUTHID and
PASSWORD fields of the SYSIBM.USERNAMES catalog table.
DSNTBIND The DSNTBIND stored procedure binds Java stored procedures.
DSNTPSMP The DB2 for z/OS SQL procedure processor, DSNTPSMP, is a REXX
stored procedure that prepares external SQL procedures for
execution.
DSNUTILS The utilities stored procedure for EBCDIC input, DSNUTILS,
invokes DB2 utilities from a local or remote client program. This
stored procedure accepts utility control statements that are encoded
in EBCDIC.
DSNUTILU The utilities stored procedure for Unicode input, DSNUTILU,
invokes DB2 utilities from a local or remote client program. This
stored procedure accepts utility control statements that are encoded
in Unicode.
| DSNWSPM The DSNWSPM stored procedure formats IFCID 148 records.
| DSNWZP The subsystem parameter stored procedure, DSNWZP, is used by
| the DB2-supplied stored procedure WLM_REFRESH.

Chapter 14. Calling a stored procedure from your application 769

Table 131. DB2-supplied stored procedures (continued)
Stored procedure name Description
| GET_CONFIG The GET_CONFIG stored procedure is a common SQL API stored
| procedure. It returns information about the data server
| configuration, including information about the following items:
| v the data sharing group
| v the DB2 subsystem parameters
| v the DDF status and configuration
| v the connected DB2 subsystem
| v the RLF tables
| v the active log data sets
| v the last DB2 restart
| This stored procedure is used primarily by DB2 tools.
| GET_MESSAGE The GET_MESSAGE stored procedure is a common SQL API stored
| procedure. It returns the short message text for an SQL code. This
| stored procedure is used primarily by DB2 tools.
| GET_SYSTEM_INFO The GET_SYSTEM_INFO stored procedure is a common SQL API
| stored procedure. It returns system information, including
| information about the following items:
| v operating system
| v product information
| v PTF level of each DB2 module
| v the SMP/E APPLY status of the requested SYSMOD
| v WLM classification rules that apply to the DB2 workload for
| subsystem types DB2 and DDF
| This stored procedure is used primarily by DB2 tools
| SQLJ.ALTER_JAVA_PATH The SQLJ.ALTER_JAVA_PATH stored procedure specifies the class
| resolution path that the JVM searches to resolve class references.
| This action is needed if a JAR that you have installed refers to
| classes in other installed JARs.
| SQLJ.DB2_INSTALL_JAR The SQLJ.DB2_INSTALL_JAR stored procedure installs a set of Java
| classes into a local or remote catalog.
| SQLJ.DB2_REMOVE_JAR The SQLJ.DB2_REMOVE_JAR stored procedure removes a Java JAR
| file and its classes from a local or remote catalog.
| SQLJ.DB2_REPLACE_JAR The SQLJ.DB2_REPLACE_JAR stored procedure replaces a
| previously installed JAR file in a local or remote catalog.
| SQLJ.DB2_UPDATEJARINFO The SQLJ.DB2_UPDATEJARINFO stored procedure inserts class,
| class source, and associated options for a previously installed JAR
| file in a local or remote catalog.
| SQLJ.INSTALL_JAR The SQLJ.INSTALL_JAR stored procedure installs a set of Java
| classes into the current SQL catalog and schema.
| SQLJ.REMOVE_JAR The SQLJ.REMOVE_JAR stored procedure removes a Java JAR file
| and its classes from a specified, local catalog.
| SQLJ.REPLACE_JAR The SQLJ.REPLACE_JAR stored procedure replaces a previously
| installed JAR file in a local catalog.
| WLM_REFRESH The WLM environment refresh stored procedure, WLM_REFRESH,
| refreshes a WLM environment from a remote workstation.
| WLM_SET_CLIENT_INFO The WLM_SET_CLIENT_INFO stored procedure sets client
| information that is associated with the current connection at the DB2
| server.

770 Application Programming and SQL Guide

Table 131. DB2-supplied stored procedures (continued)
Stored procedure name Description
| Deprecated: XDBDECOMPXML The XML decomposition stored procedure, XDBDECOMPXML,
| extracts values from serialized XML data and populates relational
| tables with the values. The XDBDECOMPXML stored procedure
| uses an XML schema, which contains annotations that indicate
| which columns and tables are to be used to store the decomposed
| XML values.
| XSR_ADDSCHEMADOC The add XML schema document stored procedure,
| XSR_ADDSCHEMADOC, adds every XML schema other than the
| primary XML schema document to the XSR.
| XSR_COMPLETE The XML schema registration completion stored procedure,
| XSR_COMPLETE, is the final stored procedure to be called as part
| of the XML schema registration process. The XML schema
| registration process registers XML schemas with the XSR.
| XSR_REGISTER The XML schema registration stored procedure, XSR_REGISTER, is
| the first stored procedure to be called as part of the XML schema
| registration process. The XML schema registration process registers
| XML schemas with the XSR.
| XSR_REMOVE The XML schema removal stored procedure, XSR_REMOVE,
| removes all components of an XML schema.

All of the MQ XML stored procedures have been deprecated.

| Table 132. Deprecated MQ XML stored procedures
| Stored procedure name Description
| DXXMQINSERT DXXMQINSERT performs the following actions:
| v returns a message that contains an XML document from an MQ message
| queue
| v decomposes the document
| v stores the data in DB2 tables that are specified by an enabled XML
| collection.
| DXXMQSHRED DXXMQSHRED performs the following actions:
| v returns a message that contains an XML document from an MQ message
| queue
| v decomposes the document
| v stores the data in DB2 tables that are specified in a document access
| definition (DAD) file
| DXXMQSHRED does not require an enabled XML collection.
| DXXMQINSERTCLOB DXXMQINSERTCLOB performs the following actions:
| v returns a message that contains an XML document from an MQ message
| queue
| v decomposes the document
| v stores the data in DB2 tables that are specified by an enabled XML
| collection.
| DXXMQINSERTCLOB is intended for an XML document with a length of
| up to 1 MB.

Chapter 14. Calling a stored procedure from your application 771

| Table 132. Deprecated MQ XML stored procedures (continued)
| Stored procedure name Description
| DXXMQSHREDCLOB DXXMQSHREDCLOB performs the following actions:
| v returns a message that contains an XML document from an MQ message
| queue
| v decomposes the document
| v stores the data in DB2 tables that are specified in a document access
| definition (DAD) file
| DXXMQSHREDCLOB does not require an enabled XML collection.
| DXXMQSHREDCLOB is intended for an XML document with a length of
| up to 1 MB.
| DXXMQINSERTALL DXXMQINSERTALL performs the following actions:
| v returns messages that contain XML documents from an MQ message
| queue
| v decomposes the documents
| v stores the data in DB2 tables that are specified by an enabled XML
| collection
| DXXMQINSERTALL is intended for XML documents with a length of up to
| 3 KB.
| DXXMQSHREDALL DXXMQSHREDALL performs the following actions:
| v returns messages that contain XML documents from an MQ message
| queue
| v decomposes the documents
| v stores the data in DB2 tables that are specified in a document access
| definition (DAD) file
| DXXMQSHREDALL does not require an enabled XML collection.
| DXXMQSHREDALL is intended for XML documents with a length of up to
| 3 KB.
| DXXMQSHREDALLCLOB DXXMQSHREDALLCLOB performs the following actions:
| v returns messages that contain XML documents from an MQ message
| queue
| v decomposes the documents
| v stores the data in DB2 tables that are specified in a document access
| definition (DAD) file
| DXXMQSHREDALLCLOB does not require an enabled XML collection.
| DXXMQSHREDALLCLOB is intended for XML documents with a length of
| up to 1 MB.
| DXXMQINSERTALLCLOB DXXMQINSERTALLCLOB performs the following actions:
| v returns messages that contain XML documents from an MQ message
| queue
| v decomposes the documents
| v stores the data in DB2 tables that are specified by an enabled XML
| collection.
| DXXMQINSERTALLCLOB is intended for XML documents with a length of
| up to 1 MB.

772 Application Programming and SQL Guide

| Table 132. Deprecated MQ XML stored procedures (continued)
| Stored procedure name Description
| DXXMQGEN DXXMQGEN performs the following actions:
| v constructs XML documents from data that is stored in the DB2 tables that
| are specified in a document access definition (DAD) file
| v sends the XML documents to an MQ message queue
| DXXMQGEN is intended for XML documents with a length of up to 3 KB.
| DXXMQRETRIEVE DXXMQRETRIEVE performs the following actions:
| v constructs XML documents from data that is stored in the DB2 tables that
| are specified in an enabled XML collection
| v sends the XML documents to an MQ message queue
| DXXMQRETRIEVE is intended for XML documents with a length of up to 3
| KB.
| DXXMQGENCLOB DXXMQGENCLOB performs the following actions:
| v constructs XML documents from data that is stored in the DB2 tables that
| are specified in a document access definition (DAD) file
| v sends the XML documents to an MQ message queue
| DXXMQGENCLOB is intended for XML documents with a length of up to
| 32 KB.
| DXXMQRETRIEVECLOB DXXMQRETRIEVECLOB performs the following actions:
| v constructs XML documents from data that is stored in the DB2 tables that
| are specified in an enabled XML collection
| v sends the XML documents to an MQ message queue
| DXXMQRETRIEVECLOB is intended for XML documents with a length of
| up to 32 KB.
|

Chapter 14. Calling a stored procedure from your application 773

Related tasks
Enabling -supplied routines (DB2 Installation and Migration)
Enabling the -supplied stored procedures for preparing Java routines (DB2
Installation and Migration)
Defining Java routines and JAR files to DB2 (Programming for Java)
Related reference
DSNLEUSR stored procedure (DB2 Administration Guide)
DSNACCOR stored procedure (DB2 Performance)
DSNAIMS2 stored procedure (DB2 Administration Guide)
GET_CONFIG stored procedure (DB2 Administration Guide)
GET_MESSAGE stored procedure (DB2 Administration Guide)
GET_SYSTEM_INFO stored procedure (DB2 Administration Guide)
SQLJ.ALTER_JAVA_PATH stored procedure (Programming for Java)
SQLJ.DB2_INSTALL_JAR stored procedure (Programming for Java)
SQLJ.DB2_REPLACE_JAR stored procedure (Programming for Java)
SQLJ.INSTALL_JAR stored procedure (Programming for Java)
DSNACCOX stored procedure (DB2 Performance)
DSNUTILS stored procedure (DB2 Utilities)
DSNUTILU stored procedure (DB2 Utilities)
Related information
Source code for activating DB2-supplied stored procedures
Stored procedures for administration (DB2 Administration Guide)

WLM_REFRESH stored procedure

The WLM_REFRESH stored procedure refreshes a WLM environment. This stored
procedure can recycle the environment in which it runs and any other WLM
environment.

Environment for WLM_REFRESH

WLM_REFRESH runs in a WLM-established stored procedures address space. The

load module for WLM_REFRESH, DSNTWR, must reside in an APF-authorized
library.

Authorization required for WLM_REFRESH

To execute the CALL statement, the SQL authorization ID of the process must have
READ access or higher to the z/OS Security Server System Authorization Facility
(SAF) resource profile ssid.WLM_REFRESH.WLM-environment-name in resource
class DSNR. This is a different resource profile from the ssid.WLMENV.WLM-
environment-name resource profile, which DB2 uses to determine whether a stored
procedure or user-defined function is authorized to run in the specified WLM
environment.

774 Application Programming and SQL Guide

WLM_REFRESH uses an extended MCS console to monitor the operating system
response to a WLM environment refresh request. The privilege to create an
extended MCS console is controlled by the resource profile MVS.MCSOPER.* in the
OPERCMDS class. If the MVS.MCSOPER.* profile exists, or if the specific profile
MVS.MCSOPER.DSNTWR exists, the task ID that is associated with the WLM
environment in which WLM_REFRESH runs must have READ access to it.

If the MVS.VARY.* profile exists, or if the specific profile MVS.VARY.WLM exists,

the task ID that is associated with the WLM environment in which
WLM_REFRESH runs must have CONTROL access to it.

For more information about permitting access to the extended MCS console, see
z/OS MVS Planning: Operations.

WLM_REFRESH syntax diagram

The WLM_REFRESH stored procedure refreshes a WLM environment.

WLM_REFRESH can recycle the environment in which it runs, as well as any other
WLM environment.

The following syntax diagram shows the SQL CALL statement for invoking
WLM_REFRESH. The linkage convention for WLM_REFRESH is GENERAL WITH
NULLS.

CALL WLM_REFRESH ( WLM-environment, ssid , status-message, return-code )


NULL
’ ’

WLM_REFRESH option descriptions

WLM-environment
Specifies the name of the WLM environment that you want to refresh. This is
an input parameter of type VARCHAR(32).
ssid
Specifies the subsystem ID of the DB2 subsystem with which the WLM
environment is associated. If this parameter is NULL or blank, DB2 uses one of
the following values for this parameter:
v In a non-data sharing environment, DB2 uses the subsystem ID of the
subsystem on which WLM_REFRESH runs.
v In a data sharing environment, DB2 uses the group attach name for the data
sharing group in which WLM_REFRESH runs.
This is an input parameter of type VARCHAR(4).
status-message
Contains an informational message about the execution of the WLM refresh.
This is an output parameter of type VARCHAR(120).
return-code
Contains the return code from the WLM_REFRESH call, which is one of the
following values:
0 WLM_REFRESH executed successfully.

Chapter 14. Calling a stored procedure from your application 775

4 One of the following conditions exists:
v The SAF resource profile ssid.WLM_REFRESH.wlm-environment is not
defined in resource class DSNR.
v The SQL authorization ID of the process (CURRENT SQLID) is not
defined to SAF.
v The wait time to obtain a response from z/OS was exceeded.
8 The SQL authorization ID of the process (CURRENT SQLID) is not
authorized to refresh the WLM environment.
990 DSNTWR received an unexpected SQLCODE while determining the
current SQLID.
993 One of the following conditions exists:
v The WLM-environment parameter value is null, blank, or contains
invalid characters.
v The ssid value contains invalid characters.
994 The extended MCS console was not activated within the number of
seconds indicated by message DSNT5461.
995 DSNTWR is not running as an authorized program.
996 DSNTWR could not activate an extended MCS console. See message
DSNT533I for more information.
997 DSNTWR made an unsuccessful request for a message from its
extended MCS console. See message DSNT533I for more information.
998 The extended MCS console for DSNTWR posted an alert. See message
DSNT534I for more information.
999 The operating system denied an authorized WLM_REFRESH request.
See message DSNT545I for more information.
return-code is an output parameter of type INTEGER.

Example of WLM_REFRESH invocation

Suppose that you want to refresh WLM environment WLMENV1, which is

associated with a DB2 subsystem with ID DSN. Assume that you already have
READ access to the DSN.WLM_REFRESH.WLMENV1 SAF profile. The CALL
statement for WLM_REFRESH looks like this:
strcpy(WLMENV,"WLMENV1");
strcpy(SSID,"DSN");
EXEC SQL CALL SYSPROC.WLM_REFRESH(:WLMENV, :SSID, :MSGTEXT, :RC);

For a complete example of setting up access to an SAF profile and calling

WLM_REFRESH, see job DSNTEJ6W, which is in data set DSN910.SDSNSAMP.

| WLM_SET_CLIENT_INFO stored procedure

| This procedure allows the caller to set client information associated with the
| current connection at the DB2 for z/OS server.

| The following DB2 for z/OS client special registers can be changed:
| v CURRENT CLIENT_ACCTNG
| v CURRENT CLIENT_USERID
| v CURRENT CLIENT_WRKSTNNAME

776 Application Programming and SQL Guide

| v CURRENT CLIENT_APPLNAME

| The existing behavior of the CLIENT_ACCTNG register is unchanged. It will

| continue to get its value from the accounting token for DSN requesters, and from
| the accounting string for SQL and other requesters.

| This procedure is not under transaction control and client information changes
| made by the procedure are independent of committing or rolling back units of
| work.

| Environment

| WLM_SET_CLIENT_INFO runs in a WLM-established stored procedures address

| space.

| Authorization

| To execute the CALL statement, the owner of the package or plan that contains the
| CALL statement must have one or more of the following privileges on each
| package that the stored procedure uses:
| v The EXECUTE privilege on the package for DSNADMSI
| v Ownership of the package
| v PACKADM authority for the package collection
| v SYSADM authority

| Syntax
|

WLM_SET_CLIENT_INFO ( client_userid , client_wrkstnname ,

| NULL NULL

|
client_applname , client_acctstr )

| NULL NULL
|

| The schema is SYSPROC.

| Procedure parameters
| client_userid
| An input argument of type VARCHAR(255) that specifies the user ID for the
| client. If NULL is specified, the value remains unchanged. If an empty string
| (″) is specified, the user ID for the client is reset to the default value, which is
| blank. If the value specified exceeds 16 bytes, it is truncated to 16 bytes. If the
| value specified is less than 16 bytes, it is padded on the right with blanks to a
| length of 16 bytes.
| client_wrkstnname
| An input argument of type VARCHAR(255) that specifies the workstation
| name for the client. If NULL is specified, the value remains unchanged. If an
| empty string (″) is specified, the workstation name for the client is reset to the
| default value, which is blank. If the value specified exceeds 18 bytes, it is
| truncated to 18 bytes. If the value specified is less than 18 bytes, it is padded
| on the right with blanks to a length of 18 bytes.
| client_applname
| An input argument of type VARCHAR(255) that specifies the application name
| for the client. If NULL is specified, the value remains unchanged. If an empty

Chapter 14. Calling a stored procedure from your application 777

| string (″) is specified, the application name for the client is reset to the default
| value, which is blank. If the value specified exceeds 32 bytes, it is truncated to
| 32 bytes. If the value specified is less than 32 bytes, it is padded on the right
| with blanks to a length of 32 bytes.
| client_acctstr
| An input argument of type VARCHAR(255) that specifies the accounting string
| for the client. If NULL is specified, the value remains unchanged. If an empty
| string (″) is specified, the accounting string for the client is reset to the default
| value, which is blank. If the requester is DB2 for z/OS, and the value specified
| exceeds 142 bytes, it is truncated to 142 bytes. Otherwise, if the value specified
| exceeds 200 bytes, it is truncated to 200 bytes.

| Examples

| Set the user ID, workstation name, application name, and accounting string for the
| client.
| strcpy(user_id, "db2user");
| strcpy(wkstn_name, "mywkstn");
| strcpy(appl_name, "db2bp.exe");
| strcpy(acct_str, "myacctstr");
| iuser_id = 0;
| iwkstn_name = 0;
| iappl_name = 0;
| iacct_str = 0;
| EXEC SQL CALL SYSPROC.WLM_SET_CLIENT_INFO(:user_id:iuser_id, :wkstn_name:iwkstn_name,
| :appl_name:iappl_name, :acct_str:iacct_str);

| Set the user ID to db2user for the client without setting the other client attributes.
| strcpy(user_id, "db2user");
| iuser_id = 0;
| iwkstn_name = -1;
| iappl_name = -1;
| iacct_str = -1;
| EXEC SQL CALL SYSPROC.WLM_SET_CLIENT_INFO(:user_id:iuser_id, :wkstn_name:iwkstn_name,
| :appl_name:iappl_name, :acct_str:iacct_str);

| Reset the user ID for the client to blank without modifying the values of the other
| client attributes.
| strcpy(user_id, "");
| iuser_id = 0;
| iwkstn_name = -1;
| iappl_name = -1;
| iacct_str = -1;
| EXEC SQL CALL SYSPROC.WLM_SET_CLIENT_INFO(:user_id:iuser_id, :wkstn_name:iwkstn_name,
| :appl_name:iappl_name, :acct_str:iacct_str);

| DSNACICS stored procedure

The CICS transaction invocation stored procedure (DSNACICS) invokes CICS
server programs.

DSNACICS gives workstation applications a way to invoke CICS server

programs while using TCP/IP as their communication protocol. The workstation
applications use TCP/IP and DB2 Connect to connect to a DB2 for z/OS
subsystem, and then call DSNACICS to invoke the CICS server programs.

The DSNACICS input parameters require knowledge of various CICS resource

definitions with which the workstation programmer might not be familiar. For this

778 Application Programming and SQL Guide

reason, DSNACICS invokes the DSNACICX user exit routine. The system
programmer can write a version of DSNACICX that checks and overrides the
parameters that the DSNACICS caller passes. If no user version of DSNACICX is
provided, DSNACICS invokes the default version of DSNACICX, which does not
modify any parameters.

Environment

DSNACICS runs in a WLM-established stored procedure address space and uses

the Resource Recovery Services attachment facility to connect to DB2.

If you use CICS Transaction Server for OS/390® Version 1 Release 3 or later, you
can register your CICS system as a resource manager with recoverable resource
management services (RRMS). When you do that, changes to DB2 databases that
are made by the program that calls DSNACICS and the CICS server program that
DSNACICS invokes are in the same two-phase commit scope. This means that
when the calling program performs an SQL COMMIT or ROLLBACK, DB2 and
RRS inform CICS about the COMMIT or ROLLBACK.

If the CICS server program that DSNACICS invokes accesses DB2 resources, the
server program runs under a separate unit of work from the original unit of work
that calls the stored procedure. This means that the CICS server program might
deadlock with locks that the client program acquires.

Authorization

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DSNACICS
v Ownership of the stored procedure
v SYSADM authority

The CICS server program that DSNACICS calls runs under the same user ID as
DSNACICS. That user ID depends on the SECURITY parameter that you specify
when you define DSNACICS.

The DSNACICS caller also needs authorization from an external security system,
such as RACF, to use CICS resources.

Syntax

The following syntax diagram shows the SQL CALL statement for invoking this
stored procedure.

Because the linkage convention for DSNACICS is GENERAL WITH NULLS, if you
pass parameters in host variables, you need to include a null indicator with every
host variable. Null indicators for input host variables must be initialized before
you execute the CALL statement.

Chapter 14. Calling a stored procedure from your application 779

CALL DSNACICS ( parm-level , pgm-name , CICS-applid , CICS-level ,

NULL NULL NULL NULL

connect-type , netname , mirror-trans , COMMAREA , COMMAREA-total-len ,

NULL NULL NULL NULL NULL

sync-opts , return-code, msg-area )


NULL

Option descriptions
parm-level
Specifies the level of the parameter list that is supplied to the stored procedure.
This is an input parameter of type INTEGER. The value must be 1.
pgm-name
Specifies the name of the CICS program that DSNACICS invokes. This is the
name of the program that the CICS mirror transaction calls, not the CICS
transaction name.
This is an input parameter of type CHAR(8).
CICS-applid
Specifies the applid of the CICS system to which DSNACICS connects.
This is an input parameter of type CHAR(8).
CICS-level
Specifies the level of the target CICS subsystem:
1 The CICS subsystem is CICS for MVS/ESA™ Version 4 Release 1, CICS
Transaction Server for OS/390 Version 1 Release 1, or CICS Transaction
Server for OS/390 Version 1 Release 2.
2 The CICS subsystem is CICS Transaction Server for OS/390 Version 1
Release 3 or later.
This is an input parameter of type INTEGER.
connect-type
Specifies whether the CICS connection is generic or specific. Possible values are
GENERIC or SPECIFIC.
This is an input parameter of type CHAR(8).
netname
If the value of connection-type is SPECIFIC, specifies the name of the specific
connection that is to be used. This value is ignored if the value of
connection-type is GENERIC.
This is an input parameter of type CHAR(8).
mirror-trans
Specifies the name of the CICS mirror transaction to invoke. This mirror
transaction calls the CICS server program that is specified in the pgm-name
parameter. mirror-trans must be defined to the CICS server region, and the
CICS resource definition for mirror-trans must specify DFHMIRS as the
program that is associated with the transaction.
If this parameter contains blanks, DSNACICS passes a mirror transaction
parameter value of null to the CICS EXCI interface. This allows an installation

780 Application Programming and SQL Guide

to override the transaction name in various CICS user-replaceable modules. If a
CICS user exit routine does not specify a value for the mirror transaction
name, CICS invokes CICS-supplied default mirror transaction CSMI.
This is an input parameter of type CHAR(4).
COMMAREA
Specifies the communication area (COMMAREA) that is used to pass data
between the DSNACICS caller and the CICS server program that DSNACICS
calls.
This is an input/output parameter of type VARCHAR(32704). In the length
field of this parameter, specify the number of bytes that DSNACICS sends to
the CICS server program.
commarea-total-len
Specifies the total length of the COMMAREA that the server program needs.
This is an input parameter of type INTEGER. This length must be greater than
or equal to the value that you specify in the length field of the COMMAREA
parameter and less than or equal to 32704. When the CICS server program
completes, DSNACICS passes the server program’s entire COMMAREA, which
is commarea-total-len bytes in length, to the stored procedure caller.
sync-opts
Specifies whether the calling program controls resource recovery, using
two-phase commit protocols that are supported by RRS. Possible values are:
1 The client program controls commit processing. The CICS server region
does not perform a syncpoint when the server program returns control
to CICS. Also, the server program cannot take any explicit syncpoints.
Doing so causes the server program to abnormally terminate.
2 The target CICS server region takes a syncpoint on successful
completion of the server program. If this value is specified, the server
program can take explicit syncpoints.
When CICS has been set up to be an RRS resource manager, the client
application can control commit processing using SQL COMMIT requests. DB2
for z/OS ensures that CICS is notified to commit any resources that the CICS
server program modifies during two-phase commit processing.
When CICS has not been set up to be an RRS resource manager, CICS forces
syncpoint processing of all CICS resources at completion of the CICS server
program. This commit processing is not coordinated with the commit
processing of the client program.
This option is ignored when CICS-level is 1. This is an input parameter of type
INTEGER.
return-code
Return code from the stored procedure. Possible values are:
0 The call completed successfully.
12 The request to run the CICS server program failed. The msg-area
parameter contains messages that describe the error.
This is an output parameter of type INTEGER.
msg-area
Contains messages if an error occurs during stored procedure execution. The
first messages in this area are generated by the stored procedure. Messages

Chapter 14. Calling a stored procedure from your application 781

that are generated by CICS or the DSNACICX user exit routine might follow
the first messages. The messages appear as a series of concatenated, viewable
text strings.
This is an output parameter of type VARCHAR(500).

User exit routine

DSNACICS always calls user exit routine DSNACICX. You can use DSNACICX to
change the values of DSNACICS input parameters before you pass those
parameters to CICS. If you do not supply your own version of DSNACICX,
DSNACICS calls the default DSNACICX, which modifies no values and does an
immediate return to DSNACICS. The source code for the default version of
DSNACICX is in member DSNASCIX in data set prefix.SDSNSAMP.. The source
code for a sample version of DSNACICX that is written in COBOL is in member
DSNASCIO in data set prefix.SDSNSAMP.

Example

The following PL/I example shows the variable declarations and SQL CALL
statement for invoking the CICS transaction that is associated with program
CICSPGM1.
/***********************/
/* DSNACICS PARAMETERS */
/***********************/
DECLARE PARM_LEVEL BIN FIXED(31);
DECLARE PGM_NAME CHAR(8);
DECLARE CICS_APPLID CHAR(8);
DECLARE CICS_LEVEL BIN FIXED(31);
DECLARE CONNECT_TYPE CHAR(8);
DECLARE NETNAME CHAR(8);
DECLARE MIRROR_TRANS CHAR(4);
DECLARE COMMAREA_TOTAL_LEN BIN FIXED(31);
DECLARE SYNC_OPTS BIN FIXED(31);
DECLARE RET_CODE BIN FIXED(31);
DECLARE MSG_AREA CHAR(500) VARYING;

DECLARE1 COMMAREA BASED(P1),

3 COMMAREA_LEN BIN FIXED(15),
3COMMAREA_INPUT CHAR(30),
3 COMMAREA_OUTPUT CHAR(100);

/***********************************************/
/* INDICATOR VARIABLES FOR DSNACICS PARAMETERS */
/***********************************************/
DECLARE 1 IND_VARS,
3 IND_PARM_LEVEL BIN FIXED(15),
3 IND_PGM_NAME BIN FIXED(15),
3 IND_CICS_APPLID BIN FIXED(15),
3 IND_CICS_LEVEL BIN FIXED(15),
3 IND_CONNECT_TYPE BINFIXED(15),
3 IND_NETNAME BIN FIXED(15),
3 IND_MIRROR_TRANSBIN FIXED(15),
3 IND_COMMAREA BIN FIXED(15),
3 IND_COMMAREA_TOTAL_LEN BIN FIXED(15),
3 IND_SYNC_OPTS BIN FIXED(15),
3 IND_RETCODE BIN FIXED(15),
3 IND_MSG_AREA BIN FIXED(15);

/**************************/

782 Application Programming and SQL Guide

/* LOCAL COPY OF COMMAREA */
/**************************/
DECLARE P1 POINTER;
DECLARE COMMAREA_STG CHAR(130) VARYING;
/**************************************************************/
/* ASSIGN VALUES TO INPUT PARAMETERS PARM_LEVEL, PGM_NAME, */
/* MIRROR_TRANS, COMMAREA, COMMAREA_TOTAL_LEN, AND SYNC_OPTS. */
/* SET THE OTHER INPUT PARAMETERS TO NULL. THE DSNACICX */
/* USER EXIT MUST ASSIGN VALUES FOR THOSE PARAMETERS. */
/**************************************************************/
PARM_LEVEL = 1;
IND_PARM_LEVEL = 0;

PGM_NAME = 'CICSPGM1';
IND_PGM_NAME = 0 ;

MIRROR_TRANS = 'MIRT';
IND_MIRROR_TRANS = 0;

P1 = ADDR(COMMAREA_STG);
COMMAREA_INPUT = 'THIS IS THE INPUT FOR CICSPGM1';
COMMAREA_OUTPUT = ' ';
COMMAREA_LEN = LENGTH(COMMAREA_INPUT);
IND_COMMAREA = 0;

COMMAREA_TOTAL_LEN = COMMAREA_LEN + LENGTH(COMMAREA_OUTPUT);

IND_COMMAREA_TOTAL_LEN = 0;

SYNC_OPTS= 1;
IND_SYNC_OPTS = 0;

IND_CICS_APPLID= -1;
IND_CICS_LEVEL = -1;
IND_CONNECT_TYPE = -1;
IND_NETNAME = -1;
/*****************************************/
/* INITIALIZE
OUTPUT PARAMETERS TO NULL. */
/*****************************************/
IND_RETCODE = -1;
IND_MSG_AREA= -1;
/*****************************************/
/* CALL DSNACICS TO INVOKE CICSPGM1. */
/*****************************************/
EXEC SQL
CALL SYSPROC.DSNACICS(:PARM_LEVEL :IND_PARM_LEVEL,
:PGM_NAME :IND_PGM_NAME,
:CICS_APPLID :IND_CICS_APPLID,
:CICS_LEVEL :IND_CICS_LEVEL,
:CONNECT_TYPE :IND_CONNECT_TYPE,
:NETNAME :IND_NETNAME,
:MIRROR_TRANS :IND_MIRROR_TRANS,
:COMMAREA_STG :IND_COMMAREA,
:COMMAREA_TOTAL_LEN :IND_COMMAREA_TOTAL_LEN,
:SYNC_OPTS :IND_SYNC_OPTS,
:RET_CODE :IND_RETCODE,
:MSG_AREA :IND_MSG_AREA);

Output

DSNACICS places the return code from DSNACICS execution in the return-code
parameter. If the value of the return code is non-zero, DSNACICS puts its own
error messages and any error messages that are generated by CICS and the
DSNACICX user exit routine in the msg-area parameter.

Chapter 14. Calling a stored procedure from your application 783

The COMMAREA parameter contains the COMMAREA for the CICS server
program that DSNACICS calls. The COMMAREA parameter has a VARCHAR
type. Therefore, if the server program puts data other than character data in the
COMMAREA, that data can become corrupted by code page translation as it is
passed to the caller. To avoid code page translation, you can change the
COMMAREA parameter in the CREATE PROCEDURE statement for DSNACICS to
VARCHAR(32704) FOR BIT DATA. However, if you do so, the client program
might need to do code page translation on any character data in the COMMAREA
to make it readable.

Restrictions

Because DSNACICS uses the distributed program link (DPL) function to invoke
CICS server programs, server programs that you invoke through DSNACICS can
contain only the CICS API commands that the DPL function supports. The list of
supported commands is documented in CICS Transaction Server for z/OS
Application Programming Reference.

| DSNACICS does not propagate the transaction identifier (XID) of the thread. The
| stored procedure runs under a new private context rather than under the native
| context of the task that called it.

Debugging

If you receive errors when you call DSNACICS, ask your system administrator to
add a DSNDUMP DD statement in the startup procedure for the address space in
which DSNACICS runs. The DSNDUMP DD statement causes DB2 to generate an
SVC dump whenever DSNACICS issues an error message.

The DSNACICX user exit routine

Use DSNACICX to change the values of DSNACICS input parameters before you
pass those parameters to CICS.

General considerations

The DSNACICX exit routine must follow these rules:

v It can be written in assembler, COBOL, PL/I, or C.
v It must follow the Language Environment calling linkage when the caller is an
assembler language program.
v The load module for DSNACICX must reside in an authorized program library
that is in the STEPLIB concatenation of the stored procedure address space
startup procedure.
You can replace the default DSNACICX in the prefix.SDSNLOAD, library, or you
can put the DSNACICX load module in a library that is ahead of
prefix.SDSNLOAD in the STEPLIB concatenation. It is recommended that you
put DSNACICX in the prefix.SDSNEXIT library. Sample installation job
DSNTIJEX contains JCL for assembling and link-editing the sample source code
for DSNACICX into prefix.SDSNEXIT. You need to modify the JCL for the
libraries and the compiler that you are using.
v The load module must be named DSNACICX.
v The exit routine must save and restore the caller’s registers. Only the contents of
register 15 can be modified.
784 Application Programming and SQL Guide
v It must be written to be reentrant and link-edited as reentrant.
v It must be written and link-edited to execute as AMODE(31),RMODE(ANY).
v DSNACICX can contain SQL statements. However, if it does, you need to
change the DSNACICS procedure definition to reflect the appropriate SQL access
level for the types of SQL statements that you use in the user exit routine.

Specifying the exit routine

DSNACICS always calls an exit routine named DSNACICX. DSNACICS calls your
DSNACICX exit routine if it finds it before the default DSNACICX exit routine.
Otherwise, it calls the default DSNACICX exit routine.

When the exit routine is taken

The DSNACICX exit routine is taken whenever DSNACICS is called. The exit
routine is taken before DSNACICS invokes the CICS server program.

Loading a new version of the exit routine

DB2 loads DSNACICX only once, when DSNACICS is first invoked. If you change
DSNACICX, you can load the new version by quiescing and then resuming the
WLM application environment for the stored procedure address space in which
DSNACICS runs:
VARY WLM,APPLENV=DSNACICS-applenv-name,QUIESCE VARY
WLM,APPLENV=DSNACICS-applenv-name,RESUME

Parameter list

At invocation, registers are set as described in the following table

Table 133. Registers at invocation of DSNACICX
Register Contains
1 Address of pointer to the exit parameter list
(XPL).
13 Address of the register save area.
14 Return address.
15 Address of entry point of exit routine.

The following table shows the contents of the DSNACICX exit parameter list, XPL.
Member DSNDXPL in data set prefix.SDSNMACS contains an assembler language
mapping macro for XPL. Sample exit routine DSNASCIO in data set
prefix.SDSNSAMP includes a COBOL mapping macro for XPL.
Table 134. Contents of the XPL exit parameter list
Corresponding
DSNACICS
Name Hex offset Data type Description parameter
XPL_EYEC 0 Character, 4 bytes Eye-catcher: ’XPL ’
XPL_LEN 4 Character, 4 bytes Length of the exit
parameter list
XPL_LEVEL 8 4-byte integer Level of the parm-level
parameter list

Chapter 14. Calling a stored procedure from your application 785

Table 134. Contents of the XPL exit parameter list (continued)
Corresponding
DSNACICS
Name Hex offset Data type Description parameter
XPL_PGMNAME C Character, 8 bytes Name of the CICS pgm-name
server program
XPL_CICSAPPLID 14 Character, 8 bytes CICS VTAM® applid CICS-applid
XPL_CICSLEVEL 1C 4-byte integer Level of CICS code CICS-level
XPL_CONNECTTYPE 20 Character, 8 bytes Specific or generic connect-type
connection to CICS
XPL_NETNAME 28 Character, 8 bytes Name of the specific netname
connection to CICS
XPL_MIRRORTRAN 30 Character, 8 bytes Name of the mirror mirror-trans
transaction that
invokes the CICS
server program
1
XPL_COMMAREAPTR 38 Address, 4 bytes Address of the
COMMAREA
2
XPL_COMMINLEN 3C 4-byte integer Length of the
COMMAREA that is
passed to the server
program
XPL_COMMTOTLEN 40 4-byte integer Total length of the commarea-total-len
COMMAREA that is
returned to the caller
XPL_SYNCOPTS 44 4-byte integer Syncpoint control sync-opts
option
XPL_RETCODE 48 4-byte integer Return code from the return-code
exit routine
XPL_MSGLEN 4C 4-byte integer Length of the output return-code
message area
XPL_MSGAREA 50 Character, 256 bytes Output message area msg-area3
Notes:
1. The area that this field points to is specified by DSNACICS parameter COMMAREA. This area does not include
the length bytes.
2. This is the same value that the DSNACICS caller specifies in the length bytes of the COMMAREA parameter.
3. Although the total length of msg-area is 500 bytes, DSNACICX can use only 256 bytes of that area.

DSNAIMS stored procedure

DSNAIMS is a stored procedure that allows DB2 applications to invoke IMS
transactions and commands easily, without maintaining their own connections to
IMS.

DSNAIMS uses the IMS Open Transaction Manager Access (OTMA) API to
connect to IMS and execute the transactions.

786 Application Programming and SQL Guide

Environment

DSNAIMS runs in a WLM-established stored procedures address space. DSNAIMS

requires DB2 with RRSAF enabled and IMS version 7 or later with OTMA Callable
Interface enabled.

| To use a two-phase commit process, you must have IMS Version 8 with UQ70789
| or later.

Authorization

To set up and run DSNAIMS, you must be authorized the perform the following
steps:
1. Use the job DSNTIJIM to issue the CREATE PROCEDURE statement for
DSNAIMS and to grant the execution of DSNAIMS to PUBLIC. DSNTIJIM is
provided in the SDSNSAMP data set. You need to customize DSNTIJIM to fit
the parameters of your system.
2. Ensure that OTMA C/I is initialized. See IMS Open Transaction Manager Access
Guide and Reference for an explanation of the C/I initialization.

Syntax

The following syntax diagram shows the SQL CALL statement for invoking this
stored procedure:

CALL SYSPROC.DSNAIMS ( dsnaims-function, dsnaims-2pc , xcf-group-name,

NULL

xcf-ims-name, racf-userid, racf-groupid , ims-lterm , ims-modname ,

NULL NULL NULL

ims-tran-name , ims-data-in , ims-data-out , otma-tpipe-name ,

NULL NULL NULL NULL

otma-dru-name , user-data-in , user-data-out, status-message, return-code )


NULL NULL

Option descriptions
dsnaims-function
A string that indicates whether the transaction is send-only, receive-only, or
send-and-receive. Possible values are:
SENDRECV
Sends and receives IMS data. SENDRECV invokes an IMS transaction
or command and returns the result to the caller. The transaction can be
an IMS full function or a fast path. SENDRECV does not support
multiple iterations of a conversational transaction
SEND Sends IMS data. SEND invokes an IMS transaction or command, but
does not receive IMS data. If result data exists, it can be retrieved with
the RECEIVE function. A send-only transaction cannot be an IMS fast
path transaction or a conversations transaction.

Chapter 14. Calling a stored procedure from your application 787

RECEIVE
Receives IMS data. The data can be the result of a transaction or
command initiated by the SEND function or an unsolicited output
message from an IMS application. The RECEIVE function does not
initiate an IMS transaction or command.
dsnaims-2pc
Specifies whether to use a two-phase commit process to perform the
transaction syncpoint service. Possible values are Y or N. For N, commits and
rollbacks that are issued by the IMS transaction do not affect commit and
rollback processing in the DB2 application that invokes DSNAIMS.
Furthermore, IMS resources are not affected by commits and rollbacks that are
| issued by the calling DB2 application. If you specify Y, you must also specify
| SENDRECV. To use a two-phase commit process, you must set the IMS control
| region parameter (RRS) to Y.
| This parameter is optional. The default is N.
xcf-group-name
Specifies the XCF group name that the IMS OTMA joins. You can obtain this
name by viewing the GRNAME parameter in IMS PROCLIB member
DFSPBxxx or by using the IMS command /DISPLAY OTMA.
xcf-ims-name
Specifies the XCF member name that IMS uses for the XCF group. If IMS is not
using the XRF or RSR feature, you can obtain the XCF member name from the
OTMANM parameter in IMS PROCLIB member DFSPBxxx. If IMS is using the
XRF or RSR feature, you can obtain the XCF member name from the USERVAR
parameter in IMS PROCLIB member DFSPBxxx.
racf-userid
Specifies the RACF user ID that is used for IMS to perform the transaction or
command authorization checking. This parameter is required if DSNAIMS is
running APF-authorized. If DSNAIMS is running unauthorized, this parameter
is ignored and the EXTERNAL SECURITY setting for the DSNAIMS stored
procedure definition determines the user ID that is used by IMS.
racf-groupid
Specifies the RACF group ID that is used for IMS to perform the transaction or
command authorization checking. This field is used for stored procedures that
are APF-authorized. It is ignored for other stored procedures.
ims-lterm
Specifies an IMS LTERM name that is used to override the LTERM name in the
I/O program communication block of the IMS application program.
This field is used as an input and an output field:
v For SENDRECV, the value is sent to IMS on input and can be updated by
IMS on output.
v For SEND, the parameter is IN only.
v For RECEIVE, the parameter is OUT only.
An empty or NULL value tells IMS to ignore the parameter.
ims-modname
Specifies the formatting map name that is used by the server to map output
data streams, such as 3270 streams. Although this invocation does not have
IMS MFS support, the input MODNAME can be used as the map name to
define the output data stream. This name is an 8-byte message output
descriptor name that is placed in the I/O program communication block.

788 Application Programming and SQL Guide

When the message is inserted, IMS places this name in the message prefix with
the map name in the program communication block of the IMS application
program.
For SENDRECV, the value is sent to IMS on input, and can be updated on
output. For SEND, the parameter is IN only. For RECEIVE it is OUT only. IMS
ignores the parameter when it is an empty or NULL value.
ims-tran-name
Specifies the name of an IMS transaction or command that is sent to IMS. If
the IMS command is longer than eight characters, specify the first eight
characters (including the ″/″ of the command). Specify the remaining
characters of the command in the ims-tran-name parameter. If you use an empty
or NULL value, you must specify the full transaction name or command in the
ims-data-in parameter.
ims-data-in
Specifies the data that is sent to IMS. This parameter is required in each of the
following cases:
v Input data is required for IMS
v No transaction name or command is passed in ims-tran-name
v The command is longer than eight characters
This parameter is ignored when for RECEIVE functions.
ims-data-out
Data returned after successful completion of the transaction. This parameter is
required for SENDRECV and RECEIVE functions. The parameter is ignored for
SEND functions.
otma-tpipe-name
Specifies an 8-byte user-defined communication session name that IMS uses for
the input and output data for the transaction or the command in a SEND or a
RECEIVE function. If the otma_tpipe_name parameter is used for a SEND
function to generate an IMS output message, the same otma_pipe_name must
be used to retrieve output data for the subsequent RECEIVE function.
otma-dru-name
Specifies the name of an IMS user-defined exit routine, OTMA destination
resolution user exit routine, if it is used. This IMS exit routine can format part
of the output prefix and can determine the output destination for an IMS
ALT_PCB output. If an empty or null value is passed, IMS ignores this
parameter.
user-data-in
This optional parameter contains any data that is to be included in the IMS
message prefix, so that the data can be accessed by IMS OTMA user exit
routines (DFSYIOE0 and DFSYDRU0) and can be tracked by IMS log records.
IMS applications that run in dependent regions do not access this data. The
specified user data is not included in the output message prefix. You can use
this parameter to store input and output correlator tokens or other information.
This parameter is ignored for RECEIEVE functions.
user-data-out
On output, this field contains the user-data-in in the IMS output prefix. IMS
user exit routines (DFSYIOE0 and DFSYDRU0) can also create user-data-out for
SENDRECV and RECEIVE functions. The parameter is not updated for SEND
functions.

Chapter 14. Calling a stored procedure from your application 789

status-message
Indicates any error message that is returned from the transaction or command,
OTMA, RRS, or DSNAIMS.
return-code
Indicates the return code that is returned for the transaction or command,
OTMA, RRS, or DSNAIMS.

Examples

The following examples show how to call DSNAIMS.

Example 1: Sample parameters for executing an IMS command:

CALL SYSPROC.DSNAIMS("SENDRECV", "N", "IMS7GRP", "IMS7TMEM",
"IMSCLNM", "", "", "", "", "",
"/LOG Hello World.", ims_data_out, "", "", "",
user_out, error_message, rc)

Example 2: Sample parameters for executing an IMS IVTNO transaction:

CALL SYSPROC.DSNAIMS("SENDRECV", "N", "IMS7GRP", "IMS7TMEM",
"IMSCLNM", "", "", "", "", "",
"IVTNO DISPLAY LAST1 "", ims_data_out
"", "", "", user_out, error_message, rc)

Example 3: Sample parameters for send-only IMS transaction:

CALL SYSPROC.DSNAIMS("SEND", "N", "IMS7GRP", "IMS7TMEM",
"IMSCLNM", "", "", "", "", "",
"IVTNO DISPLAY LAST1 "", ims_data_out,
"DSNAPIPE", "", "", user_out, error_message, rc)

Example 4: Sample parameters for receive-only IMS transaction:

CALL SYSPROC.DSNAIMS("RECEIVE", "N", "IMS7GRP", "IMS7TMEM",
"IMSCLNM", "", "", "", "", "",
"IVTNO DISPLAY LAST1 "", ims_data_out,
"DSNAPIPE", "", "", user_out, error_message, rc)

Connecting to multiple IMS subsystems with DSNAIMS

By default DSNAIMS connects to only one IMS subsystem at a time. The first
request to DSNAIMS determines to which IMS subsystem the stored procedure
connects. DSNAIMS attempts to reconnect to IMS only in the following cases:
v IMS is restarted and the saved connection is no longer valid
v WLM loads another DSNAIMS task

To connect to multiple IMS subsystems simultaneously, perform the following

steps:
1. Make a copy of the DB2-supplied job DSNTIJIM and customize it to your
environment.
2. Change the procedure name from SYSPROCC.DSNAIMS to another name, such
as DSNAIMSB.
3. Do no change the EXTERNAL NAME option. Leave it as DSNAIMS.
4. Run the new job to create a second instance of the stored procedure.
5. To ensure that you connect to the intended IMS target, consistently use the XFC
group and member names that you associate with each stored procedure
instance. For example:

790 Application Programming and SQL Guide

CALL SYSPROC.DSNAIMS("SENDRECV", "N", "IMS7GRP", "IMS7TMEM", ...)
CALL SYSPROC.DSNAIMSB("SENDRECV", "N", "IMS8GRP", "IMS8TMEM", ...)

| DSNAEXP stored procedure

| The DB2 EXPLAIN stored procedure, DSNAEXP, is a sample stored procedure that
| lets you execute an EXPLAIN statement on an SQL statement without having the
| authorization to execute that SQL statement.

| PSPI

| Environment

| DSNAEXP must run in a WLM-established stored procedure address space.

| Before you can invoke DSNAEXP, table sqlid.PLAN_TABLE must exist. sqlid is the
| value that you specify for the sqlid input parameter when you call DSNAEXP.

| Job DSNTESC in DSN8910.SDSNSAMP contains a sample CREATE TABLE

| statement for the PLAN_TABLE.

| Authorization required

| To execute the CALL DSN8.DSNAEXP statement, the owner of the package or plan
| that contains the CALL statement must have one or more of the following
| privileges on each package that the stored procedure uses:
| v The EXECUTE privilege on the package for DSNAEXP
| v Ownership of the package
| v PACKADM authority for the package collection
| v SYSADM authority

| In addition:
| v The SQL authorization ID of the process in which DSNAEXP is called must have
| the authority to execute SET CURRENT SQLID=sqlid.
| v The SQL authorization ID of the process must also have one of the following
| characteristics:
| – Be the owner of a plan table named PLAN_TABLE
| – Have an alias on a plan table named owner.PLAN_TABLE and have SELECT
| and INSERT privileges on the table

| DSNAEXP syntax diagram

| The following syntax diagram shows the CALL statement for invoking DSNAEXP.
| Because the linkage convention for DSNAEXP is GENERAL, you cannot pass null
| values to the stored procedure.
|

Chapter 14. Calling a stored procedure from your application 791

|

CALL DSNAEXP ( sqlid , queryno , sql-statement , parse ,

|
|
qualifier , sqlcode , sqlstate , error-message )

|
||

| DSNAEXP option descriptions

| sqlid
| Specifies:
| v The authorization ID under which the EXPLAIN statement is to be executed
| v The qualifier for the table into which EXPLAIN output is written:
| sqlid.PLAN_TABLE
| v The implicit qualifier for unqualified objects in the SQL statement on which
| EXPLAIN is executed, if the value of parse is ’N’
| sqlid is an input parameter of type CHAR(8).
| queryno
| Specifies a number that is to be used to identify sql-statement in the EXPLAIN
| output. This number appears in the QUERYNO column in the PLAN_TABLE.
| queryno is an input parameter of type INTEGER.
| sql-statement
| Specifies the SQL statement on which EXPLAIN is to be executed. sql-statement
| is an input parameter of type CLOB(2M).
| parse
| Specifies whether DSNAEXP adds a qualifier for unqualified table or view
| names in the input SQL statement. Valid values are ’Y’ and ’N’. If the value of
| parse is ’Y’, qualifier must contain a valid SQL qualifier name.
| If sql-statement is insert-within-select and common table expressions, you need
| to disable the parsing functionality, and add the qualifier manually.
| parse is an input parameter of type CHAR(1).
| qualifier
| Specifies the qualifier that DSNAEXP adds to unqualified table or view names
| in the input SQL statement. If the value of parse is ’N’, qualifier is ignored.
| If the statement on which EXPLAIN is run contains an INSERT within a
| SELECT or a common table expression, parse must be ’N’, and table and view
| qualifiers must be explicitly specified.
| qualifier is an input parameter of type CHAR(8).
| sqlcode
| Contains the SQLCODE from execution of the EXPLAIN statement. sqlcode is
| an output parameter of type INTEGER.
| sqlstate
| Contains the SQLSTATE from execution of the EXPLAIN statement. sqlstate is
| an output parameter of type CHAR(5).
| error-message
| Contains information about DSNAEXP execution. If the SQLCODE from
| execution of the EXPLAIN statement is not 0, error-message contains the error
| message for the SQLCODE. error-message is an output parameter of type
| VARCHAR(960).

792 Application Programming and SQL Guide

| Example of DSNAEXP invocation

| The following C example shows how to call DSNAEXP to execute an EXPLAIN

| statement.
| EXEC SQL BEGIN DECLARE SECTION;
| char hvsqlid[9]; /* Qualifier for PLAN_TABLE */
| long int hvqueryno; /* QUERYNO to give the SQL */
| struct {
| short int hvsql_stmt_len; /* Input SQL statement length */
| hvsql_stmt_txt SQL type is CLOB 2M;
| /* SQL statement text */
| } hvsql_stmt; /* SQL statement to EXPLAIN */
| char hvparse[1]; /* Qualify object names */
| /* indicator */
| char hvqualifier[9]; /* Qualifier for unqualified */
| /* objects */
| long int hvsqlcode; /* SQLCODE from CALL DSNAEXP */
| char hvsqlstate[6]; /* SQLSTATE from CALL DSNAEXP */
| struct {
| short int hvmsg_len; /* Error message length */
| char hvmsg_text[961]; /* Error message text */
| } hvmsg; /* Error message from failed */
| /* CALL DSNAEXP */
| EXEC SQL END DECLARE SECTION;
|| short
. int i;
|| .
.
| /* Set the input parameters */
| strcpy(hvsqlid,"ADMF001 ");
| hvqueryno=320;
| strcpy(hvsql_stmt.hvsql_stmt_text,"SELECT CURRENT DATE FROM SYSDUMMY1");
| hvsql_stmt.hvsql_stmt_len=strlen(hvsql_stmt.hvsql_stmt_text);
| hvparse[0]='Y';
| strcpy(hvqualifier,"SYSIBM");
| /* Initialize the output parameters */
| hvsqlcode=0;
| for (i = 0; i < 5; i++) hvsqlstate[i] = '0';
| hvsqlstate[5]='\0';
| hvmsg.hvmsg_len=0;
| for (i = 0; i < 960; i++) hvmsg.hvmsg_text[i] = ' ';
| hvmsg.hvmsg_text[960] = '\0';
| /* Call DSNAEXP to do EXPLAIN and put output in ADMF001.PLAN_TABLE */
| EXEC SQL
| CALL DSN8.DSNAEXP(:hvsqlid,
| :hvqueryno,
| :hvsql_stmt,
| :hvparse,
| :hvqualifier,
| :hvsqlcode,
| :hvsqlstate,
| :hvmsg);

| DSNAEXP output

| If DSNAEXP executes successfully, sqlid.PLAN_TABLE contains the EXPLAIN

| output. A user with SELECT authority on sqlid.PLAN_TABLE can obtain the results
| of the EXPLAIN that was executed by DSNAEXP by executing this query:
| SELECT * FROM sqlid.PLAN_TABLE WHERE QUERYNO='queryno';

| If DSNAEXP does not execute successfully, sqlcode, sqlstate, and error-message

| contain error information.

| PSPI

Chapter 14. Calling a stored procedure from your application 793

Deprecated: DXXMQINSERT stored procedure
The DXXMQINSERT stored procedure returns a message that contains an XML
document from an MQ message queue, decomposes the document, and stores the
data in DB2 tables that are specified by an enabled XML collection. Use
DXXMQINSERT for an XML document with a length of up to 3 KB.

| Restriction: DXXMQINSERT has been deprecated.

There are two versions of DXXMQINSERT:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQINSERT

DXXMQINSERT runs in a WLM-established stored procedure address space and

uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQINSERT requires that WebSphere® MQ and XML Extender are installed.

Authorization required for DXXMQINSERT

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQINSERT
v Ownership of the stored procedure
v SYSADM authority

DXXMQINSERT syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQINSERT. Because the linkage convention for DXXMQINSERT is GENERAL
WITH NULLS, if you pass parameters in host variables, you need to include a null
indicator with every host variable. Null indicators for input host variables must be
initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQINSERT ( service-name , policy-name ,

DMQXML2C NULL NULL

XML-collection-name, status )


DXXMQINSERT option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which the message is to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.

794 Application Programming and SQL Guide

policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
XML-collection-name
Specifies the name of the XML collection that specifies the DB2 tables into
which the decomposed XML document is to be inserted. XML-collection-name is
an input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQINSERT ran successfully.
The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQINSERT ran successfully, or the SQLCODE from the
most recent unsuccessful SQL statement if DXXMQINSERT ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQINSERT invocation

The following example calls the single-phase commit version of DXXMQINSERT to

retrieve an XML document from an MQ message queue and decompose it into
DB2 tables that are specified by enabled collection sales_ord. For a complete
example of DXXMQINSERT invocation, see DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char collectionName[30]; /* XML collection name */
char status[20]; /* Status of DXXMQINSERT call */
/* DXXMQINSERT is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short collectionName_ind; /* Indicator var for collectionName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the XML collection name */
strcpy(collectionName,"sales_ord");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;

Chapter 14. Calling a stored procedure from your application 795

policyName_ind = 0;
/* Initialize the indicator for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQINSERT(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:overrideType:ovtype_ind,
:override:ov_ind,
:max_row:maxrow_ind,
:num_row:numrow_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQINSERT output

If DXXMQINSERT executes successfully, the mq-num-msgs field of the status

parameter is set to 1, to indicate that a message was retrieved from the MQ
message queue and inserted into DB2 tables. If DXXMQINSERT does not execute
successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQSHRED stored procedure

The DXXMQSHRED stored procedure returns a message that contains an XML
document from an MQ message queue, decomposes the document, and stores the
data in DB2 tables that are specified in a document access definition (DAD) file.
DXXMQSHRED does not require an enabled XML collection. Use DXXMQSHRED
for an XML document with a length of up to 3 KB.

| Restriction: DXXMQSHRED has been deprecated.

There are two versions of DXXMQSHRED:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQSHRED

DXXMQSHRED runs in a WLM-established stored procedure address space and

uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQSHRED requires that WebSphere MQ and XML Extender are installed.

Authorization required for DXXMQSHRED

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQSHRED
v Ownership of the stored procedure
v SYSADM authority

DXXMQSHRED syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQSHRED. Because the linkage convention for DXXMQSHRED is GENERAL
WITH NULLS, if you pass parameters in host variables, you need to include a null

796 Application Programming and SQL Guide

indicator with every host variable. Null indicators for input host variables must be
initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQSHRED ( service-name , policy-name , DAD-file-name,

DMQXML2C NULL NULL

status )


DXXMQSHRED option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which the message is to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
DAD-file-name
Specifies the name of the (DAD) file that maps the XML document to DB2
tables. DAD-file-name must be specified, and must be the name of a valid DAD
file that exists on the system on which DXXMQSHRED runs. DAD-file-name is
an input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQSHRED ran successfully.
The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQSHRED ran successfully, or the SQLCODE from the
most recent unsuccessful SQL statement if DXXMQSHRED ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQSHRED invocation

The following example calls the single-phase commit version of DXXMQSHRED to

retrieve an XML document from an MQ message queue and decompose it into
DB2 tables that are specified by DAD file /tmp/neworder2.dad. For a complete
example of DXXMQSHRED invocation, see DSN8QXSI in DSN910.SDSNSAMP.

Chapter 14. Calling a stored procedure from your application 797

#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char dadFileName[30]; /* DAD file name */
char status[20]; /* Status of DXXMQSHRED call */
/* DXXMQSHRED is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short dadFileName_ind; /* Indicator var for dadFileName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the DAD file name */
strcpy(dadFileName,"/tmp/neworder2.dad");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicator for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQSHRED(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQSHRED output

If DXXMQSHRED executes successfully, the mq-num-msgs field of the status

parameter is set to 1, to indicate that a message was retrieved from the MQ
message queue and inserted into DB2 tables. If DXXMQSHRED does not execute
successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQINSERTCLOB stored procedure

The DXXMQINSERTCLOB stored procedure returns a message that contains an
XML document from an MQ message queue, decomposes the document, and
stores the data in DB2 tables that are specified by an enabled XML collection. Use
DXXMQINSERTCLOB for an XML document with a length of up to 1 MB.

| Restriction: DXXMQINSERTCLOB has been deprecated.

There are two versions of DXXMQINSERTCLOB:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

798 Application Programming and SQL Guide

Environment for DXXMQINSERTCLOB

DXXMQINSERTCLOB runs in a WLM-established stored procedure address space

and uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQINSERTCLOB requires that WebSphere MQ and XML Extender are

installed.

Authorization required for DXXMQINSERTCLOB

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQINSERTCLOB
v Ownership of the stored procedure
v SYSADM authority

DXXMQINSERTCLOB syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQINSERTCLOB. Because the linkage convention for DXXMQINSERTCLOB
is GENERAL WITH NULLS, if you pass parameters in host variables, you need to
include a null indicator with every host variable. Null indicators for input host
variables must be initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQINSERTCLOB ( service-name , policy-name ,

DMQXML2C NULL NULL

XML-collection-name, status )


DXXMQINSERTCLOB option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which the message is to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
XML-collection-name
Specifies the name of the XML collection that specifies the DB2 tables into
which the decomposed XML document is to be inserted. XML-collection-name
must be specified, and must be the name of an enabled collection that exists on

Chapter 14. Calling a stored procedure from your application 799

the system on which DXXMQINSERTCLOB runs. XML-collection-name is an
input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQINSERTCLOB ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQINSERTCLOB ran successfully, or the SQLCODE from
the most recent unsuccessful SQL statement if DXXMQINSERTCLOB ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQINSERTCLOB invocation

The following example calls the single-phase commit version of

DXXMQINSERTCLOB to retrieve all XML documents from an MQ message queue
and decompose them into DB2 tables that are specified by enabled collection
sales_ord. For a complete example of DXXMQINSERTCLOB invocation, see
DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char collectionName[30]; /* XML collection name */
char status[20]; /* Status of DXXMQINSERTCLOB call */
/* DXXMQINSERTCLOB is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short collectionName_ind; /* Indicator var for collectionName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the XML collection name */
strcpy(collectionName,"sales_ord");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicator for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQINSERTCLOB(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:collectionName:collectionName_ind,
:status:status_ind);
printf("SQLCODE from CALL:

800 Application Programming and SQL Guide

/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQINSERTCLOB output

If DXXMQINSERTCLOB executes successfully, the mq-num-msgs field of the status

parameter is set to 1, to indicate that a message was retrieved from the MQ
message queue and inserted into DB2 tables. If DXXMQINSERTCLOB does not
execute successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQSHREDCLOB stored procedure

The DXXMQSHREDCLOB stored procedure returns a message that contains an
XML document from an MQ message queue, decomposes the document, and
stores the data in DB2 tables that are specified in a document access definition
(DAD) file. DXXMQSHREDCLOB does not require an enabled XML collection. Use
DXXMQSHREDCLOB for an XML document with a length of up to 1 MB.

| Restriction: DXXMQSHREDCLOB has been deprecated.

There are two versions of DXXMQSHREDCLOB:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQSHREDCLOB

DXXMQSHREDCLOB runs in a WLM-established stored procedure address space

and uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQSHREDCLOB requires that WebSphere MQ and XML Extender are

installed.

Authorization required for DXXMQSHREDCLOB

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQSHREDCLOB
v Ownership of the stored procedure
v SYSADM authority

DXXMQSHREDCLOB syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQSHREDCLOB. Because the linkage convention for DXXMQSHREDCLOB is
GENERAL WITH NULLS, if you pass parameters in host variables, you need to
include a null indicator with every host variable. Null indicators for input host
variables must be initialized before you execute the CALL statement.

Chapter 14. Calling a stored procedure from your application 801

CALL DMQXML1C .DXXMQSHREDCLOB ( service-name , policy-name , DAD-file-name,

DMQXML2C NULL NULL

status )


DXXMQSHREDCLOB option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which the message is to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
DAD-file-name
Specifies the name of the (DAD) file that maps the XML document to DB2
tables. DAD-file-name is an input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQSHREDCLOB ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQSHREDCLOB ran successfully, or the SQLCODE from
the most recent unsuccessful SQL statement if DXXMQSHREDCLOB ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQSHREDCLOB invocation

The following example calls the single-phase commit version of

DXXMQSHREDCLOB to retrieve an XML document from an MQ message queue
and decompose it into DB2 tables that are specified by DAD file
/tmp/neworder2.dad. For a complete example of DXXMQSHREDCLOB
invocation, see DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char dadFileName[30]; /* DAD file name */
char status[20]; /* Status of DXXMQSHREDCLOB call */

802 Application Programming and SQL Guide

/* DXXMQSHREDCLOB is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short dadFileName_ind; /* Indicator var for dadFileName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the DAD file name */
strcpy(dadFileName,"/tmp/neworder2.dad");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicator for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQSHREDCLOB(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQSHREDCLOB output

If DXXMQSHREDCLOB executes successfully, the mq-num-msgs field of the status

parameter is set to 1, to indicate that a message was retrieved from the MQ
message queue and inserted into DB2 tables. If DXXMQSHREDCLOB does not
execute successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQINSERTALL stored procedure

The DXXMQINSERTALL stored procedure returns messages that contains XML
documents from an MQ message queue, decomposes the documents, and stores
the data in DB2 tables that are specified by an enabled XML collection. Use
DXXMQINSERTALL for XML documents with a length of up to 3 KB.

| Restriction: DXXMQINSERTALL has been deprecated.

There are two versions of DXXMQINSERTALL:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQINSERTALL

DXXMQINSERTALL runs in a WLM-established stored procedure address space

and uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQINSERTALL requires that WebSphere MQ and XML Extender are installed.

Chapter 14. Calling a stored procedure from your application 803

Authorization required for DXXMQINSERTALL

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQINSERTALL
v Ownership of the stored procedure
v SYSADM authority

DXXMQINSERTALL syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQINSERTALL. Because the linkage convention for DXXMQINSERTALL is
GENERAL WITH NULLS, if you pass parameters in host variables, you need to
include a null indicator with every host variable. Null indicators for input host
variables must be initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQINSERTALL ( service-name , policy-name ,

DMQXML2C NULL NULL

XML-collection-name, status )


DXXMQINSERTALL option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which the messages are to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
messages. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
XML-collection-name
Specifies the name of the XML collection that specifies the DB2 tables into
which the decomposed XML documents are to be inserted. XML-collection-name
must be specified, and must be the name of a valid XML collection that exists
on the system on which DXXMQINSERTALL runs.XML-collection-name is an
input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQINSERTALL ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.

804 Application Programming and SQL Guide

v sqlcode is 0 if DXXMQINSERTALL ran successfully, or the SQLCODE from
the most recent unsuccessful SQL statement if DXXMQINSERTALL ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQINSERTALL invocation

The following example calls the single-phase commit version of

DXXMQINSERTALL to retrieve all XML documents from an MQ message queue
and decompose them into DB2 tables that are specified by enabled collection
sales_ord. For a complete example of DXXMQINSERTALL invocation, see
DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char collectionName[30]; /* XML collection name */
char status[20]; /* Status of DXXMQINSERTALL call */
/* DXXMQINSERTALL is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short collectionName_ind; /* Indicator var for collectionName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the XML collection name */
strcpy(collectionName,"sales_ord");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicators for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQINSERTALL(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:collectionName:collectionName_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQINSERTALL output

If DXXMQINSERTALL executes successfully, the mq-num-msgs field of the status

parameter is set to the number of messages that were retrieved from the MQ
message queue and decomposed. If DXXMQINSERTALL does not execute
successfully, the contents of the status parameter indicate the problem.

Chapter 14. Calling a stored procedure from your application 805

Deprecated: DXXMQSHREDALL stored procedure
The DXXMQSHREDALL stored procedure returns messages that contain XML
documents from an MQ message queue, decomposes the documents, and stores
the data in DB2 tables that are specified in a document access definition (DAD)
file. DXXMQSHREDALL does not require an enabled XML collection. Use
DXXMQSHREDALL for XML documents with a length of up to 3 KB.

| Restriction: DXXMQSHREDALL has been deprecated.

There are two versions of DXXMQSHREDALL:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQSHREDALL

DXXMQSHREDALL runs in a WLM-established stored procedure address space

and uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQSHREDALL requires that WebSphere MQ and XML Extender are installed.

Authorization required for DXXMQSHREDALL

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQSHREDALL
v Ownership of the stored procedure
v SYSADM authority

DXXMQSHREDALL syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQSHREDALL. Because the linkage convention for DXXMQSHREDALL is
GENERAL WITH NULLS, if you pass parameters in host variables, you need to
include a null indicator with every host variable. Null indicators for input host
variables must be initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQSHREDALL ( service-name , policy-name , DAD-file-name,

DMQXML2C NULL NULL

status )


DXXMQSHREDALL option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which messages are to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.

806 Application Programming and SQL Guide

policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
messages. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
DAD-file-name
Specifies the name of the (DAD) file that maps the XML document to DB2
tables. DAD-file-name must be specified, and must be the name of a valid DAD
file that exists on the system on which DXXMQSHREDALL runs.DAD-file-name
is an input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQSHREDALL ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQSHREDALL ran successfully, or the SQLCODE from
the most recent unsuccessful SQL statement if DXXMQSHREDALL ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQSHREDALL invocation

The following example calls the single-phase commit version of

DXXMQSHREDALL to retrieve XML documents from an MQ message queue and
decompose them into DB2 tables that are specified by DAD file
/tmp/neworder2.dad. For a complete example of DXXMQSHREDALL invocation,
see DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char dadFileName[30]; /* DAD file name */
char status[20]; /* Status of DXXMQSHREDALL call */
/* DXXMQSHREDALL is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short dadFileName_ind; /* Indicator var for dadFileName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the DAD file name */
strcpy(dadFileName,"/tmp/neworder2.dad");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */

Chapter 14. Calling a stored procedure from your application 807

/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicator for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQSHREDALL(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQSHREDALL output

If DXXMQSHREDALL executes successfully, the mq-num-msgs field of the status

parameter is set to the number of messages that were retrieved from the MQ
message queue and inserted into DB2 tables. If DXXMQSHREDALL does not
execute successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQSHREDALLCLOB stored procedure

The DXXMQSHREDALLCLOB stored procedure returns messages that contain
XML documents from an MQ message queue, decomposes the documents, and
stores the data in DB2 tables that are specified in a document access definition
(DAD) file. DXXMQSHREDALLCLOB does not require an enabled XML collection.
Use DXXMQSHREDALLCLOB for XML documents with a length of up to 1 MB.

| Restriction: DXXMQSHREDALLCLOB has been deprecated.

There are two versions of DXXMQSHREDALLCLOB:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQSHREDALLCLOB

DXXMQSHREDALLCLOB runs in a WLM-established stored procedure address

space and uses the Resource Recovery Services attachment facility to connect to
DB2.

DXXMQSHREDALLCLOB requires that WebSphere MQ and XML Extender are

installed.

Authorization required for DXXMQSHREDALLCLOB

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQSHREDALLCLOB
v Ownership of the stored procedure
v SYSADM authority

DXXMQSHREDALLCLOB syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQSHREDALLCLOB. Because the linkage convention for

808 Application Programming and SQL Guide

DXXMQSHREDALLCLOB is GENERAL WITH NULLS, if you pass parameters in
host variables, you need to include a null indicator with every host variable. Null
indicators for input host variables must be initialized before you execute the CALL
statement.

CALL DMQXML1C .DXXMQSHREDALLCLOB ( service-name , policy-name ,

DMQXML2C NULL NULL

DAD-file-name, status )


DXXMQSHREDALLCLOB option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which messages are to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
messages. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
DAD-file-name
Specifies the name of the (DAD) file that maps the XML document to DB2
tables. DAD-file-name must be specified, and must be the name of a valid DAD
file that exists on the system on which DXXMQSHREDALLCLOB runs.
DAD-file-name is an input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQSHREDALLCLOB ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQSHREDALLCLOB ran successfully, or the SQLCODE
from the most recent unsuccessful SQL statement if
DXXMQSHREDALLCLOB ran unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQSHREDALLCLOB invocation

The following example calls the single-phase commit version of

DXXMQSHREDALLCLOB to retrieve XML documents from an MQ message queue
and decompose them into DB2 tables that are specified by DAD file

Chapter 14. Calling a stored procedure from your application 809

/tmp/neworder2.dad. For a complete example of DXXMQSHREDALLCLOB
invocation, see DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char dadFileName[30]; /* DAD file name */
char status[20]; /* Status of DXXMQSHREDALLCLOB call */
/* DXXMQSHREDALLCLOB is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short dadFileName_ind; /* Indicator var for dadFileName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the DAD file name */
strcpy(dadFileName,"/tmp/neworder2.dad");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicator for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQSHREDALLCLOB(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQSHREDALLCLOB output

If DXXMQSHREDALLCLOB executes successfully, the mq-num-msgs field of the

status parameter is set to the number of messages that were retrieved from the MQ
message queue and inserted into DB2 tables. If DXXMQSHREDALLCLOB does not
execute successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQINSERTALLCLOB stored procedure

The DXXMQINSERTALLCLOB stored procedure returns messages that contains
XML documents from an MQ message queue, decomposes the documents, and
stores the data in DB2 tables that are specified by an enabled XML collection. Use
DXXMQINSERTALLCLOB for XML documents with a length of up to 1 MB.

| Restriction: DXXMQINSERTALLCLOB has been deprecated.

There are two versions of DXXMQINSERTALLCLOB:

v A single-phase commit version, with schema name DMQXML1C.

810 Application Programming and SQL Guide

v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQINSERTALLCLOB

DXXMQINSERTALLCLOB runs in a WLM-established stored procedure address

space and uses the Resource Recovery Services attachment facility to connect to
DB2.

DXXMQINSERTALLCLOB requires that WebSphere MQ and XML Extender are

installed.

Authorization required for DXXMQINSERTALLCLOB

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQINSERTALLCLOB
v Ownership of the stored procedure
v SYSADM authority

DXXMQINSERTALLCLOB syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQINSERTALLCLOB. Because the linkage convention for
DXXMQINSERTALLCLOB is GENERAL WITH NULLS, if you pass parameters in
host variables, you need to include a null indicator with every host variable. Null
indicators for input host variables must be initialized before you execute the CALL
statement.

CALL DMQXML1C .DXXMQINSERTALLCLOB ( service-name , policy-name ,

DMQXML2C NULL NULL

XML-collection-name, status )


DXXMQINSERTALLCLOB option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination from
which the messages are to be retrieved. The service point is defined in the
DSNAMT repository file. If service-name is not listed in the DSNAMT
repository file, or service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
messages. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.

Chapter 14. Calling a stored procedure from your application 811

XML-collection-name
Specifies the name of the XML collection that specifies the DB2 tables into
which the decomposed XML documents are to be inserted. XML-collection-name
must be specified, and must be the name of a valid XML collection that exists
on the system on which DXXMQINSERTALLCLOB runs. XML-collection-name is
an input parameter of type VARCHAR(80).
status
Contains information that indicates whether DXXMQINSERTALLCLOB ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQINSERTALLCLOB ran successfully, or the SQLCODE
from the most recent unsuccessful SQL statement if
DXXMQINSERTALLCLOB ran unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQINSERTALLCLOB invocation

The following example calls the single-phase commit version of

DXXMQINSERTALLCLOB to retrieve all XML documents from an MQ message
queue and decompose them into DB2 tables that are specified by enabled collection
sales_ord. For a complete example of DXXMQINSERTALLCLOB invocation, see
DSN8QXSI in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char collectionName[30]; /* XML collection name */
char status[20]; /* Status of DXXMQINSERTALLCLOB call */
/* DXXMQINSERTALLCLOB is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short collectionName_ind; /* Indicator var for collectionName */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Initialize status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the XML collection name */
strcpy(collectionName,"sales_ord");
/* Initialize the output variable */
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
/* Initialize the indicators for the output parameter */
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQINSERTALLCLOB(:serviceName:serviceName_ind,
:policyName:policyName_ind,

812 Application Programming and SQL Guide

:collectionName:collectionName_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQINSERTALLCLOB output

If DXXMQINSERTALLCLOB executes successfully, the mq-num-msgs field of the

status parameter is set to the number of messages that were retrieved from the MQ
message queue and decomposed. If DXXMQINSERTALLCLOB does not execute
successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQGEN stored procedure

The DXXMQGEN stored procedure constructs XML documents from data that is
stored in DB2 tables that are specified in a document access definition (DAD) file,
and sends the XML documents to an MQ message queue. Use DXXMQGEN for
XML documents with a length of up to 3 KB.

| Restriction: DXXMQGEN has been deprecated.

There are two versions of DXXMQGEN:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQGEN

DXXMQGEN runs in a WLM-established stored procedure address space and uses

the Resource Recovery Services attachment facility to connect to DB2.

DXXMQGEN requires that WebSphere MQ and XML Extender are installed.

Authorization required for DXXMQGEN

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQGEN
v Ownership of the stored procedure
v SYSADM authority

DXXMQGEN syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQGEN. Because the linkage convention for DXXMQGEN is GENERAL
WITH NULLS, if you pass parameters in host variables, you need to include a null
indicator with every host variable. Null indicators for input host variables must be
initialized before you execute the CALL statement.

Chapter 14. Calling a stored procedure from your application 813

CALL DMQXML1C .DXXMQGEN ( service-name , policy-name , DAD-file-name,

DMQXML2C NULL NULL

override-type , override , max-rows , num-msgs, status )


NULL NULL NULL

DXXMQGEN option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination to
which the message is to be sent. The service point is defined in the DSNAMT
repository file. If service-name is not listed in the DSNAMT repository file, or
service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
DAD-file-name
Specifies the name of the (DAD) file that maps the XML documents to DB2
tables. DAD-file-name must be specified, and must be the name of a valid DAD
file that exists on the system on which DXXMQGEN runs. DAD-file-name is an
input parameter of type VARCHAR(80).
override-type
Specifies what the override parameter does. Possible values are:
NO_OVERRIDE
The override parameter does not override the condition in the DAD file.
This is the default.
SQL_OVERRIDE
The DAD file uses SQL mapping, and the override parameter contains
an SQL statement that overrides the SQL statement in the DAD file.
XML_OVERRIDE
The DAD file uses RDB_node mapping, and the override parameter
contains conditions that override the RDB_node mapping in the DAD
file.

override-type is an input parameter of type INTEGER. The integer equivalents

of the override-type values are defined in the dxx.h file.
override
Specifies a string that overrides the condition in the DAD file. The contents of
the string depend on the value of the override-type parameter:
v If override-type is NO_OVERRIDE, override contains a null string. This is the
default.
v If override-type is SQL_OVERRIDE, override contains a valid SQL statement
that overrides the SQL statement in the DAD file.

814 Application Programming and SQL Guide

v If override-type is XML_OVERRIDE, override contains one or more expressions
that are separated by AND. Each expression must be enclosed in double
quotation marks. This override value overrides the RDB_node mapping in the
DAD file.
override is an input parameter of type VARCHAR(1024).
max-rows
Specifies the maximum number of XML documents that DXXMQGEN can send
to the MQ message queue. The default is 1.
max-rows is an input parameter of type INTEGER.
num-rows
The actual number of XML documents that DXXMQGEN sends to the MQ
message queue.
num-rows is an output parameter of type INTEGER.
status
Contains information that indicates whether DXXMQGEN ran successfully. The
format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQGEN ran successfully, or the SQLCODE from the most
recent unsuccessful SQL statement if DXXMQGEN ran unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQGEN invocation

The following example calls the single-phase commit version of DXXMQGEN to

generate XML documents and send them to an MQ message queue. The calling
program does not override the definitions in the DAD file. For a complete example
of DXXMQGEN invocation, see DSN8QXGR in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char dadFileName[80]; /* DAD file name */
short overrideType; /* defined in dxx.h */
char override[2]; /* Override string for DAD */
short max_row; /* Maximum number of documents*/
short num_row; /* Actual number of documents */
char status[20]; /* Status of DXXMQGEN call */
/* DXXMQGEN is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short dadFileName_ind; /* Indicator var for dadFileName */
short ovtype_ind; /* Indicator var for overrideType */
short ov_ind; /* Indicator var for override */
short maxrow_ind; /* Indicator var for maxrow */
short numrow_ind; /* Indicator var for numrow */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;

Chapter 14. Calling a stored procedure from your application 815

/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the name of the DAD file for the DB2 tables */
strcpy(dadFileName,"/tmp/getstart_xcollection.dad");
/* Put null in the override parameter because we are not going */
/* to override the values in the DAD file */
override[0] = '\0';
overrideType = NO_OVERRIDE;
/* Indicate that we do not want to transfer more than 500 */
/* documents */
max_row = 500;
/* Initialize the output variables */
num_row = 0;
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
dadFileName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
maxrow_ind = 0;
/* Initialize the indicators for the output parameters */
numrow_ind = -1;
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQGEN(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:overrideType:ovtype_ind,
:override:ov_ind,
:max_row:maxrow_ind,
:num_row:numrow_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQGEN output

If DXXMQGEN executes successfully, the number of documents indicated by the

mq-num-msgs field of the status parameter are extracted from DB2 tables and
inserted into the MQ message queue. If DXXMQGEN does not execute
successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQRETRIEVE stored procedure

The DXXMQRETRIEVE stored procedure constructs XML documents from data
that is stored in DB2 tables that are specified in an enabled XML collection, and
sends the XML documents to an MQ message queue. Use DXXMQRETRIEVE for
XML documents with a length of up to 3KB.

| Restriction: DXXMQRETRIEVE has been deprecated.

There are two versions of DXXMQRETRIEVE:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQRETRIEVE

DXXMQRETRIEVE runs in a WLM-established stored procedure address space and

uses the Resource Recovery Services attachment facility to connect to DB2.

816 Application Programming and SQL Guide

DXXMQRETRIEVE requires that WebSphere MQ and XML Extender are installed.

Authorization required for DXXMQRETRIEVE

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQRETRIEVE
v Ownership of the stored procedure
v SYSADM authority

DXXMQRETRIEVE syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQRETRIEVE. Because the linkage convention for DXXMQRETRIEVE is
GENERAL WITH NULLS, if you pass parameters in host variables, you need to
include a null indicator with every host variable. Null indicators for input host
variables must be initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQRETRIEVE ( service-name , policy-name ,

DMQXML2C NULL NULL

XML-collection-name, override-type , override , max-rows , num-msgs, status )


NULL NULL NULL

DXXMQRETRIEVE option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination to
which the message is to be sent. The service point is defined in the DSNAMT
repository file. If service-name is not listed in the DSNAMT repository file, or
service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
XML-collection-name
Specifies the name of the XML collection that specifies the DB2 tables from
which the XML documents are to be retrieved. XML-collection-name must be
specified, and must be the name of a valid XML collection that exists on the
system on which DXXMQRETRIEVE runs. XML-collection-name is an input
parameter of type VARCHAR(80).
override-type
Specifies what the override parameter does. Possible values are:

Chapter 14. Calling a stored procedure from your application 817

NO_OVERRIDE
The override parameter does not override the XML collection. This is
the default.
SQL_OVERRIDE
The DAD file uses SQL mapping, and the override parameter contains
an SQL statement that overrides the SQL statement in the XML
collection.
XML_OVERRIDE
The DAD file uses RDB_node mapping, and the override parameter
contains conditions that override the conditions in the XML collection.
override-type is an input parameter of type INTEGER. The integer equivalents
of the override-type values are defined in the dxx.h file.
override-type
Specifies what the override parameter does. Possible values are:
NO_OVERRIDE
The override parameter does not override the condition in the DAD file.
This is the default.
SQL_OVERRIDE
The DAD file uses SQL mapping, and the override parameter contains
an SQL statement that overrides the SQL statement in the DAD file.
XML_OVERRIDE
The DAD file uses RDB_node mapping, and the override parameter
contains conditions that override the RDB_node mapping in the DAD
file.
override-type is an input parameter of type INTEGER. The integer equivalents
of the override-type values are defined in the dxx.h file.
override
Specifies a string that overrides the condition in the DAD file. The contents of
the string depend on the value of the override-type parameter:
v If override-type is NO_OVERRIDE, override contains a null string. This is the
default.
v If override-type is SQL_OVERRIDE, override contains a valid SQL statement
that overrides the SQL statement in the DAD file.
v If override-type is XML_OVERRIDE, override contains one or more expressions
that are separated by AND. Each expression must be enclosed in double
quotation marks. This override value overrides the RDB_node mapping in the
DAD file.
override is an input parameter of type VARCHAR(1024).
max-rows
Specifies the maximum number of XML documents that DXXMQRETRIEVE
can send to the MQ message queue. The default is 1.
max-rows is an input parameter of type INTEGER.
num-rows
The actual number of XML documents that DXXMQRETRIEVE sends to the
MQ message queue.
num-rows is an output parameter of type INTEGER.

818 Application Programming and SQL Guide

status
Contains information that indicates whether DXXMQRETRIEVE ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQRETRIEVE ran successfully, or the SQLCODE from the
most recent unsuccessful SQL statement if DXXMQRETRIEVE ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQRETRIEVE invocation

The following example calls the single-phase commit version of DXXMQRETRIEVE

to generate XML documents and send them to an MQ message queue. The calling
program does not override the definitions in the DAD file. For a complete example
of DXXMQRETRIEVE invocation, see DSN8QXGR in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char collectionName[80]; /* XML collection name */
short overrideType; /* defined in dxx.h */
char override[2]; /* Override string for DAD */
short max_row; /* Maximum number of documents*/
short num_row; /* Actual number of documents */
char status[20]; /* Status of DXXMQRETRIEVE call */
/* DXXMQRETRIEVE is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short collectionName_ind; /* Indicator var for dadFileName */
short ovtype_ind; /* Indicator var for overrideType */
short ov_ind; /* Indicator var for override */
short maxrow_ind; /* Indicator var for maxrow */
short numrow_ind; /* Indicator var for numrow */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the XML collection name */
strcpy(collectionName,"sales_ord");
/* Put null in the override parameter because we are not going */
/* to override the values in the DAD file */
override[0] = '\0';
overrideType = NO_OVERRIDE;
/* Indicate that we do not want to transfer more than 500 */
/* documents */
max_row = 500;
/* Initialize the output variables */
num_row = 0;
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
collectionName_ind = 0;

Chapter 14. Calling a stored procedure from your application 819

serviceName_ind = 0;
policyName_ind = 0;
maxrow_ind = 0;
/* Initialize the indicators for the output parameters */
numrow_ind = -1;
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQRETRIEVE(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:collectionName:collectionName_ind,
:overrideType:ovtype_ind,
:override:ov_ind,
:max_row:maxrow_ind,
:num_row:numrow_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQRETRIEVE output

If DXXMQRETRIEVE executes successfully, the number of documents indicated by

the mq-num-msgs field of the status parameter are extracted from DB2 tables and
inserted into the MQ message queue. If DXXMQRETRIEVE does not execute
successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQGENCLOB stored procedure

The DXXMQGENCLOB stored procedure constructs XML documents from data
that is stored in DB2 tables that are specified in a document access definition
(DAD) file, and sends the XML documents to an MQ message queue. Use
DXXMQGENCLOB for XML documents with a record length of up to 32 KB.

| Restriction: DXXMQGENCLOB has been deprecated.

There are two versions of DXXMQGENCLOB:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQGENCLOB

DXXMQGENCLOB runs in a WLM-established stored procedure address space

and uses the Resource Recovery Services attachment facility to connect to DB2.

DXXMQGENCLOB requires that WebSphere MQ and XML Extender are installed.

Authorization required for DXXMQGENCLOB

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQGENCLOB
v Ownership of the stored procedure
v SYSADM authority

820 Application Programming and SQL Guide

DXXMQGENCLOB syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQGENCLOB. Because the linkage convention for DXXMQGENCLOB is
GENERAL WITH NULLS, if you pass parameters in host variables, you need to
include a null indicator with every host variable. Null indicators for input host
variables must be initialized before you execute the CALL statement.

CALL DMQXML1C .DXXMQGENCLOB ( service-name , policy-name , DAD-file-name,

DMQXML2C NULL NULL

override-type , override , max-rows , num-msgs, status )


NULL NULL NULL

DXXMQGENCLOB option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination to
which the message is to be sent. The service point is defined in the DSNAMT
repository file. If service-name is not listed in the DSNAMT repository file, or
service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.
policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
DAD-file-name
Specifies the name of the (DAD) file that maps the XML documents to DB2
tables. DAD-file-name must be specified, and must be the name of a valid DAD
file that exists on the system on which DXXMQGENCLOB runs. DAD-file-name
is an input parameter of type VARCHAR(80).
override-type
Specifies what the override parameter does. Possible values are:
NO_OVERRIDE
The override parameter does not override the condition in the DAD file.
This is the default.
SQL_OVERRIDE
The DAD file uses SQL mapping, and the override parameter contains
an SQL statement that overrides the SQL statement in the DAD file.
XML_OVERRIDE
The DAD file uses RDB_node mapping, and the override parameter
contains conditions that override the RDB_node mapping in the DAD
file.

Chapter 14. Calling a stored procedure from your application 821

override-type is an input parameter of type INTEGER. The integer equivalents
of the override-type values are defined in the dxx.h file.
override
Specifies a string that overrides the condition in the DAD file. The contents of
the string depend on the value of the override-type parameter:
v If override-type is NO_OVERRIDE, override contains a null string. This is the
default.
v If override-type is SQL_OVERRIDE, override contains a valid SQL statement
that overrides the SQL statement in the DAD file.
v If override-type is XML_OVERRIDE, override contains one or more expressions
that are separated by AND. Each expression must be enclosed in double
quotation marks. This override value overrides the RDB_node mapping in the
DAD file.
override is an input parameter of type VARCHAR(1024).
max-rows
Specifies the maximum number of XML documents that DXXMQGENCLOB
can send to the MQ message queue. The default is 1.
max-rows is an input parameter of type INTEGER.
num-rows
The actual number of XML documents that DXXMQGENCLOB sends to the
MQ message queue.
num-rows is an output parameter of type INTEGER.
status
Contains information that indicates whether DXXMQGENCLOB ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQGENCLOB ran successfully, or the SQLCODE from the
most recent unsuccessful SQL statement if DXXMQGENCLOB ran
unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQGENCLOB invocation

The following example calls the two-phase commit version of DXXMQGENCLOB

to generate CLOB XML documents and send them to an MQ message queue. The
calling program does not override the definitions in the DAD file. For a complete
example of DXXMQGENCLOB invocation, see DSN8QXGR in
DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char dadFileName[80]; /* DAD file name */
short overrideType; /* defined in dxx.h */
char override[2]; /* Override string for DAD */
short max_row; /* Maximum number of documents*/
short num_row; /* Actual number of documents */

822 Application Programming and SQL Guide

char status[20]; /* Status of DXXMQGENCLOB call */
/* DXXMQGENCLOB is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short dadFileName_ind; /* Indicator var for dadFileName */
short ovtype_ind; /* Indicator var for overrideType */
short ov_ind; /* Indicator var for override */
short maxrow_ind; /* Indicator var for maxrow */
short numrow_ind; /* Indicator var for numrow */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the name of the DAD file for the DB2 tables */
strcpy(dadFileName,"/tmp/getstart_xcollection.dad");
/* Put null in the override parameter because we are not going */
/* to override the values in the DAD file */
override[0] = '\0';
overrideType = NO_OVERRIDE;
/* Indicate that we do not want to transfer more than 500 */
/* documents */
max_row = 500;
/* Initialize the output variables */
num_row = 0;
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */
dadFileName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
maxrow_ind = 0;
/* Initialize the indicators for the output parameters */
numrow_ind = -1;
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML2C.DXXMQGENCLOB(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:dadFileName:dadFileName_ind,
:overrideType:ovtype_ind,
:override:ov_ind,
:max_row:maxrow_ind,
:num_row:numrow_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQGENCLOB output

If DXXMQGENCLOB executes successfully, the number of documents indicated by

the mq-num-msgs field of the status parameter are extracted from DB2 tables and
inserted into the MQ message queue. If DXXMQGENCLOB does not execute
successfully, the contents of the status parameter indicate the problem.

Deprecated: DXXMQRETRIEVECLOB stored procedure

The DXXMQRETRIEVECLOB stored procedure constructs XML documents from
data that is stored in DB2 tables that are specified in an enabled XML collection,

Chapter 14. Calling a stored procedure from your application 823

and sends the XML documents to an MQ message queue. Use
DXXMQRETRIEVECLOB for XML documents with a length of up to 32 KB.

| Restriction: DXXMQRETRIEVECLOB has been deprecated.

There are two versions of DXXMQRETRIEVECLOB:

v A single-phase commit version, with schema name DMQXML1C.
v A two-phase commit version, with schema name DMQXML2C.

Environment for DXXMQRETRIEVECLOB

DXXMQRETRIEVECLOB runs in a WLM-established stored procedure address

space and uses the Resource Recovery Services attachment facility to connect to
DB2.

DXXMQRETRIEVECLOB requires that WebSphere MQ and XML Extender are

installed.

Authorization required for DXXMQRETRIEVECLOB

To execute the CALL statement, the owner of the package or plan that contains the
CALL statement must have one or more of the following privileges:
v The EXECUTE privilege on stored procedure DXXMQRETRIEVECLOB
v Ownership of the stored procedure
v SYSADM authority

DXXMQRETRIEVECLOB syntax diagram

The following syntax diagram shows the SQL CALL statement for invoking
DXXMQRETRIEVECLOB. Because the linkage convention for
DXXMQRETRIEVECLOB is GENERAL WITH NULLS, if you pass parameters in
host variables, you need to include a null indicator with every host variable. Null
indicators for input host variables must be initialized before you execute the CALL
statement.

CALL DMQXML1C .DXXMQRETRIEVECLOB ( service-name , policy-name ,

DMQXML2C NULL NULL

XML-collection-name, override-type , override , max-rows , num-msgs, status )


NULL NULL NULL

DXXMQRETRIEVECLOB option descriptions

service-name
Specifies the service point that is the logical WebSphere MQ destination to
which the message is to be sent. The service point is defined in the DSNAMT
repository file. If service-name is not listed in the DSNAMT repository file, or
service-name is not specified, DB2.DEFAULT.SERVICE is used.
service-name is an input parameter of type VARCHAR(48). service-name cannot
be blank, a null string, or have trailing blanks.

824 Application Programming and SQL Guide

policy-name
Specifies the WebSphere MQ AMI service policy that is used to handle the
message. The service policy is defined in the DSNAMT repository file. If
policy-name is not listed in the DSNAMT repository file, or policy-name is not
specified, DB2.DEFAULT.POLICY is used.
policy-name is an input parameter of type VARCHAR(48). policy-name cannot be
blank, a null string, or have trailing blanks.
XML-collection-name
Specifies the name of the XML collection that specifies the DB2 tables from
which the XML documents are to be retrieved. XML-collection-name must be
specified, and must be the name of a valid XML collection that exists on the
system on which DXXMQRETRIEVECLOB runs. XML-collection-name is an
input parameter of type VARCHAR(80).
override-type
Specifies what the override parameter does. Possible values are:
NO_OVERRIDE
The override parameter does not override the condition in the DAD file.
This is the default.
SQL_OVERRIDE
The DAD file uses SQL mapping, and the override parameter contains
an SQL statement that overrides the SQL statement in the DAD file.
XML_OVERRIDE
The DAD file uses RDB_node mapping, and the override parameter
contains conditions that override the RDB_node mapping in the DAD
file.
override-type is an input parameter of type INTEGER. The integer equivalents
of the override-type values are defined in the dxx.h file.
override
Specifies a string that overrides the condition in the DAD file. The contents of
the string depend on the value of the override-type parameter:
v If override-type is NO_OVERRIDE, override contains a null string. This is the
default.
v If override-type is SQL_OVERRIDE, override contains a valid SQL statement
that overrides the SQL statement in the DAD file.
v If override-type is XML_OVERRIDE, override contains one or more expressions
that are separated by AND. Each expression must be enclosed in double
quotation marks. This override value overrides the RDB_node mapping in the
DAD file.
override is an input parameter of type VARCHAR(1024).
max-rows
Specifies the maximum number of XML documents that
DXXMQRETRIEVECLOB can send to the MQ message queue. The default is 1.
max-rows is an input parameter of type INTEGER.
num-rows
The actual number of XML documents that DXXMQRETRIEVECLOB sends to
the MQ message queue.
num-rows is an output parameter of type INTEGER.

Chapter 14. Calling a stored procedure from your application 825

status
Contains information that indicates whether DXXMQRETRIEVECLOB ran
successfully. The format of status is dxx-rc:sqlcode:mq-num-msgs, where:
v dxx-rc is the return code from accessing XML Extender. dxx-rc values are
defined in dxxrc.h.
v sqlcode is 0 if DXXMQRETRIEVECLOB ran successfully, or the SQLCODE
from the most recent unsuccessful SQL statement if
DXXMQRETRIEVECLOB ran unsuccessfully.
v mq-num-msgs is the number of messages that were successfully sent to the
MQ message queue.
status is an output parameter of type CHAR(20).

Example of DXXMQRETRIEVECLOB invocation

The following example calls the single-phase commit version of

DXXMQRETRIEVECLOB to generate XML documents and send them to an MQ
message queue. The calling program does not override the definitions in the DAD
file. For a complete example of DXXMQRETRIEVECLOB invocation, see
DSN8QXGR in DSN910.SDSNSAMP.
#include "dxx.h"
#include "dxxrc.h"
EXEC SQL INCLUDE SQLCA;
EXEC SQL BEGIN DECLARE SECTION;
char serviceName[48]; /* WebSphere MQ service name */
char policyName[48]; /* WebSphere MQ policy name */
char collectionName[80]; /* XML collection name */
short overrideType; /* defined in dxx.h */
char override[2]; /* Override string for DAD */
short max_row; /* Maximum number of documents*/
short num_row; /* Actual number of documents */
char status[20]; /* Status of DXXMQRETRIEVECLOB call */
/* DXXMQRETRIEVECLOB is GENERAL WITH NULLS, so parameters need indicators */
short serviceName_ind; /* Indicator var for serviceName */
short policyName_ind; /* Indicator var for policyName */
short collectionName_ind; /* Indicator var for dadFileName */
short ovtype_ind; /* Indicator var for overrideType */
short ov_ind; /* Indicator var for override */
short maxrow_ind; /* Indicator var for maxrow */
short numrow_ind; /* Indicator var for numrow */
short status_ind; /* Indicator var for status */
EXEC SQL END DECLARE SECTION;
/* Status fields */
int dxx_rc=0;
int dxx_sql=0;
int dxx_mq=0;
/* Get the service name and policy name for the MQ message queue */
strcpy(serviceName,"DB2.DEFAULT.SERVICE");
strcpy(policyName,"DB2.DEFAULT.POLICY");
/* Get the XML collection name */
strcpy(collectionName,"sales_ord");
/* Put null in the override parameter because we are not going */
/* to override the values in the DAD file */
override[0] = '\0';
overrideType = NO_OVERRIDE;
/* Indicate that we do not want to transfer more than 500 */
/* documents */
max_row = 500;
/* Initialize the output variables */
num_row = 0;
status[0] = '\0';
/* Set the indicators to 0 for the parameters that have non-null */
/* values */

826 Application Programming and SQL Guide

collectionName_ind = 0;
serviceName_ind = 0;
policyName_ind = 0;
maxrow_ind = 0;
/* Initialize the indicators for the output parameters */
numrow_ind = -1;
status_ind = -1;
/* Call the store procedure */
EXEC SQL CALL DMQXML1C.DXXMQRETRIEVECLOB(:serviceName:serviceName_ind,
:policyName:policyName_ind,
:collectionName:collectionName_ind,
:overrideType:ovtype_ind,
:override:ov_ind,
:max_row:maxrow_ind,
:num_row:numrow_ind,
:status:status_ind);
printf("SQLCODE from CALL:
/* Get the status fields from the status parameter and print them */
sscanf(status,"dxx_rc,&dxx_sql,&dxx_mq);
printf("Status fields: dxx_rc=%d dxx_sql=%d dxx_mq=

DXXMQRETRIEVECLOB output

If DXXMQRETRIEVECLOB executes successfully, the number of documents

indicated by the mq-num-msgs field of the status parameter are extracted from DB2
tables and inserted into the MQ message queue. If DXXMQRETRIEVECLOB does
not execute successfully, the contents of the status parameter indicate the problem.

XSR_REGISTER stored procedure

The XSR_REGISTER procedure is the first stored procedure to be called as part of
the XML schema registration process, which registers XML schemas with the XSR.

The user that calls this stored procedure is considered the creator of this XML
schema. DB2 obtains the namespace attribute from the schema document when
XSR_COMPLETE is invoked.

Environment for XSR_REGISTER

XSR_REGISTER runs in a WLM-established stored procedures address space.

Authorization required for XSR_REGISTER

The user ID of the caller of the procedure must have the EXECUTE privilege on
the XSR_REGISTER stored procedure.

XSR_REGISTER syntax diagram

The following syntax diagram shows the CALL statement for invoking
XSR_REGISTER.

Chapter 14. Calling a stored procedure from your application 827

SYSPROC


CALL . XSR_REGISTER ( rschema , name , schemalocation ,

NULL NULL NULL

content , docproperty )

NULL

XSR_REGISTER option descriptions

| rschema
An input argument of type VARCHAR(128) that specifies the SQL schema for
the XML schema. If a value is specified, it must be SYSXSR. Rules for valid
characters and delimiters that apply to any SQL identifier also apply to this
argument.
name
An input and output argument of type VARCHAR(128) that specifies the name
of the XML schema. The complete SQL identifier for the XML schema is
″rschema.name″ and should be unique among all objects in the XSR. This
argument accepts a NULL value. When a NULL value is provided for this
argument, a unique value is generated and stored within the XSR. Rules for
valid characters and delimiters that apply to any SQL identifier also apply to
this argument.
schemalocation
An input argument of type VARCHAR(1000), which can have a NULL value,
that indicates the schema location of the primary XML schema document. This
argument is the ″external name″ of the XML schema, that is, the primary
document can be identified in the XML instance documents with the
xsi:schemaLocation attribute.
| content
An input parameter of type BLOB(30M) that contains the content of the
primary XML schema document. This argument cannot have a NULL value; an
XML schema document must be supplied. The content of the XML schema
document must be encoded in Unicode.
docproperty
An input parameter of type BLOB(5M) that indicates the properties for the
primary XML schema document. This parameter can have a NULL value;
otherwise, the value is an XML document.

Example of XSR_REGISTER

The following example calls the XSR_REGISTER stored procedure:

CALL SYSPROC.XSR_REGISTER(
'SYSXSR',
'POschema',
'http://myPOschema/PO.xsd',
:content_host_var,
:docproperty_host_var)

| In this example, XSR_REGISTER folds the name POschema to uppercase, so the

| registered schema name is POSCHEMA. If you do not want XSR_REGISTER to
| fold POschema to uppercase, you need to delimit the name with double quotation
| marks (″), as in the following example.

828 Application Programming and SQL Guide

| CALL SYSPROC.XSR_REGISTER(
| 'SYSXSR',
| '"POschema"',
| 'http://myPOschema/PO.xsd',
| :content_host_var,
| :docproperty_host_var)

XSR_ADDSCHEMADOC stored procedure

The XSR_ADDSCHEMADOC stored procedure adds every XML schema, other
than the primary XML schema document, to the XSR.

Each XML schema in the XSR can consist of one or more XML schema documents.
When an XML schema consists of multiple documents, you need to call
XSR_ADDSCHEMADOC for the additional documents.

Environment for XSR_ADDSCHEMADOC

XSR_ADDSCHEMADOC runs in a WLM-established stored procedures address

space.

Authorization required for XSR_ADDSCHEMADOC

The user ID of the caller of the procedure must have the EXECUTE privilege on
the XSR_ADDSCHEMADOC stored procedure.

XSR_ADDSCHEMADOC syntax diagram

The following syntax diagram shows the CALL statement for invoking
XSR_ADDSCHEMADOC.

SYSPROC


CALL . XSR_ADDSCHEMADOC ( rschema , name , schemalocation ,

NULL NULL

content , docproperty )

NULL

XSR_ADDSCHEMADOC option descriptions

| rschema
An input argument of type VARCHAR(128) that specifies the SQL schema for
the XML schema. If a value is specified, it must be SYSXSR. Rules for valid
characters and delimiters that apply to any SQL identifier also apply to this
argument.
name
An input argument of type VARCHAR(128) that specifies the name of the XML
schema. The complete SQL identifier for the XML schema is ″rschema.name″.
The XML schema name must already exist as a result of calling the
XSR_REGISTER stored procedure, and XML schema registration cannot yet be
completed. This argument cannot have a NULL value. Rules for valid
characters and delimiters that apply to any SQL identifier also apply to this
argument.

Chapter 14. Calling a stored procedure from your application 829

schemalocation
An input argument of type VARCHAR(1000), which can have a NULL value,
that indicates the schema location of the primary XML schema document to
which the XML schema document is being added. This argument is the
″external name″ of the XML schema, that is, the primary document can be
identified in the XML instance documents with the xsi:schemaLocation
attribute. The document that references the schemalocation must use valid a
URI format.
content
| An input parameter of type BLOB(30M) that contains the content of the XML
| schema document being added. This argument cannot have a NULL value. An
| XML schema document must be supplied. The content of the XML schema
| document must be encoded in Unicode.
docproperty
An input parameter of type BLOB(5M) that indicates the properties for the
XML schema document being added. This parameter can have a NULL value;
otherwise, the value is an XML document.

Example of XSR_ADDSCHEMADOC

The following example calls the XSR_ADDSCHEMADOC stored procedure:

| CALL SYSPROC.XSR_ADDSCHEMADOC(
| 'SYSXSR',
| 'POschema',
| 'http://myPOschema/PO.xsd',
| :schema_content,
| :schema_properties)

| In this example, XSR_ADDSCHEMADOC folds the name POschema to uppercase,

| so the name of the XML schema that is added is POSCHEMA. If you do not want
| XSR_ADDSCHEMADOC to fold POschema to uppercase, you need to delimit the
| name with double quotation marks (″), as in the following example.
| CALL SYSPROC.XSR_ADDSCHEMADOC(
| 'SYSXSR',
| '"POschema"',
| 'http://myPOschema/PO.xsd',
| :schema_content,
| :schema_properties)

XSR_COMPLETE stored procedure

The XSR_COMPLETE procedure is the final stored procedure to be called as part
of the XML schema registration process, which registers XML schemas with the
XSR.

An XML schema is not available for validation until the schema registration
completes through a call to this stored procedure.

Environment for XSR_COMPLETE

| XSR_COMPLETE requires a WLM-established stored procedures address space that

| is configured for running Java routines.

Authorization required for XSR_COMPLETE

The user ID of the caller of the procedure must have the EXECUTE privilege on
the XSR_COMPLETE stored procedure.

830 Application Programming and SQL Guide

XSR_COMPLETE syntax diagram

The following syntax diagram shows the CALL statement for invoking
XSR_COMPLETE.

SYSPROC


CALL . XSR_COMPLETE ( rschema , name , schemaproperties ,

issuedfordecomposition )


XSR_COMPLETE option descriptions

rschema
| An input argument of type VARCHAR(128) that specifies the SQL schema for
| the XML schema. If a value is specified, it must be SYSXSR. Rules for valid
| characters and delimiters that apply to any SQL identifier also apply to this
| argument.
name
An input argument of type VARCHAR(128) that specifies the name of the XML
schema. The complete SQL identifier for the XML schema, for which a
completion check is to be performed, is rschema.name. The XML schema name
must already exist as a result of calling the XSR_REGISTER stored procedure.
This argument cannot have a NULL value. Rules for valid characters and
delimiters that apply to any SQL identifier also apply to this argument.
schemaproperties
An input argument of type BLOB(5M) that specifies properties, if any,
associated with the XML schema. The value for this argument is either NULL,
if there are no associated properties, or an XML document representing the
properties for the XML schema.
isusedfordecomposition
An input parameter of type integer that indicates if an XML schema is to be
used for decomposition. If an XML schema is to be used for decomposition,
this value should be set to 1; otherwise, it should be set to zero. XML schema
decomposition is deprecated.

Example of XSR_COMPLETE

The following example calls the XSR_COMPLETE stored procedure:

CALL SYSPROC.XSR_COMPLETE(
'SYSXSR',
'POschema',
:schemaproperty_host_var,
0)

| In this example, XSR_COMPLETE folds the name POschema to uppercase, so the

| name of the XML schema for which registration is completed is POSCHEMA. If
| you do not want XSR_COMPLETE to fold POschema to uppercase, you need to
| delimit the name with double quotation marks (″), as in the following example.

Chapter 14. Calling a stored procedure from your application 831

CALL SYSPROC.XSR_COMPLETE(
'SYSXSR',
'"POschema"',
:schemaproperty_host_var,
0)

XSR_REMOVE stored procedure

The XSR_REMOVE procedure is used to remove all components of an XML
schema. After the XML schema is removed, you can reuse the name of the
removed XML schema when you register a new XML schema.

Environment for XSR_REMOVE

XSR_REMOVE runs in a WLM-established stored procedures address space.

Authorization required for XSR_REMOVE

The user ID of the caller of the procedure must have the EXECUTE privilege on
the XSR_REMOVE stored procedure.

XSR_REMOVE syntax diagram

The following syntax diagram shows the CALL statement for invoking
XSR_REMOVE.

SYSPROC


CALL . XSR_REMOVE ( rschema , name )

NULL

XSR_REMOVE option descriptions

| rschema
An input argument of type VARCHAR (128) that specifies the SQL schema for
the XML schema. If a value is specified, it must be SYSXSR. Rules for valid
characters and delimiters that apply to any SQL identifier also apply to this
argument.
name
An input argument of type VARCHAR (128) that specifies the name of the
XML schema. The complete SQL identifier for the XML schema, for which a
completion check is to be performed, is ″rschema.name″. The XML schema
name must already exist as a result of calling the XSR_REGISTER stored
procedure, and XML schema registration cannot yet be completed. This
argument cannot have a NULL value. Rules for valid characters and delimiters
that apply to any SQL identifier also apply to this argument.

Example of XSR_REMOVE

The following example calls the XSR_REMOVE stored procedure:

CALL SYSPROC.XSR_REMOVE(
'SYSXSR',
'POschema')

| In this example, XSR_REMOVE folds the name POschema to uppercase, so the

| name of the XML schema that is removed is POSCHEMA. If you do not want

832 Application Programming and SQL Guide

| XSR_REMOVE to fold POschema to uppercase, you need to delimit the name with
| double quotation marks (″), as in the following example.
CALL SYSPROC.XSR_REMOVE(
'SYSXSR',
'"POschema"')

Deprecated: XDBDECOMPXML stored procedure

The XDBDECOMPXML procedure extracts values from textual XML data and
populates relational tables with the values.

The XDBDECOMPXML stored procedure uses an XML schema, which contains

annotations that indicate which columns and tables should be used to store the
decomposed XML values. The referenced XML schema must exist in the XSR and
must be enabled for decomposition. You can enable an XML schema for
decomposition by using the XSR_COMPLETE stored procedure. If your XML
schema references tables that did not exist when you invoked the XSR_COMPLETE
stored procedure, DB2 will return an error.

Environment for XDBDECOMPXML

XDBDECOMPXML runs in a WLM-established stored procedures address space.

Authorization required for XDBDECOMPXML

To invoke the XDBDECOMPXML stored procedure, you must have:

v The EXECUTE privilege on XDBDECOMPXML
v The INSERT privilege on tables that are specified in the annotations

XDBDECOMPXML syntax diagram

The following syntax diagram shows the CALL statement for invoking
XDBDECOMPXML.

SYSPROC


CALL . XDBDECOMPXML ( rschema , name , xmldoc , documentid )

NULL NULL

XDBDECOMPXML option descriptions

rschema
An input argument of type VARCHAR(128) that specifies the SQL schema for
the XML schema. If a value is specified, it must be SYSXSR.
name
An input argument of type VARCHAR(128) that specifies the name of the XML
schema. The complete SQL identifier for the XML schema, for which
decomposition is to be performed, is ″rschema.name″. The XML schema name
must already exist and be enabled for decomposition as a result of calling the
XSR_COMPLETE stored procedure. This argument cannot have a NULL value.
Rules for valid characters and delimiters that apply to any SQL identifier also
apply to this argument.

Chapter 14. Calling a stored procedure from your application 833

xmldoc
An input parameter of type CLOB AS LOCATOR that points to the XML value
that is to be decomposed. This parameter cannot be null.
documentid
An input parameter of type VARCHAR(1024) that contains a string that the
caller can use to identify the input XML document. This parameter can be null.

834 Application Programming and SQL Guide

Chapter 15. Coding methods for distributed data
You can access distributed data by using three-part table names or explicit connect
statements.

Three-part table names are described in “Accessing distributed data by using

three-part table names.” Explicit connect statements are described in “Accessing
distributed data by using explicit CONNECT statements” on page 837.

These two methods of coding applications for distributed access are illustrated by
the following example.

Example: Spiffy Computer has a master project table that supplies information
about all projects that are currently active throughout the company. Spiffy has
several branches in various locations around the world, each a DB2 location that
maintains a copy of the project table named DSN8910.PROJ. The main branch
location occasionally inserts data into all copies of the table. The application that
makes the inserts uses a table of location names. For each row that is inserted, the
application executes an INSERT statement in DSN8910.PROJ for each location.

Copying a table from a remote location: To copy a table from one location to
another, you can either write your own application program or use the DB2
DataPropagator™ product.

Accessing distributed data by using three-part table names

You can use three-part table names to access data at a remote location through
DRDA access or DB2 private protocol access.

When you use three-part table names, the way you code your application is the
same, regardless of the access method you choose. You determine the access
method when you bind the SQL statements into a package or plan. If you use
DRDA access, you must bind the DBRMs for the SQL statements to be executed at
the server to packages that reside at that server.

Recommendation: If you plan to port a distributed application that runs on a

z/OS client to another client, avoid the use of three-part names. If a client
application includes three-part names, and the z/OS client or Linux, UNIX, and
Windows client directly accesses a DB2 for Linux, UNIX, and Windows server, an
error occurs.

In a three-part table name, the first part denotes the location. The local DB2 makes
and breaks an implicit connection to a remote server as needed.

When a three-part name is parsed and forwarded to a remote location, any special
register settings are automatically propagated to remote server. This allows the
SQL statements to process the same way no matter at what site a statement is run.

The following example assumes that all systems involved implement two-phase
commit. This example suggests updating several systems in a loop and ending the
unit of work by committing only when the loop is complete. Updates are
coordinated across the entire set of systems.

© Copyright IBM Corp. 1983, 2009 835

Spiffy’s application uses a location name to construct a three-part table name in an
INSERT statement. It then prepares the statement and executes it dynamically. The
values to be inserted are transmitted to the remote location and substituted for the
parameter markers in the INSERT statement.

The following overview shows how the application uses three-part names:
Read input values
Do for all locations
Read location name
Set up statement to prepare
Prepare statement
a Execute statement
End loop
Commit

After the application obtains a location name, for example ’SAN_JOSE’, it next
creates the following character string:
INSERT INTO SAN_JOSE.DSN8910.PROJ VALUES (?,?,?,?,?,?,?,?)

The application assigns the character string to the variable INSERTX and then
executes these statements:
EXEC SQL
PREPARE STMT1 FROM :INSERTX;
EXEC SQL
EXECUTE STMT1 USING :PROJNO, :PROJNAME, :DEPTNO, :RESPEMP,
:PRSTAFF, :PRSTDATE, :PRENDATE, :MAJPROJ;

The host variables for Spiffy’s project table match the declaration for the sample
project table.

To keep the data consistent at all locations, the application commits the work only
when the loop has executed for all locations. Either every location has committed
the INSERT or, if a failure has prevented any location from inserting, all other
locations have rolled back the INSERT. (If a failure occurs during the commit
process, the entire unit of work can be indoubt.)

Recommendation: You might find it convenient to use aliases when creating

character strings that become prepared statements, instead of using full three-part
names like SAN_JOSE.DSN8910.PROJ.

Three-part names and multiple servers: If you use a three-part name, or an alias
that resolves to one, in a statement that is executed at a remote server by DRDA
access, and if the location name is not that of the server, then the method by which
the remote server accesses data at the named location depends on the value of
DBPROTOCOL. If the package at the first remote server is bound with
DBPROTOCOL(PRIVATE), DB2 uses DB2 private protocol access to access the
second remote server. If the package at the first remote server is bound with
DBPROTOCOL(DRDA), DB2 uses DRDA access to access the second remote server.
The following steps are recommended so that access to the second remote server is
by DRDA access:
1. Rebind the package at the first remote server with DBPROTOCOL(DRDA).
2. Bind the package that contains the three-part name at the second server.

836 Application Programming and SQL Guide

Related concepts
“Dynamic SQL” on page 162
Aliases and synonyms (SQL Reference)
Related tasks
“Binding packages at a remote location” on page 917
Related reference
Project table (.) (Introduction to DB2 for z/OS)

Accessing remote declared temporary tables by using

three-part table names
You can access a remote declared temporary table by using a three-part name only
if you use DRDA access. However, if you combine explicit CONNECT statements
and three-part names in your application, a reference to a remote declared
temporary table must be a forward reference.

Example

You can perform the following series of actions, which includes a forward
reference to a declared temporary table:
EXEC SQL CONNECT TO CHICAGO; /* Connect to the remote site */
EXEC SQL
DECLARE GLOBAL TEMPORARY TABLE T1 /* Define the temporary table */
(CHARCOL CHAR(6) NOT NULL); /* at the remote site */
EXEC SQL CONNECT RESET; /* Connect back to local site */
EXEC SQL INSERT INTO CHICAGO.SESSION.T1
(VALUES 'ABCDEF'); /* Access the temporary table*/
/* at the remote site (forward reference) */

However, you cannot perform the following series of actions, which includes a
backward reference to the declared temporary table:
EXEC SQL
DECLARE GLOBAL TEMPORARY TABLE T1 /* Define the temporary table */
(CHARCOL CHAR(6) NOT NULL); /* at the local site (ATLANTA)*/
EXEC SQL CONNECT TO CHICAGO; /* Connect to the remote site */
EXEC SQL INSERT INTO ATLANTA.SESSION.T1
(VALUES 'ABCDEF'); /* Cannot access temp table */
/* from the remote site (backward reference)*/

Accessing distributed data by using explicit CONNECT statements

When use explicit CONNECT statements to access distributed data, the application
program explicitly connects to each new server.

You must bind the DBRMs for the SQL statements to be executed at the server to
packages that reside at that server.

The following example assumes that all systems involved implement two-phase
commit. This example suggests updating several systems in a loop and ending the
unit of work by committing only when the loop is complete. Updates are
coordinated across the entire set of systems.

In this example, Spiffy’s application executes CONNECT for each server in turn,
and the server executes INSERT. In this case, the tables to be updated each have
the same name, although each table is defined at a different server. The application
executes the statements in a loop, with one iteration for each server.

Chapter 15. Coding methods for distributed data 837

The application connects to each new server by means of a host variable in the
CONNECT statement. CONNECT changes the special register CURRENT SERVER
to show the location of the new server. The values to insert in the table are
transmitted to a location as input host variables.

The following overview shows how the application uses explicit CONNECTs:
Read input values
Do for all locations
Read location name
Connect to location
Execute insert statement
End loop
Commit
Release all

For example, the application inserts a new location name into the variable
LOCATION_NAME and executes the following statements:
EXEC SQL
CONNECT TO :LOCATION_NAME;
EXEC SQL
INSERT INTO DSN8910.PROJ VALUES (:PROJNO, :PROJNAME, :DEPTNO, :RESPEMP,
:PRSTAFF, :PRSTDATE, :PRENDATE, :MAJPROJ);

To keep the data consistent at all locations, the application commits the work only
when the loop has executed for all locations. Either every location has committed
the INSERT or, if a failure has prevented any location from inserting, all other
locations have rolled back the INSERT. (If a failure occurs during the commit
process, the entire unit of work can be indoubt.)

The host variables for Spiffy’s project table match the declaration for the sample
project table. LOCATION_NAME is a character-string variable of length 16.
Related reference
Project table (.) (Introduction to DB2 for z/OS)

Specifying a location alias name for multiple sites

You can override the location name that an application uses to access a server.

DB2 uses the DBALIAS value in the SYSIBM.LOCATIONS table to override the
location name that an application uses to access a server.

For example, suppose that an employee database is deployed across two sites and
that both sites make themselves known as location name EMPLOYEE. To access
each site, insert a row for each site into SYSIBM.LOCATIONS with the location
names SVL_EMPLOYEE and SJ_EMPLOYEE. Both rows contain EMPLOYEE as the
DBALIAS value. When an application issues a CONNECT TO SVL_EMPLOYEE
statement, DB2 searches the SYSIBM.LOCATIONS table to retrieve the location and
network attributes of the database server. Because the DBALIAS value is not blank,
DB2 uses the alias EMPLOYEE, and not the location name, to access the database.

If the application uses fully qualified object names in its SQL statements, DB2
sends the statements to the remote server without modification. For example,
suppose that the application issues the statement SELECT * FROM
SVL_EMPLOYEE.authid.table with the fully-qualified object name. However, DB2
accesses the remote server by using the EMPLOYEE alias. The remote server must
identify itself as both SVL_EMPLOYEE and EMPLOYEE; otherwise, it rejects the
SQL statement with a message indicating that the database is not found. If the

838 Application Programming and SQL Guide

remote server is DB2, the location SVL_EMPLOYEE might be defined as a location
alias for EMPLOYEE. DB2 z/OS servers are defined with this alias by using the
DDF ALIAS statement of the DSNJU003 change log inventory utility. DB2 locally
executes any SQL statements that contain fully qualified object names if the
high-level qualifier is the location name or any of its alias names.

Releasing connections
When you connect to remote locations explicitly, you must also break those
connections explicitly.

To break the connections, you can use the RELEASE statement. The RELEASE
statement differs from the CONNECT statement in the following ways:
v While the CONNECT statement makes an immediate connection, the RELEASE
statement does not immediately break a connection. The RELEASE statement
labels connections for release at the next commit point. A connection that has
been labeled for release is in the release-pending state and can still be used before
the next commit point.
v While the CONNECT statement connects to exactly one remote system, you can
use the RELEASE statement to specify a single connection or a set of connections
for release at the next commit point.

Example: By using the RELEASE statement, you can place any of the following
connections in the release-pending state:
v A specific connection that the next unit of work does not use:
EXEC SQL RELEASE SPIFFY1;
v The current SQL connection, whatever its location name:
EXEC SQL RELEASE CURRENT;
v All connections except the local connection:
EXEC SQL RELEASE ALL;
v All DB2 private protocol connections. If the first phase of your application
program uses DB2 private protocol access and the second phase uses DRDA
access, open DB2 private protocol connections from the first phase could cause a
CONNECT operation to fail in the second phase. To prevent that error, execute
the following statement before the commit operation that separates the two
phases:
EXEC SQL RELEASE ALL PRIVATE;

PRIVATE refers to DB2 private protocol connections, which exist only between
instances of DB2 for z/OS.

Transmitting mixed data

Mixed data means that the data contains both character and graphic data.

If you transmit mixed data between your local system and a remote system, put
the data in varying-length character strings instead of fixed-length character
strings.

Converting mixed data:

When ASCII MIXED data or Unicode MIXED data is converted to EBCDIC

MIXED, the converted string is longer than the source string. An error occurs if

Chapter 15. Coding methods for distributed data 839

that conversion is performed on a fixed-length input host variable. The remedy is
to use a varying-length string variable with a maximum length that is sufficient to
contain the expansion.

Identifying the server at run time

You can request the location name of the system to which you are connected.

The special register CURRENT SERVER contains the location name of the system
you are connected to. You can assign that name to a host variable with a statement
like this:
EXEC SQL SET :CS = CURRENT SERVER;

SQL limitations at dissimilar servers

When you execute SQL statements on a remote server that is running another DB2
family product, certain limitations exist. Generally, a program that uses DRDA
access can use SQL statements and clauses that are supported by a remote server,
even if they are not supported by the local server.

The following examples suggest what to expect from dissimilar servers:

v They support SELECT, INSERT, UPDATE, DELETE, DECLARE CURSOR, and
FETCH, but details vary.
Example: DB2 for Linux, UNIX, and Windows and DB2 for i support a form of
INSERT that allows for multiple rows of input data. In this case, the VALUES
clause is followed by multiple lists in parentheses. Each list represents the values
to be inserted for a row of data. DB2 for z/OS does not support this form of
INSERT.
v Data definition statements vary more widely.
Example: DB2 for z/OS supports ROWID columns; DB2 for Linux, UNIX, and
Windows does not support ROWID columns. Any data definition statements
that use ROWID columns cannot run across all platforms.
v Statements can have different limits.
Example: A query in DB2 for z/OS can have 750 columns; for other systems, the
maximum is higher. But a query using 750 or fewer columns could execute in all
systems.
v Some statements are not sent to the server but are processed completely by the
requester. You cannot use those statements in a remote package even though the
server supports them.
v In general, if a statement to be executed at a remote server contains host
variables, a DB2 requester assumes them to be input host variables unless it
supports the syntax of the statement and can determine otherwise. If the
assumption is not valid, the server rejects the statement.

Support for executing long SQL statements in a distributed

environment
A distributed application can send prepared SQL statements that are greater than
32 KB to the server. If the statements are greater than 32 KB, the server must
support these long statements. If you are using DB2 private protocol access, long
SQL statements are not supported.

840 Application Programming and SQL Guide

If a distributed application assigns an SQL statement to a DBCLOB (UTF-16)
variable and sends the prepared statement to a remote server, the remote DB2
server converts it to UTF-8. If the remote server does not support UTF-8, the
requester converts the statement to the system EBCDIC CCSID before sending it to
the remote server.

Distributed queries against ASCII or Unicode tables

When you perform a distributed query, the server determines the encoding scheme
of the result table.

When a distributed query against an ASCII or Unicode table arrives at the DB2 for
z/OS server, the server indicates in the reply message that the columns of the
result table contain ASCII or Unicode data, rather than EBCDIC data. The reply
message also includes the CCSIDs of the data to be returned. The CCSID of data
from a column is the CCSID that was in effect when the column was defined.

The encoding scheme in which DB2 returns data depends on two factors:
v The encoding scheme of the requesting system.
If the requester is ASCII or Unicode, the returned data is ASCII or Unicode. If
the requester is EBCDIC, the returned data is EBCDIC, even though it is stored
at the server as ASCII or Unicode. However, if the SELECT statement that is
used to retrieve the data contains an ORDER BY clause, the data displays in
ASCII or Unicode order.
v Whether the application program overrides the CCSID for the returned data. The
ways to do this are as follows:
– For static SQL
You can bind a plan or package with the ENCODING bind option to control
the CCSIDs for all static data in that plan or package. For example, if you
specify ENCODING(UNICODE) when you bind a package at a remote DB2
for z/OS system, the data that is returned in host variables from the remote
system is encoded in the default Unicode CCSID for that system.
For more information about the ENCODING bind options, see the topic
“BIND and REBIND options” in DB2 Command Reference.
– For static or dynamic SQL
An application program can specify overriding CCSIDs for individual host
variables in DECLARE VARIABLE statements. See “Setting the CCSID for
host variables” on page 146 for information about how to specify the CCSID
for a host variable.
An application program that uses an SQLDA can specify an overriding
CCSID for the returned data in the SQLDA. When the application program
executes a FETCH statement, you receive the data in the CCSID that is
specified in the SQLDA.

Restrictions when using scrollable cursors to access distributed data

The restrictions that exist for scrollable cursors depend on what the requestor and
the server support.

If a DB2 for z/OS server processes an OPEN cursor statement for a scrollable
cursor, and the OPEN cursor statement comes from a requester that does not
support scrollable cursors, the DB2 for z/OS server returns an SQL error. However,
if a stored procedure at the server uses a scrollable cursor to return a result set, the
down-level requester can access data through that cursor. The DB2 for z/OS server
Chapter 15. Coding methods for distributed data 841
converts the scrollable result set cursor to a non-scrollable cursor. The requester can
retrieve the data using sequential FETCH statements.

Restrictions when using rowset-positioned cursors to access

distributed data
The restrictions that exist for row-positioned cursors depend on what the requestor
and the server support.

If a DB2 for z/OS server processes an OPEN cursor statement for a

rowset-positioned cursor, and the OPEN cursor statement comes from a requester
that does not support rowset-positioned cursors, the DB2 for z/OS server returns
an SQL error. However, if a stored procedure at the server uses a rowset-positioned
cursor to return a result set, the down-level requester can access data through that
cursor by using row-positioned FETCH statements.

WebSphere MQ with DB2

WebSphere MQ is a message handling system that enables applications to
communicate in a distributed environment across different operating systems and
networks.

| WebSphere MQ handles the communication from one program to another by using

| application programming interfaces (APIs). You can use any of the following APIs
| to interact with the WebSphere MQ message handling system:
| v Message Queue Interface (MQI)
| v Application Messaging Interface (AMI)
| v WebSphere MQ classes for Java
| v WebSphere MQ classes for Java Message Service (JMS)

| Restriction: The AMI has been deprecated.

| DB2 provides its own application programming interface to the WebSphere MQ

| message handling system through a set of external user-defined functions, which
| are called DB2 MQ functions. You can use these functions in SQL statements to
| combine DB2 database access with WebSphere MQ message handling. The DB2
| MQ functions use either the AMI or the MQI.

Restriction: All DB2 MQ functions that use AMI are deprecated. You can convert
those applications that use the AMI-based functions to use the MQI-based
functions.
Related tasks
“Converting applications to use the MQI functions” on page 861
Related information
WebSphere MQ information center

WebSphere MQ messages
WebSphere MQ uses messages to pass information between applications.

Messages consist of the following parts:

v The message attributes, which identify the message and its properties.
v The message data, which is the application data that is carried in the message.

842 Application Programming and SQL Guide

Related concepts
“DB2 MQ functions and DB2 MQ XML stored procedures” on page 846

| WebSphere MQ message handling

| Conceptually, the WebSphere MQ message handling system takes a piece of
| information (the message) and sends it to its destination. MQ guarantees delivery
| despite any network disruptions that might occur.

| In WebSphere MQ, a destination is called a message queue, and a queue resides in

| a queue manager. Applications can put messages on queues or get messages from
| them.

| DB2 communicates with the WebSphere message handling system through a set of
| external user-defined functions, which are called DB2 MQ functions. These
| functions use either the MQI or the AMI.

| Restriction: The AMI and all DB2 MQ functions that use the AMI have been
| deprecated.

| When you send a message, you must specify the following three components:
| message data
| Defines what is sent from one program to another.
| service
| Defines where the message is going to or coming from. The parameters for
| managing a queue are defined in the service, which is typically defined by
| a system administrator. The complexity of the parameters in the service is
| hidden from the application program.
| policy Defines how the message is handled. Policies control such items as:
| v The attributes of the message, for example, the priority.
| v Options for send and receive operations, for example, whether an
| operation is part of a unit of work.

| The default service and policy are set as part of defining the WebSphere MQ
| configuration for a particular installation of DB2. (This action is typically
| performed by a system administrator.) DB2 provides the default service
| DB2.DEFAULT.SERVICE and the default policy DB2.DEFAULT.POLICY.

| How services and policies are stored and managed depends on whether you are
| using the AMI or the MQI.
| Related tasks
| Enabling WebSphere MQ user-defined functions (DB2 Installation and
| Migration)
| Related information
| WebSphere MQ information center

| WebSphere MQ message handling with the MQI:

| One way to send and receive WebSphere MQ messages from DB2 applications is to
| use the DB2 MQ functions that use MQI.

| These MQI-based functions use the services and policies that are defined in two
| DB2 tables, SYSIBM.MQSERVICE_TABLE and SYSIBM.MQPOLICY_TABLE. These

Chapter 15. Coding methods for distributed data 843

| tables are user-managed and are typically created and maintained by a system
| administrator. Each table contains a row for the default service and policy that are
| provided by DB2.

| The application program does not need know the details of the services and
| policies that are defined in these tables. The application need only specify which
| service and policy to use for each message that it sends and receives. The
| application specifies this information when it calls a DB2 MQ function.
| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures” on page 846
| Related reference
| “DB2 MQ tables” on page 853

| DB2 MQI services:

| A service describes a destination to which an application sends messages or from

| which an application receives messages. DB2 MQI services are defined in the DB2
| table SYSIBM.MQSERVICE_TABLE.

| The MQI-based DB2 MQ functions use the services that are defined in the DB2
| table SYSIBM.MQSERVICE_TABLE. This table is user-managed and is typically
| created and maintained by a system administrator. This table contains a row for
| each defined service, including your customized services and the default service
| that is provided by DB2.

| The application program does not need know the details of the defined services.
| When an application program calls an MQI-based DB2 MQ function, the program
| selects a service from SYSIBM.MQSERVICE_TABLE by specifying it as a parameter.
| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures” on page 846
| “WebSphere MQ message handling” on page 843
| Related reference
| “DB2 MQ tables” on page 853

| DB2 MQI policies:

| A policy controls how the MQ messages are handled. DB2 MQI policies are
| defined in the DB2 table SYSIBM.MQPOLICY_TABLE.

| The MQI-based DB2 MQ functions use the policies that are defined in the DB2
| table SYSIBM.MQPOLICY_TABLE. This table is user-managed and is typically
| created and maintained by a system administrator. This table contains a row for
| each defined policy, including your customized policies and the default policy that
| is provided by DB2.

| The application program does not need know the details of the defined policies.
| When an application program calls an MQI-based DB2 MQ function, the program
| selects a policy from SYSIBM.MQPOLICY_TABLE by specifying it as a parameter.

844 Application Programming and SQL Guide

| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures” on page 846
| “WebSphere MQ message handling” on page 843
| Related reference
| “DB2 MQ tables” on page 853

| WebSphere MQ message handling with the AMI:

| One way to send and receive WebSphere MQ messages from DB2 applications is to
| use the DB2 MQ functions that use AMI. However, be aware that this interface and
| the associated DB2 MQ functions have been deprecated.

| Restriction: The AMI and the DB2 MQ functions that use the AMI have been
| deprecated. You can convert those applications that use the AMI-based functions to
| use the MQI-based functions.

| The AMI-based functions use the services and policies that are defined in AMI
| configuration files, which are in XML format. Typically, these files are created and
| maintained by a system administrator. These files also define any default services
| and policies, including the defaults that are provided by DB2.

| The application program does not need know the details of the services and
| policies that are defined in these files. The application need only specify which
| service and policy to use for each message that it sends and receives. The
| application specifies this information when it calls a DB2 MQ function.

| The AMI uses the service and policy to interpret and construct the MQ headers
| and message descriptors. The AMI does not act on the message data.
| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures” on page 846
| Related tasks
| “Converting applications to use the MQI functions” on page 861
| Related information
| WebSphere MQ information center

| AMI services:

| A service describes a destination to which an application sends messages or from

| which an application receives messages. AMI services are defined in AMI
| configuration files.

| Restriction: The AMI and the DB2 MQ functions that use the AMI have been
| deprecated.

| The AMI-based DB2 MQ functions use the services that are defined in AMI
| configuration files, which are in XML format. These files are typically created and
| maintained by a system administrator. These files contain all of the defined
| services, including your customized services and any default services, such as the
| one that DB2 provides.

| The application program does not need know the details of the defined services.
| When an application program calls an AMI-based DB2 MQ function, the program
| selects a service from the AMI configuration file by specifying it as a parameter.

Chapter 15. Coding methods for distributed data 845

| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures”
| “WebSphere MQ message handling” on page 843

| AMI policies:

| A policy controls how the MQ messages are handled. AMI policies are defined in
| AMI configuration files.

| Restriction: The AMI and the DB2 MQ functions that use the AMI have been
| deprecated.

| The AMI-based DB2 MQ functions use the policies that are defined in AMI
| configuration files, which are in XML format. These files are typically created and
| maintained by a system administrator. These files contain all of the defined
| policies, including your customized policies and any default policies, such as the
| one that DB2 provides.

| The application program does not need know the details of the defined policies.
| When an application program calls an AMI-based DB2 MQ function, the program
| selects a policy from the AMI configuration file by specifying it as a parameter.
| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures”
| “WebSphere MQ message handling” on page 843

DB2 MQ functions and DB2 MQ XML stored procedures

You can use the DB2 MQ functions and stored procedures to send messages to a
message queue or to receive messages from the message queue.

The DB2 MQ functions support the following types of operations:

v Send and forget, where no reply is needed.
v Read or receive, where one or all messages are either read without removing
them from the queue, or received and removed from the queue.
v Request and response, where a sending application needs a response to a
request.
v Publish and subscribe, where messages are assigned to specific publisher
services and are sent to queues. Applications that subscribe to the corresponding
subscriber service can monitor specific messages.

You can use the DB2 MQ functions and stored procedures to send messages to a
message queue or to receive messages from the message queue. You can send a
request to a message queue and receive a response, and you can also publish
messages to the WebSphere MQ publisher and subscribe to messages that have
been published with specific topics. The DB2 MQ XML functions and stored
procedures enable you to query XML documents and then publish the results to a
message queue.

| The WebSphere MQ server is located on the same z/OS system as the DB2
| database server. The DB2 MQ functions and stored procedures are registered with
| the DB2 database server and provide access to the WebSphere MQ server by using
| the MQI.

846 Application Programming and SQL Guide

| The WebSphere MQ server is located on the same z/OS system as the DB2
| database server. The DB2 MQ functions and stored procedures are registered with
| the DB2 database server and provide access to the WebSphere MQ server by using
| either the AMI or the MQI.

| The DB2 MQ functions include scalar functions, table functions, and XML-specific
| functions. For each of these functions, you can call a version that uses the MQI or
| a version that uses the AMI. (Any exceptions are noted in the description of these
| functions.) The function signatures are the same. However, the qualifying schema
| names are different. To call an MQI-based function, specify the schema name
| DB2MQ. To call an AMI-based function, specify the schema names DB2MQ1C,
| DB2MQ1N, DB2MQ2C, or DB2MQ2N.

| Restriction: All DB2 MQ functions that use the AMI have been deprecated. You
| can convert those applications that use the AMI-based functions to use the
| MQI-based functions.

| Requirement: Before you can call the version of these functions that uses MQI ,
| you need to populate the DB2 MQ tables.

The following table describes the DB2 MQ scalar functions.

| Table 135. DB2 MQ scalar functions
| Scalar function Description
| MQPUBLISH (publisher-service, MQPUBLISH publishes a message, as specified in the msg-data variable, to the
| service-policy, msg-data, topic-list, WebSphere MQ publisher that is specified in the publisher-service variable. It
| correlation-id) uses the quality of service policy as specified in the service-policy variable. The
| topic-list variable specifies a list of topics for the message. The optional
| correlation-id variable specifies the correlation id that is to be associated with
| this message. The return value is 1 if successful or 0 if not successful.
| Restriction: MQPublish uses the AMI only. A version of MQPublish that uses
| the MQI is not available.
| MQREAD (receive-service, MQREAD returns a message in a VARCHAR variable from the MQ location
| service-policy) specified by receive-service, using the policy defined in service-policy. This
| operation does not remove the message from the head of the queue but instead
| returns it. If no messages are available to be returned, a null value is returned.
| MQREADCLOB (receive-service, MQREADCLOB returns a message in a CLOB variable from the MQ location
| service-policy) specified by receive-service, using the policy defined in service-policy. This
| operation does not remove the message from the head of the queue but instead
| returns it. If no messages are available to be returned, a null value is returned.
| MQRECEIVE (receive-service, MQRECEIVE returns a message in a VARCHAR variable from the MQ location
| service-policy, correlation-id) specified by receive-service, using the policy defined in service-policy. This
| operation removes the message from the queue. If correlation-id is specified, the
| first message with a matching correlation identifier is returned; if correlation-id is
| not specified, the message at the beginning of queue is returned. If no messages
| are available to be returned, a null value is returned.
| MQRECEIVECLOB (receive-service, MQRECEIVECLOB returns a message in a CLOB variable from the MQ location
| service-policy, correlation-id) specified by receive-service, using the policy defined in service-policy. This
| operation removes the message from the queue. If correlation-id is specified, the
| first message with a matching correlation identifier is returned; if correlation-id is
| not specified, the message at the head of queue is returned. If no messages are
| available to be returned, a null value is returned.
| MQSEND (send-service, MQSEND sends the data in a VARCHAR or CLOB variable msg-data to the MQ
| service-policy, msg-data, correlation-id) location specified by send-service, using the policy defined in service-policy. An
| optional user-defined message correlation identifier can be specified by
| correlation-id. The return value is 1 if successful or 0 if not successful.

Chapter 15. Coding methods for distributed data 847

| Table 135. DB2 MQ scalar functions (continued)
| Scalar function Description
| MQSUBSCRIBE (subscriber-service, MQSUBSCRIBE registers interest in WebSphere MQ messages that are
| service-policy, topic-list) published to the list of topics that are specified in the topic-list variable. The
| subscriber-service variable specifies a logical destination for messages that match
| the specified list of topics. Messages that match each topic are placed on the
| queue at the specified destination, using the policy specified in the service-policy
| variable. These messages can be read or received by issuing a subsequent call to
| MQREAD, MQREADALL, MQREADCLOB, MQREADALLCLOB, MQRECEIVE,
| MQRECEIVEALL, MQRECEIVECLOB, or MQRECEIVEALLCLOB. The return
| value is 1 if successful or 0 if not successful.
| Restriction: MQSUBSCRIBE uses the AMI only. A version of MQSUBSCRIBE
| that uses the MQI is not available.
| MQUNSUBSCRIBE MQUNSUBSCRIBE unregisters previously specified interest in WebSphere MQ
| (subscriber-service, service-policy, messages that are published to the list of topics that are specified in the topic-list
| topic-list) variable. The subscriber-service, service-policy, and topic-list variables specify
| which subscription is to be cancelled. The return value is 1 if successful or 0 if
| not successful.
| Restriction: MQUNSUBSCRIBE uses the AMI only. A version of
| MQUNSUBSCRIBE that uses the MQI is not available.
| Notes:
| 1. You can send or receive messages in VARCHAR variables or CLOB variables. The maximum length for a message
| in a VARCHAR variable is 32 KB. The maximum length for a message in a CLOB variable is 2 MB.
| 2.
| Restriction: The versions of these MQ functions that are in the DB2MQ1C, DB2MQ1N, DB2MQ2C, and
| DB2MQ2N schemas are deprecated. (Those functions use the AMI.) Instead use the version of these functions in
| the DB2MQ schema. (Those functions use the MQI.) The exceptions are MQPUBLISH, MQSUBSCRIBE, and
| MQUNSUBSCRIBE. Although the AMI-based versions of these functions are deprecated, a version of these
| functions does not exist in the DB2MQ schema.
|

The following table describes the MQ table functions that DB2 can use.
Table 136. DB2 MQ table functions
Table function Description
MQREADALL (receive-service, MQREADALL returns a table that contains the messages and message metadata
service-policy, num-rows) in VARCHAR variables from the MQ location specified by receive-service, using
the policy defined in service-policy. This operation does not remove the messages
from the queue. If num-rows is specified, a maximum of num-rows messages is
returned; if num-rows is not specified, all available messages are returned.
MQREADALLCLOB (receive-service, MQREADALLCLOB returns a table that contains the messages and message
service-policy, num-rows) metadata in CLOB variables from the MQ location specified by receive-service,
using the policy defined in service-policy. This operation does not remove the
messages from the queue. If num-rows is specified, a maximum of num-rows
messages is returned; if num-rows is not specified, all available messages are
returned.
MQRECEIVEALL (receive-service, MQRECEIVEALL returns a table that contains the messages and message
service-policy, correlation-id, metadata in VARCHAR variables from the MQ location specified by
num-rows) receive-service, using the policy defined in service-policy. This operation removes
the messages from the queue. If correlation-id is specified, only those messages
with a matching correlation identifier are returned; if correlation-id is not
specified, all available messages are returned. If num-rows is specified, a
maximum of num-rows messages is returned; if num-rows is not specified, all
available messages are returned.

848 Application Programming and SQL Guide

Table 136. DB2 MQ table functions (continued)
Table function Description
MQRECEIVEALLCLOB MQRECEIVEALLCLOB returns a table that contains the messages and message
(receive-service, service-policy, metadata in CLOB variables from the MQ location specified by receive-service,
correlation-id, num-rows) using the policy defined in service-policy. This operation removes the messages
from the queue. If correlation-id is specified, only those messages with a
matching correlation identifier are returned; if correlation-id is not specified, all
available messages are returned. If num-rows is specified, a maximum of
num-rows messages is returned; if num-rows is not specified, all available
messages are returned.
Notes:
1. You can send or receive messages in VARCHAR variables or CLOB variables. The maximum length for a message
in a VARCHAR variable is 32 KB. The maximum length for a message in a CLOB variable is 2 MB.
2. The first column of the result table of a DB2 MQ table function contains the message.
3.
Restriction: The versions of these MQ functions that are in the DB2MQ1C, DB2MQ1N, DB2MQ2C, and
DB2MQ2N schemas are deprecated. (Those functions use the AMI.) Instead use the version of these functions in
the DB2MQ schema. (Those functions use the MQI.)

The following table describes the MQ functions that DB2 can use to work with
XML data.

| Restriction: All of these DB2 MQ XML-specific functions have been deprecated.

| Instead of using these XML-specific functions, you can use the other DB2 MQ
| functions with data of type XML by first casting that data to type VARCHAR or
| CLOB.
Table 137. DB2 MQ XML-specific functions
XML-specific function Description
MQREADXML (receive-service, MQREADXML returns the first message in a queue without removing the
service-policy) message from the queue.
MQREADALLXML (receive-service, MQREADALLXML returns a table that contains messages from a queue without
service-policy) removing the messages from the queue.
MQRECEIVEXML (receive-service, MQRECEIVEXML returns a message from the queue and removes that message
service-policy, correlation-id) from the queue.
MQRECEIVEALLXML MQRECEIVEALLXML returns a table that contains messages from a queue and
(receive-service, service-policy, removes the messages from the queue.
correlation-id)
MQSENDXML (send-service, MQSENDXML sends a message and does not expect a reply.
service-policy, correlation-id)
MQSENDXMLFILE (send-service, MQSENDXMLFILE sends a message that contains a file and does not expect a
service-policy, correlation-id) reply.
MQSENDXMLFILECLOB MQSENDXMLFILECLOB sends a message that contains a file and does not
(send-service, service-policy, expect a reply.
correlation-id)
MQPUBLISHXML (publisher-service, MQPUBLISHXML sends a message to a queue to be picked up by applications
service-policy, correlation-id) that monitor the queue.

You can use the WebSphere MQ XML stored procedures to retrieve an XML
document from a message queue, decompose it into untagged data, and store the
data in DB2 tables. You can also compose an XML document from DB2 data and
send the document to an MQSeries(R) message queue.

Chapter 15. Coding methods for distributed data 849

The following table shows WebSphere MQ XML stored procedures for
decomposition.

| Restriction: All of these DB2 MQ XML decomposition stored procedures have

| been deprecated. Instead of using these decomposition stored procedures, you can
| shred XML documents from an MQ message queue.
Table 138. DB2 MQ XML decomposition stored procedures
XML decomposition stored
procedure Description
DXXMQINSERT and Decompose incoming XML documents from a message queue and store the data
DXXMQINSERTALL in new or existing database tables. The DXXMQINSERT and
DXXMQINSERTALL stored procedures require an enabled XML collection name
as input.
DXXMQINSERTCLOB and Decompose incoming XML documents from a message queue and store the data
DXXMQINSERTALLCLOB in new or existing database tables. The DXXMQINSERTCLOB and
DXXMQINSERTALLCLOB stored procedures require an enabled XML collection
name as input.
DXXMQSHRED and Shred incoming XML documents from a message queue and store the data in
DXXMQSHREDAll new or existing database tables. The DXXMQSHRED and DXXMQSHREDAll
stored procedures take a DAD file as input; they do not require an enabled
XML collection name as input.
DXXMQSHREDCLOB and Shred incoming XML documents from a message queue and store the data in
DXXMQSHREDALLCLOB new or existing database tables. The DXXMQSHREDCLOB and
DXXMQSHREDALLCLOB stored procedures take a DAD file as input; they do
not require an enabled XML collection name as input.

The following table shows WebSphere MQ XML stored procedures for

composition.

| Restriction: All of these DB2 MQ XML composition stored procedures have been
| deprecated. Instead of using these composition stored procedures, you can
| generate XML documents from existing tables and send them to an MQ message
| queue.
Table 139. DB2 MQ XML composition stored procedures
XML composition stored
procedure Description
DXXMQGEN and Generate XML documents from existing database tables and send the generated
DXXMQGENALL XML documents to a message queue. The DXXMQGEN and DXXMQGENALL
stored procedures take a DAD file as input; they do not require an enabled
XML collection name as input.
DXXMQRETRIEVE and Generate XML documents from existing database tables and send the generated
DXXMQRETRIEVECLOB XML documents to a message queue. The DXXMQRETRIEVE and
DXXMQRETRIEVECLOB stored procedures require an enabled XML collection
name as input.

850 Application Programming and SQL Guide

Related concepts
“DB2-supplied stored procedures” on page 766
Related tasks
“Converting applications to use the MQI functions” on page 861
“Generating XML documents from existing tables and sending them to an MQ
message queue” on page 852
“Shredding XML documents from an MQ message queue” on page 852
Enabling WebSphere MQ user-defined functions (DB2 Installation and
Migration)
Related reference
“DB2 MQ tables” on page 853
MQREADALL (SQL Reference)
MQREADALLCLOB (SQL Reference)
MQRECEIVEALL (SQL Reference)
MQRECEIVEALLCLOB (SQL Reference)
Related information
WebSphere MQ information center

Commit environment for AMI-based DB2 MQ functions and

stored procedures
| DB2 provides two versions of commit when you use AMI-based DB2 MQ functions
| and stored procedures: a single-phase commit and a two-phase commit.

| Restriction: The AMI and the DB2 MQ functions that use the AMI have been
| deprecated.

| The schema name when you use AMI-based DB2 MQ functions and stored
| procedures for a single-phase commit is DB2MQ1N. The schema name when you
| use AMI-based DB2 MQ functions and stored procedures for a two-phase commit
| is DB2MQ2N. The schema names DB2MQ1C and DB2MQ2C, are still valid, but
| they do not support the parameter style that allows the value to contain binary ’0’.

| You need to assign these two versions of the AMI-based DB2 MQ functions and
| stored procedures to different WLM environments, which guarantees that the
| versions are never invoked from the same address space.

| For MQI-based DB2 MQ functions, you can specify whether the function is for
| one-phase commit or two-phase commit by using the value in the SYNCPOINT
| column of the table SYSIBM.MQPOLICY_TABLE.

Single-phase commit in WebSphere MQ:

If your application uses single-phase commit, any DB2 COMMIT or ROLLBACK

operations are independent of WebSphere MQ operations. If a transaction is rolled
back, the messages that have been sent to a queue within the current unit of work
are not discarded.

This type of commit is typically used in the case of application error. You might
want to use WebSphere MQ messaging functions to notify a system programmer

Chapter 15. Coding methods for distributed data 851

that an application error has occurred. The application issues a ROLLBACK after
the error occurs, but the message is still delivered to the queue that contains the
error messages.

In a single-phase commit environment, WebSphere MQ controls its own queue

operations. A DB2 COMMIT or ROLLBACK does not affect when or if messages
are added to or deleted from an MQ queue.

Two-phase commit in WebSphere MQ:

If your application uses two-phase commit, RRS coordinates the commit process. If
a transaction is rolled back, the messages that have been sent to a queue within the
current unit of work are discarded.

This type of commit is typically used when a transaction causes a message to be

sent, which causes another transaction to be initiated. For example, assume that a
sales transaction causes a WebSphere MQ message to be sent to a queue. The
message causes your inventory system to order replacement merchandise. That
message should be discarded if the transaction representing the sale is rolled back.

| In a two-phase commit environment, if you want to force messages to be added to

| or deleted from an MQ queue, you need to issue a COMMIT in your application
| program after you call an AMI-based DB2 MQ function.
Related reference
“DB2 MQ tables” on page 853

| Generating XML documents from existing tables and sending

| them to an MQ message queue
| You can send data from a DB2 table to the MQ message queue by first putting the
| data in an XML document and then sending that document to the message queue.

| The DB2 MQ XML stored procedures for composing XML documents have been
| deprecated. Instead of using those stored procedures, you can achieve the same
| result by completing the steps in this task.

| To generate XML documents from existing tables and send them to an MQ

| message queue:
| 1. Compose an XML document by using the DB2 XML publishing functions.
| 2. Cast the XML document to type VARCHAR or CLOB.
| 3. Send the document to an MQ message queue by using the appropriate DB2
| MQ function.
| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures” on page 846
| Functions for constructing XML values (Programming for XML)

| Shredding XML documents from an MQ message queue

| When you retrieve XML data from an MQ message queue, you can shred that data
| into DB2 tables for easy retrievability.

| The DB2 MQ XML stored procedures for decomposing XML documents have been
| deprecated. Instead of using those stored procedures, you can achieve the same
| result by completing the steps in this task.

852 Application Programming and SQL Guide

| To shred XML documents from an MQ message queue:
| 1. Retrieve the XML document from an MQ message queue by using the
| appropriate MQ function.
| 2. Shred the retrieved message to DB2 tables by using the XML decomposition
| stored procedure (XDBDECOMPXML).
| Related concepts
| “DB2 MQ functions and DB2 MQ XML stored procedures” on page 846

| DB2 MQ tables
| The DB2 MQ tables contain service and policy definitions that are used by the
| MQI-based DB2 MQ functions. You must populate the DB2 MQ tables before you
| can use these MQI-based functions.

| The DB2 MQ tables are SYSIBM.MQSERVICE_TABLE and

| SYSIBM.MQPOLICY_TABLE. These tables are user-managed. You need to create
| them during the installation or migration process. Sample job DSNTIJSG creates
| these tables with one default row in each table.

| If you previously used the AMI-based DB2 MQ functions, you used AMI
| configuration files instead of these tables. To use the MQI-based DB2 MQ
| functions, you need to move the data from those configuration files to the DB2
| tables SYSIBM.MQSERVICE_TABLE and SYSIBM.MQPOLICY_TABLE .

| The following table describes the columns for SYSIBM.MQSERVICE_TABLE.

| Table 140. SYSIBM.MQSERVICE_TABLE column descriptions
| Column name Description
| SERVICENAME This column contains the service name, which is an
| optional input parameter of the MQ functions.

| This column is the primary key for the

| SYSIBM.MQSERVICE_TABLE table.
| QUEUEMANAGER This column contains the name of the queue manager
| where the MQ functions are to establish a connection.
| INPUTQUEUE This column contains the name of the queue from which
| the MQ functions are to send and retrieve messages.
| CODEDCHARSETID This column contains the character set identifier for
| character data in the messages that are sent and received
| by the MQ functions.

| This column corresponds to the CodedCharSetId field in

| the message descriptor structure (MQMD). MQ functions
| use the value in this column to set the CodedCharSetId
| field.

| The default value for this column is 0, which sets the

| CodedCharSetId field of the MQMD to the value
| MQCCSI_Q_MGR.

Chapter 15. Coding methods for distributed data 853

| Table 140. SYSIBM.MQSERVICE_TABLE column descriptions (continued)
| Column name Description
| ENCODING This column contains the encoding value for the numeric
| data in the messages that are sent and received by the
| MQ functions.

| This column corresponds to the Encoding field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Encoding field.

| The default value for this column is 0, which sets the

| Encoding field in the MQMD to the value
| MQENC_NATIVE.
| DESC_SHORT This column contains the short description of the service.
| DESC_LONG This column contains the detailed description of the
| service.
|

| The following table describes the columns for SYSIBM.MQPOLICY_TABLE.

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions
| Column name Description
| POLICYNAME This column contains the policy name, which is an
| optional input parameter of the MQ functions.

| This column is the primary key for the

| SYSIBM.MQPOLICY_TABLE table.
| SEND_PRIORITY This column contains the priority of the message.

| This column corresponds to the Priority field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Priority field.

| The default value for this column is -1, which sets the
| Priority field in the MQMD to the value
| MQQPRI_PRIORITY_AS_Q_DEF.
| SEND_PERSISTENCE This column indicates whether the message persists
| despite any system failures or instances of restarting the
| queue manager.

| This column corresponds to the Persistence field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Persistence field.

| This column can have the following values:

| Q Sets the Persistence field in the MQMD to the value
| MQPER_PERSISTENCE_AS_Q_DEF. This value is the
| default.
| Y Sets the Persistence field in the MQMD to the value
| MQPER_PERSISTENT.
| N Sets the Persistence field in the MQMD to the value
| MQPER_NOT_ PERSISTENT.

854 Application Programming and SQL Guide

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| SEND_EXPIRY This column contains the message expiration time, in
| tenths of a second.

| This column corresponds to the Expiry field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Expiry field.

| The default value is -1, which sets the Expiry field to the
| value MQEI_UNLIMITED.
| SEND_RETRY_COUNT This column contains the number of times that the MQ
| function is to try to send a message if the procedure fails.

| The default value is 5.

| SEND_RETRY_INTERVAL This column contains the interval, in milliseconds,
| between each attempt to send a message.

| The default value is 1000.

| SEND_NEW_CORRELID This column specifies how the correlation identifier is to
| be set if a correlation identifier is not passed as an input
| parameter in the MQ function. The correlation identifier
| is set in the CorrelId field in the message descriptor
| structure (MQMD).

| This column can have one of the following values:

| N Sets the CorrelId field in the MQMD to binary zeros.
| This value is the default.
| Y Specifies that the queue manager is to generate a
| new correlation identifier and set the CorrelId field
| in the MQMD to that value. This ’Y’ value is
| equivalent to setting the
| MQPMO_NEW_CORREL_ID option in the Options
| field in the put message options structure (MQPMO).
| SEND_RESPONSE_MSGID This column specifies how the MsgId field in the message
| descriptor structure (MQMD) is to be set for report and
| reply messages.

| This column corresponds to the Report field in the

| MQMD. MQ functions use the value in this column to set
| the Report field.

| This column can have one of the following values:

| N Sets the MQRO_NEW_MSG_ID option in the Report
| field in the MQMD. This value is the default.
| P Sets the MQRO_PASS_MSG_ID option in the Report
| field in the MQMD.

Chapter 15. Coding methods for distributed data 855

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| SEND_RESPONSE_CORRELID This column specifies how the CorrelID field in the
| message descriptor structure (MQMD) is to be set for
| report and reply messages.

| This column corresponds to the Report field in the

| MQMD. MQ functions use the value in this column to set
| the Report field.

| This column can have one of the following values:

| C Sets the MQRO_COPY_MSG_ID_TO_CORREL_ID
| option in the Report field in the MQMD. This value
| is the default.
| P Sets the MQRO_PASS_CORREL_ID option in the
| Report field in the MQMD.
| SEND_EXCEPTION_ACTION This column specifies what to do with the original
| message when it cannot be delivered to the destination
| queue.

| This column corresponds to the Report field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Report field.

| This column can have one of the following values:

| Q Sets the MQRO_DEAD_LETTER_Q option in the
| Report field in the MQMD. This value is the default.
| D Sets the MQRO_DISCARD_MSG option in the Report
| field in the MQMD.
| P Sets the MQRO_PASS_DISCARD_AND_EXPIRY
| option in the Report field in the MQMD.
| SEND_REPORT_EXCEPTION This column specifies whether an exception report
| message is to be generated when a message cannot be
| delivered to the specified destination queue and if so,
| what that report message should contain.

| This column corresponds to the Report field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Report field.

| This column can have one of the following values:

| N Specifies that an exception report message is not to
| be generated. No options in the Report field are set.
| This value is the default.
| E Sets the MQRO_EXCEPTION option in the Report
| field in the MQMD.
| D Sets the MQRO_EXCEPTION_WITH_DATA option in
| the Report field in the MQMD.
| F Sets the MQRO_EXCEPTION_WITH_FULL_DATA
| option in the Report field in the MQMD.

856 Application Programming and SQL Guide

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| SEND_REPORT_COA This column specifies whether the queue manager is to
| send a confirm-on-arrival (COA) report message when
| the message is placed in the destination queue, and if so,
| what that COA message is to contain.

| This column corresponds to the Report field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Report field.

| This column can have one of the following values:

| N Specifies that a COA message is not to be sent. No
| options in the Report field are set. This value is the
| default
| C Sets the MQRO_COA option in the Report field in
| the MQMD
| D Sets the MQRO_COA_WITH_DATA option in the
| Report field in the MQMD.
| F Sets the MQRO_COA_WITH_FULL_DATA option in
| the Report field in the MQMD.
| SEND_REPORT_COD This column specifies whether the queue manager is to
| send a confirm-on-delivery (COD) report message when
| an application retrieves and deletes a message from the
| destination queue, and if so, what that COD message is
| to contain.

| This column corresponds to the Report field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Report field.

| This column can have one of the following values:

| N Specifies that a COD message is not to be sent. No
| options in the Report field are set. This value is the
| default.
| C Sets the MQRO_COD option in the Report field in
| the MQMD.
| D Sets the MQRO_COD_WITH_DATA option in the
| Report field in the MQMD.
| F Sets the MQRO_COD_WITH_FULL_DATA option in
| the Report field in the MQMD.

Chapter 15. Coding methods for distributed data 857

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| SEND_REPORT_EXPIRY This column specifies whether the queue manager is to
| send an expiration report message if a message is
| discarded before it is delivered to an application, and if
| so, what that message is to contain.

| This column corresponds to the Report field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Report field.

| This column can have one of the following values:

| N Specifies that an expiration report message is not to
| be sent. No options in the Report field are set.This
| value is the default.
| C Sets the MQRO_EXPIRATION option in the Report
| field in the MQMD.
| D Sets the MQRO_EXPIRATION_WITH_DATA option
| in the Report field in the MQMD.
| F Sets the MQRO_EXPIRATION_WITH_FULL_DATA
| option in the Report field in the MQMD.
| SEND_REPORT_ACTION This column specifies whether the receiving application
| sends a positive action notification (PAN), a negative
| action notification (NAN), or both.

| This column corresponds to the Report field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the Report field.

| This column can have one of the following values:

| N Specifies that neither notification is to be sent. No
| options in the Report field are set. This value is the
| default.
| P Sets the MQRO_PAN option in the Report field in
| the MQMD.
| T Sets the MQRO_NAN option in the Report field in
| the MQMD.
| B Sets both the MQRO_PAN and MQRO_NAN options
| in the Report field in the MQMD.

858 Application Programming and SQL Guide

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| SEND_MSG_TYPE This column contains the type of message.

| This column corresponds to the MsqType field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the MsqType field.

| This column can have one of the following values:

| DTG
| Sets the MsgType field in the MQMD to
| MQMT_DATAGRAM. This value is the default.
| REQ
| Sets the MsgType field in the MQMD to
| MQMT_REQUEST.
| RLY
| Sets the MsgType field in the MQMD to
| MQMT_REPLY.
| RPT
| Sets the MsgType field in the MQMD to
| MQMT_REPORT.
| REPLY_TO_Q This column contains the name of the message queue to
| which the application that issued the MQGET call is to
| send reply and report messages.

| This column corresponds to the ReplyToQ field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the ReplyToQ field.

| The default value for this column is SAME AS INPUT_Q,

| which sets the name to the queue name that is defined in
| the service that was used for sending the message. If no
| service was specified, the name is set to
| DB2MQ_DEFAULT_Q, which is the name of the input
| queue for the default service.
| REPLY_TO_QMGR This column contains the name of the queue manager to
| which the reply and report messages are to be sent.

| This column corresponds to the ReplyToQMgr field in the

| message descriptor structure (MQMD). MQ functions use
| the value in this column to set the ReplyToQMgr field.

| The default value for this column is SAME AS

| INPUT_QMGR, which sets the name to the queue
| manager name that is defined in the service that was
| used for sending the message. If no service was specified,
| the name is set to the name of the queue manager for the
| default service.
| RCV_WAIT_INTERVAL This column contains the time, in milliseconds, that DB2
| is to wait for messages to arrive in the queue.

| This column corresponds to the WaitInterval field in the

| get message options structure (MQGMO). MQ functions
| use the value in this column to set the WaitInterval field.

| The default is 10.

Chapter 15. Coding methods for distributed data 859

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| RCV_CONVERT This column indicates whether to convert the application
| data in the message to conform to the CodedCharSetId
| and Encoding values of the specified MQ service.

| This column corresponds to the Options field in the get

| message options structure (MQGMO). MQ functions use
| the value in this column to set the Options field.

| This column can have one of the following values:

| Y Sets the MQGMO_CONVERT option in the Options
| field in the MQGMO. This value is the default.
| N Specifies that no data is to be converted.
| RCV_ACCEPT_TRUNC_MSG This column specifies the behavior of the MQ function
| when oversized messages are retrieved.

| This column corresponds to the Options field in the get

| message options structure (MQGMO). MQ functions use
| the value in this column to set the Options field.

| This column can have one of the following values:

| Y Sets the MQGMO_ACCEPT_TRUNCATED_MSG
| option in the Options field in the MQGMO. This
| value is the default.
| N Specifies that no messages are to be truncated. If the
| message is too large to fit in the buffer, the MQ
| function terminates with an error.
| Recommendation: Set this column to Y. In this case, if
| the message buffer is too small to hold the complete
| message, the MQ function can fill the buffer with as
| much of the message as the buffer can hold.
| REV_OPEN_SHARED This column specifies the input queue mode when
| messages are retrieved.

| This column corresponds to the Options parameter for an

| MQOPEN call. MQ functions use the value in this
| column to set the Options parameter.

| This column can have one of the following values:

| S Sets the MQOO_INPUT_SHARED option. This value
| is the default.
| E Sets the MQ option MQOO_INPUT_EXCLUSIVE
| option.
| D Sets the MQ option MQOO_INPUT_AS_Q_DEF
| option.

860 Application Programming and SQL Guide

| Table 141. SYSIBM.MQPOLICY_TABLE column descriptions (continued)
| Column name Description
| SYNCPOINT This column indicates whether the MQ function is to
| operate within the protocol for a normal unit of work.

| This column can have one of the following values:

| Y Specifies that the MQ function is to operate within
| the protocol for a normal unit of work. Use this
| value for two-phase commit environments. This
| value is the default.
| N Specifies that the MQ function is to operate outside
| the protocol for a normal unit of work. Use this
| value for one-phase commit environments.
| DESC_SHORT This column contains the short description of the policy.
| DESC_LONG This column contains the long description of the policy.
|
| Related tasks
| “Converting applications to use the MQI functions”
| Related information
| WebSphere MQ information center

| Converting applications to use the MQI functions

| The AMI-based DB2 MQ functions have been deprecated. You need to make some
| changes to any applications that reference these AMI-based functions so that they
| reference the replacement MQI-based functions.

| The DB2 MQ functions were originally implemented with the Application

| Messaging Interface (AMI). These AMI-based functions have since been
| deprecated. A newer version of these MQ functions is implemented with the
| Message Queue Interface (MQI). These MQI-based functions have the same
| signatures as the AMI-based functions, but have different qualifying schema
| names. Also, the MQI-based functions use DB2 tables instead of AMI configuration
| files.

| To convert an application to use the MQI functions, perform the following actions:
| 1. Set up the DB2 MQ functions that are based on MQI by performing the
| following actions:
| a. Run installation job DSNTIJSG. This job binds the new MQI-based DB2 MQ
| functions and creates the tables SYSIBM.MQSERVICE_TABLE and
| SYSIBM.MQPOLICY_TABLE.
| b. Convert the contents of the AMI configuration files to rows in the tables
| SYSIBM.MQSERVICE_TABLE and SYSIBM.MQPOLICY_TABLE.
| 2. If the application contains unqualified references to DB2 MQ functions, set the
| CURRENT PATH special register to the schema name DB2MQ.
| 3. If the application contains qualified references to DB2 MQ functions, change the
| schema names in those references from the old names (DB2MQ1N, DB2MQ2N,
| DB2MQ1C, and DB2MQ2C) to DB2MQ.
| 4. Change the size of any host variables to accommodate for the following larger
| message sizes:
| v DB2 MQ functions for VARCHAR data can have a maximum message size
| of 32 KB.

Chapter 15. Coding methods for distributed data 861

| v DB2 MQ functions for CLOB data can have a maximum message size of 2
| MB.
| Related tasks
| Converting from the AMI-based MQ functions to the MQI-based MQ functions
| (DB2 Installation and Migration)
| Related reference
| “DB2 MQ tables” on page 853

Basic messaging with WebSphere MQ

The most basic form of messaging with the DB2 MQ functions occurs when all
database applications connect to the same DB2 database server. Clients can be local
to the database server or distributed in a network environment.

In a simple scenario, client A invokes the MQSEND function to send a user-defined

string to the location that is defined by the default service. DB2 executes the MQ
functions that perform this operation on the database server. At some later time,
client B invokes the MQRECEIVE function to remove the message at the head of
the queue that is defined by the default service, and return it to the client. DB2
executes the MQ functions that perform this operation on the database server.

Database clients can use simple messaging in a number of ways:

v Data collection
Information is received in the form of messages from one or more sources. An
information source can be any application. The data is received from queues and
stored in database tables for additional processing.
v Workload distribution
Work requests are posted to a queue that is shared by multiple instances of the
same application. When an application instance is ready to perform some work,
it receives a message that contains a work request from the head of the queue.
Multiple instances of the application can share the workload that is represented
by a single queue of pooled requests.
v Application signaling
In a situation where several processes collaborate, messages are often used to
coordinate their efforts. These messages might contain commands or requests for
work that is to be performed. For more information about this technique, see
“Application to application connectivity with WebSphere MQ” on page 865.

The following scenario extends basic messaging to incorporate remote messaging.

Assume that machine A sends a message to machine B.
1. The DB2 client executes an MQSEND function call, specifying a target service
that has been defined to be a remote queue on machine B.
2. The MQ functions perform the work to send the message. The WebSphere MQ
server on machine A accepts the message and guarantees that it will deliver it
to the destination that is defined by the service and the current MQ
configuration of machine A. The server determines that the destination is a
queue on machine B. The server then attempts to deliver the message to the
WebSphere MQ server on machine B, retrying as needed.
3. The WebSphere MQ server on machine B accepts the message from the server
on machine A and places it in the destination queue on machine B.
4. A WebSphere MQ client on machine B requests the message at the head of the
queue.

862 Application Programming and SQL Guide

Sending messages with WebSphere MQ
When you send messages with WebSphere MQ, you choose what data to send,
where to send it and when to send it. This type of messaging is called send and
forget; the sender sends a message and relies on WebSphere MQ to ensure that the
message reaches its destination.

To send messages with WebSphere MQ, use MQSEND.

If you send more than one column of information, separate the columns with the
characters || ' ' ||.

Example: MQSEND (LASTNAME || ' ' || FIRSTNAME)

The following examples use the DB2MQ2N schema for two-phase commit, with
the default service DB2.DEFAULT.SERVICE and the default policy
DB2.DEFAULT.POLICY.

Example: The following SQL SELECT statement sends a message that consists of
the string ″Testing msg″:
SELECT DB2MQ2N.MQSEND ('Testing msg')
FROM SYSIBM.SYSDUMMY1;
COMMIT;

The MQSEND function is invoked once because SYSIBM.SYSDUMMY1 has only

one row. Because this MQSEND function uses two-phase commit, the COMMIT
statement ensures that the message is added to the queue.

When you use single-phase commit, you do not need to use a COMMIT statement.
For example:
SELECT DB2MQ1N.MQSEND ('Testing msg')
FROM SYSIBM.SYSDUMMY1;

The MQ operation causes the message to be added to the queue.

Example: Assume that you have an EMPLOYEE table, with VARCHAR columns
LASTNAME, FIRSTNAME, and DEPARTMENT. To send a message that contains
this information for each employee in DEPARTMENT 5LGA, issue the following
SQL SELECT statement:
SELECT DB2MQ2N.MQSEND (LASTNAME || ' ' || FIRSTNAME || ' ' || DEPARTMENT)
FROM EMPLOYEE WHERE DEPARTMENT = '5lGA';
COMMIT;

Message content can be any combination of SQL statements, expressions, functions,

and user-specified data. Because this MQSEND function uses two-phase commit,
the COMMIT statement ensures that the message is added to the MQ queue.

Retrieving messages with WebSphere MQ

With WebSphere MQ, programs can read or receive messages. Both reading and
receiving operations return the message at the head of the queue. However, the
reading operation does not remove the message from the queue, whereas the
receiving operation does.

A message that is retrieved using a receive operation can be retrieved only once,
whereas a message that is retrieved using a read operation allows the same
message to be retrieved many times.

Chapter 15. Coding methods for distributed data 863

The following examples use the DB2MQ2N schema for two-phase commit, with
the default service DB2.DEFAULT.SERVICE and the default policy
DB2.DEFAULT.POLICY.

Example: The following SQL SELECT statement reads the message at the head of
the queue that is specified by the default service and policy:
SELECT DB2MQ2N.MQREAD()
FROM SYSIBM.SYSDUMMY1;

The MQREAD function is invoked once because SYSIBM.SYSDUMMY1 has only

one row. The SELECT statement returns a VARCHAR(4000) string. If no messages
are available to be read, a null value is returned. Because MQREAD does not
change the queue, you do not need to use a COMMIT statement.

Example: The following SQL SELECT statement causes the contents of a queue to
be materialized as a DB2 table:
SELECT T.*
FROM TABLE(DB2MQ2N.MQREADALL()) T;

The result table T of the table function consists of all the messages in the queue,
which is defined by the default service, and the metadata about those messages.
The first column of the materialized result table is the message itself, and the
remaining columns contain the metadata. The SELECT statement returns both the
messages and the metadata.

To return only the messages, issue the following statement:

SELECT T.MSG
FROM TABLE(DB2MQ2N.MQREADALL()) T;

The result table T of the table function consists of all the messages in the queue,
which is defined by the default service, and the metadata about those messages.
This SELECT statement returns only the messages.

Example: The following SQL SELECT statement receives (removes) the message at
the head of the queue:
SELECT DB2MQ2N.MQRECEIVE()
FROM SYSIBM.SYSDUMMY1;
COMMIT;

The MQRECEIVE function is invoked once because SYSIBM.SYSDUMMY1 has

only one row. The SELECT statement returns a VARCHAR(4000) string. Because
this MQRECEIVE function uses two-phase commit, the COMMIT statement
ensures that the message is removed from the queue. If no messages are available
to be retrieved, a null value is returned, and the queue does not change.

Example: Assume that you have a MESSAGES table with a single

VARCHAR(2000) column. The following SQL INSERT statement inserts all of the
messages from the default service queue into the MESSAGES table in your DB2
database:
INSERT INTO MESSAGES
SELECT T.MSG
FROM TABLE(DB2MQ2N.MQRECEIVEALL()) T;
COMMIT;

864 Application Programming and SQL Guide

The result table T of the table function consists of all the messages in the default
service queue and the metadata about those messages. The SELECT statement
returns only the messages. The INSERT statement stores the messages into a table
in your database.

Application to application connectivity with WebSphere MQ

Application-to-application connectivity is typically used when putting together a
diverse set of application subsystems. To facilitate application integration,
WebSphere MQ provides the means to interconnect applications.

The following two scenarios are very common when interconnecting applications:
v Request-and-reply communication method
v Publish-and-subscribe method

Request-and-reply communication method:

The request-and-reply method enables one application to request the services of

another application. One way to do this is for the requester to send a message to
the service provider to request that some work be performed. When the work has
been completed, the provider might decide to send results, or just a confirmation
of completion, back to the requester. Unless the requester waits for a reply before
continuing, WebSphere MQ must provide a way to associate the reply with its
request.

WebSphere MQ provides a correlation identifier to correlate messages in an

exchange between a requester and a provider. The requester marks a message with
a known correlation identifier. The provider marks its reply with the same
correlation identifier. To retrieve the associated reply, the requester provides that
correlation identifier when receiving messages from the queue. The first message
with a matching correlation identifier is returned to the requester.

The following examples use the DB2MQ1N schema for single-phase commit.

Example: The following SQL SELECT statement sends a message consisting of the
string ″Msg with corr id″ to the service MYSERVICE, using the policy MYPOLICY
with correlation identifier CORRID1:
SELECT DB2MQ1N.MQSEND ('MYSERVICE', 'MYPOLICY', 'Msg with corr id', 'CORRID1')
FROM SYSIBM.SYSDUMMY1;

The MQSEND function is invoked once because SYSIBM.SYSDUMMY1 has only

one row. Because this MQSEND uses single-phase commit, WebSphere MQ adds
the message to the queue, and you do not need to use a COMMIT statement.

Example: The following SQL SELECT statement receives the first message that
matches the identifier CORRID1 from the queue that is specified by the service
MYSERVICE, using the policy MYPOLICY:
SELECT DB2MQ1N.MQRECEIVE ('MYSERVICE', 'MYPOLICY', 'CORRID1')
FROM SYSIBM.SYSDUMMY1;

The SELECT statement returns a VARCHAR(4000) string. If no messages are

available with this correlation identifier, a null value is returned, and the queue
does not change.

Publish-and-subscribe method:

Chapter 15. Coding methods for distributed data 865

Another common method of application integration is for one application to notify
other applications about events of interest. An application can do this by sending a
message to a queue that is monitored by other applications. The message can
contain a user-defined string or can be composed from database columns.

Simple data publication: In many cases, only a simple message needs to be sent
using the MQSEND function. When a message needs to be sent to multiple
recipients concurrently, the distribution list facility of the MQSeries® AMI can be
used.

You define distribution lists by using the AMI administration tool. A distribution list
comprises a list of individual services. A message that is sent to a distribution list
is forwarded to every service defined within the list. Publishing messages to a
distribution list is especially useful when there are multiple services that are
interested in every message.

Example: The following example shows how to send a message to the distribution
list ″InterestedParties″:
SELECT DB2MQ2N.MQSEND ('InterestedParties','Information of general interest')
FROM SYSIBM.SYSDUMMY1;

When you require more control over the messages that a particular service should
receive, you can use the MQPUBLISH function, in conjunction with the WebSphere
MQSeries Integrator facility. This facility provides a publish-and-subscribe system,
which provides a scalable, secure environment in which many subscribers can
register to receive messages from multiple publishers. Subscribers are defined by
queues, which are represented by service names.

MQPUBLISH enables you to specify a list of topics that are associated with a
message. Topics enable subscribers to more clearly specify the messages they
receive. The following sequence illustrates how the publish-and-subscribe
capabilities are used:
1. An MQSeries administrator configures the publish-and-subscribe capability of
the WebSphere MQSeries Integrator facility.
2. Interested applications subscribe to subscriber services that are defined in the
WebSphere MQSeries Integrator configuration. Each subscriber selects relevant
topics and can also use the content-based subscription techniques that are
provided by Version 2 of the WebSphere MQSeries Integrator facility.
3. A DB2 application publishes a message to a specified publisher service. The
message indicates the topic it concerns.
4. The MQSeries functions provided by DB2 for z/OS handle the mechanics of
publishing the message. The message is sent to the WebSphere MQSeries
Integrator facility by using the specified service policy.
5. The WebSphere MQSeries Integrator facility accepts the message from the
specified service, performs any processing defined by the WebSphere MQSeries
Integrator configuration, and determines which subscriptions the message
satisfies. It then forwards the message to the subscriber queues that match the
subscriber service and topic of the message.
6. Applications that subscribe to the specific service, and register an interest in the
specific topic, will receive the message in their receiving service.

Example: To publish the last name, first name, department, and age of employees
who are in department 5LGA, using all the defaults and a topic of EMP, you can
use the following statement:

866 Application Programming and SQL Guide

SELECT DB2MQ2N.MQPUBLISH (LASTNAME || ' ' || FIRSTNAME || ' ' ||
DEPARTMENT || ' ' || char(AGE), 'EMP')
FROM DSN8910.EMP
WHERE DEPARTMENT = '5LGA';

Example: The following statement publishes messages that contain only the last
name of employees who are in department 5LGA to the HR_INFO_PUB publisher
service using the SPECIAL_POLICY service policy:
SELECT DB2MQ2N.MQPUBLISH ('HR_INFO_PUB', 'SPECIAL_POLICY', LASTNAME,
'ALL_EMP:5LGA', 'MANAGER')
FROM DSN8910.EMP
WHERE DEPARTMENT = '5LGA';

The messages indicate that the sender has the MANAGER correlation id. The topic
string demonstrates that multiple topics, concatenated using a ’:’ (a colon) can be
specified. In this example, the use of two topics enables subscribers of both the
ALL_EMP and the 5LGA topics to receive these messages.

To receive published messages, you must first register your application’s interest in
messages of a given topic and indicate the name of the subscriber service to which
messages are sent. An AMI subscriber service defines a broker service and a
receiver service. The broker service is how the subscriber communicates with the
publish-and-subscribe broker. The receiver service is the location where messages
that match the subscription request are sent.

Example: The following statement subscribes to the topic ALL_EMP and indicates
that messages be sent to the subscriber service, ″aSubscriber″:
SELECT DB2MQ2N.MQSUBSCRIBE ('aSubscriber','ALL_EMP')
FROM SYSIBM.SYSDUMMY1;

When an application is subscribed, messages published with the topic, ALL_EMP,

are forwarded to the receiver service that is defined by the subscriber service. An
application can have multiple concurrent subscriptions. Messages that match the
subscription topic can be retrieved by using any of the standard message retrieval
functions.

Example: The following statement non-destructively reads the first message, where
the subscriber service, ″aSubscriber″, defines the receiver service as
″aSubscriberReceiver″:
SELECT DB2MQ2N.MQREAD ('aSubscriberReceiver')
FROM SYSIBM.SYSDUMMY1;

To display both the messages and the topics with which they are published, you
can use one of the table functions.

Example: The following statement receives the first five messages from
″aSubscriberReceiver″ and display both the message and the topic for each of the
five messages:
SELECT t.msg, t.topic
FROM table (DB2MQ2N.MQRECEIVEALL ('aSubscriberReceiver',5)) t;

Example: To read all of the messages with the topic ALL_EMP, issue the following
statement:
SELECT t.msg
FROM table (DB2MQ2N.MQREADALL ('aSubscriberReceiver')) t
WHERE t.topic = 'ALL_EMP';

Chapter 15. Coding methods for distributed data 867

Note: If you use MQRECEIVEALL with a constraint, your application receives the
entire queue, not just those messages that are published with the topic ALL_EMP.
This is because the table function is performed before the constraint is applied.

When you are no longer interested in having your application subscribe to a

particular topic, you must explicitly unsubscribe.

Example: The following statement unsubscribes from the ALL_EMP topic of the
″aSubscriber″ subscriber service:
SELECT DB2MQ2N.MQUNSUBSCRIBE ('aSubscriber', 'ALL_EMP')
FROM SYSIBM.SYSDUMMY1;

After you issue the preceding statement, the publish-and-subscribe broker no

longer delivers messages that match the ALL_EMP topic to the ″aSubscriber″
subscriber service.

Automated Publication: Another important method in application message

publishing is automated publication. Using the trigger facility within DB2 for
z/OS, you can automatically publish messages as part of a trigger invocation.
Although other techniques exist for automated message publication, the
trigger-based approach gives you more freedom in constructing the message
content and more flexibility in defining the actions of a trigger. As with the use of
any trigger, you must be aware of the frequency and cost of execution.

Example: The following example shows how you can use the MQSeries functions
of DB2 for z/OS with a trigger to publish a message each time a new employee is
hired:
CREATE TRIGGER new_employee AFTER INSERT ON DSN8910.EMP
REFERENCING NEW AS n
FOR EACH ROW MODE DB2SQL
SELECT DB2MQ2N.MQPUBLISH ('HR_INFO_PUB', current date || ' ' ||
LASTNAME || ' ' || DEPARTMENT, 'NEW_EMP');

Any users or applications that subscribe to the HR_INFO_PUB service with a

registered interest in the NEW_EMP topic will receive a message that contains the
date, the name, and the department of each new employee when rows are inserted
into the DSN8910.EMP table.

Asynchronous messaging in DB2 for z/OS

Programs can communicate with each other by sending data in messages rather
than using constructs like synchronous remote procedure calls. With asynchronous
messaging, the program that sends the message proceeds with its processing after
sending the message without waiting for a reply.

If the program needs information from the reply, the program suspends processing
and waits for a reply message. If the messaging programs use an intermediate
queue that holds messages, the requestor program and the receiver program do
not need to be running at the same time. The requestor program places a request
message on a queue and then exits. The receiver program retrieves the request
from the queue and processes the request.

Asynchronous operations require that the service provider is capable of accepting

requests from clients without notice. An asynchronous listener is a program that
monitors message transporters, such as WebSphere MQ, and performs actions
based on the message type. An asynchronous listener can use WebSphere MQ to
receive all messages that are sent to an endpoint. An asynchronous listener can

868 Application Programming and SQL Guide

also register a subscription with a publish or subscribe infrastructure to restrict the
messages that are received to messages that satisfy specified constraints.

Examples: The following examples show some common uses of asynchronous

messaging:
Message accumulator
You can accumulate the messages that are sent asynchronously so that the
listener checks for messages and stores those messages automatically in a
database. This database, which acts as a message accumulator, can save all
messages for a particular endpoint, such as an audit trail. The
asynchronous listener can subscribe to a subset of messages, such as save
only high value stock trades. The message accumulator stores entire
messages, and does not provide for selection, transformation, or mapping
of message contents to database structures. The message accumulator does
not reply to messages.
Message event handler
The asynchronous event handler listens for messages and invokes the
appropriate handler (such as a stored procedure) for the message endpoint.
You can call any arbitrary stored procedure. The asynchronous listener lets
you select, map, or reformat message contents for insertion into one or
more database structures.

Asynchronous messaging has the following benefits:

v The client and database do not need to be available at the same time. If the
client is available intermittently, or if the client fails between the time the request
is issued and the response is sent, it is still possible for the client to receive the
reply. Or, if the client is on a mobile computer and becomes disconnected from
the database, and if a response is sent, the client can still receive the reply.
v The content of the messages in the database contain information about when to
process particular requests. The messages in the database use priorities and the
request contents to determine how to schedule the requests.
v An asynchronous message listener can delegate a request to a different node. It
can forward the request to a second computer to complete the processing. When
the request is complete, the second computer returns a response directly to the
endpoint that is specified in the message.
v An asynchronous listener can respond to a message from a supplied client, or
from a user-defined application. The number of environments that can act as a
database client is greatly expanded. Clients such as factory automation
equipment, pervasive devices, or embedded controllers can communicate with
DB2® Universal Database™ either directly through WebSphere MQ or through
some gateway that supports WebSphere MQ.

MQListener in DB2 for z/OS

DB2 for z/OS provides an asynchronous listener, MQListener. MQListener is a
framework for tasks that read from WebSphere MQ queues and call DB2 stored
procedures with messages as those messages arrive.

MQListener combines messaging with database operations. You can configure the
MQListener daemon to listen to the WebSphere MQ message queues that you
specify in a configuration database. MQListener reads the messages that arrive
from the queue and calls DB2 stored procedures using the messages as input
parameters. If the message requires a reply, MQListener creates a reply from the

Chapter 15. Coding methods for distributed data 869

output that is generated by the stored procedure. The message retrieval order is
fixed at the highest priority first, and then within each priority the first message
received is the first message served.

MQListener runs as a single multi-threaded process on z/OS UNIX System

Services. Each thread or task establishes a connection to its configured message
queue for input. Each task also connects to a DB2 database on which to run the
stored procedure. The information about the queue and the stored procedure is
stored in a table in the configuration database. The combination of the queue and
the stored procedure is a task.

MQListener tasks are grouped together into named configurations. By default, the
configuration name is empty. If you do not specify the name of a configuration for
a task, MQListener uses the configuration with an empty name.

Transaction support: There is support for both one-phase and two-phase commit
environments. A one-phase commit environment is where DB interactions and MQ
interactions are independent. A two-phase commit environment is where DB
interactions and MQ interactions are combined in a single unit of work.

’db2mqln1’ is the name of the executable for one phase and ’db2mqln2’ is the
name of the executable for two phase.

| Logical ordering of messages: The two-phase commit version of the MQListener

| stored procedure processes messages that are in a group in logical order. The
| single-phase commit version of the MQListener stored procedure processes
| messages that are in a group in physical order.

| Stored Procedure Interface: The stored procedure interface for MQListener takes
| the incoming message as input and returns the reply, which might be NULL, as
| output:
| schema.proc(in inMsg inMsgType, out outMsg outMsgType)

| The data type for inMsgType and the data type for outMsgType can be VARCHAR,
| VARBINARY, CLOB, or BLOB of any length and are determined at startup. The
| input data type and output data type can be different data types. If an incoming
| message is a request and has a specified reply-to queue, the message in outMsg
| will be sent to the specified queue. The incoming message can be one of the
| following message types:
| v Datagram
| v Datagram with report requested
| v Request message with reply
| v Request message with reply and report requested

Configuring MQListener in DB2 for z/OS:

Before you can use MQListener, you must configure your database environment so
that your applications can use messaging with database operations. You must also
configure WebSphere MQ for MQListener.

Use the following procedure to configure the environment for MQListener and to
develop a simple application that receives a message, inserts the message in a
table, and creates a simple response message:
1. Configure MQListener to run in the DB2 environment.

870 Application Programming and SQL Guide

2. Configure WebSphere MQ for MQListener.
3. Configure MQListener task.
4. Create the sample stored procedure to work with MQListener.
5. Run a simple MQListener application.

Configuring MQListener to run in the DB2 environment:

Configure your database environment so that your applications can use messaging
with database operations.

Customize and run installation job DSNTIJML, which is located in

prefix.SDSNSAMP data set. The job will do the following tasks:
1. Untar and create the necessary files and libraries in z/OS UNIX System
Services under the path where MQListener is installed.
2. Create the MQListener configuration table (SYSMQL.LISTENERS) in the default
database DSNDB04.
3. Bind the DBRM’s to the plan DB2MQLSN.

Note: If MQListener is not installed in the default path, ’/usr/lpp/db2mql_910’ ,

you must replace all occurrences of the string ’/usr/lpp/db2910_mql’ in the
samples DSNTEJML, DSNTEJSP and DSNTIJML with the path name where
MQListener is installed before you run DSNTIJML.

The samples DSNTEJML, DSNTEJSP and DSNTIJML are located in

prefix.SDSNSAMP data set.

Ensure that the person who runs the installation job has required authority to
create the configuration table and to bind the DBRM’s.

Follow the instructions in the README file that is created in the MQListener
installation path in z/OS UNIX System Services to complete the configuration
process.

Configuring Websphere MQ for MQListener:

You can run a simple MQListener application with a simple WebSphere MQ

configuration. More complex applications might need a more complex
configuration. Configure at least two kinds of WebSphere MQ entities: the queue
manager and some local queues. Configure these entities for use in such instances
as transaction management, deadletter queue, backout queue, and backout retry
threshold.

To configure WebSphere MQ for a simple MQListener application, do the

following:
1. Create MQSeries QueueManager. Define the MQSeries subsystem to z/OS and
then issue the following command from a z/OS console to start the queue
manager:
<command-prefix-string> START QMGR
command-prefix-string is the command prefix for the MQSeries subsystem.
2. Create Queues under MQSeries QueueManager:

In a simple MQListener application, you typically use the following WebSphere

MQ queues:

Chapter 15. Coding methods for distributed data 871

Deadletter queue
The deadletter queue in WebSphere MQ holds messages that cannot be
processed. MQListener uses this queue to hold replies that cannot be
delivered, for example, because the queue to which the replies should be
sent is full. A deadletter queue is useful in any MQ installation especially
for recovering messages that are not sent.
Backout queue
For MQListener tasks that use two-phase commit, the backout queue
serves a similar purpose as the deadletter queue. MQListener places the
original request in the backout queue after the request is rolled back a
specified number of times (called the backout threshold).
Administration queue
The administration queue is used for routing control messages, such as
shutdown and restart, to MQListener. If you do not supply an
administration queue, the only way to shut down MQListener is to issue a
kill command.
Application input and output queues
The application uses input queues and output queues. The application
receives messages from the input queue and sends replies and exceptions
to the output queue.

Create your local queues by using CSQUTIL utility or by using MQSeries

operations and control panels from ISPF (csqorexx). The following is an example of
the JCL that is used to create your local queues. In this example, MQND is the
name of the queue manager:
//*
//* ADMIN_Q : Admin queue
//* BACKOUT_Q : Backout queue
//* IN_Q : Input queue having a backout queue with threshold=3
//* REPLY_Q : output queue or reply queue
//* DEADLLETTER_Q: Dead letter queue
//*
//DSNTECU EXEC PGM=CSQUTIL,PARM='MQND'
//STEPLIB DD DSN=MQS.SCSQANLE,DISP=SHR
// DD DSN=MQS.SCSQAUTH,DISP=SHR
//SYSPRINT DD SYSOUT=*
//SYSIN DD *
COMMAND DDNAME(CREATEQ)
/*
//CREATEQ DD *
DEFINE QLOCAL('ADMIN_Q') REPLACE +
DESCR('INPUT-OUTPUT') +
PUT(ENABLED) +
DEFPRTY(0) +
DEFPSIST(NO) +
SHARE +
DEFSOPT(SHARED) +
GET(ENABLED)
DEFINE QLOCAL('BACKOUT_Q') REPLACE +
DESCR('INPUT-OUTPUT') +
PUT(ENABLED) +
DEFPRTY(0) +
DEFPSIST(NO) +
SHARE +
DEFSOPT(SHARED) +
GET(ENABLED)
DEFINE QLOCAL('REPLY_Q') REPLACE +
DESCR('INPUT-OUTPUT') +
PUT(ENABLED) +
DEFPRTY(0) +

872 Application Programming and SQL Guide

DEFPSIST(NO) +
SHARE +
DEFSOPT(SHARED) +
GET(ENABLED)
DEFINE QLOCAL('IN_Q') REPLACE +
DESCR('INPUT-OUTPUT') +
PUT(ENABLED) +
DEFPRTY(0) +
DEFPSIST(NO) +
SHARE +
DEFSOPT(SHARED) +
GET(ENABLED) +
BOQNAME('BACKOUT_Q') +
BOTHRESH(3)
DEFINE QLOCAL('DEADLETTER_Q') REPLACE +
DESCR('INPUT-OUTPUT') +
PUT(ENABLED) +
DEFPRTY(0) +
DEFPSIST(NO) +
SHARE +
DEFSOPT(SHARED) +
GET(ENABLED)
ALTER QMGR DEADQ ('DEADLETTER_Q') REPLACE
/*

Environment variables for logging and tracing MQListener:

Two environment variables control logging and tracing for MQListener. These
variables are defined in the file .profile.
MQLSNTRC
When this ENV variable is set to 1, it will write function entry, data, and
| exit points to a unique HFS or zFS file. A unique trace file will be
generated whenever any of the MQListener commands are run. This trace
file will be used by IBM software support for debugging if the customer
reports any problem. Unless requested, this variable should not be defined.
MQLSNLOG
The log file contains diagnostic information about the major events. This
ENV variable is set to the name of the file where all log information will
be written. All instances of MQListener daemon running one or more tasks
will share the same file. For monitoring MQListener daemon, this variable
should always be set. When MQListener daemon is running, open the
log/trace files only in read mode (use cat/more/tail commands in z/OS
UNIX System Services to open the files) as they are used by the daemon
process for writing.

Refer to the README file for more details about these variables.

Configuration table: SYSMQL.LISTENERS:

If you use MQListener, you must create the MQListener configuration table
SYSMQL.LISTENERS by running installation job DSNTIJML.

The following table describes each of the columns of the configuration table
SYSMQL.LISTENERS.

Chapter 15. Coding methods for distributed data 873

Table 142. Description of columns in the SYSMQL.LISTENERS table
Column name Description
CONFIGURATIONNAME The configuration name. The configuration name enables
you to group several tasks into the same configuration.
A single instance of MQListener can run all of the tasks
that are defined within a configuration name.
QUEUEMANAGER The name of the Websphere MQ subsystem that contains
the queues that are to be used.
INPUTQUEUE The name of the queue in the Websphere MQ subsystem
that is to be monitored for incoming messages. The
combination of the input queue and the queue manager
are unique within a configuration
PROCNODE Currently unused
PROCSCHEMA The schema name of the stored procedure that will be
called by MQListener
PROCNAME The name of the stored procedure that will be called by
MQListener
PROCTYPE Currently unused
NUMINSTANCES The number of duplicate instances of a single task that
are to run in this configuration
WAITMILLIS The time MQListener waits (in milliseconds) after
processing the current message before it looks for the
next message
MINQUEDEPTH Currently unused

Configuring MQListener tasks:

As part of configuring MQListener in DB2 for z/OS, you must configure at least
one MQListener task.

Use the MQListener command, db2mqln1 or db2mqln2, to configure MQListener

tasks. Issue the command from z/OS UNIX System Services command line in any
directory. Alternatively, You can put the command in a file, grant execute
permission and use the BPXBATCH utility to invoke the script from JCL. The
sample script files are provided and are located in /MQListener-install-path/
mqlsn/listener/script directory in z/OS UNIX System Services. Sample JCL
(DSNTEJML) is also provided that invokes the script files and is located in
prefix.SDSNSAMP. The add parameter with the db2mqln1 or db2mqln2 command
updates a row in the DB2 table SYSMQL.LISTENERS.
v To add an MQListener configuration, issue the following command:
db2mqln1/db2mqln2 add
-ssID <subsystem name>
-config <configuration name>
-queueManager <queuemanager name>
-inputQueue <inputqueue name>
-procName <stored-procedure name>
-procSchema <stored-procedure schema name>
-numInstances <number of instances>
v To display information about the configuration, issue the following command:
db2mqln1/db2mqln2 show
-ssID <subsystem name>
-config <configuration name>

874 Application Programming and SQL Guide

To display information about all the configurations, issue the following
command:
db2mqln1/db2mqln2 show
-ssID <subsystem name>
-config all
v To remove the messaging tasks, issue the following command:
db2mqln1/db2mqln2 remove
-ssID <subsystem name>
-config <configuration name>
-queueManager <queuemanager name>
-inputQueue <inputqueue name>
v To run the MQListener task, issue the following command:
db2mqln1/db2mqln2 run
-ssID <subsystem name>
-config <configuration name>
-adminQueue <adminqueue name>
-adminQMgr <adminqueuemanager name>
v To shutdown the MQListener daemon, issue the following command:
db2mqln1/db2mqln2 admin
-adminQueue <adminqueue name>
-adminQMgr <adminqueuemanager name>
-adminCommand shutdown
v To restart the MQListener daemon, issue the following command:
db2mqln1/db2mqln2 admin
-adminQueue <adminqueue name>
-adminQMgr <adminqueuemanager name>
-adminCommand restart
v To get help with the command and the valid parameters, issue the following
command:
db2mqln1/db2mqln2 help
v To get help for a particular parameter, issue the following command, where
’command’ is a specific parameter:
db2mqln1/db2mqln2 help <command>

Restriction:
v Use the same queue manager for the request queue and the reply queue.
v MQListener does not support logical messages that are composed of multiple
physical messages. MQListener processes physical messages independently.

Creating a sample stored procedure to use with MQ Listener:

You can create a sample stored procedure, APROC, that can be used by
MQListener to store a message in a table. The stored procedure returns the string
OK if the message is successfully inserted into the table.

The following steps create DB2 objects that you can use with MQListener
applications:
| 1. Create a table using SPUFI, DSNTEP2, or the command line processor in the
| subsystem where you want to run MQListener:
| CREATE TABLE PROCTABLE (MSG VARCHAR(25) CHECK (MSG NOT LIKE 'FAIL

| The table contains a check constraint so that messages that start with the
| characters FAIL cannot be inserted into the table. The check constraint is used
| to demonstrate the behavior of MQListener when the stored procedure fails.
2. Create the following SQL procedure and define it to the same DB2 subsystem:

Chapter 15. Coding methods for distributed data 875

CREATE PROCEDURE TEST.APROC (
IN PIN VARCHAR(25),
OUT POUT VARCHAR(2))
LANGUAGE SQL
FENCED
NOT DETERMINISTIC
NO DBINFO
COLLID TESTLSRN
WLM ENVIRONMENT TESTWLMX
ASUTIME NO LIMIT
STAY RESIDENT NO
PROGRAM TYPE MAIN
SECURITY USER
PROCEDURE1: BEGIN
INSERT INTO PROCTABLE VALUES(PIN);
SET POUT = 'OK';
END PROCEDURE1

TESTLSRN is the name of the collection that is used for this stored procedure
and TESTWLMX is the name of the WLM environment where this stored
procedure will run.
3. Optional: Bind the collection TESTLSRN to the plan DB2MQLSN, which is used
by MQListener:
BIND PLAN(DB2MQLSN) +
PKLIST(LSNR.*,TESTLSRN.*) +
ACTION(REP) DISCONNECT(EXPLICIT);
If your application calls a stored procedure or user defined function that is
defined with the COLLID option, the application does not need to include the
collection ID in its plan. Thus, this step is optional.

| MQListener error processing:

| MQListener reads from WebSphere MQ message queues and calls DB2 stored
| procedures with those messages. If any errors occur during this process and the
| conditions are such that the message is to be sent to the deadletter queue,
| MQListener returns a reason code to the deadletter queue.

| Specifically, MQListener performs the following actions:

| v prefixes the message with an MQ dead letter header (MQDLH) structure
| v sets the reason field in the MQDLH structure to the appropriate reason code
| v sends the message to the deadletter queue

| The following table describes the reason codes that the MQListener daemon
| returns.
| Table 143. Reason codes that MQListener returns
| Reason code Explanation
| 900 The call to a stored procedure was successful but an error occurred during the DB2
| commit process and either of the following conditions were true:
| v No exception report was requested.1
| v An exception report was requested, but could not be delivered.
| This reason code applies only to one-phase commit environments.
| 901 The call to the specified stored procedure failed and the disposition of the MQ message is
| that an exception report be generated and the original message be sent the deadletter
| queue.

876 Application Programming and SQL Guide

| Table 143. Reason codes that MQListener returns (continued)
| Reason code Explanation
| 902 All of the following conditions occurred:
1
| v The disposition of the MQ message is that an exception report is not to be generated.
| v The stored procedure was called unsuccessfully the number of times that is specified as
| the backout threshold.
| v The name of the backout queue is the same as the deadletter queue.
| This reason code applies only to two-phase commit environments.
| MQRC_TRUNCATED_ The size of the MQ message is greater than the input parameter of the stored procedure
| MSG__FAILED that is to be invoked. In one-phase commit environments, this oversized message is sent to
| the dead letter queue. In two-phase commit environments, this oversized message is sent
| to the deadletter queue only when the message cannot be delivered to the backout queue.
|

| Note:
| 1. To specify that the receiver application generate exception reports if errors
| occur, set the report field in the MQMD structure that was used when sending
| the message to one of the following values:
| v MQRO_EXCEPTION
| v MQRO_EXCEPTION_WITH_DATA
| v MQRO_EXCEPTION_WITH_FULL_DATA
| For more information about the report field, see the WebSphere MQ
| Information Center at http://publib.boulder.ibm.com/infocenter/wmqv6/
| v6r0/index.jsp.

| MQListener examples:

These examples show a simple MQListener application. The application receives a

message, inserts the message into a table, and generates a simple response
message.

To simulate a processing failure, the application includes a check constraint on the

table that contains the message. The constraint prevents any string that begins with
the characters ’fail’ from being inserted into the table. If you attempt to insert a
message that violates the check constraint, the example application returns an error
message and re-queues the failing message to the backout queue.

In this example, the following assumptions are made:

v MQListener is installed and configured for subsystem DB7A.
v MQND is the name of MQSeries subsystem that is defined. The Queue Manager
is running, and the following local queues are defined in the DB7A subsystem:
ADMIN_Q : Admin queue
BACKOUT_Q : Backout queue
IN_Q : Input queue that has a backout queue withthreshold = 3
REPLY_Q : Output queue or Reply queue
DEADLLETTER_Q : Dead letter queue
v The person who is running the MQListener daemon has execute permission on
the DB2MQLSN plan.

Before you run the MQListener daemon, add the following configuration, named
ACFG, to the configuration table by issuing the following command:

Chapter 15. Coding methods for distributed data 877

db2mqln2 add
-ssID DB7A
-config ACFG
-queueManager MQND
-inputQueue IN_Q
-procName APROC
-procSchema TEST

Run the MQListener daemon for two-phase commit for the added configuration
’ACFG’. To run MQListener with all of the tasks specified in a configuration, issue
the following command:
db2mqln2 run
-ssID DB7A
-config ACFG
-adminQueue ADMIN_Q
-adminQMgr MQND

The following examples show how to use MQListener to send a simple message
and then inspect the results of the message in the WebSphere MQ queue manager
and the database. The examples include queries to determine if the input queue
contains a message or to determine if a record is placed in the table by the stored
procedure.

MQListener example 1: Running a simple application:

1. Start with a clean database table by issuing the following SQL statement:
delete from PROCTABLE
2. Send a datagram to the input queue, ’IN_Q’, with the message as ’sample
message’. Refer to Websphere MQ sample CSQ4BCK1 to send a message to the
queue. Specify the MsgType option for ’Message Descriptor’ as
’MQMT_DATAGRAM’.
3. Query the table by using the following statement to verify that the sample
message is inserted:
select * from PROCTABLE
4. Display the number of messages that remain on the input queue to verify that
the message has been removed. Issue the following command from a z/OS
console:
/-MQND display queue('In_Q') curdepth

MQListener example 2: Sending requests to the input queue and inspecting the
reply:
1. Start with a clean database table by issuing the following SQL statement:
delete from PROCTABLE
2. Send a request to the input queue, ’IN_Q’, with the message as ’another sample
message’. Refer to Websphere MQ sample CSQ4BCK1 to send a message to the
queue. Specify the MsgType option for ’Message Descriptor’ as
’MQMT_REQUEST’ and the queue name for ReplytoQ option.
3. Query the table by using the following statement to verify that the sample
message is inserted:
select * from PROCTABLE
4. Display the number of messages that remain on the input queue to verify that
the message has been removed. Issue the following command from a z/OS
console:
/-MQND display queue('In_Q') curdepth

878 Application Programming and SQL Guide

5. Look at the ReplytoQ name that you specified when you sent the request
message for the reply by using the WebSphere MQ sample program CSQ4BCJ1.
Verify that the string ’OK’ is generated by the stored procedure.

MQListener example 3: Testing an unsuccessful insert operation: If you send a

message that starts with the string ’fail’, the constraint in the table definition is
violated, and the stored procedure fails.
1. Start with a clean database table by issuing the following SQL statement:
delete from PROCTABLE
2. Send a request to the input queue, ’IN_Q’, with the message as ’failing sample
message’. Refer to Websphere MQ sample CSQ4BCK1 to send a message to the
queue. Specify the MsgType option for ’Message Descriptor’ as
’MQMT_REQUEST’ and the queue name for ReplytoQ option.
3. Query the table by using the following statement to verify that the sample
message is not inserted:
select * from PROCTABLE
4. Display the number of messages that remain on the input queue to verify that
the message has been removed. Issue the following command from a z/OS
console:
/-MQND display queue('In_Q') curdepth
5. Look at the Backout queue and find the original message by using the
WebSphere MQ sample program CSQ4BCJ1.

Note: In this example, if a request message with added options for ’exception
report’ is sent (the Report option is specified for ’Message Descriptor’), an
exception report is sent to reply queue and original message is sent to the
deadletter queue.

Chapter 15. Coding methods for distributed data 879

880 Application Programming and SQL Guide
Chapter 16. DB2 as a Web services consumer and provider
Web services are a set of resources and components that applications can use over
HTTP. You can use DB2 as a web services provider and a web services consumer.

DB2 as a web services consumer: DB2 can act as a client for web services, which
enables you to be a consumer of web services in your DB2 applications. web
services employs Simple Object Access Protocol (SOAP). SOAP is an XML protocol
that consists of the following characteristics:
v An envelope that defines a framework for describing the contents of a message
and how to process the message
v A set of encoding rules for expressing instances of application-defined data types
v A convention for representing SOAP requests and responses

DB2 as a web services provider: You can enable your DB2 data and applications
as web services through the Web Services Object Runtime Framework (WORF).
You can define a web service in DB2 by using a Document Access Definition
Extension (DADX). In the DADX file, you can define web services based on SQL
statements and stored procedures. Based on your definitions in the DADX file,
WORF performs the following actions:
v Handles the connection to DB2 and the execution of the SQL and the stored
procedure call
v Converts the result to a web service
v Handles the generation of any Web Services Definition Language (WSDL) and
UDDI (Universal Description, Discovery, and Integration) information that the
client application needs
For more information about using DB2 as a web services provider, see DB2
Information Integrator Application Developer’s Guide.

The SOAPHTTPV and SOAPHTTPC user-defined functions

DB2 provides user-defined functions with which you can work with SOAP and
consume web services in SQL statements. The user-defined functions are two
varieties of SOAPHTTPV for VARCHAR data and two varieties of SOAPHTTPC
for CLOB data.

The user-defined functions perform the following actions:

1. Compose a SOAP request
2. Post the request to the service endpoint
3. Receive the SOAP response
4. Return the content of the SOAP body

When a consumer receives the result of a web services request, the SOAP envelope
is stripped and the XML document is returned. An application program can
process the result data and perform a variety of operations, including inserting or
updating a table with the result data.

SOAPHTTPV and SOAPHTTPC are user-defined functions that enable DB2 to

work with SOAP and to consume web services in SQL statements. These functions
are overloaded functions that are used for VARCHAR or CLOB data of different

© Copyright IBM Corp. 1983, 2009 881

sizes, depending on the SOAP body. Web services can be invoked in one of four
ways, depending on the size of the input data and the result data. SOAPHTTPV
returns VARCHAR(32672) data and SOAPHTTPC returns CLOB(1M) data. Both
functions accept either VARCHAR(32672) or CLOB(1M) as the input body.

Example: The following example shows an HTTP post header that posts a SOAP
request envelope to a host. The SOAP envelope body shows a temperature request
for Barcelona.
POST /soap/servlet/rpcrouter HTTP/1.0
Host: services.xmethods.net
Connection: Keep-Alive User-Agent: DB2SOAP/1.0
Content-Type: text/xml; charset="UTF-8"
SOAPAction: ""
Content-Length: 410

<?xml version='1.0' encoding='UTF-8'?>

<SOAP-ENV:Envelope xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/
xmlns:SOAP-ENC=http://schemas.xmlsoap.org/soap/encoding/
xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance
xmlns:xsd=http://www.w3.org/2001/XMLSchema >
<SOAP-ENV:Body>
<ns:getTemp xmlns:ns="urn:xmethods-Temperature">
<city>Barcelona</city>
</ns:getTemp>
</SOAP-ENV:Body>
</SOAP-ENV:Envelope>

Example: The following example is the result of the preceding example. This
example shows the HTTP response header with the SOAP response envelope. The
result shows that the temperature is 85 degrees Fahrenheit in Barcelona.
HTTP/1.1 200 OK
Date: Wed, 31 Jul 2002 22:06:41 GMT
Server: Enhydra-MultiServer/3.5.2
Status: 200
Content-Type: text/xml; charset=utf-8
Servlet-Engine: Lutris Enhydra Application Server/3.5.2
(JSP 1.1; Servlet 2.2; Java™ 1.3.1_04;
Linux 2.4.7-10smp i386; java.vendor=Sun Microsystems Inc.)
Content-Length: 467
Set-Cookie:JSESSIONID=JLEcR34rBc2GTIkn-0F51ZDk;Path=/soap
X-Cache: MISS from www.xmethods.net
Keep-Alive: timeout=15, max=10
Connection: Keep-Alive

<?xml version='1.0' encoding='UTF-8'?>

<SOAP-ENV:Envelope xmlns:SOAP-ENV=http://schemas.xmlsoap.org/soap/envelope/
xmlns:xsi=http://www.w3.org/2001/XMLSchema-instance
xmlns:xsd=http://www.w3.org/2001/XMLSchema >
<SOAP-ENV:Body>
<ns1:getTempResponse xmlns:ns1="urn:xmethods-Temperature"
SOAP-ENV:encodingStyle=http://schemas.xmlsoap.org/soap/encoding/ >
<return xsi:type="xsd:float">85</return>
</ns1:getTempResponse>
</SOAP-ENV:Body></SOAP-ENV:Envelope>

Example: The following example shows how to insert the result from a web
service into a table
INSERT INTO MYTABLE(XMLCOL) VALUES (DB2XML.SOAPHTTPC(
'http://www.myserver.com/services/db2sample/list.dadx/SOAP',
'http://tempuri.org/db2sample/list.dadx'
'<listDepartments xmlns="http://tempuri.org/db2sample/listdadx">
<deptno>A00</deptno>
</ListDepartments>'))

882 Application Programming and SQL Guide

| The SOAPHTTPNV and SOAPHTTPNC user-defined functions
| DB2 provides SOAPHTTPNV and SOAPHTTPNC user-defined functions with
| which you can work with SOAP and consume web services in SQL statements. The
| user-defined functions are two varieties of SOAPHTTPNV for VARCHAR data and
| two varieties of SOAPHTTPNC for CLOB data.

| The user-defined functions perform the following actions:

| 1. Post the input SOAP request to the service endpoint
| 2. Receive and return the SOAP response

| SOAPHTTPNV and SOAPHTTPNC allow you to specify a complete SOAP

| message as input and return complete SOAP messages from the specified web
| service as a CLOB or VARCHAR representation of the returned XML data. .
| SOAPHTTPNV returns VARCHAR(32672) data and SOAPHTTPNC returns
| CLOB(1M) data. Both functions accept either VARCHAR(32672) or CLOB(1M) as
| the input body.

| Example

| The following example shows how to insert the complete result from a web service
| into a table using SOAPHTTPNC.
| INSERT INTO EMPLOYEE(XMLCOL)
| VALUES (DB2XML.SOAPHTTPNC(
| 'http://www.myserver.com/services/db2sample/list.dadx/SOAP',
| 'http://tempuri.org/db2sample/list.dadx',
| '<?xml version="1.0" encoding="UTF-8" ?>' ||
| '<SOAP-ENV:Envelope ' ||
| 'xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" ' ||
| 'xmlns:xsd="http://www.w3.org/2001/XMLSchema" ' ||
| 'xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">' ||
| '<SOAP-ENV:Body>' ||
| '<listDepartments xmlns="http://tempuri.org/db2sample/list.dadx">
| <deptNo>A00</deptNo>
| </listDepartments>' ||
| '</SOAP-ENV:Body>' ||
| '</SOAP-ENV:Envelope>'))

SQLSTATEs for DB2 as a Web services consumer

DB2 returns SQLSTATE values for error conditions related to using DB2 as a web
services consumer.

The following tables show possible SQLSTATE values.

Table 144. SQLSTATE values for SOAPHTTPV and SOAPHTTPC user-defined functions
SQLSTATE Description
38301 An unexpected NULL value was pass as input to the function.
38302 The function was unable to allocate space.
38304 An unknown protocol was specified ion the endpoint URL.
38305 An invalid URL was specified on the endpoint URL.
38306 An error occurred while attempting to create a TCP/IP socket.
38307 An error occurred while attempting to bind a TCP/IP socket.
38308 The function could not resolve the specified host name.

Chapter 16. DB2 as a Web services consumer and provider 883

Table 144. SQLSTATE values for SOAPHTTPV and SOAPHTTPC user-defined
functions (continued)
SQLSTATE Description
38309 An error occurred while attempting to connect to the specified server.
38310 An error occurred while attempting to retrieve information from the
protocol.
38311 An error occurred while attempting to set socket options.
38312 The function received unexpected data returned for the web service.
38313 The web service did not return data of the proper content type.
38314 An error occurred while initializing the XML parser.
38315 An error occurred while creating the XML parser.
38316 An error occurred while establishing a handler for the XML parser.
38317 The XML parser encountered an error while parsing the result data.
38318 The XML parser could not convert the result data to the database code
page.
38319 The function could not allocate memory when creating a TCP/IP socket.
38320 An error occurred while attempting to send the request to the specified
server.
38321 The function was unable to send the entire request to the specified server.
38322 An error occurred while attempting to read the result data from the
specified server.
38323 An error occurred while waiting for data to be returned from the specified
server.
38324 The function encountered an internal error while attempting to format the
input message.
38325 The function encountered an internal error while attempting to add
namespace information to the input message.
38327 The XML parser could not strip the SOAP envelope from the result
message.
38328 An error occurred while processing an SSL connection.

Table 145. SQLSTATE values for SOAPHTTPNV and SOAPHTTPNC user-defined functions
SQLSTATE Description
| 38350 An unexpected NULL value was specified for the endpoint, action, or
| SOAP input.
| 38351 A dynamic memory allocation error.
| 38352 An unknown or unsupported transport protocol.
| 38353 An invalid URL was specified.
| 38354 An error occurred while resolving the hostname.
| 38355 A memory exception for socket.
| 38356 An error occurred during socket connect.
| 38357 An error occurred while setting socket options.
| 38358 An error occurred during input/output control (ioctl) to verify HTTPS
| enablement.
| 38359 An error occurred while reading from the socket.

884 Application Programming and SQL Guide

Table 145. SQLSTATE values for SOAPHTTPNV and SOAPHTTPNC user-defined
functions (continued)
SQLSTATE Description
| 38360 An error occurred due to socket timeout.
| 38361 No response from the specified host.
| 38362 An error occurred due to an unexpected HTTP return or content type
| 38363 The TCP/IP stack was not enabled for HTTPS.

Related tasks
Enabling Web service user-defined functions (DB2 Installation and Migration)

Chapter 16. DB2 as a Web services consumer and provider 885

886 Application Programming and SQL Guide
Chapter 17. Preparing an application to run on DB2 for z/OS
To prepare and run applications that contain embedded static or dynamic SQL
statements, you must precompile, compile, link-edit and bind them.

You can perform these steps by using one of the following methods:

Productivity hint: To avoid rework, first test your SQL statements using SPUFI.
Then compile your program without SQL statements, and resolve all compiler
errors. Finally, proceed with the preparation and the DB2 precompiler or with the
host compiler that supports that DB2 coprocessor.

The following types of applications require different methods of program

preparation:
v Applications that contain ODBC calls
v Applications in interpreted languages, such as REXX
v Java applications, which can contain JDBC calls or embedded SQL statements

For information about running REXX programs, which you do not prepare for
execution, see “Running a DB2 REXX application” on page 998.

Steps in program preparation:

The following topics provide details on preparing and running a DB2 application:
“Processing SQL statements” on page 890
“Compiling and link-editing an application” on page 915
“Binding an application” on page 916
Chapter 18, “Running an application on DB2 for z/OS,” on page 995.

Binding a package is not necessary in all cases. These instructions assume that you
bind some of your DBRMs into packages and include a package list in your plan.

If you use CICS, you might need additional steps; see:

v “Translating command-level statements in a CICS program” on page 901
v “Example of calling applications in a command procedure” on page 1008

For more information about when to bind a package, see “DB2 program
preparation overview” on page 947.

Preparing applications by using JCL procedures:

A number of methods are available for preparing an application to run. You can:
v Use DB2 interactive (DB2I) panels, which lead you step by step through the
preparation process.
v Submit a background job using JCL (which the program preparation panels can
create for you).
v Start the DSNH CLIST in TSO foreground or background.
v Use TSO prompters and the DSN command processor.
v Use JCL procedures added to your SYS1.PROCLIB (or equivalent) at DB2 install
time.

© Copyright IBM Corp. 1983, 2009 887

| v For C and C++ only, you can invoke the coprocessor from UNIX System Services
| and, if the DBRM is generated in a HFS file, you can use the command line
| processor to bind the resulting DBRM. Optionally, you can also copy the DBRM
| into a partitioned data set member by using the oput and oget commands and
| then bind it by using conventional JCL.

This topic describes how to use JCL procedures to prepare a program.

For information about using the DB2I panels, see Chapter 17, “Preparing an
application to run on DB2 for z/OS,” on page 887.

For information about using the DSNH CLIST, see the topic “DSNH (TSO CLIST)”
in DB2 Command Reference.

For information about the DSN command processor, see the topic “TSO attachment
facility” in DB2 Administration Guide.

For information about using the command line processor, see the topic “Command
line processor” in DB2 Command Reference.

Preparing applications by the DB2 Program Preparation panels:

If you develop programs using TSO and ISPF, you can prepare them to run by
using the DB2 Program Preparation panels. These panels guide you step by step
through the process of preparing your application to run. Other ways of preparing
a program to run are available, but using DB2 Interactive (DB2I) is the easiest
because it leads you automatically from task to task.

Important: If your C++ program satisfies both of the following conditions, you
must use a JCL procedure to prepare it:
v The program consists of more than one data set or member.
v More than one data set or member contains SQL statements.

To prepare an application by using the DB2 Program Preparation panels:

1. If you want to display or suppress message IDs during program preparation,
specify one of the following commands on the ISPF command line:
TSO PROFILE MSGID
Message IDs are displayed
TSO PROFILE NOMSGID
Message IDs are supressed
2. Open the DB2I Primary Option Menu.
3. Select the option that corresponds to the Program Preparation panel.
4. Complete the Program Preparation panel and any subsequent panels. After you
complete each panel, DB2I automatically displays the next appropriate panel.

Preparation guidelines for DL/I batch programs:

Use the following guidelines when you prepare a program to access DB2 and DL/I
in a batch program:
v “Processing SQL statements by using the DB2 precompiler” on page 892
v “Binding a batch program” on page 930
v “Compiling and link-editing an application” on page 915
v “Loading and running a batch program” on page 1002

888 Application Programming and SQL Guide

Setting the DB2I defaults
When you use the DB2 Interactive (DB2I) panels to prepare an application, you can
specify the defaults that DB2I is to use for values such as application language and
default JCL JOB statement. Otherwise, DB2I uses the system defaults that were set
at installation time.

To set the DB2I defaults:

As DB2I leads you through a series a panels, enter the default values that you
want on the following panels when they are displayed.
Table 146. DB2I panels to use to set default values
If you want to set the following default values... Use this panel

v subsystem ID DB2I Defaults Panel 1 panel

v number of additional times to attempt to connect to
DB2
v programming language
v number of lines on each page of listing or SPUFI
output
v lowest level of message to return to you during the
BIND phase
v SQL string delimiter for COBOL programs
v how to represent decimal separators
v smallest value of the return code (from precompile,
compile, link-edit, or bind) that prevents later steps
from running
v default number of input entry rows to generate on the
initial display of ISPF panels
v user ID to associate with the trusted connection for the
current DB2I session

v default JOB statement DB2I Defaults Panel 2 panel

v symbol used to delimit a string in a COBOL statement
in a COBOL application
v whether DCLGEN generates a picture clause that has
the form PIC G(n) DISPLAY-1 or PIC N(n).

Chapter 17. Preparing an application to run on DB2 for z/OS 889

Table 146. DB2I panels to use to set default values (continued)
If you want to set the following default values... Use this panel
The following package and plan characteristics Defaults for Bind Package panel
v isolation level
Defaults for Bind Plan panel
v whether to check authorization at run time or at bind
time
v when to release locks on resources
v whether to obtain EXPLAIN information about how
SQL statements in the plan or package execute
v whether you need data currency for ambiguous cursors
opened at remote locations
v whether to use parallel processing
v whether DB2 determines access paths at bind time and
again at execution time
v whether to defer preparation of dynamic SQL
statements
v whether DB2 keeps dynamic SQL statements after
commit points
v whether DB2 uses DRDA protocol or DB2 private
protocol to execute statements that contain three-part
names
v the application encoding scheme
v whether you want to use optimization hints to
determine access paths
v when DB2 writes the changes for updated group buffer
pool-dependent pages
v whether run-time (RUN) or bind-time (BIND) rules
apply to dynamic SQL statements at run time
v whether to continue to create a package after finding
SQL errors (packages only)
v when to acquire locks on resources (plans only)
v whether a CONNECT (Type 2) statement executes
according to DB2 rules (DB2) or the SQL standard
(STD). (plans only)
v which remote connections end during a commit or a
rollback (plans only)

Related reference
“DB2I Defaults Panel 1” on page 961
“DB2I Defaults Panel 2” on page 963
“Defaults for Bind Package panel” on page 973
“Defaults for Bind Plan panel” on page 976

Processing SQL statements

The first step in preparing an SQL application to run is to process the SQL
statements in the program by using either the DB2 precompiler or the DB2
coprocessor. During this step, the SQL statements are replaced with calls to DB2
language interface modules, and a DBRM is created.

For assembler or Fortran applications, use the DB2 precompiler to prepare the SQL
statements.

890 Application Programming and SQL Guide

For C, C++, COBOL, or PL/I applications, you can use one of the following
techniques to process SQL statements:
v Use the DB2 precompiler before you compile your program.
You can use this technique with any supported version of C or C++, COBOL, or
PL/I. (For a list of supported versions, see DB2 Program Directory.)
| v Invoke the DB2 coprocessor for the host language that you are using as you
| compile your program. You can use the DB2 coprocessor with C, C++, COBOL,
| and PL/I host compilers. To invoke the DB2 coprocessor, specify the SQL
| compiler option followed by its suboptions, which are those options that are
| defined for the DB2 precompiler. Some DB2 precompiler options are ignored.
| – For C or C++, you need IBM z/OS Version 1 Release 8 C/C++ or later. For
| more information about the DB2 coprocessor, see z/OS C/C++ Programming
| Guide. For C and C++, you can also invoke the coprocessor from UNIX
| System Services on z/OS to generate a DBRM in either a partitioned data set
| or an HFS file.
| – For COBOL, you need Enterprise COBOL for z/OS Version 3 Release 4 or
| later to use this technique. For more information about the COBOL DB2
| coprocessor, see Enterprise COBOL for z/OS Programming Guide.
| – For PL/I, you need Enterprise PL/I for z/OS Version 3 Release 4 or later to
| use this technique. For more information about the PL/I DB2 coprocessor, see
| IBM Enterprise PL/I for z/OS Programming Guide
For information about the differences between the DB2 precompiler and the DB2
coprocessor, see “Differences between the DB2 precompiler and the DB2
coprocessor” on page 902.

CICSIf the application contains CICS commands, you must translate the program
before you compile it. (See “Translating command-level statements in a CICS
program” on page 901.)

| DB2 version in DSNHDECP module: When you process SQL statements in your
| program, if the DB2 version in DSNHDECP is the default system-provided version,
| DB2 issues a warning and processing continues. In this case, ensure that the
| information in DSNHDECP that DB2 uses accurately reflects your environment.

SQL statement processing:

Because most compilers do not recognize SQL statements, you can prevent
compiler errors by using either the DB2 precompiler or the DB2 coprocessor.

The precompiler scans the program and returns modified source code, which you
can then compile and link edit. The precompiler also produces a DBRM (database
request module). You can bind this DBRM to a package or plan using the BIND
subcommand. (For information about packages and plans, see “DB2 program
preparation overview” on page 947.) When you complete these steps, you can run
your DB2 application.

Alternatively, you can use the DB2 coprocessor for the host language. The DB2
coprocessor performs DB2 precompiler functions at compile time. When you use
the DB2 coprocessor, the compiler (rather than the precompiler) scans the program
and returns the modified source code. The DB2 coprocessor also produces a
DBRM.

Chapter 17. Preparing an application to run on DB2 for z/OS 891

Processing SQL statements by using the DB2 precompiler
The DB2 precompiler scans a program and copies all of the SQL statements and
host variable information into a DBRM (database request module). The
precompiler also returns source code that has been modified so that the SQL
statements will not cause errors when you compile the program. You can then
compile and link-edit this modified source code.

Before you run the DB2 precompiler, use DCLGEN to obtain accurate SQL
DECLARE TABLE statements. The precompiler checks table and column references
against SQL DECLARE TABLE statements in the program, not the actual tables
and columns. For information about DCLGEN, see “DCLGEN (declarations
generator)” on page 129.

DB2 does not need to be active when you precompile your program.

You do not need to precompile the program on the same DB2 subsystem on which
you bind the DBRM and run the program. You can bind a DBRM and run it on a
DB2 subsystem at the previous release level, if the original program does not use
any properties of DB2 that are unique to the current release. You can also run
applications on the current release that were previously bound on subsystems at
the previous release level.

To process SQL statements by using the DB2 precompiler:

1. Ensure that your program is ready to be processed by the DB2 precompiler by
performing the following actions: For information about the criteria for
programs that are passed to the precompiler, see “Input to the DB2
precompiler” on page 895.
2. If you plan to run multiple precompilation jobs and are not using the
DFSMSdfp™ partitioned data set extended (PDSE), change the DB2 language
preparation procedures (DSNHCOB, DSNHCOB2, DSNHICOB, DSNHFOR,
DSNHC, DSNHPLI, DSNHASM, DSNHSQL) to specify the DISP=OLD
parameter instead of the DISP=SHR parameter. The DB2 language preparation
procedures in job DSNTIJMV use the DISP=OLD parameter to enforce data
integrity. However, the installation process converts the DISP=OLD parameter
for the DBRM library data set to DISP=SHR, which can cause data integrity
problems when you run multiple precompilation jobs.
3. Start the precompile process by using one of the following methods:
v DB2I panels. Use the Precompile panel or the DB2 Program Preparation
panels.
v The DSNH command procedure (a TSO CLIST). For a description of that
CLIST, see the topic “DSNH (TSO CLIST)” in DB2 Command Reference.
v JCL procedures that are supplied with DB2. For more information about this
method, see “DB2-supplied JCL procedures for preparing an application” on
page 952.
Recommendation: Specify the SOURCE and XREF precompiler options to get
complete diagnostic output from the DB2 precompiler. This output is useful if
you need to precompile and compile program source statements several times
before they are error-free and ready to link-edit.
The output that is returned from the DB2 precompiler is described in “Output
from the DB2 precompiler” on page 897.

Preparing a program with object-oriented extensions by using JCL:

892 Application Programming and SQL Guide

If your C++ or Enterprise COBOL for z/OS program satisfies both of these
conditions, you need special JCL to prepare it:
v The program consists of more than one data set or member.
v More than one data set or member contains SQL statements.

You must precompile the contents of each data set or member separately, but the
prelinker must receive all of the compiler output together.

JCL procedure DSNHCPP2, which is in member DSNTIJMV of data set

DSN910.SDSNSAMP, shows you one way to do this for C++.

Precompiling a batch program: When you add SQL statements to an application

program, you must precompile the application program and bind the resulting
DBRM into a plan or package, as described in Chapter 17, “Preparing an
application to run on DB2 for z/OS,” on page 887.

| Data sets that the precompiler uses

| When you invoke the precompiler you need to provide data sets that contain input
| for the precompiler, such as the host programming statements and SQL statements.
| You also need to provide data sets where the precompiler can store its output, such
| as the modified source code and diagnostics messages.
| Table 147. DD statements and data sets that the DB2 precompiler uses
| DD statement Data set description Required?
| DBRMLIB Output data set, which Yes
| contains the SQL statements
| and host variable
| information that the DB2
| precompiler extracted from
| the source program. It is
| called Database Request
| Module (DBRM). This data
| set becomes the input to the
| DB2 bind process. The DCB
| attributes of the data set are
| RECFM FB, LRECL 80.
| DBRMLIB has to be a PDS
| and a member name must be
| specified. You can use
| IEBCOPY, IEHPROGM, TSO
| commands, COPY and
| DELETE, or PDS
| management tools for
| maintaining the data set.

Chapter 17. Preparing an application to run on DB2 for z/OS 893

| Table 147. DD statements and data sets that the DB2 precompiler uses (continued)
| DD statement Data set description Required?
| STEPLIB Step library for the job step. No, but recommended
| In this DD statement, you
| can specify the name of the
| library for the precompiler
| load module, DSNHPC, and
| the name of the library for
| your DB2 application
| programming defaults
| member, DSNHDECP.
| Recommendation: Always
| use the STEPLIB DD
| statement to specify the
| library where your DB2
| DSNHDECP module resides
| to ensure that the proper
| application defaults are used
| by the DB2 precompiler. The
| library that contains your
| DB2 DSNHDECP module
| needs to be allocated ahead
| of the prefix.SDSNLOAD
| library.
| SYSCIN Output data set, which Yes
| contains the modified source
| that the DB2 precompiler
| writes out. This data set
| becomes the input data set to
| the compiler or assembler.
| This data set must have
| attributes RECFM F or FB,
| and LRECL 80. SYSCIN can
| be a PDS or a sequential data
| set. If a PDS is used, the
| member name must be
| specified.
| SYSIN Input data set, which Yes
| contains statements in the
| host programming language
| and embedded SQL
| statements. This data set
| must have the attributes
| RECFM F or FB, LRECL 80.
| SYSIN can be a PDS or a
| sequential data set. If a PDS
| is used, the member name
| must be specified.

894 Application Programming and SQL Guide

| Table 147. DD statements and data sets that the DB2 precompiler uses (continued)
| DD statement Data set description Required?
| SYSLIB INCLUDE library, which No
| contains additional SQL and
| host language statements.
| The DB2 precompiler
| includes the member or
| members that are referenced
| by SQL INCLUDE
| statements in the SYSIN
| input from this DD
| statement. Multiple data sets
| can be specified, but they
| must be partitioned data sets
| with attributes RECFM F or
| FB, LRECL 80. SQL
| INCLUDE statements cannot
| be nested.
| SYSPRINT Output data set, which Yes
| contains the output listing
| from the DB2 precompiler.
| This data set must have an
| LRECL of 133 and a RECFM
| of FBA. SYSPRINT must be a
| sequential data set
| SYSTERM Terminal output file, which No
| contains diagnostic messages
| from the DB2 precompiler.
| SYSTERM) must be a
| sequential data set
|

| Input to the DB2 precompiler

The primary input for the precompiler consists of statements in the host
programming language and embedded SQL statements.

You can use the SQL INCLUDE statement to get secondary input from the include
library, SYSLIB. The SQL INCLUDE statement reads input from the specified
member of SYSLIB until it reaches the end of the member.

Another preprocessor, such as the PL/I macro preprocessor, can generate source
statements for the precompiler. Any preprocessor that runs before the precompiler
must be able to pass on SQL statements. Similarly, other preprocessors can process
the source code, after you precompile and before you compile or assemble.

| Input to the DB2 precompiler has the following restrictions:

| v The size of a source program that DB2 can precompile is limited by the region
| size and the virtual memory available to the precompiler. These amounts vary
| with each system installation.
| v The forms of source statements that can pass through the precompiler are
| limited. For example, constants, comments, and other source syntax that are not
| accepted by the host compilers (such as a missing right brace in C) can interfere
| with precompiler source scanning and cause errors. To check for such
| unacceptable source statements, run the host compiler before the precompiler.
| You can ignore the compiler error messages for SQL statements or comment out
| the SQL statements. After the source statements are free of unacceptable

Chapter 17. Preparing an application to run on DB2 for z/OS 895

| compiler errors, you can then uncomment any SQL statements that you
| previously commented out and continue with the normal DB2 program
| preparation process for that host language.
| v You must write host language statements and SQL statements using the same
| margins, as specified in the precompiler option MARGINS.
| v The input data set, SYSIN, must have the attributes RECFM F or FB, LRECL 80.
| v SYSLIB must be a partitioned data set, with attributes RECFM F or FB, LRECL
| 80.
| v Input from the INCLUDE library cannot contain other precompiler INCLUDE
| statements.

Starting the precompiler dynamically when using JCL

procedures
You can call the precompiler from an assembler program by using a macro.

You can call the precompiler from an assembler program by using one of the
macro instructions ATTACH, CALL, LINK, or XCTL. For more information about
these macros, see z/OS MVS Programming: Assembler Services Reference, Volumes 1
and 2.

To call the precompiler, specify DSNHPC as the entry point name. You can pass
three address options to the precompiler; the following topics describe their
formats. The options are addresses of:
v A precompiler option list
v A list of alternative DD names for the data sets that the precompiler uses
v A page number to use for the first page of the compiler listing on SYSPRINT

Precompiler option list format:

When you call the precompiler, you can specify a number of options for SQL
statement processing. You must specify that option list in a particular format.

The option list must begin on a 2-byte boundary. The first 2 bytes contain a binary
count of the number of bytes in the list (excluding the count field). The remainder
of the list is EBCDIC and can contain precompiler option keywords, separated by
one or more blanks, a comma, or both.

DD name list format:

When you call the precompiler, you can specify a list of alternative DD names for
the data sets that the precompiler uses. You must specify this list in a particular
format.

The DD name list must begin on a 2-byte boundary. The first 2 bytes contain a
binary count of the number of bytes in the list (excluding the count field). Each
entry in the list is an 8-byte field, left-justified, and padded with blanks if needed.

The following table gives the following sequence of entries:

Table 148. DDNAME list entries
Entry Standard ddname Usage
1 Not applicable
2 Not applicable
3 Not applicable

896 Application Programming and SQL Guide

Table 148. DDNAME list entries (continued)
Entry Standard ddname Usage
4 SYSLIB Library input
5 SYSIN Source input
6 SYSPRINT Diagnostic listing
7 Not applicable
8 SYSUT1 Work data
9 SYSUT2 Work data
10 SYSUT3 Work data
11 Not applicable
12 SYSTERM Diagnostic listing
13 Not applicable
14 SYSCIN Changed source output
15 Not applicable
16 DBRMLIB DBRM output

Page number format:

When you call the precompiler, you can specify a page number to use for the first
page of the compiler listing on SYSPRINT . You must specify this page number in
a particular format.

A 6-byte field beginning on a 2-byte boundary contains the page number. The first
2 bytes must contain the binary value 4 (the length of the remainder of the field).
The last 4 bytes contain the page number in character or zoned-decimal format.

The precompiler adds 1 to the last page number that is used in the precompiler
listing and puts this value into the page-number field before returning control to
the calling routine. Thus, if you call the precompiler again, page numbering is
continuous.

Output from the DB2 precompiler

The major output from the DB2 precompiler is a database request module (DBRM).
However, the DB2 precompiler also produces modified source statements, a list of
source statements, a list of statements that refer to host names and columns, and
diagnostics.

Specifically, the precompiler produces the following types of output:

listing output
The DB2 precompiler writes the following information in the SYSPRINT data
set:
v Precompiler source listing
If the DB2 precompiler option SOURCE is specified, a source listing is
produced. The source listing includes precompiler source statements, with
line numbers that are assigned by the precompiler.
v Precompiler diagnostics
The precompiler produces diagnostic messages that include precompiler line
numbers of statements that have errors.
v Precompiler cross-reference listing

Chapter 17. Preparing an application to run on DB2 for z/OS 897

If the DB2 precompiler option XREF is specified, a cross-reference listing is
produced. The cross-reference listing shows the precompiler line numbers of
SQL statements that refer to host names and columns.
| The SYSPRINT data set has an LRECL of 133 and a RECFM of FBA. This data
| set uses the CCSID of the source program. Statement numbers in the output of
| the precompiler listing are displayed as they appear in the listing.
Terminal diagnostics
If a terminal output file, SYSTERM, exists, the DB2 precompiler writes
diagnostic messages to it. A portion of the source statement accompanies the
messages in this file. You can often use the SYSTERM file instead of the
SYSPRINT file to find errors. This data set uses EBCDIC.
Modified source statements
The DB2 precompiler writes the source statements that it processes to SYSCIN,
the input data set to the compiler or assembler. This data set must have
attributes RECFM F or FB, and LRECL 80. The modified source code contains
calls to the DB2 language interface. The SQL statements that the calls replace
appear as comments. This data set uses the CCSID of the source program.
Database request modules
The database request module (DBRM) is a data set that contains the SQL
statements and host variable information that is extracted from the source
program, along with information that identifies the program and ties the
DBRM to the translated source statements. It becomes the input to the bind
process.
The data set requires space to hold all the SQL statements plus space for each
host variable name and some header information. The header information
alone requires approximately two records for each DBRM, 20 bytes for each
SQL record, and 6 bytes for each host variable.
For an exact format of the DBRM, see the DBRM mapping macros,
DSNXDBRM and DSNXNBRM, in library prefix.SDSNMACS. The DCB
attributes of the data set are RECFM FB, LRECL 80. The precompiler sets the
characteristics. You can use IEBCOPY, IEHPROGM, TSOCOPY and DELETE
commands, or other PDS management tools for maintaining these data sets.
| Restriction: Do not modify the contents of the DBRM. If you do, unpredictable
| results can occur. DB2 does not support modified DBRMs.
| In a DBRM, the SQL statements and the list of host variable names use the
| UTF-8 character encoding scheme.
| All other character fields in a DBRM use EBCDIC. The current release marker
| (DBRMMRIC) in the header of a DBRM is marked according to the release of
| the precompiler, regardless of the value of NEWFUN.

| Processing SQL statements by using the DB2 coprocessor

| As an alternative to the DB2 precompiler, you can use the DB2 coprocessor to
| process SQL statements. The DB2 coprocessor performs DB2 precompiler functions
| at compile time.

| Exception: For PL/I, the DB2 coprocessor is called from the PL/I SQL preprocessor
| instead of the compiler.

| The DB2 coprocessor has fewer restrictions on SQL programs than the DB2
| precompiler. When you process SQL statements with the DB2 coprocessor, you can
| do the following things in your program:

898 Application Programming and SQL Guide

| v Use fully qualified names for structured host variables.
| v Include SQL statements at any level of a nested program, instead of in only the
| top-level source file.(Although you can include SQL statements at any level of a
| nested program, you must compile the entire program as one unit.)
| v Use nested SQL INCLUDE statements.
| v For C or C++ programs only: Write applications with variable length format.
| v For C or C++ programs only: Use codepage-dependent characters, such as left
| and right brackets, without using tri-graph notation when the programs use
| different code pages.

| To process SQL statements by using the DB2 coprocessor, perform one of the
| following actions:
| v Submit a JCL job to process that SQL statement. Include the following
| information:
| – Specify the SQL compiler option when you compile your program:
| The SQL compiler option indicates that you want the compiler to invoke the
| DB2 coprocessor. Specify a list of SQL processing options in parentheses after
| the SQL keyword. Table 150 on page 904 lists the options that you can specify.
| For COBOL and PL/I, enclose the list of SQL processing options in single or
| double quotation marks. For PL/I, separate options in the list by a comma,
| blank, or both.
| Examples:
| C/C++
| SQL(APOSTSQL STDSQL(NO))
| COBOL
| SQL("APOSTSQL STDSQL(NO)")
| PL/I
| PP(SQL("APOSTSQL,STDSQL(NO)")
| – For PL/I programs that use BIGINT or LOB data types, specify the following
| compiler options when you compile your program: LIMITS(FIXEDBIN(63),
| FIXEDDEC(31))
| – If needed, increase the user’s region size so that it can accommodate more
| memory for the DB2 coprocessor.
| – Include DD statements for the following data sets in the JCL for your compile
| step:
| - DB2 load library (prefix.SDSNLOAD)
| The DB2 coprocessor calls DB2 modules to process the SQL statements. You
| therefore need to include the name of the DB2 load library data set in the
| STEPLIB concatenation for the compile step.
| - DBRM library
| The DB2 coprocessor produces a DBRM. DBRMs and the DBRM library are
| described in “Output from the DB2 precompiler” on page 897. You need to
| include a DBRMLIB DD statement that specifies the DBRM library data set.
| - Library for SQL INCLUDE statements
| If your program contains SQL INCLUDE member-name statements that
| specify secondary input to the source program, you need to also specify the
| data set for member-name. Include the name of the data set that contains
| member-name in the SYSLIB concatenation for the compile step.

Chapter 17. Preparing an application to run on DB2 for z/OS 899

| v For C/C++ only: Invoke the DB2 coprocessor from UNIX System Services on
| z/OS. If you invoke the C/C++ DB2 coprocessor from UNIX System Services,
| you can choose to have the DBRM generated in a partitioned data set or an HFS
| file.
| When you invoke the DB2 coprocessor, include the following information:
| – Specify the SQL compiler option.
| The SQL compiler option indicates that you want the compiler to invoke the
| DB2 coprocessor. Specify a list of SQL processing options in parentheses after
| the SQL keyword. Table 150 on page 904 lists the options that you can specify.
| – Specify a location for the DBRM as the parameter for the dbrmlib option. You
| can specify one of the following items:
| - The name of a partitioned data set
| Example: The following example invokes the C/C++ DB2 coprocessor to
| compile (with the c89 compiler) a sample C program and requests that the
| resulting DBRM is stored in the test member of the userid.dbrmlib.data
| data set:
| c89 -Wc,"sql,dbrmlib(//'userid.dbrmlib.data(test)'),langlvl(extended)" -c t.c
| - The name of an HFS file
| The file name can be qualified, partially qualified, or unqualified. The file
| path can contain a maximum of 1024 characters, and the file name can
| contain a maximum of 255 characters. The first 8 characters of the file
| name, not including the file extension, should be unique within the file
| system.
| Assume that your directory structure is /u/USR001/c/example and that your
| current working directory is /u/USR001/c. The following table shows
| examples of how to specify the HFS file names with the dbrmlib option
| and how the file names are resolved.
| Table 149. How to specify HFS files to store DBRMs
| If you specify... The DBRM is generated in...
|| dbrmlib(/u/USR001/sample.dbrm) /u/USR001/sample.dbrm
|| dbrmlib(example/sample.dbrm) /u/USR001/c/example/sample.dbrm
|| dbrmlib(../sample.dbrm) /u/USR001/sample.dbrm
|| dbrmlib(sample.dbrm) /u/USR001/c/sample.dbrm
|
| Example: The following example invokes the DB2 coprocessor to compile
| (with the c89 compiler) a sample C program and requests that the resulting
| DBRM is stored in the file test.dbrm in the tmp directory:
| c89 -Wc,"sql,dbrmlib(/tmp/test.dbrm),langlvl(extended)" -c t.c
| If you request that the DBRM be generated in an HFS file, you can bind the
| resulting DBRM by using the command line processor BIND command. For
| more information about using the command line processor BIND command,
| see “Binding a DBRM that is in a HFS file to a package or collection” on page
| 919. Optionally, you can also copy the DBRM into a partitioned data set
| member by using the oput and oget commands and then bind the DBRM by
| using conventional JCL.

| Support for compiling a COBOL program that includes SQL from

| an assembler program
| The COBOL compiler provides a facility that allows you to invoke the COBOL
| compiler via an assembler program.

900 Application Programming and SQL Guide

| If you intend to use the DB2 coprocessor and start the COBOL compiler from an
| assembler program as part of your DB2 application preparation, you can use the
| SQL compiler option and provide the alternate DBRMLIB DD name the same way
| that you can specify other alternate DD names. The DB2 coprocessor creates the
| DBRM member according to your DBRM PDS library and the DBRM member that
| you specified using the alternate DBRMLIB DD name.

| To use the alternate DBRMLIB DD name, Enterprise COBOL V4.1 and above is
| required.
| Related information
| IBM System z Enterprise Development Tools & Compilers information center

Translating command-level statements in a CICS program

You can translate CICS applications with the CICS command language translator
as a part of the program preparation process. CICS command language translators
are available only for assembler, C, COBOL, and PL/I languages; no translator is
available for Fortran.

CICS

Prepare your CICS program in either of these sequences:

Use the DB2 precompiler first, followed by the CICS Command Language
Translator. This sequence is the preferred method of program preparation and
the one that the DB2I Program Preparation panels support. If you use the DB2I
panels for program preparation, you can specify translator options
automatically, rather than needing to provide a separate option string.
Use the CICS command language translator first, followed by the DB2
precompiler. This sequence results in a warning message from the CICS
translator for each EXEC SQL statement that it encounters. The warning
messages have no effect on the result. If you are using double-byte character
sets (DBCS), precompiling is recommended before translating, as described
previously.

Program and process requirements: Use the DB2 precompiler before the CICS
translator to prevent the precompiler from mistaking CICS translator output for
graphic data.

If your source program is in COBOL, you must specify a string delimiter that is
the same for the DB2 precompiler, COBOL compiler, and CICS translator. The
defaults for the DB2 precompiler and COBOL compiler are not compatible with the
default for the CICS translator.

If the SQL statements in your source program refer to host variables that a pointer
stored in the CICS TWA addresses, you must make the host variables addressable
to the TWA before you execute those statements. For example, a COBOL
application can issue the following statement to establish addressability to the
TWA:
EXEC CICS ADDRESS
TWA (address-of-twa-area)
END-EXEC

You can run CICS applications only from CICS address spaces. This restriction
applies to the RUN option on the second program DSN command processor. All of
those possibilities occur in TSO.

Chapter 17. Preparing an application to run on DB2 for z/OS 901

To prepare an application program, you can append JCL from a job that is created
by the DB2 Program Preparation panels to the JCL for the CICS command
language translator. To run the prepared program under CICS, you might need to
define programs and transactions to CICS. Your system programmer must make
the appropriate CICS resource or table entries. For information about the required
resource entries, see CICS Transaction Server for z/OS Resource Definition Guide.

prefix.SDSNSAMP contains examples of the JCL that is used to prepare and run a
CICS program that includes SQL statements. For a list of CICS program names and
JCL member names, see “Sample applications in CICS” on page 1077. The set of
JCL includes:
v PL/I macro phase
v DB2 precompiling
v CICS Command Language Translation
v Compiling of the host language source statements
v Link-editing of the compiler output
v Binding of the DBRM
v Running of the prepared application.

Differences between the DB2 precompiler and the DB2

coprocessor
Because the DB2 precompiler and DB2 coprocessor have architectural differences,
you cannot switch from one to the other without considering those differences and
adjusting your program accordingly.

| Recommendation: Use the coprocessor instead of the precompiler when using

| Unicode variables in COBOL or PL/I applications.

Depending on whether you use the DB2 precompiler or the DB2 coprocessor,
ensure that you account for the following differences:
v Differences in handling source CCSIDs:
The DB2 precompiler and DB2 coprocessor convert the SQL statements of your
source program to UTF-8 for parsing.
| The precompiler or DB2 coprocessor uses the source CCSID(n) value, as
| described in Table 150 on page 904, to convert from that CCSID to CCSID 1208
| (UTF-8). The CCSID value must be an EBCDIC CCSID. If you want to prepare a
| source program that is written in a CCSID that cannot be directly converted to
| or from CCSID 1208, you must create an indirect conversion. For information
| about indirect conversions, see z/OS Support for Unicode.
v Differences in handling host variable CCSIDs:
– COBOL:
DB2 precompiler:
The DB2 precompiler sets CCSIDs for alphanumeric host variables only
when the program includes an explicit DECLARE :hv VARIABLE
statement.
DB2 coprocessor:
The COBOL compiler with National Character Support always sets
CCSIDs for alphanumeric variables, including host variables that are used
within SQL, to the source CCSID. Alternatively, you can specify that you
want the COBOL DB2 coprocessor to handle CCSIDs the same way as the
precompiler. For more information about this option, see Enterprise
COBOL for z/OS Programming Guide.

902 Application Programming and SQL Guide

Recommendation: If you have problems with host variable CCSIDs, use the
DB2 precompiler or change your application to include the DECLARE :hv
VARIABLE statement to overwrite the CCSID that is specified by the COBOL
compiler.

Example: Assume that DB2 has mapped a FOR BIT DATA column to a host
variable in the following way:
01 hv1 pic x(5).
01 hv2 pic x(5).

EXEC SQL CREATE TABLE T1 (colwbit char(5) for bit data,

rowid char(5)) END-EXEC.

EXEC SQL
INSERT INTO T1 VALUES (:hv1, :hv2)
END-EXEC.

DB2 precompiler: In the modified source from the DB2 precompiler, hv1 and
hv2 are represented to DB2 through SQLDA in the following way, without
CCSIDs:
for hv1: NO CCSID

20 SQL-PVAR-NAMEL1 PIC S9(4) COMP-4 VALUE +0.

20 SQL-PVAR-NAMEC1 PIC X(30) VALUE ' '.

for hv2: NO CCSID

20 SQL-PVAR-NAMEL2 PIC S9(4) COMP-4 VALUE +0.

20 SQL-PVAR-NAMEC2 PIC X(30) VALUE ' '

DB2 coprocessor: In the modified source from the DB2 coprocessor with the
National Character Support for COBOL, hv1 and hv2 are represented to DB2
in the following way, with CCSIDs: (Assume that the source CCSID is 1140.)
for hv1 and hv2, the value for CCSID is set to '1140' ('474'x) in input SQLDA
of the INSERT statement.

'7F00000474000000007F'x

To ensure that no discrepancy exists between the column with FOR BIT
DATA and the host variable with CCSID 1140, add the following statement
for :hv1 or use the DB2 precompiler:
EXEC SQL DECLARE : hv1 VARIABLE FOR BIT DATA END-EXEC.

for hv1 declared with for bit data. The value in SQL---AVAR-NAME-DATA is
set to 'FFFF'x for CCSID instead of '474x'.

'7F0000FFFF000000007F'x <<= with DECLARE :hv1 VARIABLE FOR BIT DATA

vs.
'7F00000474000000007F'x <<= without
– PL/I
DB2 coprocessor:
You can specify whether CCSIDs are to be associated with host variables
by using the following PL/I SQL preprocessor options:
CCSID0
Specifies that the PL/I SQL preprocessor is not to set the CCSIDs for
all host variables unless they are defined with the SQL DECLARE :hv
VARIABLE statement.

Chapter 17. Preparing an application to run on DB2 for z/OS 903

NOCCSID0
Specifies that the PL/I SQL preprocessor is to set the CCSIDs for all
host variables.

For more information about these options, see IBM Enterprise PL/I for z/OS
Programming Guide.

Options for SQL statement processing

Use SQL processing options to specify how the DB2 precompiler and the DB2
coprocessor interpret and process input, and how they present output.

If you are using the DB2 precompiler, specify SQL processing options in one of the
following ways:
v With DSNH operands
v With the PARM.PC option of the EXEC JCL statement
v On DB2I panels

If you are using the DB2 coprocessor, specify SQL processing options in one of the
following ways:
v For C or C++, specify the options as the argument of the SQL compiler option.
v For COBOL, specify the options as the argument of the SQL compiler option.
v For PL/I, specify the options as the argument of the PP(SQL(’option,...’))
compiler option.
For examples of how to specify the DB2 coprocessor options, see “Processing SQL
statements by using the DB2 coprocessor” on page 898

DB2 assigns default values for any SQL processing options for which you do not
explicitly specify a value. Those defaults are the values that are specified on the
APPLICATION PROGRAMMING DEFAULTS installation panels.

Descriptions of SQL processing options

You can specify any SQL processing options whether you use the DB2 precompiler
or the DB2 coprocessor. However, the DB2 coprocessor might ignore certain
options because host language compiler options exist that provide the same
information.

The following table shows the options that you can specify when you use the DB2
precompiler or DB2 coprocessor. The table also includes abbreviations for those
options and indicates which options are ignored for a particular host language or
by the DB2 coprocessor. This table uses a vertical bar (|) to separate mutually
exclusive options, and brackets ([ ]) to indicate that you can sometimes omit the
enclosed option.
Table 150. SQL processing options
Option keyword Meaning
1
APOST Indicates that the DB2 precompiler is to use the apostrophe (’) as the string delimiter
in host language statements that it generates.

This option is not available in all languages; see Table 152 on page 912.

APOST and QUOTE are mutually exclusive options. The default is in the field
STRING DELIMITER on Application Programming Defaults Panel 1 during
installation. If STRING DELIMITER is the apostrophe (’), APOST is the default.

904 Application Programming and SQL Guide

Table 150. SQL processing options (continued)
Option keyword Meaning
APOSTSQL Recognizes the apostrophe (’) as the string delimiter and the double quotation mark
(″) as the SQL escape character within SQL statements.

APOSTSQL and QUOTESQL are mutually exclusive options. The default is in the
field SQL STRING DELIMITER on Application Programming Defaults Panel 1
during installation. If SQL STRING DELIMITER is the apostrophe (’), APOSTSQL is
the default.
ATTACH(TSO|CAF|RRSAF) Specifies the attachment facility that the application uses to access DB2. TSO, CAF,
and RRSAF applications that load the attachment facility can use this option to
specify the correct attachment facility, instead of coding a dummy DSNHLI entry
point.

This option is not available for Fortran applications.

The default is ATTACH(TSO).

CCSID(n)
| Specifies the numeric value n of the CCSID in which the source program is written.
| The number n must be an EBCDIC CCSID.

The default setting is the EBCDIC system CCSID as specified on the panel DSNTIPF
during installation.

The DB2 coprocessor uses the following process to determine the CCSID of the
source statements:
1. If the CCSID of the source program is specified by a compiler option, such as
the COBOL CODEPAGE compiler option, the DB2 coprocessor uses that CCSID.
2. If the CCSID is not specified by a compiler option:
a. If the CCSID suboption of the SQL compiler option is specified and contains
a valid EBCDIC CCSID, that CCSID is used.
b. If the CCSID suboption of the SQL compiler option is not specified, and the
compiler supports an option for specifying the CCSID, such as the COBOL
CODEPAGE compiler option, the default for the CCSID compiler option is
used.
c. If the CCSID suboption of the SQL compiler option is not specified, and the
compiler does not support an option for specifying the CCSID, the default
CCSID from DSNHDECP is used.
d. If the CCSID suboption of the SQL option is specified and contains an invalid
CCSID, compilation terminates.

| CCSID supersedes the GRAPHIC and NOGRAPHIC SQL processing options.

If you specify CCSID(1026) or CCSID(1155), the DB2 coprocessor does not support
the code point ’FC’X for the double quotation mark (″).
COMMA Recognizes the comma (,) as the decimal point indicator in decimal or floating point
literals in the following cases:
v For static SQL statements in COBOL programs
v For dynamic SQL statements, when the value of installation parameter DYNRULS
is NO and the package or plan that contains the SQL statements has
DYNAMICRULES bind, define, or invoke behavior.

COMMA and PERIOD are mutually exclusive options. The default (COMMA or
PERIOD) is chosen under DECIMAL POINT IS on Application Programming
Defaults Panel 1 during installation.

Chapter 17. Preparing an application to run on DB2 for z/OS 905

Table 150. SQL processing options (continued)
Option keyword Meaning
CONNECT(2|1) CT(2|1) Determines whether to apply type 1 or type 2 CONNECT statement rules.
CONNECT(2) Default: Apply rules for the CONNECT (Type 2) statement
CONNECT(1) Apply rules for the CONNECT (Type 1) statement
If you do not specify the CONNECT option when you precompile a program, the
rules of the CONNECT (Type 2) statement apply.
DATE(ISO|USA Specifies that date output should always be returned in a particular format,
|EUR|JIS|LOCAL) regardless of the format that is specified as the location default. For more
information about the description of these formats, see the topic “Datetime values”
in DB2 SQL Reference.

The default is specified in the field DATE FORMAT on Application Programming

Defaults Panel 2 during installation.

The default format is determined by the installation defaults of the system where
the program is bound, not by the installation defaults of the system where the
program is precompiled.

You cannot use the LOCAL option unless you have a date exit routine.
DEC(15|31)D(15.s|31.s) Specifies the maximum precision for decimal arithmetic operations. See “Precision
for operations with decimal numbers” on page 657.

The default is in the field DECIMAL ARITHMETIC on Application Programming

Defaults Panel 1 during installation.

If the form Dpp.s is specified, pp must be either 15 or 31, and s, which represents the
minimum scale to be used for division, must be a number between 1 and 9.
FLAG(I|W|E|S)1 Suppresses diagnostic messages below the specified severity level (Informational,
Warning, Error, and Severe error for severity codes 0, 4, 8, and 12 respectively).

The default setting is FLAG(I).

FLOAT(S390|IEEE) Determines whether the contents of floating-point host variables in assembler, C,
C++, or PL/I programs are in IEEE floating-point format or z/Architecture
hexadecimal floating-point format. DB2 ignores this option if the value of HOST is
anything other than ASM, C, CPP, or PLI.

The default setting is FLOAT(S390).

| GRAPHIC This option is no longer used for SQL statement processing.

Indicates that the source code might use mixed data, and that X’0E’and X’0F’ are
special control characters (shift-out and shift-in) for EBCDIC data.

GRAPHIC and NOGRAPHIC are mutually exclusive options. The default

(GRAPHIC or NOGRAPHIC) is specified in the field MIXED DATA on Application
Programming Defaults Panel 1 during installation.

906 Application Programming and SQL Guide

Table 150. SQL processing options (continued)
Option keyword Meaning
1
HOST (ASM|C[(FOLD)]| Defines the host language that contains the SQL statements.
CPP[(FOLD)]|IBMCOB|PLI|
FORTRAN) Use IBMCOB for Enterprise COBOL for z/OS.

For C, specify:
v C if you do not want DB2 to fold lowercase letters in SBCS SQL ordinary
identifiers to uppercase
v C(FOLD) if you want DB2 to fold lowercase letters in SBCS SQL ordinary
identifiers to uppercase

For C++, specify:

v CPP if you do not want DB2 to fold lowercase letters in SBCS SQL ordinary
identifiers to uppercase
v CPP(FOLD) if you want DB2 to fold lowercase letters in SBCS SQL ordinary
identifiers to uppercase

If you omit the HOST option, the DB2 precompiler issues a level-4 diagnostic
message and uses the default value for this option.

The default is in the field LANGUAGE DEFAULT on Application Programming

Defaults Panel 1 during installation.

This option also sets the language-dependent defaults; see Table 152 on page 912.
LEVEL[(aaaa)]L Defines the level of a module, where aaaa is any alphanumeric value of up to seven
characters. This option is not recommended for general use, and the DSNH CLIST
and the DB2I panels do not support it. For more information, see “Setting the
program level” on page 931.

For assembler, C, C++, Fortran, and PL/I, you can omit the suboption (aaaa). The
resulting consistency token is blank. For COBOL, you need to specify the suboption.
LINECOUNT1(n)LC Defines the number of lines per page to be n for the DB2 precompiler listing. This
includes header lines that are inserted by the DB2 precompiler. The default setting is
LINECOUNT(60).
MARGINS1(m,n[,c]) MAR Specifies what part of each source record contains host language or SQL statements.
For assembler, this option also specifies where column continuations begin. The first
option (m) is the beginning column for statements. The second option (n) is the
ending column for statements. The third option (c) specifies where assembler
continuations begin. Otherwise, the DB2 precompiler places a continuation indicator
in the column immediately following the ending column. Margin values can range
from 1 to 80.

Default values depend on the HOST option that you specify; see Table 152 on page
912.

The DSNH CLIST and the DB2I panels do not support this option. In assembler, the
margin option must agree with the ICTL instruction, if presented in the source.

Chapter 17. Preparing an application to run on DB2 for z/OS 907

Table 150. SQL processing options (continued)
Option keyword Meaning
| NEWFUN(YES|NO) Indicates whether to accept the function syntax that is new for the current version of
| DB2.

| NEWFUN(YES) causes the precompiler to accept syntax that is new for the current
| version of DB2.

| NEWFUN(NO) causes the precompiler to reject any syntax that is introduced in the
| current version.

| Regardless of whether you specify NEWFUN(YES) or NEWFUN(NO), a successful

| precompilation produces a Unicode DBRM. If the DBRM does not contain any
| syntax that is new for the current version, you can bind it on DB2 Version 8 or later.
| If the DBRM does contain new syntax for the current version, you can bind it only
| under the current version or later releases.

| The NEWFUN option applies only to the precompilation process by either the
| precompiler or the DB2 coprocessor, regardless of the current migration mode. You
| are responsible for ensuring that you bind the resulting DBRM on a subsystem in
| the correct migration mode. For example, suppose that you have an application that
| contains new syntax for the current version of DB2. You can use NEWFUN(YES) to
| precompile that application on a subsystem in any migration mode. However, you
| cannot bind the resulting DBRM on a subsystem that is not in new-function mode.
NOFOR In static SQL, eliminates the need for the FOR UPDATE or FOR UPDATE OF clause
in DECLARE CURSOR statements. When you use NOFOR, your program can make
positioned updates to any columns that the program has DB2 authority to update.

When you do not use NOFOR, if you want to make positioned updates to any
columns that the program has DB2 authority to update, you need to specify FOR
UPDATE with no column list in your DECLARE CURSOR statements. The FOR
UPDATE clause with no column list applies to static or dynamic SQL statements.

Regardless of whether you use NOFOR, you can specify FOR UPDATE OF with a
column list to restrict updates to only the columns that are named in the clause, and
you can specify the acquisition of update locks.

You imply NOFOR when you use the option STDSQL(YES).

If the resulting DBRM is very large, you might need extra storage when you specify
NOFOR or use the FOR UPDATE clause with no column list.
| NOGRAPHIC This option is no longer used for SQL statement processing.

Indicates the use of X’0E’and X’0F’ in a string, but not as control characters.

GRAPHIC and NOGRAPHIC are mutually exclusive options. The default

(GRAPHIC or NOGRAPHIC) is specified in the field MIXED DATA on Application
Programming Defaults Panel 1 during installation.

| The NOGRAPHIC option applies to only EBCDIC data.

NOOPTIONSNOOPTN Suppresses the DB2 precompiler options listing.
NOPADNTSTR Indicates that output host variables that are NUL-terminated strings are not padded
with blanks. That is, additional blanks are not inserted before the NUL-terminator is
placed at the end of the string.

PADNTSTR and NOPADNTSTR are mutually exclusive options. The default

(PADNTSTR or NOPADNTSTR) is specified in the field PAD NUL-TERMINATED
on Application Programming Defaults Panel 2 during installation.

| This option applies to only C and C++ applications.

908 Application Programming and SQL Guide

Table 150. SQL processing options (continued)
Option keyword Meaning
2
NOSOURCE NOS Suppresses the DB2 precompiler source listing. This is the default.
2
NOXREF NOX Suppresses the DB2 precompiler cross-reference listing. This is the default.
ONEPASSON Processes in one pass, to avoid the additional processing time for making two
passes. Declarations must appear before SQL references.

Default values depend on the HOST option specified; see Table 152 on page 912.

ONEPASS and TWOPASS are mutually exclusive options.

1
OPTIONS OPTN Lists DB2 precompiler options. This is the default.
| PADNTSTR Indicates that output host variables that are NUL-terminated strings are padded
| with blanks with the NUL-terminator placed at the end of the string.

PADNTSTR and NOPADNTSTR are mutually exclusive options. The default

(PADNTSTR or NOPADNTSTR) is specified in the field PAD NUL-TERMINATED
on Application Programming Defaults Panel 2 during installation.

| This option applies to only C and C++ applications.

PERIOD Recognizes the period (.) as the decimal point indicator in decimal or floating point
literals in the following cases:
v For static SQL statements in COBOL programs
v For dynamic SQL statements, when the value of installation parameter DYNRULS
is NO and the package or plan that contains the SQL statements has
DYNAMICRULES bind, define, or invoke behavior.

COMMA and PERIOD are mutually exclusive options. The default (COMMA or
PERIOD) is specified in the field DECIMAL POINT IS on Application Programming
Defaults Panel 1 during installation.
QUOTE1Q Indicates that the DB2 precompiler is to use the quotation mark (″) as the string
delimiter in host language statements that it generates.

QUOTE is valid only for COBOL applications. QUOTE is not valid for either of the
following combinations of precompiler options:
v CCSID(1026) and HOST(IBMCOB)
v CCSID(1155) and HOST(IBMCOB)

The default is specified in the field STRING DELIMITER on Application

Programming Defaults Panel 1 during installation. If STRING DELIMITER is the
double quotation mark (″) or DEFAULT, QUOTE is the default.

APOST and QUOTE are mutually exclusive options.

QUOTESQL Recognizes the double quotation mark (″) as the string delimiter and the apostrophe
(’) as the SQL escape character within SQL statements. This option applies only to
COBOL.

The default is specified in the field SQL STRING DELIMITER on Application

Programming Defaults Panel 1 during installation. If SQL STRING DELIMITER is
the double quotation mark (″) or DEFAULT, QUOTESQL is the default.

APOSTSQL and QUOTESQL are mutually exclusive options.

1
SOURCE S Lists DB2 precompiler source and diagnostics.

Chapter 17. Preparing an application to run on DB2 for z/OS 909

Table 150. SQL processing options (continued)
Option keyword Meaning
SQL(ALL|DB2) Indicates whether the source contains SQL statements other than those recognized
by DB2 for z/OS.

SQL(ALL) is recommended for application programs whose SQL statements must

execute on a server other that DB2 for z/OS using DRDA access. SQL(ALL)
indicates that the SQL statements in the program are not necessarily for DB2 for
z/OS. Accordingly, the SQL statement processor then accepts statements that do not
conform to the DB2 syntax rules. The SQL statement processor interprets and
processes SQL statements according to distributed relational database architecture
(DRDA) rules. The SQL statement processor also issues an informational message if
the program attempts to use IBM SQL reserved words as ordinary identifiers.
SQL(ALL) does not affect the limits of the SQL statement processor.

SQL(DB2), the default, means to interpret SQL statements and check syntax for use
by DB2 for z/OS. SQL(DB2) is recommended when the database server is DB2 for
z/OS.
STDSQL(NO|YES)3 Indicates to which rules the output statements should conform.

STDSQL(YES)3 indicates that the precompiled SQL statements in the source program
conform to certain rules of the SQL standard. STDSQL(NO) indicates conformance
to DB2 rules.

The default is specified in the field STD SQL LANGUAGE on Application

Programming Defaults Panel 2 during installation.

STDSQL(YES) automatically implies the NOFOR option.

TIME(ISO|USA|EUR|JIS| Specifies that time output always return in a particular format, regardless of the
LOCAL) format that is specified as the location default. For a description of these formats,
see the topic “Datetime values” in DB2 SQL Reference.

The default is specified in the field TIME FORMAT on Application Programming

Defaults Panel 2 during installation.

The default format is determined by the installation defaults of the system where
the program is bound, not by the installation defaults of the system where the
program is precompiled.

You cannot use the LOCAL option unless you have a time exit routine.
TWOPASSTW Processes in two passes, so that declarations need not precede references. Default
values depend on the HOST option that is specified; see Table 152 on page 912.

ONEPASS and TWOPASS are mutually exclusive options.

| For the DB2 coprocessor, you can specify the TWOPASS option for only PL/I
| applications. For C/C++ and COBOL applications, the DB2 coprocessor uses the
| ONEPASS option.

910 Application Programming and SQL Guide

Table 150. SQL processing options (continued)
Option keyword Meaning
| VERSION(aaaa|AUTO) Defines the version identifier of a package, program, and the resulting DBRM. A
| version identifier is an SQL identifier of up to 64 EBCDIC bytes.

When you specify VERSION, the SQL statement processor creates a version
identifier in the program and DBRM. This affects the size of the load module and
DBRM. DB2 uses the version identifier when you bind the DBRM to a plan or
package.

If you do not specify a version at precompile time, an empty string is the default
version identifier. If you specify AUTO, the SQL statement processor uses the
consistency token to generate the version identifier. If the consistency token is a
timestamp, the timestamp is converted into ISO character format and is used as the
version identifier. The timestamp that is used is based on the store clock value. For
information about using VERSION, see “Creating a package version” on page 918.
XREF1 Includes a sorted cross-reference listing of symbols that are used in SQL statements
in the listing output.
Notes:
1. The DB2 coprocessor ignores this option when the DB2 coprocessor is invoked by the compiler to prepare the
application.
2. This option is always in effect when the DB2 coprocessor is invoked by the compiler to prepare the application.
3. You can use STDSQL(86) as in prior releases of DB2. The SQL statement processor treats it the same as
STDSQL(YES).
4. Precompiler options do not affect ODBC behavior.

Defaults for SQL processing options

Some SQL statement processing options have defaults based on values that are
specified on the Application Programming Defaults panels.

The following table shows those options and defaults.

Table 151. IBM-supplied installation default SQL statement processing options. The installer can change these
defaults.
Equivalent SQL statement Available SQL statement
Install option Install default processing option processing options
STRING DELIMITER quotation mark (″) QUOTE APOSTQUOTE
SQL STRING DELIMITER quotation mark (″) QUOTESQL APOSTSQLQUOTESQL
DECIMAL POINT IS PERIOD PERIOD COMMAPERIOD
DATE FORMAT ISO DATE(ISO) DATE(ISO|USA|
EUR|JIS|LOCAL)
DECIMAL ARITHMETIC DEC15 DEC(15) DEC(15|31)
| MIXED DATA NO CCSID(n) CCSID(n)
LANGUAGE DEFAULT COBOL HOST(COBOL) HOST(ASM|C[(FOLD)]|
CPP[(FOLD)]|IBMCOB|
FORTRAN|PLI)
STD SQL LANGUAGE NO STDSQL(NO) STDSQL(YES|NO|86)
TIME FORMAT ISO TIME(ISO) TIME(IS|USA|EUR|
JIS|LOCAL)

Chapter 17. Preparing an application to run on DB2 for z/OS 911

Table 151. IBM-supplied installation default SQL statement processing options (continued). The installer can change
these defaults.
Equivalent SQL statement Available SQL statement
Install option Install default processing option processing options
Notes: For dynamic SQL statements, another application programming default, USE FOR DYNAMICRULES,
determines whether DB2 uses the application programming default or the SQL statement processor option for the
following installation options:
| v STRING DELIMITER
| v SQL STRING DELIMITER
| v DECIMAL POINT IS
| v DECIMAL ARITHMETIC
If the value of USE FOR DYNAMICRULES is YES, dynamic SQL statements use the application programming
defaults. If the value of USE FOR DYNAMICRULES is NO, dynamic SQL statements in packages or plans with bind,
define, and invoke behavior use the SQL statement processor options. See “DYNAMICRULES bind option” on page
932 for an explanation of bind, define, and invoke behavior.

Some SQL statement processor options have default values based on the host
language. Some options do not apply to some languages. Table 152 shows the
language-dependent options and defaults.
Table 152. Language-dependent DB2 precompiler options and defaults
HOST value Defaults
ASM APOST1, APOSTSQL1, PERIOD1, TWOPASS, MARGINS(1,71,16)
C or CPP APOST1, APOSTSQL1, PERIOD1, ONEPASS, MARGINS(1,72)
IBMCOB QUOTE2, QUOTESQL2, PERIOD, ONEPASS1, MARGINS(8,72)1
FORTRAN APOST1, APOSTSQL1, PERIOD1, ONEPASS1, MARGINS(1,72)1
PLI APOST1, APOSTSQL1, PERIOD1, ONEPASS, MARGINS(2,72)
Notes:
1. Forced for this language; no alternative is allowed.
2. The default is chosen on Application Programming Defaults Panel 1 during installation. The IBM-supplied
installation defaults for string delimiters are QUOTE (host language delimiter) and QUOTESQL (SQL escape
character). The installer can replace the IBM-supplied defaults with other defaults. The precompiler options that
you specify override any defaults that are in effect.

SQL statement processing defaults for dynamic statements: Generally, dynamic

statements use the defaults that are specified during installation. However, if the
value of DSNHDECP parameter DYNRULS is NO, you can use these options for
dynamic SQL statements in packages or plans with bind, define, or invoke
behavior:
| v COMMA or PERIOD
| v APOST or QUOTE
| v APOSTSQL or QUOTESQL
| v DEC(15) or DEC(31)

SQL options for DRDA access

Certain SQL statement processing options are relevant when preparing a package
to be run using DRDA access.

The following SQL statement processing options are relevant for DRDA access:
CONNECT
Use CONNECT(2), explicitly or by default.

912 Application Programming and SQL Guide

CONNECT(1) causes your CONNECT statements to allow only the restricted
function known as “remote unit of work”. Be particularly careful to avoid
CONNECT(1) if your application updates more than one DBMS in a single
unit of work.
SQL
Use SQL(ALL) explicitly for a package that runs on a server that is not DB2 for
z/OS. The precompiler then accepts any statement that obeys DRDA rules.
Use SQL(DB2), explicitly or by default, if the server is DB2 for z/OS only. The
precompiler then rejects any statement that does not obey the rules of DB2 for
z/OS.

Program preparation options for remote packages

When preparing packages for remote servers, consider how to set all of the SQL
processing options and bind options.

The following table gives generic descriptions of program preparation options, lists
the equivalent DB2 option for each one, and indicates if appropriate, whether it is
a bind package (B) or a precompiler (P) option. In addition, the table indicates
whether a DB2 server supports the option.
Table 153. Program preparation options for packages
Bind or
Precompile
Generic option description Equivalent for Requesting DB2 Option DB2 Server Support
Package replacement: protect ACTION(ADD) B Supported
existing packages
Package replacement: replace ACTION(REPLACE) B Supported
existing packages
Package replacement: version ACTION(REPLACE REPLVER B Supported
name (version-id))
Statement string delimiter APOSTSQL/QUOTESQL P Supported
DRDA access: SQL CONNECT CONNECT(1) P Supported
(Type 1)
DRDA access: SQL CONNECT CONNECT(2) P Supported
(Type 2)
Block protocol: Do not block data CURRENTDATA(YES) B Supported
for an ambiguous cursor
Block protocol: Block data when CURRENTDATA(NO) B Supported
possible
Block protocol: Never block data (Not available) Not supported
Name of remote database CURRENTSERVER(location name) B Supported as a BIND
PLAN option
Date format of statement DATE P Supported
Protocol for remote access DBPROTOCOL B Not supported
Maximum decimal precision: 15 DEC(15) P Supported
Maximum decimal precision: 31 DEC(31) P Supported
Defer preparation of dynamic DEFER(PREPARE) B Supported
SQL
Do not defer preparation of NODEFER(PREPARE) B Supported
dynamic SQL

Chapter 17. Preparing an application to run on DB2 for z/OS 913

Table 153. Program preparation options for packages (continued)
Bind or
Precompile
Generic option description Equivalent for Requesting DB2 Option DB2 Server Support
Dynamic SQL Authorization DYNAMICRULES B Supported
Encoding scheme for static SQL ENCODING B Not supported
statements
Explain option EXPLAIN B Supported
Immediately write group IMMEDWRITE B Supported
bufferpool-dependent page sets
or partitions in a data sharing
environment
Package isolation level: CS ISOLATION(CS) B Supported
Package isolation level: RR ISOLATION(RR) B Supported
Package isolation level: RS ISOLATION(RS) B Supported
Package isolation level: UR ISOLATION(UR) B Supported
Keep prepared statements after KEEPDYNAMIC B Supported
commit points
Consistency token LEVEL P Supported
Package name MEMBER B Supported
Package owner OWNER B Supported
Schema name list for user-defined PATH B Supported
functions, distinct types, and
stored procedures
Statement decimal delimiter PERIOD/COMMA P Supported
Default qualifier QUALIFIER B Supported
Use access path hints OPTHINT B Supported
Lock release option RELEASE B Supported
Choose access path at each run REOPT(ALWAYS) B Supported
time
Choose access path at bind time REOPT(NONE) B Supported
only
Choose and cache access path at REOPT(ONCE) B Supported
only the first run or open time
| Choose access path at run time. REOPT(AUTO B Supported
| Each time a statement is
| executed, DB2 determines if a
| new access path is needed to
| improve the performance of the
| statement.
Creation control: create a package SQLERROR(CONTINUE) B Supported
despite errors
Creation control: create no SQLERROR(NO PACKAGE) B Supported
package if there are errors
Creation control: create no (Not available) Supported
package
Time format of statement TIME P Supported
Existence checking: full VALIDATE(BIND) B Supported

914 Application Programming and SQL Guide

Table 153. Program preparation options for packages (continued)
Bind or
Precompile
Generic option description Equivalent for Requesting DB2 Option DB2 Server Support
Existence checking: deferred VALIDATE(RUN) B Supported
Package version VERSION P Supported
Default character subtype: system (Not available) Supported
default
Default character subtype: BIT (Not available) Not supported
Default character subtype: SBCS (Not available) Not supported
Default character subtype: DBCS (Not available) Not supported
Default character CCSID: SBCS (Not available) Not supported
Default character CCSID: Mixed (Not available) Not supported
Default character CCSID: Graphic (Not available) Not supported
Package label (Not available) Ignored when received;
no error is returned
Privilege inheritance: retain default Supported
Privilege inheritance: revoke (Not available) Not supported

Compiling and link-editing an application

If you use the DB2 precompiler, your next step in the program preparation process
is to compile and link-edit your program. As with the precompile step, you have a
choice of methods.

You can use one of the following methods to compile and link-edit an application:
v DB2I panels
v The DSNH command procedure (a TSO CLIST)
v JCL procedures supplied with DB2
v JCL procedures supplied with a host language compiler

| If you use the DB2 coprocessor, you process SQL statements as you compile your
| program. For programs other than C and C++ programs, you must use JCL
| procedures when you use the DB2 coprocessor. For C and C++ programs, you can
| use either JCL procedures or UNIX System Services on z/OS to invoke the DB2
| coprocessor.

The purpose of the link-edit step is to produce an executable load module. To

enable your application to interface with the DB2 subsystem, you must use a
link-edit procedure that builds a load module that satisfies environment-specific
requirements.

TSO and batch: Include the DB2 TSO attachment facility language interface
module (DSNELI) or DB2 call attachment facility language interface module
(DSNALI). For a program that uses 31-bit addressing, link-edit the program with
the AMODE=31 and RMODE=ANY options. For more details, see the appropriate
z/OS publication.

Chapter 17. Preparing an application to run on DB2 for z/OS 915

IMS: Include the DB2 IMS (Version 1 Release 3 or later) language interface module
(DFSLI000), which contains the DSNHLI entry point. Also, the IMS RESLIB must
precede the SDSNLOAD library in the link list, JOBLIB, or STEPLIB
concatenations.

IMS and DB2 share a common alias name, DSNHLI, for the language interface
module. You must do the following when you concatenate your libraries:
v If you use IMS, be sure to concatenate the IMS library first so that the
application program compiles with the correct IMS version of DSNHLI.
v If you run your application program only under DB2, be sure to concatenate the
DB2 library first.

CICS: Include the DB2 CICS language interface module (DSNCLI). You can link
DSNCLI with your program in either 24-bit or 31-bit addressing mode
(AMODE=31). If your application program runs in 31-bit addressing mode, you
should link-edit the DSNCLI stub to your application with the attributes
AMODE=31 and RMODE=ANY so that your application can run above the 16-MB
line.

You also need the CICS EXEC interface module that is appropriate for the
programming language. CICS requires that this module be the first control section
(CSECT) in the final load module.

The size of the executable load module that is produced by the link-edit step varies
depending on the values that the SQL statement processor inserts into the source
code of the program.

Link-editing a batch program: DB2 has language interface routines for each
unique supported environment. DB2 requires the IMS language interface routine
for DL/I batch. You need to have DFSLI000 link-edited with the application
program.
Related tasks
Chapter 17, “Preparing an application to run on DB2 for z/OS,” on page 887
Related reference
DSNH (TSO CLIST) (DB2 Command Reference)
Related information
z/OS Internet Library
CICS Transaction Server Library at ibm.com

Binding an application
You must bind the DBRM that is produced by the SQL statement processor to a
plan or package before your DB2 application can run.

A plan can contain DBRMs, a package list that specifies packages or collections of
packages, or a combination of DBRMs and a package list. The plan must contain at
least one package or at least one directly bound DBRM. Each package that you
bind can contain only one DBRM.

Exception: You do not need to bind a DBRM if the only SQL statement in the
program is SET CURRENT PACKAGESET.

916 Application Programming and SQL Guide

Because you do not need a plan or package to execute the SET CURRENT
PACKAGESET statement, the ENCODING bind option does not affect the SET
CURRENT PACKAGESET statement. An application that needs to provide a host
variable value in an encoding scheme other than the system default encoding
scheme must use the DECLARE VARIABLE statement to specify the encoding
scheme of the host variable.

You must bind plans locally, regardless of whether they reference packages that
run remotely. However, you must bind the packages that run at remote locations at
those remote locations.

| For C and C++ programs whose corresponding DBRMs are in HFS files, you can
| use the command line processor to bind the DBRMs to packages. Optionally, you
| can also copy the DBRM into a partitioned data set member by using the oput and
| oget commands and then bind it by using conventional JCL.

From a DB2 requester, you can run a plan by specifying it in the RUN
subcommand, but you cannot run a package directly. You must include the
package in a plan and then run the plan.

Develop a naming convention and strategy for the most effective and efficient use
of your plans and packages.
v To bind a new plan or package, other than a trigger package, use the
subcommand BIND PLAN or BIND PACKAGE with the option
ACTION(REPLACE).
To bind a new trigger package, recreate the trigger associated with the trigger
package.

Binding a DBRM to a package

You can bind a DBRM to a package and then bind that package to a plan, or you
can bind a DBRM directly to a plan. The main advantage of binding the DBRM to
a package is easier maintenance. When you change one SQL statement, you need
to rebind only the associated package, not the entire plan.

When you bind a package, you specify the collection to which the package
belongs. The collection is not a physical entity, and you do not create it; the
collection name is merely a convenient way of referring to a group of packages.

To bind a package, you must have the proper authorization.

Binding packages at a remote location

When your application accesses data through DRDA access, you must bind
packages on the systems on which they will run.

If a local stored procedure uses a cursor to access data through DRDA access, and
the cursor-related statement is bound in a separate package under the stored
procedure, you must bind this separate package both locally and remotely. In
addition, the invoker or owner of the stored procedure must be authorized to
execute both local and remote packages. At your local system, you must bind a
plan whose package list includes all those packages, local and remote.

To bind a package at a remote DB2 system, you must have all the privileges or
authority there that you would need to bind the package on your local system. To

Chapter 17. Preparing an application to run on DB2 for z/OS 917

bind a package at another type of a system, such as DB2 Server for VSE & VM,
you need any privileges that the other system requires to execute its SQL
statements and use its data objects.

The bind process for a remote package is the same as for a local package, except
that the local communications database must be able to recognize the location
name that you use as resolving to a remote location.

Example:

To bind the DBRM PROGA at the location PARIS, in the collection GROUP1, use:
BIND PACKAGE(PARIS.GROUP1)
MEMBER(PROGA)

Then, include the remote package in the package list of a local plan, such as
PLANB, by using:
BIND PLAN (PLANB)
PKLIST(PARIS.GROUP1.PROGA)

The ENCODING bind option has the following effect on a remote application:
v If you bind a package locally, which is recommended, and you specify the
ENCODING bind option for the local package, the ENCODING bind option for
the local package applies to the remote application.
v If you do not bind a package locally, and you specify the ENCODING bind
option for the plan, the ENCODING bind option for the plan applies to the
remote application.
v If you do not specify an ENCODING bind option for the package or plan at the
local site, the value of APPLICATION ENCODING that was specified on
installation panel DSNTIPF at the local site applies to the remote application.

When you bind or rebind, DB2 checks authorizations, reads and updates the
catalog, and creates the package in the directory at the remote site. DB2 does not
read or update catalogs or check authorizations at the local site.

If you specify the option EXPLAIN(YES) and you do not specify the option
SQLERROR(CONTINUE), PLAN_TABLE must exist at the location that is specified
on the BIND or REBIND subcommand. This location could also be the default
location.

If you bind with the option COPY, the COPY privilege must exist locally. DB2
performs authorization checking, reads and updates the catalog, and creates the
package in the directory at the remote site. DB2 reads the catalog records that are
related to the copied package at the local site. DB2 converts values that are
returned from the remote site in ISO format if all of the following conditions are
true:
v If the local site is installed with time or date format LOCAL
v A package is created at a remote site with the COPY option
v The SQL statement does not specify a different format.

After you bind a package, you can rebind, free, or bind it with the REPLACE
option using either a local or a remote bind.

Creating a package version

If you want to run different versions of a program without having to make
changes to the associated application plan, use package versions. This technique is
918 Application Programming and SQL Guide
useful if you need to make changes to your program without causing an
interruption to the availability of the program.

You can create a different package version for each version of the program. Each
package has the same package name and collection name, but a different version
number is associated with each package. The plan that includes that package
includes all versions of that package. Thus, you can run a program that is
associated with any one of the package versions without having to rebind the
application plan, rename the plan, or change any RUN subcommands that use it.

To create a package version:

1. Precompile your program with the option VERSION(version-identifier).
2. Bind the resulting DBRM with the same collection name and package name as
any existing versions of that package. When you run the program, DB2 uses
the package version that you specified when you precompiled it.

Example: Suppose that you bound a plan with the following statement:
BIND PLAN (PLAN1) PKLIST (COLLECT.*)

The following steps show how to create two versions of a package, one for each of
two programs.

Step number For package version 1 For package version 2

1 Precompile program 1. Specify Precompile program version 2.
VERSION(1). Specify VERSION(2).
2 Bind the DBRM with the collection Bind the DBRM with the collection
name COLLECT and the package name COLLECT and package name
name PACKA. PACKA.
3 Link-edit program 1 into your Link-edit program 2 into your
application. application.
4 Run the application; it uses Run the application; it uses
program 1 and PACKA, VERSION program 2 and PACKA, VERSION
1. 2.

| Binding a DBRM that is in a HFS file to a package or collection

| If DBRMs are in HFS files, you can use the command line processor to bind the
| DBRMs to packages at the target DB2 server. Optionally, you can also copy the
| DBRM into a partitioned data set member by using the oput and oget commands
| and then bind it by using conventional JCL.

| Only DBRMs for C and C++ programs can be generated to HFS files.

| Restrictions:

| You cannot specify the REBIND command with the command line processor.
| Alternatively, specify the BIND command with the ACTION(REPLACE) option.

| You cannot specify the FREE PACKAGE command with the command line
| processor. Alternatively, specify the DROP PACKAGE statement to drop the
| existing packages.

| To bind a DBRM that is in an HFS file to a package or collection:

| 1. Invoke the command line processor and connect to the target DB2 server.

Chapter 17. Preparing an application to run on DB2 for z/OS 919

| 2. Specify the BIND command with the appropriate options.
| Related concepts
| Command Line Processor (DB2 Command Reference)
| Related tasks
| “Processing SQL statements by using the DB2 coprocessor” on page 898
| Related reference
| “Command line processor BIND command”

| Command line processor BIND command:

| Use the command line processor BIND command to bind DBRMs that are in HFS
| files to packages.

| The following diagram shows the syntax for the command line processor BIND
| command.

| (2)


BIND dbrm-file-name options-clause

(1)
-COLLECTION collection-name
|
| Notes:
| 1 If you do not specify a collection, DB2 uses NULLID.
| 2 You can specify the options after collection-name in any order.
||

| options-clause:
|

920 Application Programming and SQL Guide

| QUALIFIER(ID that is used during connect) OWNER(ID that is used during connect)
|



QUALIFIER(qualifier-name) OWNER(authorization-ID)

| NODEFER(PREPARE) ACTION (REPLACE)

|


DEFER(PREPARE) ACTION (REPLACE) REPLVER(version-id)
(ADD)

| CURRENTDATA (YES) DBPROTOCOL(DRDA) DEGREE(1)

|


CURRENTDATA ( NO ) DBPROTOCOL(PRIVATE) DEGREE(ANY)
ALL

| DYNAMICRULES(RUN) EXPLAIN(NO)
|


DYNAMICRULES( BIND ) ENCODING ( ASCII ) EXPLAIN( YES )
DEFINEBIND EBCDIC ALL
DEFINERUN UNICODE
INVOKEBIND ccsid
INVOKERUN

| IMMEDWRITE(NO) KEEPDYNAMIC(NO) ISOLATION(CS)

|


IMMEDWRITE( YES ) KEEPDYNAMIC(YES) ISOLATION( RR )
PH1 RS
UR
NC

| (1)
| REOPT(NONE) RELEASE(COMMIT)



(2) RELEASE(DEALLOCATE) OPTHINT(’hint-ID’)
REOPT(ALWAYS)

| SQLERROR(NOPACKAGE) VALIDATE(RUN) PATH( )

|


SQLERROR( CONTINUE ) VALIDATE(BIND) ,
CHECK
PATH(  schema-name )
USER

|
| Notes:
| 1 You can specify NOREOPT(VARS) as a synonym of REOPT(NONE).
| 2 You can specify REOPT(VARS) as a synonym of REOPT(ALWAYS).
||

| The following options are unique to this diagram:

| CURRENTDATA (ALL)
| Specifies that for all cursors data currency is required and block fetching is
| inhibited.

Chapter 17. Preparing an application to run on DB2 for z/OS 921

| SQLERROR(CHECK)
| Specifies that the command line processor is to only check for SQL errors in
| the DBRM. No package is generated.
| IMMEDWRITE(PH1)
| Specifies that normal write activity is done. This option is equivalent to
| IMMEDWRITE(NO).
| EXPLAIN(ALL)
| Specifies that DB2 is to insert information into the appropriate EXPLAIN
| tables. This option is equivalent to EXPLAIN (YES).
| Related reference
| BIND and REBIND options (DB2 Command Reference)

Binding an application plan

An application plan can include DBRMs, package lists, or both.

Recommendation: Although you can include as many DBRMs in a plan as you

want, do not include too many (more than 500, for example). If you include too
many, you could have trouble maintaining the plan. If you have a lot of DBRMs,
consider binding each DBRM separately as a package. Specify the same collection
for all of these packages. Then bind a plan that specifies that collection in the
package list. If the design of the application prevents this method, ask your system
administrator to increase the size of the EDM pool to be at least 10 times the size
of either the largest database descriptor (DBD) or the plan, whichever is greater.

To bind an application plan, use the BIND PLAN subcommand with at least one of
the following options:
MEMBER
Specify this option to bind DBRMs directly to the plan. After the keyword
MEMBER, specify the member names of the DBRMS.
PKLIST
Specify this option to include package lists in the plan. After the keyword
PKLIST, specify the names of the packages to include in the package list. To
include an entire collection of packages in the list, use an asterisk after the
collection name. For example, PKLIST(GROUP1.*).

The resulting plan consists of the following information:

v Any programs that are associated with DBRMs in the MEMBER list
v Any programs that are associated with packages and collections that are
identified in PKLIST

Example of binding DBRMS directly to an application plan: The following

statement binds three DBRMs, PROGA, PROGB, and PROGC, directly to plan
PLANW.
BIND PLAN(PLANW)
MEMBER(PROGA,PROGB,PROGC)

Example of including both DBRMs and packages in an application plan: This

example statement binds a plan that includes:
v The DBRMs PROG1 and PROG2
v All the packages in the collection TEST2
v The packages PROGA and PROGC in the collection GROUP1

922 Application Programming and SQL Guide

BIND PLAN(PLANY)
MEMBER(PROG1,PROG2)
PKLIST(TEST2.*,GROUP1.PROGA,GROUP1.PROGC)

Specifying the package list for the PKLIST option of BIND PLAN:

The order in which you specify packages in a package list can affect run-time
performance. Searching for the specific package involves searching the DB2
directory, which can be costly. When you use collection-id.* with the PKLIST
keyword, you should specify first the collections in which DB2 is most likely to
find a package.

For example, assume that you perform the following bind:

BIND PLAN (PLAN1) PKLIST (COLL1.*, COLL2.*, COLL3.*, COLL4.*)

Then you execute program PROG1. DB2 does the following package search:
1. Checks to see if program PROG1 is bound as part of the plan
2. Searches for COLL1.PROG1.timestamp
3. If it does not find COLL1.PROG1.timestamp, searches for
COLL2.PROG1.timestamp
4. If it does not find COLL2.PROG1.timestamp, searches for
COLL3.PROG1.timestamp
5. If it does not find COLL3.PROG1.timestamp, searches for
COLL4.PROG1.timestamp.

| When both special registers CURRENT PACKAGE PATH and CURRENT

| PACKAGESET contain an empty string: If you do not set these special registers,
DB2 searches for a DBRM or a package in one of these sequences:
v At the local location (if CURRENT SERVER is blank or specifies that location
explicitly), the order is:
1. All DBRMs that are bound directly to the plan.
2. All packages that are already allocated to the plan while the plan is running.
3. All unallocated packages that are explicitly specified in, and all collections
that are completely included in, the package list of the plan. DB2 searches for
packages in the order that they appear in the package list.
v At a remote location, the order is:
1. All packages that are already allocated to the plan at that location while the
plan is running.
2. All unallocated packages that are explicitly specified in, and all collections
that are completely included in, the package list of the plan, whose locations
match the value of CURRENT SERVER. DB2 searches for packages in the
order that they appear in the package list.
If you use the BIND PLAN option DEFER(PREPARE), DB2 does not search all
collections in the package list.

If the order of search is not important: In many cases, the order in which DB2
searches the packages is not important to you and does not affect performance. For
an application that runs only at your local DB2 system, you can name every
package differently and include them all in the same collection. The package list on
your BIND PLAN subcommand can read:
PKLIST (collection.*)

Chapter 17. Preparing an application to run on DB2 for z/OS 923

You can add packages to the collection even after binding the plan. DB2 lets you
bind packages having the same package name into the same collection only if their
version IDs are different.

If your application uses DRDA access, you must bind some packages at remote
locations. Use the same collection name at each location, and identify your package
list as:
PKLIST (*.collection.*)

If you use an asterisk for part of a name in a package list, DB2 checks the
authorization for the package to which the name resolves at run time. To avoid the
checking at run time in the preceding example, you can grant EXECUTE authority
for the entire collection to the owner of the plan before you bind the plan.
Related tasks
“Maximizing the performance of an application that accesses distributed data” on
page 34
Related reference
BIND PLAN (DSN) (DB2 Command Reference)

How DB2 identifies packages at run time

The DB2 precompiler or DB2 coprocessor identifies each call to DB2 with a
consistency token. The same consistency token identifies the DBRM that the SQL
statement processor produces and the plan or package to which you bound the
DBRM. When you run the program, DB2 uses the consistency token in matching
the call to DB2 to the correct DBRM.

(Usually, the consistency token is in an internal DB2 format. You can override that
token if you want: see “Setting the program level” on page 931.)

You also need other identifiers. The consistency token alone uniquely identifies a
DBRM that is bound directly to a plan, but it does not necessarily identify a
unique package. When you bind DBRMs directly to a particular plan, you bind
each one only once. But you can bind the same DBRM to many packages, at
different locations and in different collections, and then you can include all those
packages in the package list of the same plan. All those packages will have the
same consistency token. You can specify a particular location or a particular
collection at run time.

Specifying the location of the package that DB2 is to use

When your program executes an SQL statement, DB2 uses the value in the
CURRENT SERVER special register to determine the location of the necessary
package or DBRM. If the current server is your local DB2 subsystem and it does
not have a location name, the value is blank.

You can change the value of CURRENT SERVER by using the SQL CONNECT
statement in your program. If you do not use CONNECT, the value of CURRENT
SERVER is the location name of your local DB2 subsystem (or blank, if your DB2
subsystem has no location name).

Specifying the package collection that DB2 is to use

To ensure that DB2 uses the intended package collection and does not waste time
searching for package collections, explicitly specify the package collection that you
want DB2 to use.

924 Application Programming and SQL Guide

You can use the special register CURRENT PACKAGE PATH or CURRENT
PACKAGESET (if CURRENT PACKAGE PATH is not set) to specify the collections
that are to be used for package resolution. The CURRENT PACKAGESET special
register contains the name of a single collection, and the CURRENT PACKAGE
PATH special register contains a list of collection names.

| If you do not set these registers, they contain an empty string when your
| application begins to run, and they remain as an empty string. In this case, DB2
| searches the available collections, using methods described in “Binding an
| application plan” on page 922.

However, explicitly specifying the intended collection by using the special registers
can avoid a potentially costly search through a package list that has many
qualifying entries. In addition, DB2 uses the values in these special registers for
applications that do not run under a plan. How DB2 uses these special registers is
described in “Overriding the values that DB2 uses to resolve package lists.”

| When you call a stored procedure, the special register CURRENT PACKAGESET
| contains the value that you specified for the COLLID parameter when you defined
| the stored procedure. If the routine was defined without a value for the COLLID
| parameter, the value of the special register is inherited from the calling program.
| Also, the special register CURRENT PACKAGE PATH contains the value that you
| specified for the PACKAGE PATH parameter when you defined the stored
| procedure. When the stored procedure returns control to the calling program, DB2
| restores this register to the value that it contained before the call.

Overriding the values that DB2 uses to resolve package lists

DB2 resolves package lists by searching the available collections in a particular
order. To avoid this search, you can specify the values that DB2 should use for
package resolution.

If you set the special register CURRENT PACKAGE PATH or CURRENT

PACKAGESET, DB2 skips the check for programs that are part of a plan and uses
the values in these registers for package resolution.

If you set CURRENT PACKAGE PATH, DB2 uses the value of CURRENT
PACKAGE PATH as the collection name list for package resolution. For example, if
CURRENT PACKAGE PATH contains the list COLL1, COLL2, COLL3, COLL4,
DB2 searches for the first package that exists in the following order:
COLL1.PROG1.timestamp
COLL2.PROG1.timestamp
COLL3.PROG1.timestamp
COLL4.PROG1.timestamp

If you set CURRENT PACKAGESET and not CURRENT PACKAGE PATH, DB2
uses the value of CURRENT PACKAGESET as the collection for package
resolution. For example, if CURRENT PACKAGESET contains COLL5, DB2 uses
COLL5.PROG1.timestamp for the package search.

When CURRENT PACKAGE PATH is set, the server that receives the request
ignores the collection that is specified by the request and instead uses the value of
CURRENT PACKAGE PATH at the server to resolve the package. Specifying a
collection list with the CURRENT PACKAGE PATH special register can avoid the
need to issue multiple SET CURRENT PACKAGESET statements to switch
collections for the package search.

Chapter 17. Preparing an application to run on DB2 for z/OS 925

The following table shows examples of the relationship between the CURRENT
PACKAGE PATH special register and the CURRENT PACKAGESET special
register.
Table 154. Scope of CURRENT PACKAGE PATH
Example What happens

SET CURRENT PACKAGESET The collection in PACKAGESET determines which

SELECT ... FROM T1 ... package is invoked.

SET CURRENT PACKAGE PATH The collections in PACKAGE PATH determine which
SELECT ... FROM T1 ... package is invoked.

SET CURRENT PACKAGESET The collections in PACKAGE PATH determine which

SET CURRENT PACKAGE PATH package is invoked.
SELECT ... FROM T1 ...

SET CURRENT PACKAGE PATH PACKAGE PATH at server S2 is an empty string

CONNECT TO S2 ... because it has not been explicitly set. The values from
SELECT ... FROM T1 ... the PKLIST bind option of the plan that is at the
requester determine which package is invoked.1

SET CURRENT PACKAGE PATH The collections in PACKAGE PATH that are set at
= 'A,B' server S2 determine which package is invoked.
CONNECT TO S2 ...
SET CURRENT PACKAGE PATH
= 'X,Y'
SELECT ... FROM T1 ...

SET CURRENT PACKAGE PATH Three-part table name. On implicit connection to

SELECT ... FROM server S2, PACKAGE PATH at server S2 is inherited
S2.QUAL.T1 ... from the local server. The collections in PACKAGE
PATH at server S2 determine which package is
invoked.
Notes:
1. When CURRENT PACKAGE PATH is set at the requester (and not at the remote server),
DB2 passes one collection at a time from the list of collections to the remote server until
a package is found or until the end of the list. Each time a package is not found at the
server, DB2 returns an error to the requester. The requester then sends the next collection
in the list to the remote server.

Bind process for remote access

These examples show different bind processes for DRDA and DB2 private protocol
access.

Example

| Suppose that you need to access data at a remote server CHICAGO, by using the
| following query:
SELECT * FROM CHICAGO.DSN8910.EMP
WHERE EMPNO = '0001000';

This statement can be executed with DRDA access or DB2 private protocol access.

The method of access depends on the DBPROTOCOL bind option that you specify
when you bind your DBRMs into packages. DRDA is used by default if you do not
specify a DBPROTOCOL bind option.

Recommendation: Specify DRDA as the DBPROTOCOL bind option.

926 Application Programming and SQL Guide

If you bind the DBRM that contains the statement into a plan at the local DB2 and
specify the bind option DBPROTOCOL(PRIVATE), you access the server by using
DB2 private protocol access.

If you bind the DBRM that contains the statement by using one of the following
processes, you access the server using DRDA access:
Local-bind DRDA access process:
1. Bind the DBRM into a package at the local DB2 using the bind option
DBPROTOCOL(DRDA).
2. Bind the DBRM into a package at the remote location (CHICAGO).
3. Bind the packages into a plan using bind option
DBPROTOCOL(DRDA).
Remote-bind DRDA access process:
1. Bind the DBRM into a package at the remote location.
2. Bind the remote package and the DBRM into a plan at the local site,
using the bind option DBPROTOCOL(DRDA).

In some cases you cannot use private protocol to access distributed data. The
following examples require DRDA access.

Example

Suppose that you need to access data at a remote server CHICAGO, by using the
following CONNECT and SELECT statements:
EXEC SQL
CONNECT TO CHICAGO;
EXEC SQL SELECT * FROM DSN8910.EMP
WHERE EMPNO = '0001000';

This example requires DRDA access and the correct binding procedure to work
from a remote server. Before you can execute the query at location CHICAGO, you
must bind the application as a remote package at the CHICAGO server. Before you
can run the application, you must also bind a local package and a local plan with a
package list that includes the local and remote package.

Example

Suppose that you need to call a stored procedure at the remote server ATLANTA,
by using the following CONNECT and CALL statements:
EXEC SQL
CONNECT TO ATLANTA;
EXEC SQL
CALL procedure_name (parameter_list);

This example requires DRDA access because private protocol does not support
stored procedures. The parameter list is a list of host variables that is passed to the
stored procedure and into which it returns the results of its execution. To execute,
the stored procedure must already exist at the ATLANTA server.

Bind options for DRDA access

For the most part, binding a package to run at a remote location is like binding a
package to run at your local DB2 subsystem. Binding a plan to run the package is
like binding any other plan. However, a few differences exist.

Chapter 17. Preparing an application to run on DB2 for z/OS 927

For the general instructions, see Chapter 17, “Preparing an application to run on
DB2 for z/OS,” on page 887.

BIND PLAN options for DRDA access

The following options of BIND PLAN are particularly relevant to binding a plan
that uses DRDA access:
DISCONNECT
For most flexibility, use DISCONNECT(EXPLICIT), explicitly or by default.
That requires you to use RELEASE statements in your program to explicitly
end connections.
The other values of the option are also useful.
DISCONNECT(AUTOMATIC) ends all remote connections during a
commit operation, without the need for RELEASE statements in your
program.
DISCONNECT(CONDITIONAL) ends remote connections during a
commit operation except when an open cursor defined as WITH HOLD is
associated with the connection.
SQLRULES
Use SQLRULES(DB2), explicitly or by default.
SQLRULES(STD) applies the rules of the SQL standard to your CONNECT
statements, so that CONNECT TO x is an error if you are already connected to
x. Use STD only if you want that statement to return an error code.
If your program selects LOB data from a remote location, and you bind the
plan for the program with SQLRULES(DB2), the format in which you retrieve
the LOB data with a cursor is restricted. After you open the cursor to retrieve
the LOB data, you must retrieve all of the data using a LOB variable, or
retrieve all of the data using a LOB locator variable. If the value of SQLRULES
is STD, this restriction does not exist.
If you intend to switch between LOB variables and LOB locators to retrieve
data from a cursor, execute the SET SQLRULES=STD statement before you
connect to the remote location.
CURRENTDATA
Use CURRENTDATA(NO) to force block fetch for ambiguous cursors. See
“Maximizing the performance of an application that accesses distributed data”
on page 34 for more information.
DBPROTOCOL
Use DBPROTOCOL(PRIVATE) if you want DB2 to use DB2 private protocol
access for accessing remote data that is specified with three-part names.
Use DBPROTOCOL(DRDA) if you want DB2 to use DRDA access to access
remote data that is specified with three-part names. You must bind a package
at all locations whose names are specified in three-part names.
The package value for the DBPROTOCOL option overrides the plan option.
For example, if you specify DBPROTOCOL(DRDA) for a remote package and
DBPROTOCOL(PRIVATE) for the plan, DB2 uses DRDA access when it
accesses data at that location using a three-part name. If you do not specify
any value for DBPROTOCOL, DB2 uses the value of DATABASE PROTOCOL
on installation panel DSNTIP5.

928 Application Programming and SQL Guide

ENCODING
Use this option to control the encoding scheme that is used for static SQL
statements in the plan and to set the initial value of the CURRENT
APPLICATION ENCODING SCHEME special register.
For applications that execute remotely and use explicit CONNECT statements,
DB2 uses the ENCODING value for the plan. For applications that execute
remotely and use implicit CONNECT statements, DB2 uses the ENCODING
value for the package that is at the site where a statement executes.

BIND PACKAGE options for DRDA access

The following options of BIND PACKAGE are relevant to binding a package to be

run using DRDA access:
location-name
Name the location of the server at which the package runs.
The privileges needed to run the package must be granted to the owner of the
package at the server. If you are not the owner, you must also have SYSCTRL
authority or the BINDAGENT privilege that is granted locally.
SQLERROR
Use SQLERROR(CONTINUE) if you used SQL(ALL) when precompiling.
That creates a package even if the bind process finds SQL errors, such as
statements that are valid on the remote server but that the precompiler did not
recognize. Otherwise, use SQLERROR(NOPACKAGE), explicitly or by default.
CURRENTDATA
Use CURRENTDATA(NO) to force block fetch for ambiguous cursors. See
“Maximizing the performance of an application that accesses distributed data”
on page 34 for more information.
OPTIONS
When you make a remote copy of a package using BIND PACKAGE with the
COPY option, use this option to control the default bind options that DB2 uses.
Specify:
COMPOSITE to cause DB2 to use any options you specify in the BIND
PACKAGE command. For all other options, DB2 uses the options of the
copied package. COMPOSITE is the default.
COMMAND to cause DB2 to use the options you specify in the BIND
PACKAGE command. For all other options, DB2 uses the defaults for the
server on which the package is bound. This helps ensure that the server
supports the options with which the package is bound.
DBPROTOCOL
Use DBPROTOCOL(PRIVATE) if you want DB2 to use DB2 private protocol
access for accessing remote data that is specified with three-part names.
Use DBPROTOCOL(DRDA) if you want DB2 to use DRDA access to access
remote data that is specified with three-part names. You must bind a package
at all locations whose names are specified in three-part names.
ENCODING
Use this option to control the encoding scheme that is used for static SQL
statements in the package and to set the initial value of the CURRENT
APPLICATION ENCODING SCHEME special register.

Chapter 17. Preparing an application to run on DB2 for z/OS 929

The default ENCODING value for a package that is bound at a remote DB2 for
z/OS server is the system default for that server. The system default is
specified at installation time in the APPLICATION ENCODING field of panel
DSNTIPF.
For applications that execute remotely and use explicit CONNECT statements,
DB2 uses the ENCODING value for the plan. For applications that execute
remotely and use implicit CONNECT statements, DB2 uses the ENCODING
value for the package that is at the site where a statement executes.

Checking which BIND PACKAGE options a particular server

supports
You can request only the options of the BIND PACKAGE command that are
supported by the server by specifying those options at the requester and using the
requester’s syntax for the BIND PACKAGE command.

To find out which options are supported by a specific server DBMS, refer to the
documentation provided for that server.

For specific DB2 bind information, refer to the following documentation:

v For guidance in using DB2 bind options and performing a bind process, see
Chapter 17, “Preparing an application to run on DB2 for z/OS,” on page 887.
v For the syntax of DB2 BIND command, see the topics BIND PACKAGE (DSN)
(DB2 Command Reference) and BIND PLAN (DSN) (DB2 Command Reference).
v For the syntax of DB2 REBIND command, see the topics REBIND PACKAGE
(DSN) (DB2 Command Reference) and REBIND PLAN (DSN) (DB2 Command
Reference).
v For a list of DB2 bind options in generic terms, including options you cannot
request from DB2 but can use if you request from a non-DB2 server, see
“Program preparation options for remote packages” on page 913.

Binding a batch program

Before a batch program can issue SQL statements, a DB2 plan must exist.

The owner of the plan or package must have all the privileges that are required to
execute the SQL statements embedded in it.

You can specify the plan name to DB2 in one of the following ways:
v In the DDITV02 input data set.
v In subsystem member specification.
v By default; the plan name is then the application load module name that is
specified in DDITV02.

DB2 passes the plan name to the IMS attach package. If you do not specify a plan
name in DDITV02, and a resource translation table (RTT) does not exist or the
name is not in the RTT, DB2 uses the passed name as the plan name. If the name
exists in the RTT, the name translates to the plan that is specified for the RTT.

Recommendation: Give the DB2 plan the same name as that of the application
load module, which is the IMS attachment facility default. The plan name must be
the same as the program name.

930 Application Programming and SQL Guide

Converting an existing plan into packages to run remotely
If you have an existing application that you want to run at a remote location by
using DRDA access, you need to rebind the DBRMs in the current plan as
packages at the remote location. You also need a new plan that includes those
remote packages in its package list.

To turn an existing plan into packages to run remotely, perform the following
actions for each remote location:
1. Choose a name for a collection to contain all the packages in the plan, such as
REMOTE1. (You can use more than one collection if you like, but one is
enough.)
2. Assuming that the server is a DB2 system, at the remote location execute:
a. GRANT CREATE IN COLLECTION REMOTE1 TO authorization-name;
b. GRANT BINDADD TO authorization-name;
where authorization-name is the owner of the package.
3. Bind each DBRM as a package at the remote location, using the instructions
under “Binding packages at a remote location” on page 917. Before run time,
the package owner must have all the data access privileges that are needed at
the remote location. If the owner does not yet have those privileges when you
are binding, use the VALIDATE(RUN) option. The option lets you create the
package, even if the authorization checks fail. DB2 checks the privileges again
at run time.
4. Bind a new application plan at your local DB2 system, using these options:
PKLIST (location-name.REMOTE1.*)
CURRENTSERVER (location-name)
where location-name is the value of LOCATION, in SYSIBM.LOCATIONS at
your local DB2 system, that denotes the remote location at which you intend to
run. You do not need to bind any DBRMs directly to that plan; the package list
is sufficient.

When you now run the existing application at your local DB2 system using the
new application plan, these things happen:
v You connect immediately to the remote location that is named in the
CURRENTSERVER option.
v DB2 searches for the package in the collection REMOTE1 at the remote location.
v Any UPDATE, DELETE, or INSERT statements in your application affect tables
at the remote location.
v Any results from SELECT statements are returned to your existing application
program, which processes them as though they came from your local DB2
system.

Setting the program level

The program level defines the level for a particular module. This information is
stored in the consistency token, which is in an internal DB2 format. You can
override the program level in that token if needed, but you should avoid changing
this level unless you need to.

To override the construction of the consistency token by DB2, use the LEVEL (aaaa)
option. DB2 uses the value that you choose for aaaa to generate the consistency
token. Although this method is not recommended for general use and the DSNH
CLIST or the DB2 Program Preparation panels do not support it, this method
enables you to perform the following actions:

Chapter 17. Preparing an application to run on DB2 for z/OS 931

1. Change the source code (but not the SQL statements) in the DB2 precompiler
output of a bound program.
2. Compile and link-edit the changed program.
3. Run the application without rebinding a plan or package.

DYNAMICRULES bind option

The DYNAMICRULES bind option and the run-time environment determine the
values for the dynamic SQL attributes.

The BIND or REBIND option DYNAMICRULES determines what values apply at

run time for the following dynamic SQL attributes:
v The authorization ID that is used to check authorization
v The qualifier that is used for unqualified objects
v The source for application programming options that DB2 uses to parse and
semantically verify dynamic SQL statements
v Whether dynamic SQL statements can include GRANT, REVOKE, ALTER,
CREATE, DROP, and RENAME statements

In addition, the run-time environment of a package controls how dynamic SQL

statements behave at run time. The two possible run-time environments are:
v The package runs as part of a stand-alone program.
v The package runs as a stored procedure or user-defined function package, or it
runs under a stored procedure or user-defined function.
A package that runs under a stored procedure or user-defined function is a
package whose associated program meets one of the following conditions:
– The program is called by a stored procedure or user-defined function.
– The program is in a series of nested calls that start with a stored procedure or
user-defined function.

Dynamic SQL statement behavior:

The dynamic SQL attributes that are determined by the value of the
DYNAMICRULES bind option and the run-time environment are collectively called
the dynamic SQL statement behavior. The four behaviors are:
v Run behavior
v Bind behavior
v Define behavior
v Invoke behavior

The following table shows the combination of DYNAMICRULES value and

run-time environment that yield each dynamic SQL behavior.
Table 155. How DYNAMICRULES and the run-time environment determine dynamic SQL
statement behavior
Behavior of dynamic SQL
Behavior of dynamic SQL statements in a user-defined
statements in a stand-alone function or stored procedure
DYNAMICRULES value program environment environment
BIND Bind behavior Bind behavior
RUN Run behavior Run behavior
DEFINEBIND Bind behavior Define behavior

932 Application Programming and SQL Guide

Table 155. How DYNAMICRULES and the run-time environment determine dynamic SQL
statement behavior (continued)
Behavior of dynamic SQL
Behavior of dynamic SQL statements in a user-defined
statements in a stand-alone function or stored procedure
DYNAMICRULES value program environment environment
DEFINERUN Run behavior Define behavior
INVOKEBIND Bind behavior Invoke behavior
INVOKERUN Run behavior Invoke behavior
Note: The BIND and RUN values can be specified for packages and plans. The other
values can be specified only for packages.

The following table shows the dynamic SQL attribute values for each type of
dynamic SQL behavior.
Table 156. Definitions of dynamic SQL statement behaviors
Setting for dynamic SQL attributes
Dynamic SQL attribute Bind behavior Run behavior Define behavior Invoke behavior
Authorization ID Plan or package Current SQLID User-defined Authorization ID of
owner function or stored invoker1
procedure owner
| Default qualifier for Bind OWNER or CURRENT User-defined Authorization ID of
| unqualified objects QUALIFIER value SCHEMA function or stored invoker
procedure owner
CURRENT SQLID2 Not applicable Applies Not applicable Not applicable
Source for application Determined by Install panel Determined by Determined by
programming options DSNHDECP DSNTIP4 DSNHDECP DSNHDECP
parameter parameter parameter
DYNRULS3 DYNRULS3 DYNRULS3
Can execute GRANT, No Yes No No
REVOKE, CREATE,
ALTER, DROP, RENAME?
Notes:
1. If the invoker is the primary authorization ID of the process or the CURRENT SQLID value, secondary
authorization IDs are also checked if they are needed for the required authorization. Otherwise, only one ID, the
ID of the invoker, is checked for the required authorization.
2. DB2 uses the value of CURRENT SQLID as the authorization ID for dynamic SQL statements only for plans and
packages that have run behavior. For the other dynamic SQL behaviors, DB2 uses the authorization ID that is
associated with each dynamic SQL behavior, as shown in this table.
The value to which CURRENT SQLID is initialized is independent of the dynamic SQL behavior. For stand-alone
programs, CURRENT SQLID is initialized to the primary authorization ID.
You can execute the SET CURRENT SQLID statement to change the value of CURRENT SQLID for packages with
any dynamic SQL behavior, but DB2 uses the CURRENT SQLID value only for plans and packages with run
behavior.
3. The value of DSNHDECP parameter DYNRULS, which you specify in field USE FOR DYNAMICRULES in
installation panel DSNTIP4, determines whether DB2 uses the SQL statement processing options or the
application programming defaults for dynamic SQL statements. See “Options for SQL statement processing” on
page 904 for more information.

Chapter 17. Preparing an application to run on DB2 for z/OS 933

Determining the authorization cache size for plans
You can specify the size of this cache when you bind the plan. The default
CACHESIZE value is 1024 or the size that is specified at installation time

The CACHESIZE option (optional) enables you to specify the size of the cache to
acquire for the plan. DB2 uses this cache for caching the authorization IDs of those
users that are running a plan. An authorization ID can take up to 128 bytes of
storage. DB2 uses the CACHESIZE value to determine the amount of storage to
acquire for the authorization cache. DB2 acquires storage from the EDM storage
pool. .

The size of the cache that you specify depends on the number of individual
authorization IDs that are actively using the plan. Required overhead takes 32
bytes, and each authorization ID takes up 8 bytes of storage. The minimum cache
size is 256 bytes (enough for 28 entries and overhead information) and the
maximum is 4096 bytes (enough for 508 entries and overhead information). You
should specify size in multiples of 256 bytes; otherwise, the specified value rounds
up to the next highest value that is a multiple of 256.

If you run the plan infrequently, or if authority to run the plan is granted to
PUBLIC, you might want to turn off caching for the plan so that DB2 does not use
unnecessary storage. To do this, specify a value of 0 for the CACHESIZE option.

Any plan that you run repeatedly is a good candidate for tuning by using the
CACHESIZE option. Also, if you have a plan that a large number of users run
concurrently, you might want to use a larger CACHESIZE.

Authorization cache
DB2 uses the authorization cache for caching the authorization IDs of those users
that are running a plan.

When DB2 determines that you have the EXECUTE privilege on a plan, package
collection, stored procedure, or user-defined function, DB2 can cache your
authorization ID. When you run the plan, package, stored procedure, or
user-defined function, DB2 can check your authorization more quickly.

Determining the authorization cache size for packages

DB2 provides a single package authorization cache for an entire DB2 subsystem.
The DB2 installer sets the size of the package authorization cache by entering a
size in field PACKAGE AUTH CACHE of DB2 installation panel DSNTIPP.

A 32-KB authorization cache is large enough to hold authorization information for

about 375 package collections.

For more information about setting the size of the package authorization cache, see
the topic “Protection panel: DSNTIPP” in DB2 Installation Guide.

Dynamic plan selection

The benefit of using dynamic plan selection and packages together is that you can
convert individual programs in an application that contains many programs and
plans, one at a time, to use a combination of plans and packages. This reduces the
number of plans per application; having fewer plans reduces the effort that is
needed to maintain the dynamic plan exit routine.

934 Application Programming and SQL Guide

CICSYou can use packages and dynamic plan selection together, but when you
dynamically switch plans, the following conditions must exist:
v All special registers, including CURRENT PACKAGESET, must contain their
initial values.
v The value in the CURRENT DEGREE special register cannot have changed
during the current transaction.

Assume that you develop the following programs and DBRMs:

Table 157. Example programs and DBRMs
Program Name DBRM Name
MAIN MAIN
PROGA PLANA
PROGB PKGB
PROGC PLANC

You could create packages and plans using the following bind statements:
BIND PACKAGE(PKGB) MEMBER(PKGB)
BIND PLAN(MAIN) MEMBER(MAIN,PLANA) PKLIST(*.PKGB.*)
BIND PLAN(PLANC) MEMBER(PLANC)

The following scenario illustrates thread association for a task that runs program
MAIN. Suppose that you execute the following SQL statements in the indicated
order. For each SQL statement, the resulting event is described.
1. EXEC CICS START TRANSID(MAIN)
TRANSID(MAIN) executes program MAIN.
2. EXEC SQL SELECT...
Program MAIN issues an SQL SELECT statement. The default dynamic plan
exit routine selects plan MAIN.
3. EXEC CICS LINK PROGRAM(PROGA)
Program PROGA is invoked.
4. EXEC SQL SELECT...
DB2 does not call the default dynamic plan exit routine, because the program
does not issue a sync point. The plan is MAIN.
5. EXEC CICS LINK PROGRAM(PROGB)
Program PROGB is invoked.
6. EXEC SQL SELECT...
DB2 does not call the default dynamic plan exit routine, because the program
does not issue a sync point. The plan is MAIN and the program uses package
PKGB.
7. EXEC CICS SYNCPOINT
DB2 calls the dynamic plan exit routine when the next SQL statement
executes.
8. EXEC CICS LINK PROGRAM(PROGC)
Program PROGC is invoked.
9. EXEC SQL SELECT...
DB2 calls the default dynamic plan exit routine and selects PLANC.
10. EXEC SQL SET CURRENT SQLID = 'ABC'

Chapter 17. Preparing an application to run on DB2 for z/OS 935

The CURRENT SQLID special register is assigned the value ’ABC.’
11. EXEC CICS SYNCPOINT
DB2 does not call the dynamic plan exit routine when the next SQL statement
executes because the previous statement modifies the special register
CURRENT SQLID.
12. EXEC CICS RETURN
Control returns to program PROGB.
13. EXEC SQL SELECT...

CICS With packages, you probably do not need dynamic plan selection and its
accompanying exit routine. A package that is listed within a plan is not accessed
until it is executed. However, you can use dynamic plan selection and packages
together, which can reduce the number of plans in an application and the effort to
maintain the dynamic plan exit routine.

Rebinding an application
You need to rebind an application if you want to change any bind options or when
you make changes that affect the plan or package, such as creating an index, but
have not changed the SQL statements. In some cases, DB2 automatically rebinds
the plan or package for you.

If you change the SQL statements, you need to replace the plan or package.

Rebinding a package
You need to rebind a package when you make changes that affect the package but
have not changed the SQL statements. For example, if you create a new index, you
need to rebind the package. If you change the SQL, you need to use the BIND
PACKAGE command with the ACTION(REPLACE) option.

To rebind a package, other than a trigger package, use the REBIND subcommand.
To rebind a trigger package, use the REBIND TRIGGER PACKAGE subcommand.
You can change any of bind options for a package when you rebind it.

The following table clarifies which packages are bound, depending on how you
specify collection-id (coll-id), package-id (pkg-id), and version-id (ver-id) on the
REBIND PACKAGE subcommand. For syntax and descriptions of this
subcommand, see the topic “REBIND PACKAGE (DSN)” in DB2 Command
Reference.

REBIND PACKAGE does not apply to packages for which you do not have the
BIND privilege. An asterisk (*) used as an identifier for collections, packages, or
versions does not apply to packages at remote sites.
Table 158. Behavior of REBIND PACKAGE specification. ″All″ means all collections,
packages, or versions at the local DB2 server for which the authorization ID that issues the
command has the BIND privilege.
Collections Packages
Input affected affected Versions affected

* all all all

*.*.(*) all all all

*.* all all all

936 Application Programming and SQL Guide

Table 158. Behavior of REBIND PACKAGE specification (continued). ″All″ means all
collections, packages, or versions at the local DB2 server for which the authorization ID that
issues the command has the BIND privilege.
Collections Packages
Input affected affected Versions affected

*.*.(ver-id) all all ver-id

*.*.() all all empty string

coll-id.* coll-id all all

coll-id.*.(*) coll-id all all

coll-id.*.(ver-id) coll-id all ver-id

coll-id.*.() coll-id all empty string

coll-id.pkg-id.(*) coll-id pkg-id all

coll-id.pkg-id coll-id pkg-id empty string

coll-id.pkg-id.() coll-id pkg-id empty string

coll-id.pkg-id.(ver-id) coll-id pkg-id ver-id

*.pkg-id.(*) all pkg-id all

*.pkg-id all pkg-id empty string

*.pkg-id.() all pkg-id empty string

*.pkg-id.(ver-id) all pkg-id ver-id

Example: The following example shows the options for rebinding a package at the
remote location. The location name is SNTERSA. The collection is GROUP1, the
package ID is PROGA, and the version ID is V1. The connection types shown in
the REBIND subcommand replace connection types that are specified on the
original BIND subcommand. For information about the REBIND subcommand
options, see the topic “BIND and REBIND options” in DB2 Command Reference.
REBIND PACKAGE(SNTERSA.GROUP1.PROGA.(V1)) ENABLE(CICS,REMOTE)

You can use the asterisk on the REBIND subcommand for local packages, but not
for packages at remote sites. Any of the following commands rebinds all versions
of all packages in all collections, at the local DB2 system, for which you have the
BIND privilege.
REBIND PACKAGE (*)
REBIND PACKAGE (*.*)
REBIND PACKAGE (*.*.(*))

Either of the following commands rebinds all versions of all packages in the local
collection LEDGER for which you have the BIND privilege.
REBIND PACKAGE (LEDGER.*)
REBIND PACKAGE (LEDGER.*.(*))

Either of the following commands rebinds the empty string version of the package
DEBIT in all collections, at the local DB2 system, for which you have the BIND
privilege.
REBIND PACKAGE (*.DEBIT)
REBIND PACKAGE (*.DEBIT.())

Chapter 17. Preparing an application to run on DB2 for z/OS 937

Related reference
BIND and REBIND options (DB2 Command Reference)

Rebinding a plan
You need to rebind a plan when you make changes that affect the plan but have
not changed the SQL statements. For example, if you create a new index, you need
to rebind the plan. If you change the SQL, you need to use the BIND PLAN
command with the ACTION(REPLACE) option.

To rebind a plan use the REBIND subcommand. You can change any of bind
options for that plan.

When you rebind a plan, use the PKLIST keyword to replace any previously
specified package list. Omit the PKLIST keyword to use of the previous package
list for rebinding. Use the NOPKLIST keyword to delete any package list that was
specified when the plan was previously bound.

Example: Rebinds PLANA and changes the package list:

REBIND PLAN(PLANA) PKLIST(GROUP1.*) MEMBER(ABC)

Example: Rebinds the plan and drops the entire package list:
REBIND PLAN(PLANA) NOPKLIST
Related reference
BIND and REBIND options (DB2 Command Reference)

Rebinding lists of plans and packages

In some situations, you need to rebind a set of plans or packages that cannot be
described by using asterisks. For example, if a rebind operation terminated, you
can generate a rebind subcommand for each object that was not bound.

One situation in which this technique is useful is to complete a rebind operation

that has terminated due to lack of resources. A rebind for many objects, such as
REBIND PACKAGE (*) for an ID with SYSADM authority, terminates if a needed
resource becomes unavailable. As a result, some objects are successfully rebound
and others are not. If you repeat the subcommand, DB2 attempts to rebind all the
objects again. But if you generate a rebind subcommand for each object that was
not rebound, and issue those subcommands, DB2 does not repeat any work that
was already done and is not likely to run out of resources.

For a description of the technique and several examples of its use, see “Sample
program to create REBIND subcommands for lists of plans and packages” on page
939.

Generating lists of REBIND commands

You can generate a list of REBIND subcommands for a set of plans or packages
that cannot be described by using asterisks, by using information in the DB2
catalog. You can then issue the list of subcommands through DSN.

The following list is an overview of the procedures for REBIND PLAN:

1. Use DSNTIAUL to generate the REBIND PLAN subcommands for the selected
plans.

938 Application Programming and SQL Guide

2. Use TSO edit commands to add TSO DSN commands to the sequential data
set.
3. Use DSN to execute the REBIND PLAN subcommands for the selected plans.
The following list is an overview of the procedures for REBIND PACKAGE:
1. Use DSNTIAUL to generate the REBIND PACKAGE subcommands for the
selected packages.
2. Use DSNTEDIT CLIST to delete extraneous blanks from the REBIND
PACKAGE subcommands.
3. Use TSO edit commands to add DSN commands to the sequential data set.
4. Use DSN to execute the REBIND PACKAGE subcommands for the selected
packages.

Sample program to create REBIND subcommands for lists of

plans and packages
If a list of packages or plans that you want to rebind is not easily specified using
asterisks, you might be able to create the needed REBIND subcommands
automatically, using the sample program DSNTIAUL.

One situation in which this technique might be useful is when a resource becomes
unavailable during a rebind of many plans or packages. DB2 normally terminates
the rebind and does not rebind the remaining plans or packages. Later, however,
you might want to rebind only the objects that remain to be rebound. You can
build REBIND subcommands for the remaining plans or packages by using
DSNTIAUL to select the plans or packages from the DB2 catalog and to create the
REBIND subcommands. You can then submit the subcommands through the DSN
command processor, as usual.

You might first need to edit the output from DSNTIAUL so that DSN can accept it
as input. The CLIST DSNTEDIT can perform much of that task for you.

This section contains the following topics:

v “Generating lists of REBIND commands” on page 938
v “Sample SELECT statements for generating REBIND commands”
v “Sample JCL for running lists of REBIND commands” on page 942

Sample SELECT statements for generating REBIND commands

These examples show how to select specific plans or packages to be rebound,
concatenate the REBIND subcommand syntax around the plan or package names,
convert a varying-length string to a fixed-length string, and append additional
blanks to the REBIND PLAN and REBIND PACKAGE subcommands, so that the
DSN command processor can accept the record length as valid input.

Building REBIND subcommands: The examples that follow illustrate the following
techniques:
v Using SELECT to select specific packages or plans to be rebound
v Using the CONCAT operator to concatenate the REBIND subcommand syntax
around the plan or package names
v Using the SUBSTR function to convert a varying-length string to a fixed-length
string
v Appending additional blanks to the REBIND PLAN and REBIND PACKAGE
subcommands, so that the DSN command processor can accept the record length
as valid input

Chapter 17. Preparing an application to run on DB2 for z/OS 939

If the SELECT statement returns rows, then DSNTIAUL generates REBIND
subcommands for the plans or packages identified in the returned rows. Put those
subcommands in a sequential data set, where you can then edit them.

For REBIND PACKAGE subcommands, delete any extraneous blanks in the

package name, using either TSO edit commands or the DB2 CLIST DSNTEDIT.

For both REBIND PLAN and REBIND PACKAGE subcommands, add the DSN
command that the statement needs as the first line in the sequential data set, and
add END as the last line, using TSO edit commands. When you have edited the
sequential data set, you can run it to rebind the selected plans or packages.

If the SELECT statement returns no qualifying rows, then DSNTIAUL does not
generate REBIND subcommands.

The examples in this topic generate REBIND subcommands that work in DB2 for
z/OS Version 9.1. You might need to modify the examples for prior releases of DB2
that do not allow all of the same syntax.
Example 1:
REBIND all plans without terminating because of unavailable resources.
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') ',1,45)
FROM SYSIBM.SYSPLAN;
Example 2:
REBIND all versions of all packages without terminating because of
unavailable resources.
SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID CONCAT'.'
CONCAT NAME CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE;
Example 3:
REBIND all plans bound before a given date and time.
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') ',1,45)
FROM SYSIBM.SYSPLAN
WHERE BINDDATE <= 'yyyymmdd' AND
BINDTIME <= 'hhmmssth';

where yyyymmdd represents the date portion and hhmmssth represents the
time portion of the timestamp string.
Example 4:
REBIND all versions of all packages bound before a given date and time.
SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID CONCAT'.'
CONCAT NAME CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE
WHERE BINDTIME <= 'timestamp';

where timestamp is an ISO timestamp string.

Example 5:
REBIND all plans bound since a given date and time.
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') ',1,45)
FROM SYSIBM.SYSPLAN
WHERE BINDDATE >= 'yyyymmdd' AND
BINDTIME >= 'hhmmssth';

940 Application Programming and SQL Guide

where yyyymmdd represents the date portion and hhmmssth represents the
time portion of the timestamp string.
Example 6:
REBIND all versions of all packages bound since a given date and time.
SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID
CONCAT'.'CONCAT NAME
CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE
WHERE BINDTIME >= 'timestamp';

where timestamp is an ISO timestamp string.

Example 7:
REBIND all plans bound within a given date and time range.
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') ',1,45)
FROM SYSIBM.SYSPLAN
WHERE
(BINDDATE >= 'yyyymmdd' AND
BINDTIME >= 'hhmmssth') AND
BINDDATE <= 'yyyymmdd' AND
BINDTIME <= 'hhmmssth');

where yyyymmdd represents the date portion and hhmmssth represents the
time portion of the timestamp string.
Example 8:
REBIND all versions of all packages bound within a given date and time
range.
SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID CONCAT'.'
CONCAT NAME CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE
WHERE BINDTIME >= 'timestamp1' AND
BINDTIME <= 'timestamp2';

where timestamp1 and timestamp2 are ISO timestamp strings.

Example 9:
REBIND all invalid plans.
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') ',1,45)
FROM SYSIBM.SYSPLAN
WHERE VALID = 'N';
Example 10:
REBIND all invalid versions of all packages.
SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID CONCAT'.'
CONCAT NAME CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE
WHERE VALID = 'N';
Example 11:
REBIND all plans bound with ISOLATION level of cursor stability.
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') ',1,45)
FROM SYSIBM.SYSPLAN
WHERE ISOLATION = 'S';
Example 12:
REBIND all versions of all packages that allow CPU and/or I/O
parallelism.

Chapter 17. Preparing an application to run on DB2 for z/OS 941

SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID CONCAT'.'
CONCAT NAME CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE
WHERE DEGREE='ANY';

Sample JCL for running lists of REBIND commands

This example JCL shows how to rebind all versions of all packages that are bound
within a specified date and time period.

You specify the date and time period for which you want packages to be rebound
in a WHERE clause of the SELECT statement that contains the REBIND command.
In The following example, the WHERE clause looks like the following clause:
WHERE BINDTIME >= 'YYYY-MM-DD-hh.mm.ss' AND
BINDTIME <= 'YYYY-MM-DD-hh.mm.ss'

The date and time period has the following format:

YYYY The four-digit year. For example: 2003.
MM The two-digit month, which can be a value between 01 and 12.
DD The two-digit day, which can be a value between 01 and 31.
hh The two-digit hour, which can be a value between 01 and 24.
mm The two-digit minute, which can be a value between 00 and 59.
ss The two-digit second, which can be a value between 00 and 59.
//REBINDS JOB MSGLEVEL=(1,1),CLASS=A,MSGCLASS=A,USER=SYSADM,
// REGION=1024K
//*********************************************************************/
//SETUP EXEC PGM=IKJEFT01
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB91) PARMS('SQL') -
LIB('DSN910.RUNLIB.LOAD')
END
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSPUNCH DD SYSOUT=*
//SYSREC00 DD DSN=SYSADM.SYSTSIN.DATA,
// UNIT=SYSDA,DISP=SHR
//*********************************************************************/
//*
//* GENER= '<SUBCOMMANDS TO REBIND ALL PACKAGES BOUND IN 1994
//*
//*********************************************************************/
//SYSIN DD *
SELECT SUBSTR('REBIND PACKAGE('CONCAT COLLID CONCAT'.'
CONCAT NAME CONCAT'.(*)) ',1,55)
FROM SYSIBM.SYSPACKAGE
WHERE BINDTIME >= 'YYYY-MM-DD-hh.mm.ss' AND
BINDTIME <= 'YYYY-MM-DD-hh.mm.ss';
/*
//*********************************************************************/
//*
//* STRIP THE BLANKS OUT OF THE REBIND SUBCOMMANDS
//*
//*********************************************************************/
//STRIP EXEC PGM=IKJEFT01
//SYSPROC DD DSN=SYSADM.DSNCLIST,DISP=SHR
//SYSTSPRT DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//SYSOUT DD SYSOUT=*

942 Application Programming and SQL Guide

//SYSTSIN DD *
DSNTEDIT SYSADM.SYSTSIN.DATA
//SYSIN DD DUMMY
/*
//*********************************************************************/
//*
//* PUT IN THE DSN COMMAND STATEMENTS
//*
//*********************************************************************/
//EDIT EXEC PGM=IKJEFT01
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
EDIT 'SYSADM.SYSTSIN.DATA' DATA NONUM
TOP
INSERT DSN SYSTEM(DSN)
BOTTOM
INSERT END
TOP
LIST * 99999
END SAVE
/*
//*********************************************************************/
//*
//* EXECUTE THE REBIND PACKAGE SUBCOMMANDS THROUGH DSN
//*
//*********************************************************************/
//LOCAL EXEC PGM=IKJEFT01
//DBRMLIB DD DSN=DSN910.DBRMLIB.DATA,
// DISP=SHR
//SYSTSPRT DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSTSIN DD DSN=SYSADM.SYSTSIN.DATA,
// UNIT=SYSDA,DISP=SHR
/*

The following example shows some sample JCL for rebinding all plans bound
without specifying the DEGREE keyword on BIND with DEGREE(ANY).
//REBINDS JOB MSGLEVEL=(1,1),CLASS=A,MSGCLASS=A,USER=SYSADM,
// REGION=1024K
//*********************************************************************/
//SETUP EXEC TSOBATCH
//SYSPRINT DD SYSOUT=*
//SYSPUNCH DD SYSOUT=*
//SYSREC00 DD DSN=SYSADM.SYSTSIN.DATA,
// UNIT=SYSDA,DISP=SHR
//*********************************************************************/
//*
//* REBIND ALL PLANS THAT WERE BOUND WITHOUT SPECIFYING THE DEGREE
//* KEYWORD ON BIND WITH DEGREE(ANY)
//*
//*********************************************************************/
//SYSTSIN DD *
DSN S(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB91) PARM('SQL')
END
//SYSIN DD *
SELECT SUBSTR('REBIND PLAN('CONCAT NAME
CONCAT') DEGREE(ANY) ',1,45)
FROM SYSIBM.SYSPLAN
WHERE DEGREE = ' ';
/*
//*********************************************************************/
//*
//* PUT IN THE DSN COMMAND STATEMENTS
//*

Chapter 17. Preparing an application to run on DB2 for z/OS 943

//*********************************************************************/
//EDIT EXEC PGM=IKJEFT01
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
EDIT 'SYSADM.SYSTSIN.DATA' DATA NONUM
TOP
INSERT DSN S(DSN)
BOTTOM
INSERT END
TOP
LIST * 99999
END SAVE
/*
//*********************************************************************/
//*
//* EXECUTE THE REBIND SUBCOMMANDS THROUGH DSN
//*
//*********************************************************************/
//REBIND EXEC PGM=IKJEFT01
//STEPLIB DD DSN=SYSADM.TESTLIB,DISP=SHR
// DD DSN=DSN910.SDSNLOAD,DISP=SHR
//DBRMLIB DD DSN=SYSADM.DBRMLIB.DATA,DISP=SHR
//SYSTSPRT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSPRINT DD SYSOUT=*
//SYSOUT DD SYSOUT=*
//SYSTSIN DD DSN=SYSADM.SYSTSIN.DATA,DISP=SHR
//SYSIN DD DUMMY
/*

Automatic rebinding
Automatic rebind might occur if an authorized user invokes a plan or package
when the attributes of the data on which the plan or package depends change, or
if the environment in which the package executes changes. Whether the automatic
rebind occurs depends on the value of the field AUTO BIND on installation panel
DSNTIPO.

The options used for an automatic rebind are the options used during the most
recent bind process.

| If a package has previous or original copies as a result of rebinding with the

| PLANMGMT(BASIC) or PLANMGMT(EXTENDED) options or having the
| PLANMGMT subsystem parameter set to BASIC or EXTENDED, those copies are
| not affected by automatic rebind. Automatic rebind replaces only the current copy.

In most cases, DB2 marks a plan or package that needs to be automatically

rebound as invalid. A few common situations in which DB2 marks a plan or
package as invalid are:
v When a package is dropped
v When a plan depends on the execute privilege of a package that is dropped
v When a table, index, or view on which the plan or package depends is dropped
v When the authorization of the owner to access any of those objects is revoked
v When the authorization to execute a stored procedure is revoked from a plan or
package owner, and the plan or package uses the CALL procedure-name form of
the CALL statement to call the stored procedure
v When a table on which the plan or package depends is altered to add a TIME,
TIMESTAMP, or DATE column

944 Application Programming and SQL Guide

v When a table is altered to add a self-referencing constraint or a constraint with a
delete rule of SET NULL or CASCADE
v When the limit key value of a partitioned index on which the plan or package
depends is altered
v When the definition of an index on which the plan or package depends is
altered from NOT PADDED to PADDED
v When the definition of an index on which the plan or package depends is
altered from PADDED to NOT PADDED
v When the AUDIT attribute of a table on which the plan or package depends is
altered
| v When the length attribute of a CHAR, VARCHAR, GRAPHIC, VARGRAPHIC,
| BINARY, or VARBINARY column in a table on which the plan or package
| depends is altered
v When the data type, precision, or scale of a column in a table on which the plan
or package depends is altered
v When a plan or package depends on a view that DB2 cannot regenerate after a
column in the underlying table is altered
v When a created temporary table on which the plan or package depends is
altered to add a column
v When a user-defined function on which the plan or package depends is altered
| v When a column is renamed in a table on which a plan or package is dependent

Whether a plan or package is valid is recorded in column VALID of catalog tables

SYSPLAN and SYSPACKAGE.

| In the following cases, DB2 automatically rebinds a plan or package that has not
| been marked as invalid if the ABIND subsystem parameter is set to YES (the
| default):
v A plan or package that is bound on a release of DB2 that is more recent than the
release in which it is being run. This situation can happen in a data sharing
environment or after a DB2 subsystem has fallen back to a previous release of
DB2.
| v A plan or package that was bound prior to DB2 Version 4 Release 1. Plans and
| packages that are bound prior to Version 4 Release 1 are automatically rebound
| when they are run on the current release of DB2.
v A plan or package that has a location dependency and runs at a location other
than the one at which it was bound. This situation can happen when members
of a data sharing group are defined with location names, and a package runs on
a different member from the one on which it was bound.

| In the following cases, DB2 automatically rebinds a plan or package that has not
| been marked as invalid if the ABIND subsystem parameter is set to COEXIST:
| v The subsystem on which the plan or package runs is in a data sharing group.
| v The plan or package was previously bound on the current DB2 release and is
| now running on the previous DB2 release.

If the ABIND subsystem parameter is set to NO and you attempt to execute a plan
or package that requires a rebind, but cannot be automatically rebound, DB2
returns an error.

Chapter 17. Preparing an application to run on DB2 for z/OS 945

DB2 marks a plan or package as inoperative if an automatic rebind fails. Whether a
plan or package is operative is recorded in column OPERATIVE of SYSPLAN and
SYSPACKAGE.

Whether EXPLAIN runs during automatic rebind depends on the value of the field
EXPLAIN PROCESSING on installation panel DSNTIPO, and on whether you
specified EXPLAIN(YES). Automatic rebind fails for all EXPLAIN errors except
“PLAN_TABLE not found.”

The SQLCA is not available during automatic rebind. Therefore, if you encounter
lock contention during an automatic rebind, DSNT501I messages cannot
accompany any DSNT376I messages that you receive. To see the matching
DSNT501I messages, you must issue the subcommand REBIND PLAN or REBIND
PACKAGE.
Related reference
AUTO BIND field (ABIND subsystem parameter) (DB2 Installation and
Migration)

Specifying the rules that apply to SQL behavior at run time

You can specify whether DB2 rules or SQL standard rules apply to SQL behavior at
run time.

Not only does SQLRULES specify the rules under which a type 2 CONNECT
statement executes, but it also sets the initial value of the special register
CURRENT RULES when the database server is the local DB2 system. When the
server is not the local DB2 system, the initial value of CURRENT RULES is DB2.
After binding a plan, you can change the value in CURRENT RULES in an
application program by using the statement SET CURRENT RULES.

CURRENT RULES determines the SQL rules, DB2 or SQL standard, that apply to
SQL behavior at run time. For example, the value in CURRENT RULES affects the
behavior of defining check constraints by issuing the ALTER TABLE statement on a
populated table:
v If CURRENT RULES has a value of STD and no existing rows in the table
violate the check constraint, DB2 adds the constraint to the table definition.
Otherwise, an error occurs and DB2 does not add the check constraint to the
table definition.
If the table contains data and is already in a check pending status, the ALTER
TABLE statement fails.
v If CURRENT RULES has a value of DB2, DB2 adds the constraint to the table
definition, defers the enforcing of the check constraints, and places the table
space or partition in CHECK-pending status.

You can use the statement SET CURRENT RULES to control the action that the
statement ALTER TABLE takes. Assuming that the value of CURRENT RULES is
initially STD, the following SQL statements change the SQL rules to DB2, add a
check constraint, defer validation of that constraint, place the table in
CHECK-pending status, and restore the rules to STD.
EXEC SQL
SET CURRENT RULES = 'DB2';
EXEC SQL

946 Application Programming and SQL Guide

ALTER TABLE DSN8910.EMP
ADD CONSTRAINT C1 CHECK (BONUS <= 1000.0);
EXEC SQL
SET CURRENT RULES = 'STD';

See “Check constraints” on page 434 for information about check constraints.

You can also use CURRENT RULES in host variable assignments. For example, if
you want to store the value of the CURRENT RULES special register at a
particular point in time, you can use assign the value to a host variable, as in the
following statement:
SET :XRULE = CURRENT RULES;

You can also use CURRENT RULES as the argument of a search-condition. For
example, the following statement retrieves rows where the COL1 column contains
the same value as the CURRENT RULES special register.
SELECT * FROM SAMPTBL WHERE COL1 = CURRENT RULES;

DB2 program preparation overview

Before you can run an application program on DB2 for z/OS, you need to prepare
it by creating a load module, possibly one or more packages, and an application
plan.

If your application program includes SQL statements, you need to process those
SQL statements by using either the DB2 precompiler or the DB2 coprocessor that is
provided with a compiler. Both the precompiler and the coprocessor perform the
following actions:
v Replaces the SQL statements in your source programs with calls to DB2
language interface modules
v Creates a database request module (DBRM), which communicates your SQL
requests to DB2 during the bind process

The following figure illustrates the program preparation process when you use the
DB2 precompiler. After you process SQL statements in your source program by
using the DB2 precompiler, you create a load module, possibly one or more
packages, and an application plan. Creating a load module involves compiling the
modified source code that is produced by the precompiler into an object program,
and link-editing the object program to create a load module. Creating a package or
an application plan, a process unique to DB2, involves binding one or more
DBRMs, which are created by the DB2 precompiler, using the BIND PACKAGE or
BIND PLAN commands.

Chapter 17. Preparing an application to run on DB2 for z/OS 947

Figure 43. Program preparation with the DB2 precompiler

The following figure illustrates the program preparation process when you use the
DB2 coprocessor. The process is similar to the process for the DB2 precompiler,
except that the DB2 coprocessor does not create modified source for your
application program.

948 Application Programming and SQL Guide

Source
program

Compile and
process SQL DBRM

Object
program Bind package Bind plan

Plan

Link edit Package

Load
module
Figure 44. Program preparation with the DB2 coprocessor

Input and output data sets for DL/I batch jobs

DL/I batch jobs require an input data set with DD name DDITV02 and an output
data set with DD name DDOTV02.

DB2 DL/I batch input:

Before you can run a DL/I batch job, you need to provide values for a number of
input parameters. The input parameters are positional and delimited by commas.

You can specify values for the following parameters using a DDITV02 data set or a
subsystem member:
SSN,LIT,ESMT,RTT,REO,CRC

You can specify values for the following parameters only in a DDITV02 data set:
CONNECTION_NAME,PLAN,PROG

If you use the DDITV02 data set and specify a subsystem member, the values in
the DDITV02 DD statement override the values in the specified subsystem
member. If you provide neither, DB2 abnormally terminates the application
program with system abend code X’04E’ and a unique reason code in register 15.

DDITV02 is the DD name for a data set that has DCB options of LRECL=80 and
RECFM=F or FB.

A subsystem member is a member in the IMS procedure library. Its name is

derived by concatenating the value of the SSM parameter to the value of the

Chapter 17. Preparing an application to run on DB2 for z/OS 949

IMSID parameter. You specify the SSM parameter and the IMSID parameter when
you invoke the DLIBATCH procedure, which starts the DL/I batch processing
environment.

The meanings of the input parameters are:

Field Content
SSN Specifies the name of the DB2 subsystem. This value is required. You must
specify a name in order to make a connection to DB2.
The SSN value can be from one to four characters long.
If the value in the SSN parameter is the name of an active subsystem in
the data sharing group, the application attaches to that subsystem. If the
SSN parameter value is not the name of an active subsystem, but the value
is a group attachment name, the application attaches to an active DB2
subsystem in the data sharing group.
LIT Specifies a language interface token. DB2 requires a language interface
token to route SQL statements when operating in the online IMS
environment. Because a batch application program can connect to only one
DB2 system, DB2 does not use the LIT value.
The LIT value can be from zero to four characters long.
Recommendation: Specify the LIT value as SYS1.
You can omit the LIT value by entering SSN,,ESMT.
ESMT Specifies the name of the DB2 initialization module, DSNMIN10. This
value is required.
The ESMT value must be eight characters long.
RTT Specifies the resource translation table. This value is optional.
The RTT can be from zero to eight characters long.
REO Specifies the region error option. This option determines what to do if DB2
is not operational or the plan is not available. The three options are:
v R, the default, results in returning an SQL return code to the application
program. The most common SQLCODE issued in this case is -923
(SQLSTATE ’57015’).
v Q results in an abend in the batch environment; however, in the online
environment, this value places the input message in the queue again.
v A results in an abend in both the batch environment and the online
environment.
If the application program uses the XRST call, and if coordinated recovery
is required on the XRST call, REO is ignored. In that case, the application
program terminates abnormally if DB2 is not operational.
The REO value can be from zero to one character long.
CRC Specifies the command recognition character. Because DB2 commands are
not supported in the DL/I batch environment, the command recognition
character is not used at this time.
The CRC value can be from zero to one character long.

950 Application Programming and SQL Guide

CONNECTION_NAME
Represents the name of the job step that coordinates DB2 activities. This
value is optional. If you do not specify this option, the connection name
defaults are:
Type of application
Default connection name
Batch job
Job name
Started task
Started task name
TSO user
TSO authorization ID
If a batch update job fails, you must use a separate job to restart the batch
job. The connection name used in the restart job must be the same as the
name that is used in the batch job that failed. Alternatively, if the default
connection name is used, the restart job must have the same job name as
the batch update job that failed.
DB2 requires unique connection names. If two applications try to connect
with the same connection name, the second application program fails to
connect to DB2.
The CONNECTION_NAME value can be from one to eight characters
long.
PLAN Specifies the DB2 plan name. This value is optional. If you do not specify
the plan name, the application program module name is checked against
the optional resource translation table. If the resource translation table has
a match, the translated name is used as the DB2 plan name. If no match
exists in the resource translation table, the application program module
name is used as the plan name.
The PLAN value can be from zero to eight characters long.
PROG Specifies the application program name. This value is required. It identifies
the application program that is to be loaded and to receive control.
The PROG value can be from one to eight characters long.

Example: An example of the fields in the record is shown below:

DSN,SYS1,DSNMIN10,,R,-,BATCH001,DB2PLAN,PROGA

DB2 DL/I batch output:

In an online IMS environment, DB2 sends unsolicited status messages to the

master terminal operator (MTO) and records on indoubt processing and diagnostic
information to the IMS log. In a batch environment, DB2 sends this information to
the output data set that is specified in the DDOTV02 DD statement. Ensure that
the output data set has DCB options of RECFM=V or VB, LRECL=4092, and
BLKSIZE of at least LRECL + 4. If the DD statement is missing, DB2 issues the
message IEC130I and continues processing without any output.

You might want to save and print the data set, as the information is useful for
diagnostic purposes. You can use the IMS module, DFSERA10, to print the
variable-length data set records in both hexadecimal and character format.

Chapter 17. Preparing an application to run on DB2 for z/OS 951

Related concepts
Submitting work to be processed (DB2 Data Sharing Planning and
Administration)

DB2-supplied JCL procedures for preparing an application

You can precompile and prepare an application program using a DB2-supplied JCL
procedure.

DB2 has a unique JCL procedure for each supported language, with appropriate
defaults for starting the DB2 precompiler and host language compiler or assembler.
The procedures are in prefix.SDSNSAMP member DSNTIJMV, which installs the
procedures.
Table 159. Procedures for precompiling programs
Language Procedure Invocation included in...
High-level assembler DSNHASM DSNTEJ2A
C DSNHC DSNTEJ2D
2
C++ DSNHCPPDSNHCPP2 DSNTEJ2EN/A
| Enterprise COBOL DSNHICOB DSNTEJ2C1
Fortran DSNHFOR DSNTEJ2F
PL/I DSNHPLI DSNTEJ2P
SQL DSNHSQL DSNTEJ63
Notes:
1. You must customize these programs to invoke the procedures that are listed in this table.
2. This procedure demonstrates how you can prepare an object-oriented program that
consists of two data sets or members, both of which contain SQL.

If you use the PL/I macro processor, you must not use the PL/I *PROCESS
statement in the source to pass options to the PL/I compiler. You can specify the
needed options on the PARM.PLI= parameter of the EXEC statement in the
DSNHPLI procedure.

JCL to include the appropriate interface code when using the

DB2-supplied JCL procedures
To include the proper interface code when you submit the JCL procedures, use an
INCLUDE SYSLIB statement in your link-edit JCL that specifies the correct
language interface module for the environment.

TSO, batch, and CAF

//LKED.SYSIN DD *
INCLUDE SYSLIB(member)
/*

member must be DSNELI, except for FORTRAN, in which case member must be
DSNHFT.

952 Application Programming and SQL Guide

IMS
//LKED.SYSIN DD *
INCLUDE SYSLIB(DFSLI000)
ENTRY (specification)
/*

DFSLI000 is the module for DL/I batch attach.

ENTRY specification varies depending on the host language. Include one of the
following:
DLITCBL, for COBOL applications
PLICALLA, for PL/I applications
The program name, for assembler language applications.

| Recommendation: For COBOL applications, specify the PSB linkage directly on

| the PROCEDURE DIVISION statement instead of on a DLITCBL entry point. When
| you specify the PSB linkage directly on the PROCEDURE DIVISION statement,
| you can either omit the ENTRY specification or specify the application program
| name instead of the DLITCBL entry point.

CICS
//LKED.SYSIN DD *
INCLUDE SYSLIB(DSNCLI)
/*
Related tasks
“Making the CAF language interface (DSNALI) available” on page 52
“Compiling and link-editing an application” on page 915

Tailoring DB2-supplied JCL procedures for preparing CICS

programs
Instead of using the DB2 Program Preparation panels to prepare your CICS
program, you can tailor CICS-supplied JCL procedures to do that. To tailor a CICS
procedure, you need to add some steps and change some DD statements.

Make changes as needed to perform the following actions:

v Process the program with the DB2 precompiler.
v Bind the application plan. You can do this any time after you precompile the
program. You can bind the program either online by the DB2I panels or as a
batch step in this or another z/OS job.
v Include a DD statement in the linkage editor step to access the DB2 load library.
v Be sure the linkage editor control statements contain an INCLUDE statement for
the DB2 language interface module.

The following example illustrates the necessary changes. This example assumes the
use of a COBOL program. For any other programming language, change the CICS
procedure name and the DB2 precompiler options.
//TESTC01 JOB
//*
//*********************************************************
//* DB2 PRECOMPILE THE COBOL PROGRAM
//*********************************************************
(1) //PC EXEC PGM=DSNHPC,
(1) // PARM='HOST(COB2),XREF,SOURCE,FLAG(I),APOST'
(1) //STEPLIB DD DISP=SHR,DSN=prefix.SDSNEXIT
(1) // DD DISP=SHR,DSN=prefix.SDSNLOAD

Chapter 17. Preparing an application to run on DB2 for z/OS 953

(1) //DBRMLIB DD DISP=OLD,DSN=USER.DBRMLIB.DATA(TESTC01)
(1) //SYSCIN DD DSN=&&DSNHOUT,DISP=(MOD,PASS),UNIT=SYSDA,
(1) // SPACE=(800,(500,500))
(1) //SYSLIB DD DISP=SHR,DSN=USER.SRCLIB.DATA
(1) //SYSPRINT DD SYSOUT=*
(1) //SYSTERM DD SYSOUT=*
(1) //SYSUDUMP DD SYSOUT=*
(1) //SYSUT1 DD SPACE=(800,(500,500),,,ROUND),UNIT=SYSDA
(1) //SYSUT2 DD SPACE=(800,(500,500),,,ROUND),UNIT=SYSDA
(1) //SYSIN DD DISP=SHR,DSN=USER.SRCLIB.DATA(TESTC01)
(1) //*
//********************************************************************
//*** BIND THIS PROGRAM.
//********************************************************************
(2) //BIND EXEC PGM=IKJEFT01,
(2) // COND=((4,LT,PC))
(2) //STEPLIB DD DISP=SHR,DSN=prefix.SDSNEXIT
(2) // DD DISP=SHR,DSN=prefix.SDSNLOAD
(2) //DBRMLIB DD DISP=OLD,DSN=USER.DBRMLIB.DATA(TESTC01)
(2) //SYSPRINT DD SYSOUT=*
(2) //SYSTSPRT DD SYSOUT=*
(2) //SYSUDUMP DD SYSOUT=*
(2) //SYSTSIN DD *
(2) DSN S(DSN)
(2) BIND PLAN(TESTC01) MEMBER(TESTC01) ACTION(REP) RETAIN ISOLATION(CS)
(2) END
//********************************************************************
//* COMPILE THE COBOL PROGRAM
//********************************************************************
(3) //CICS EXEC DFHEITVL
(4) //TRN.SYSIN DD DSN=&&DSNHOUT,DISP=(OLD,DELETE)
(5) //LKED.SYSLMOD DD DSN=USER.RUNLIB.LOAD
(6) //LKED.CICSLOAD DD DISP=SHR,DSN=prefix.SDFHLOAD
//LKED.SYSIN DD *
(7) INCLUDE CICSLOAD(DSNCLI)
NAME TESTC01(R)
//********************************************************************

The procedure accounts for these steps:

Step 1. Precompile the program. The output of the DB2 precompiler becomes
the input to the CICS command language translator.
Step 2. Bind the application plan.
Step 3. Call the CICS procedure to translate, compile, and link-edit a COBOL
program. This procedure has several options that you need to consider.
Step 4. Reflect an application load library in the data set name of the
SYSLMOD DD statement. You must include the name of this load library in the
DFHRPL DD statement of the CICS run-time JCL.
Step 5. Name the CICS load library that contains the module DSNCLI.
Step 6. Direct the linkage editor to include the CICS-DB2 language interface
module (DSNCLI). In this example, the order of the various control sections
(CSECTs) is of no concern because the structure of the procedure automatically
satisfies any order requirements.

For more information about the procedure DFHEITVL, other CICS procedures, or
CICS requirements for application programs, please see the appropriate CICS
manual.

If you are preparing a particularly large or complex application, you can use
another preparation method. For example, if your program requires four of your
own link-edit include libraries, you cannot prepare the program with DB2I,
because DB2I limits the number of include libraries to three, plus language, IMS or

954 Application Programming and SQL Guide

CICS, and DB2 libraries. Therefore, you would need another preparation method.
Be careful to use the correct language interface.

DB2I primary option menu

The DB2I Primary Option menu is the starting point for all DB2I tasks.

Figure 45 shows an example of the DB2I Primary Option Menu. From this point,
you can access all of the DB2I panels without passing through panels that you do
not need. For example, to bind a program, enter the number that corresponds to
BIND/REBIND/FREE to reach the BIND PLAN panel without seeing the ones
previous to it.

DSNEPRI DB2I PRIMARY OPTION MENU SSID: DSN

COMMAND ===> 3_

Select one of the following DB2 functions and press ENTER.

1 SPUFI (Process SQL statements)

2 DCLGEN (Generate SQL and source language declarations)
3 PROGRAM PREPARATION (Prepare a DB2 application program to run)
4 PRECOMPILE (Invoke DB2 precompiler)
5 BIND/REBIND/FREE (BIND, REBIND, or FREE plans or packages)
6 RUN (RUN an SQL program)
7 DB2 COMMANDS (Issue DB2 commands)
8 UTILITIES (Invoke DB2 utilities)
D DB2I DEFAULTS (Set global parameters)
X EXIT (Leave DB2I)

Figure 45. Initiating program preparation through DB2I. Specify Program Preparation on the
DB2I Primary Option Menu.

The following descriptions explain the functions on the DB2I Primary Option
Menu.
1 SPUFI
Lets you develop and execute one or more SQL statements interactively.
For further information, see “Executing SQL by using SPUFI” on page
1013.
2 DCLGEN
Lets you generate C, COBOL, or PL/I data declarations of tables. For
further information, see “DCLGEN (declarations generator)” on page 129.
3 PROGRAM PREPARATION
Lets you prepare and run an application program to run. For more
information, see “DB2 Program Preparation panel” on page 957.
4 PRECOMPILE
Lets you convert embedded SQL statements into statements that your host
language can process. For further information, see “Precompile panel” on
page 964.
5 BIND/REBIND/FREE
Lets you bind, rebind, or free a package or application plan. For more
information, see “Bind/Rebind/Free Selection panel” on page 985.
6 RUN
Lets you run an application program in a TSO or batch environment. For
more information, see “DB2I Run panel” on page 996.

Chapter 17. Preparing an application to run on DB2 for z/OS 955

7 DB2 COMMANDS
Lets you issue DB2 commands.
8 UTILITIES
Lets you call DB2 utility programs.
D DB2I DEFAULTS
Lets you set DB2I defaults. See “DB2I Defaults Panel 1” on page 961.
X EXIT
Lets you exit DB2I.

DB2I panels that are used for program preparation

DB2I contains a set of panels that let you prepare an application for execution.

The following table describes each of the panels that you need to use to prepare an
application.
Table 160. DB2I panels used for program preparation
Panel name Panel description
DB2 Program Lets you choose specific program preparation functions to
Preparation“DB2 Program perform. For the functions that you choose, you can also
Preparation panel” on page display the associated panels to specify options for performing
957 those functions.

This panel also lets you change the DB2I default values and
perform other precompile and prelink functions.
DB2I Defaults Panel 1“DB2I Lets you change many of the system defaults that are set at
Defaults Panel 1” on page DB2 installation time.
961
DB2I Defaults Panel 2“DB2I Lets you change your default job statement and set additional
Defaults Panel 2” on page COBOL options.
963
Precompile“Precompile Lets you specify values for precompile functions.
panel” on page 964
You can reach this panel directly from the DB2I Primary
Option Menu or from the DB2 Program Preparation panel. If
you reach this panel from the Program Preparation panel,
many of the fields contain values from the Primary and
Precompile panels.
Bind Package“Bind Package Lets you change many options when you bind a package.
panel” on page 967
You can reach this panel directly from the DB2I Primary
Option Menu or from the DB2 Program Preparation panel. If
you reach this panel from the DB2 Program Preparation panel,
many of the fields contain values from the Primary and
Precompile panels.
Bind Plan“Bind Plan panel” Lets you change options when you bind an application plan.
on page 969
You can reach this panel directly from the DB2I Primary
Option Menu or as a part of the program preparation process.
This panel also follows the Bind Package panels.
Defaults for Bind or Rebind Let you change the defaults for BIND or REBIND PACKAGE
Package or Plan or PLAN.
panels“Defaults for Bind
Package panel” on page 973

956 Application Programming and SQL Guide

Table 160. DB2I panels used for program preparation (continued)
Panel name Panel description
System Connection Types Lets you specify a system connection type.
panel“System Connection
Types panel” on page 980 This panel displays if you choose to enable or disable
connections on the Bind or Rebind Package or Plan panels.
Panels for entering lists of Let you enter or modify an unlimited number of values. A list
values“Panels for entering panel looks similar to an ISPF edit session and lets you scroll
lists of values” on page 981 and use a limited set of commands.
Program Prep: Compile, Lets you perform the last two steps in the program
Prelink, Link, and preparation process (compile and link-edit).
Run“Program Preparation:
Compile, Link, and Run This panel also lets you do the PL/I MACRO PHASE for
panel” on page 982 programs that require this option.

For TSO programs, the panel also lets you run programs.

DB2 Program Preparation panel

The Program Preparation panel lets you choose whether to perform specific
program preparation functions.

For the functions you choose, you can also choose to display the associated panels
to specify options for performing those functions. Some of the functions you can
select are:
v Precompile. The panel for this function lets you control the DB2 precompiler. See
page “Precompile panel” on page 964.
v Bind a package. The panel for this function lets you bind your program’s DBRM
to a package (see page “Bind Package panel” on page 967), and change your
defaults for binding the packages (see page “Defaults for Bind Package panel”
on page 973).
v Bind a plan. The panel for this function lets you create your program’s
application plan (see page “Bind Plan panel” on page 969), and change your
defaults for binding the plans (see page “Defaults for Bind Package panel” on
page 973).
v Compile, link, and run. The panel for these functions let you control the
compiler or assembler and the linkage editor. See page “Program Preparation:
Compile, Link, and Run panel” on page 982.
TSO and batchFor TSO programs, you can use the program preparation
programs to control the host language run-time processor and the program itself.

The Program Preparation panel also lets you change the DB2I default values, and
perform other precompile and prelink functions.

On the DB2 Program Preparation panel, shown in the following figure, enter the
name of the source program data set (this example uses SAMPLEPG.COBOL) and
specify the other options you want to include. When finished, press ENTER to
view the next panel.

Chapter 17. Preparing an application to run on DB2 for z/OS 957

DSNEPP01 DB2 PROGRAM PREPARATION SSID: DSN
COMMAND ===>_

Enter the following:

1 INPUT DATA SET NAME .... ===> SAMPLEPG.COBOL
2 DATA SET NAME QUALIFIER ===> TEMP (For building data set names)
3 PREPARATION ENVIRONMENT ===> FOREGROUND (FOREGROUND, BACKGROUND, EDITJCL)
4 RUN TIME ENVIRONMENT ... ===> TSO (TSO, CAF, CICS, IMS, RRSAF)
5 OTHER DSNH OPTIONS ..... ===>
(Optional DSNH keywords)
Select functions: Display panel? Perform function?
6 CHANGE DEFAULTS ........ ===> Y (Y/N)
7 PL/I MACRO PHASE ....... ===> N (Y/N) ===> N (Y/N)
8 PRECOMPILE ............. ===> Y (Y/N) ===> Y (Y/N)
9 CICS COMMAND TRANSLATION ===> N (Y/N)
10 BIND PACKAGE ........... ===> Y (Y/N) ===> Y (Y/N)
11 BIND PLAN............... ===> Y (Y/N) ===> Y (Y/N)
12 COMPILE OR ASSEMBLE .... ===> Y (Y/N) ===> Y (Y/N)
13 PRELINK................. ===> N (Y/N) ===> N (Y/N)
14 LINK.................... ===> N (Y/N) ===> Y (Y/N)
15 RUN..................... ===> N (Y/N) ===> Y (Y/N)

Figure 46. The DB2 Program Preparation panel. Enter the source program data set name
and other options.

The following explains the functions on the DB2 Program Preparation panel and
how to fill in the necessary fields in order to start program preparation.
1 INPUT DATA SET NAME
Lets you specify the input data set name. The input data set name can be a
PDS or a sequential data set, and can also include a member name. If you
do not enclose the data set name in apostrophes, a standard TSO prefix
(user ID) qualifies the data set name.
The input data set name you specify is used to precompile, bind, link-edit,
and run the program.
2 DATA SET NAME QUALIFIER
Lets you qualify temporary data set names involved in the program
preparation process. Use any character string from 1 to 8 characters that
conforms to normal TSO naming conventions. (The default is TEMP.)
For programs that you prepare in the background or that use EDITJCL for
the PREPARATION ENVIRONMENT option, DB2 creates a data set named
tsoprefix.qualifier.CNTL to contain the program preparation JCL. The name
tsoprefix represents the prefix TSO assigns, and qualifier represents the value
you enter in the DATA SET NAME QUALIFIER field. If a data set with
this name already exists, DB2 deletes it.
3 PREPARATION ENVIRONMENT
Lets you specify whether program preparation occurs in the foreground or
background. You can also specify EDITJCL, in which case you are able to
edit and then submit the job. Use:
FOREGROUND to use the values you specify on the Program
Preparation panel and to run immediately.
BACKGROUND to create and submit a file containing a DSNH CLIST
that runs immediately using the JOB control statement from either the
DB2I Defaults panel or your site’s SUBMIT exit. The file is saved.
EDITJCL to create and open a file containing a DSNH CLIST in edit
mode. You can then submit the CLIST or save it.
4 RUN TIME ENVIRONMENT
Lets you specify the environment (TSO, CAF, CICS, IMS, RRSAF) in which
your program runs.

958 Application Programming and SQL Guide

All programs are prepared under TSO, but can run in any of the
environments. If you specify CICS, IMS, or RRSAF, then you must set the
RUN field to NO because you cannot run such programs from the
Program Preparation panel. If you set the RUN field to YES, you can
specify only TSO or CAF.
(Batch programs also run under the TSO Terminal Monitor Program. You
therefore need to specify TSO in this field for batch programs.)
5 OTHER DSNH OPTIONS
Lets you specify a list of DSNH options that affect the program
preparation process, and that override options specified on other panels. If
you are using CICS, these can include options you want to specify to the
CICS command translator.
If you specify options in this field, separate them by commas. You can
continue listing options on the next line, but the total length of the option
list can be no more than 70 bytes.

Fields 6 through 15 let you select the function to perform and to choose whether to
show the DB2I panels for the functions you select. Use Y for YES, or N for NO.

If you are willing to accept default values for all the steps, enter N under Display
panel? for all the other preparation panels listed.

To make changes to the default values, entering Y under Display panel? for any
panel you want to see. DB2I then displays each of the panels that you request.
After all the panels display, DB2 proceeds with the steps involved in preparing
your program to run.

Variables for all functions used during program preparation are maintained
separately from variables entered from the DB2I Primary Option Menu. For
example, the bind plan variables you enter on the Program Preparation panel are
saved separately from those on any Bind Plan panel that you reach from the
Primary Option Menu.
6 CHANGE DEFAULTS
Lets you specify whether to change the DB2I defaults. Enter Y in the
Display panel? field next to this option; otherwise enter N. Minimally, you
should specify your subsystem identifier and programming language on
the Defaults panel.
7 PL/I MACRO PHASE
Lets you specify whether to display the “Program Preparation: Compile,
Link, and Run” panel to control the PL/I macro phase by entering PL/I
options in the OPTIONS field of that panel. That panel also displays for
options COMPILE OR ASSEMBLE, LINK, and RUN.
This field applies to PL/I programs only. If your program is not a PL/I
program or does not use the PL/I macro processor, specify N in the
Perform function field for this option, which sets the Display panel? field
to the default N.
8 PRECOMPILE
Lets you specify whether to display the Precompile panel. To see this panel
enter Y in the Display panel? field next to this option; otherwise enter N.
9 CICS COMMAND TRANSLATION
Lets you specify whether to use the CICS command translator. This field
applies to CICS programs only.

Chapter 17. Preparing an application to run on DB2 for z/OS 959

IMS and TSOIf you run under TSO or IMS, ignore this step; this allows
the Perform function field to default to N.
CICSIf you are using CICS and have precompiled your program, you must
translate your program using the CICS command translator.
The command translator does not have a separate DB2I panel. You can
specify translation options on the Other Options field of the DB2 Program
Preparation panel, or in your source program if it is not an assembler
program.
Because you specified a CICS run-time environment, the Perform function
column defaults to Y. Command translation takes place automatically after
you precompile the program.
10 BIND PACKAGE
Lets you specify whether to display the Bind Package panel. To see it,
enter Y in the Display panel? field next to this option; otherwise, enter N.
11 BIND PLAN
Lets you specify whether to display the Bind Plan panel. To see it, enter Y
in the Display panel? field next to this option; otherwise, enter N.
12 COMPILE OR ASSEMBLE
Lets you specify whether to display the “Program Preparation: Compile,
Link, and Run” panel. To see this panel enter Y in the Display panel? field
next to this option; otherwise, enter N.
13 PRELINK
Lets you use the prelink utility to make your C, C++, or Enterprise COBOL
for z/OS program reentrant. This utility concatenates compile-time
initialization information from one or more text decks into a single
initialization unit. To use the utility, enter Y in the Display panel? field next
to this option; otherwise, enter N. If you request this step, then you must
also request the compile step and the link-edit step.
For more information about the prelink utility, see z/OS Language
Environment Programming Guide.
14 LINK
Lets you specify whether to display the “Program Preparation: Compile,
Link, and Run” panel. To see it, enter Y in the Display panel? field next to
this option; otherwise, enter N. If you specify Y in the Display panel? field
for the COMPILE OR ASSEMBLE option, you do not need to make any
changes to this field; the panel displayed for COMPILE OR ASSEMBLE is
the same as the panel displayed for LINK. You can make the changes you
want to affect the link-edit step at the same time you make the changes to
the compile step.
15 RUN
Lets you specify whether to run your program. The RUN option is
available only if you specify TSO or CAF for RUN TIME ENVIRONMENT.
If you specify Y in the Display panel? field for the COMPILE OR
ASSEMBLE or LINK option, you can specify N in this field, because the
panel displayed for COMPILE OR ASSEMBLE and for LINK is the same as
the panel displayed for RUN.
IMS and CICSIMS and CICS programs cannot run using DB2I. If you are
using IMS or CICS, use N in these fields.

960 Application Programming and SQL Guide

TSO and batchIf you are using TSO and want to run your program, you
must enter Y in the Perform function column next to this option. You can
also indicate that you want to specify options and values to affect the
running of your program, by entering Y in the Display panel column.

Pressing ENTER takes you to the first panel in the series you specified, in this
example to the DB2I Defaults panel. If, at any point in your progress from panel to
panel, you press the END key, you return to this first panel, from which you can
change your processing specifications. Asterisks (*) in the Display panel? column of
rows 7 through 14 indicate which panels you have already examined. You can see
a panel again by writing a Y over an asterisk.
Related reference
“Bind Package panel” on page 967
“Bind Plan panel” on page 969
“DB2I Defaults Panel 1”
“Precompile panel” on page 964
“Program Preparation: Compile, Link, and Run panel” on page 982
DSNH (TSO CLIST) (DB2 Command Reference)

DB2I Defaults Panel 1

DB2I Defaults Panel 1 lets you change many of the system defaults that were set at
DB2 install time.

The following figure shows the fields that affect the processing of the other DB2I
panels.

| DSNEOP01 DB2I DEFAULTS PANEL 1

| COMMAND ===>_
|
| Change defaults as desired:
|
| 1 DB2 NAME ............. ===> DSN (Subsystem identifier)
| 2 DB2 CONNECTION RETRIES ===> 0 (How many retries for DB2 connection)
| 3 APPLICATION LANGUAGE ===> IBMCOB (ASM, C, CPP, IBMCOB, FORTRAN, PLI)
| 4 LINES/PAGE OF LISTING ===> 60 (A number from 5 to 999)
| 5 MESSAGE LEVEL ........ ===> I (Information, Warning, Error, Severe)
| 6 SQL STRING DELIMITER ===> DEFAULT (DEFAULT, ' or ")
| 7 DECIMAL POINT ........ ===> . (. or ,)
| 8 STOP IF RETURN CODE >= ===> 8 (Lowest terminating return code)
| 9 NUMBER OF ROWS ===> 20 (For ISPF Tables)
| 10 AS USER ===> (User ID to associate with trusted connection)
|
|
|
Figure 47. DB2I Defaults Panel 1

The following explains the fields on DB2I Defaults Panel 1.

1 DB2 NAME
Lets you specify the DB2 subsystem that processes your DB2I requests. If
you specify a different DB2 subsystem, its identifier displays in the SSID
(subsystem identifier) field located at the top, right side of your screen. The
default is DSN.
2 DB2 CONNECTION RETRIES
Lets you specify the number of additional times to attempt to connect to

Chapter 17. Preparing an application to run on DB2 for z/OS 961

DB2, if DB2 is not up when the program issues the DSN command. The
program preparation process does not use this option.
Use a number from 0 to 120. The default is 0. Connections are attempted at
30-second intervals.
3 APPLICATION LANGUAGE
Lets you specify the default programming language for your application
program. You can specify any of the following:
ASM
For High Level Assembler/z/OS
C For C language
CPP
For C++
IBMCOB
For Enterprise COBOL for z/OS. This option is the default.
FORTRAN
For VS Fortran
PLI
For PL/I

If you specify IBMCOB, DB2 prompts you for more COBOL defaults on
panel DSNEOP02. See “DB2I Defaults Panel 2” on page 963.
You cannot specify FORTRAN for IMS or CICS programs.
4 LINES/PAGE OF LISTING
Lets you specify the number of lines to print on each page of listing or
SPUFI output. The default is 60.
5 MESSAGE LEVEL
Lets you specify the lowest level of message to return to you during the
BIND phase of the preparation process. Use:
I For all information, warning, error, and severe error messages
W For warning, error, and severe error messages
E For error and severe error messages
S For severe error messages only
6 SQL STRING DELIMITER
Lets you specify the symbol used to delimit a string in SQL statements in
COBOL programs. This option is valid only when the application language
is IBMCOB. Use:
DEFAULT
To use the default defined at installation time
’ For an apostrophe
″ For a quotation mark
7 DECIMAL POINT
Lets you specify how your host language source program represents
decimal separators and how SPUFI displays decimal separators in its
output. Use a comma (,) or a period (.). The default is a period (.).
8 STOP IF RETURN CODE >=
Lets you specify the smallest value of the return code (from precompile,
compile, link-edit, or bind) that will prevent later steps from running. Use:
4 To stop on warnings and more severe errors.
8 To stop on errors and more severe errors. The default is 8.
9 NUMBER OF ROWS
Lets you specify the default number of input entry rows to generate on the

962 Application Programming and SQL Guide

initial display of ISPF panels. The number of rows with non-blank entries
determines the number of rows that appear on later displays.
| 10 AS USER
| Lets you specify a user ID to associate with the trusted connection for the
| current DB2I session.
| DB2 establishes the trusted connection for the user that you specify if the
| following conditions are true:
| v The primary authorization ID that DB2 obtains after running the
| connection exit is allowed to use the trusted connection without
| authentication.
| v The security label, if defined either implicitly or explicitly in the trusted
| context for the user, is defined in RACF for the user.
| After DB2 establishes the trusted connection, the primary authorization ID,
| any secondary authorization IDs, any role, and any security label that is
| associated with the user ID that is specified in the AS USER field are used
| for the trusted connection. DB2 uses this security label to verify multilevel
| security for the user.
| If the primary authorization ID that is associated with the user ID that is
| specified in the AS USER field is not allowed to use the trusted connection
| or requires authentication information, the connection request fails. If DB2
| cannot verify the security label, the connection request also fails.
| The value that you enter in this field is retained only for the length of the
| DB2I session. The field is reset to blank when you exit DB2I.

Suppose that the default programming language is PL/I and the default number of
lines per page of program listing is 60. Your program is in COBOL, so you want to
change field 3, APPLICATION LANGUAGE. You also want to print 80 lines to the
page, so you need to change field 4, LINES/PAGE OF LISTING, as well. Figure 47
on page 961 shows the entries that you make in DB2I Defaults Panel 1 to make
these changes. In this case, pressing ENTER takes you to DB2 Defaults Panel 2.

DB2I Defaults Panel 2

After you press Enter on the DB2I Defaults Panel 1, the DB2I Defaults Panel 2 is
displayed. If you chose IBMCOB as the language on the DB2I Defaults Panel 1,
three fields are displayed. Otherwise, only the first field is displayed.

The following figure shows the DB2I Defaults Panel 2 when IBMCOB is selected.

DSNEOP02 DB2I DEFAULTS PANEL 2

COMMAND ===>_

Change defaults as desired:

1 DB2I JOB STATEMENT: (Optional if your site has a SUBMIT exit)

===> //USRT001A JOB (ACCOUNT),'NAME'
===> //*
===> //*
===> //*

COBOL DEFAULTS: (For IBMCOB)

2 COBOL STRING DELIMITER ===> DEFAULT (DEFAULT, ' or ")
3 DBCS SYMBOL FOR DCLGEN ===> G (G/N - Character in PIC clause)

Figure 48. DB2I Defaults Panel 2

Chapter 17. Preparing an application to run on DB2 for z/OS 963

1 DB2I JOB STATEMENT
Lets you change your default job statement. Specify a job control
statement, and optionally, a JOBLIB statement to use either in the
background or the EDITJCL program preparation environment. Use a
JOBLIB statement to specify run-time libraries that your application
requires. If your program has a SUBMIT exit routine, DB2 uses that
routine. If that routine builds a job control statement, you can leave this
field blank.
2 COBOL STRING DELIMITER
Lets you specify the symbol used to delimit a string in a COBOL statement
in a COBOL application. Use:
DEFAULT
To use the default defined at install time
’ For an apostrophe
″ For a quotation mark

Leave this field blank to accept the default value.

3 DBCS SYMBOL FOR DCLGEN
Lets you enter either G (the default) or N, to specify whether DCLGEN
generates a picture clause that has the form PIC G(n) DISPLAY-1 or PIC
N(n).
Leave this field blank to accept the default value.

Pressing ENTER takes you to the next panel you specified on the DB2 Program
Preparation panel, in this case, to the Precompile panel.

Precompile panel
After you set the DB2I defaults, you can precompile your application. You can
reach the Precompile panel in two ways: you can either specify it as a part of the
program preparation process from the DB2 Program Preparation panel, or you can
reach it directly from the DB2I Primary Option Menu.

The way you choose to reach the panel determines the default values of the fields
it contains. Figure 49 shows the Precompile panel.

DSNETP01 PRECOMPILE SSID: DSN

COMMAND ===>_

Enter precompiler data sets:

1 INPUT DATA SET .... ===> SAMPLEPG.COBOL
2 INCLUDE LIBRARY ... ===> SRCLIB.DATA

3 DSNAME QUALIFIER .. ===> TEMP (For building data set names)

4 DBRM DATA SET ..... ===>

Enter processing options as desired:

5 WHERE TO PRECOMPILE ===> FOREGROUND (FOREGROUND, BACKGROUND, or EDITJCL)
6 VERSION ........... ===>
(Blank, VERSION, or AUTO)
7 OTHER OPTIONS ..... ===>

Figure 49. The Precompile panel. Specify the include library, if any, that your program should
use, and any other options you need.

The following explains the functions on the Precompile panel, and how to enter
the fields for preparing to precompile.

964 Application Programming and SQL Guide

1 INPUT DATA SET
Lets you specify the data set name of the source program and SQL
statements to precompile.
If you reached this panel through the DB2 Program Preparation panel, this
field contains the data set name specified there. You can override it on this
panel if you wish.
If you reached this panel directly from the DB2I Primary Option Menu,
you must enter the data set name of the program you want to precompile.
The data set name can include a member name. If you do not enclose the
data set name with apostrophes, a standard TSO prefix (user ID) qualifies
the data set name.
2 INCLUDE LIBRARY
Lets you enter the name of a library containing members that the
precompiler should include. These members can contain output from
DCLGEN. If you do not enclose the name in apostrophes, a standard TSO
prefix (user ID) qualifies the name.
You can request additional INCLUDE libraries by entering DSNH CLIST
parameters of the form PnLIB(dsname), where n is 2, 3, or 4) on the OTHER
OPTIONS field of this panel or on the OTHER DSNH OPTIONS field of
the Program Preparation panel.
3 DSNAME QUALIFIER
Lets you specify a character string that qualifies temporary data set names
during precompile. Use any character string from 1 to 8 characters in
length that conforms to normal TSO naming conventions.
If you reached this panel through the DB2 Program Preparation panel, this
field contains the data set name qualifier specified there. You can override
it on this panel if you wish.
If you reached this panel from the DB2I Primary Option Menu, you can
either specify a DSNAME QUALIFIER or let the field take its default
value, TEMP.
IMS and TSOFor IMS and TSO programs, DB2 stores the precompiled
source statements (to pass to the compile or assemble step) in a data set
named tsoprefix.qualifier.suffix. A data set named tsoprefix.qualifier.PCLIST
contains the precompiler print listing.
For programs prepared in the background or that use the PREPARATION
ENVIRONMENT option EDITJCL (on the DB2 Program Preparation panel),
a data set named tsoprefix.qualifier.CNTL contains the program preparation
JCL.
In these examples, tsoprefix represents the prefix TSO assigns, often the
same as the authorization ID. qualifier represents the value entered in the
DSNAME QUALIFIER field. suffix represents the output name, which is
one of the following: COBOL, FORTRAN, C, PLI, ASM, DECK, CICSIN,
OBJ, or DATA. In the example in Figure 49 on page 964, the data set
tsoprefix.TEMP.COBOL contains the precompiled source statements, and
tsoprefix.TEMP.PCLIST contains the precompiler print listing. If data sets
with these names already exist, then DB2 deletes them.
CICSFor CICS programs, the data set tsoprefix.qualifier.suffix receives the
precompiled source statements in preparation for CICS command
translation.

Chapter 17. Preparing an application to run on DB2 for z/OS 965

If you do not plan to do CICS command translation, the source statements
in tsoprefix.qualifier.suffix, are ready to compile. The data set
tsoprefix.qualifier.PCLIST contains the precompiler print listing.
When the precompiler completes its work, control passes to the CICS
command translator. Because there is no panel for the translator, translation
takes place automatically. The data set tsoprefix.qualifier.CXLIST contains the
output from the command translator.
4 DBRM DATA SET
Lets you name the DBRM library data set for the precompiler output. The
data set can also include a member name.
When you reach this panel, the field is blank. When you press ENTER,
however, the value contained in the DSNAME QUALIFIER field of the
panel, concatenated with DBRM, specifies the DBRM data set:
qualifier.DBRM.
You can enter another data set name in this field only if you allocate and
catalog the data set before doing so. This is true even if the data set name
that you enter corresponds to what is otherwise the default value of this
field.
The precompiler sends modified source code to the data set qualifier.host,
where host is the language specified in the APPLICATION LANGUAGE
field of DB2I Defaults panel 1.
5 WHERE TO PRECOMPILE
Lets you indicate whether to precompile in the foreground or background.
You can also specify EDITJCL, in which case you are able to edit and then
submit the job.
If you reached this panel from the DB2 Program Preparation panel, the
field contains the preparation environment specified there. You can
override that value if you wish.
If you reached this panel directly from the DB2I Primary Option Menu,
you can either specify a processing environment or allow this field to take
its default value. Use:
FOREGROUND to immediately precompile the program with the
values you specify in these panels.
BACKGROUND to create and immediately submit to run a file
containing a DSNH CLIST using the JOB control statement from either
DB2I Defaults Panel 2 or your site’s SUBMIT exit. The file is saved.
EDITJCL to create and open a file containing a DSNH CLIST in edit
mode. You can then submit the CLIST or save it.
6 VERSION
Lets you specify the version of the program and its DBRM. If the version
contains the maximum number of characters permitted (64), you must
enter each character with no intervening blanks from one line to the next.
This field is optional.
7 OTHER OPTIONS
Lets you enter any option that the DSNH CLIST accepts, which gives you
greater control over your program. The DSNH options you specify in this
field override options specified on other panels. The option list can
continue to the next line, but the total length of the list can be no more
than 70 bytes.

966 Application Programming and SQL Guide

For more information about DSNH options, see the topic “DSNH (TSO
CLIST)” in DB2 Command Reference.

Bind Package panel

The Bind Package panel is the first of two DB2I panels that request information
about how you want to bind a package.

You can reach the Bind Package panel either directly from the DB2I Primary
Option Menu, or as a part of the program preparation process. If you enter the
Bind Package panel from the Program Preparation panel, many of the Bind
Package entries contain values from the Primary and Precompile panels. Figure 50
shows the Bind Package panel.

DSNEBP07 BIND PACKAGE SSID: DSN

COMMAND ===>_

Specify output location and collection names:

1 LOCATION NAME ............. ===> (Defaults to local)
2 COLLECTION-ID ............. ===> (Required)
Specify package source (DBRM or COPY):
3 DBRM: COPY: ===> DBRM (Specify DBRM or COPY)
4 MEMBER or COLLECTION-ID ===>
5 PASSWORD or PACKAGE-ID .. ===>
6 LIBRARY or VERSION ..... ===>
(Blank, or COPY version-id)
7 ........ -- OPTIONS ..... ===> (COMPOSITE or COMMAND)
Enter options as desired:
8 CHANGE CURRENT DEFAULTS? ===> NO (NO or YES)
9 ENABLE/DISABLE CONNECTIONS? ===> NO (NO or YES)
10 OWNER OF PACKAGE (AUTHID).. ===> (Leave blank for primary ID)
11 QUALIFIER ................ ===> (Leave blank for OWNER)
12 ACTION ON PACKAGE ........ ===> REPLACE (ADD or REPLACE)
13 INCLUDE PATH? ............ ===> NO (NO or YES)
14 REPLACE VERSION .......... ===> (Replacement version-id)

Figure 50. The Bind Package panel

The following information explains the functions on the Bind Package panel and
how to fill the necessary fields in order to bind your program.
1 LOCATION NAME
Lets you specify the system at which to bind the package. You can use
from 1 to 16 characters to specify the location name. The location name
must be defined in the catalog table SYSIBM.LOCATIONS. The default is
the local DBMS.
2 COLLECTION-ID
| Lets you specify the collection the package is in. You can use from 1 to 18
| characters to specify the collection, and the first character must be
| alphabetic.
3 DBRM: COPY:
Lets you specify whether you are creating a new package (DBRM) or
making a copy of a package that already exists (COPY). Use:
DBRM
To create a new package. You must specify values in the LIBRARY,
PASSWORD, and MEMBER fields.

Chapter 17. Preparing an application to run on DB2 for z/OS 967

COPY
To copy an existing package. You must specify values in the
COLLECTION-ID and PACKAGE-ID fields. (The VERSION field is
optional.)
4 MEMBER or COLLECTION-ID
MEMBER (for new packages): If you are creating a new package, this
option lets you specify the DBRM to bind. You can specify a member name
from 1 to 8 characters. The default name depends on the input data set
name.
v If the input data set is partitioned, the default name is the member name
of the input data set specified in the INPUT DATA SET NAME field of
the DB2 Program Preparation panel.
v If the input data set is sequential, the default name is the second
qualifier of this input data set.
| COLLECTION-ID (for copying a package): If you are copying a package,
| this option specifies the collection ID that contains the original package.
| You can specify a collection ID from 1 to 18 characters, which must be
| different from the collection ID specified on the PACKAGE ID field.
5 PASSWORD or PACKAGE-ID
PASSWORD (for new packages): If you are creating a new package, this
lets you enter password for the library you list in the LIBRARY field. You
can use this field only if you reached the Bind Package panel directly from
the DB2 Primary Option Menu.
PACKAGE-ID (for copying packages): If you are copying a package, this
option lets you specify the name of the original package. You can enter a
package ID from 1 to 8 characters.
6 LIBRARY or VERSION
LIBRARY (for new packages): If you are creating a new package, this lets
you specify the names of the libraries that contain the DBRMs specified on
the MEMBER field for the bind process. Libraries are searched in the order
specified and must in the catalog tables.
VERSION (for copying packages): If you are copying a package, this
option lets you specify the version of the original package. You can specify
a version ID from 1 to 64 characters.
7 OPTIONS
Lets you specify which bind options DB2 uses when you issue BIND
PACKAGE with the COPY option. Specify:
v COMPOSITE (default) to cause DB2 to use any options you specify in
the BIND PACKAGE command. For all other options, DB2 uses the
options of the copied package.
v COMMAND to cause DB2 to use the options you specify in the BIND
PACKAGE command. For all other options, DB2 uses the following
values:
– For a local copy of a package, DB2 uses the defaults for the local DB2
subsystem.
– For a remote copy of a package, DB2 uses the defaults for the server
on which the package is bound.
8 CHANGE CURRENT DEFAULTS?
Lets you specify whether to change the current defaults for binding
packages. If you enter YES in this field, you see the Defaults for Bind

968 Application Programming and SQL Guide

Package panel as your next step. You can enter your new preferences there;
for instructions, see “Defaults for Bind Package panel” on page 973.
9 ENABLE/DISABLE CONNECTIONS?
Lets you specify whether you want to enable and disable system
connections types to use with this package. This is valid only if the
LOCATION NAME field names your local DB2 system.
Placing YES in this field displays a panel (shown in Figure 54 on page 980)
that lets you specify whether various system connections are valid for this
application. You can specify connection names to further identify enabled
connections within a connection type. A connection name is valid only
when you also specify its corresponding connection type.
The default enables all connection types.
10 OWNER OF PACKAGE (AUTHID)
Lets you specify the primary authorization ID of the owner of the new
package. That ID is the name owning the package, and the name
associated with all accounting and trace records produced by the package.
The owner must have the privileges required to run SQL statements
contained in the package.
The default is the primary authorization ID of the bind process.
11 QUALIFIER
| Lets you specify the default schema for unqualified tables, views, indexes,
| and aliases. You can specify a schema name from 1 to 8 characters. The
| default is the authorization ID of the package owner.
12 ACTION ON PACKAGE
Lets you specify whether to replace an existing package or create a new
one. Use:
REPLACE (default) to replace the package named in the PACKAGE-ID
field if it already exists, and add it if it does not. (Use this option if you
are changing the package because the SQL statements in the program
changed. If only the SQL environment changes but not the SQL
statements, you can use REBIND PACKAGE.)
ADD to add the package named in the PACKAGE-ID field, only if it
does not already exist.
13 INCLUDE PATH?
Indicates whether you will supply a list of schema names that DB2
searches when it resolves unqualified distinct type, user-defined function,
and stored procedure names in SQL statements. The default is NO. If you
specify YES, DB2 displays a panel in which you specify the names of
schemas for DB2 to search.
14 REPLACE VERSION
Lets you specify whether to replace a specific version of an existing
package or create a new one. If the package and the version named in the
PACKAGE-ID and VERSION fields already exist, you must specify
REPLACE. You can specify a version ID from 1 to 64 characters. The
default version ID is that specified in the VERSION field.

Bind Plan panel

The Bind Plan panel is the first of two DB2I panels that request information about
how you want to bind an application plan.

Chapter 17. Preparing an application to run on DB2 for z/OS 969

Like the Precompile panel, you can reach the Bind Plan panel either directly from
the DB2I Primary Option Menu, or as a part of the program preparation process.
You must have an application plan, even if you bind your application to packages;
this panel also follows the Bind Package panels.

If you enter the Bind Plan panel from the Program Preparation panel, many of the
Bind Plan entries contain values from the Primary and Precompile panels.

DSNEBP02 BIND PLAN SSID: DSN

COMMAND ===>_

Enter DBRM data set name(s):

1 MEMBER .......... ===> SAMPLEPG
2 PASSWORD ........ ===>
3 LIBRARY ......... ===> TEMP.DBRM
4 ADDITIONAL DBRMS? ........ ===> NO (YES to list more DBRMs)

Enter options as desired:

5 PLAN NAME ................ ===> SAMPLEPG (Required to create a plan)
6 CHANGE CURRENT DEFAULTS? ===> NO (NO or YES)
7 ENABLE/DISABLE CONNECTIONS?===> NO (NO or YES)
8 INCLUDE PACKAGE LIST?..... ===> NO (NO or YES)
9 OWNER OF PLAN (AUTHID) ... ===> (Leave blank for your primary ID)
10 QUALIFIER ................ ===> (For tables, views, and aliases)
11 CACHESIZE ................ ===> 0 (Blank, or value 0-4096)
12 ACTION ON PLAN ........... ===> REPLACE (REPLACE or ADD)
13 RETAIN EXECUTION AUTHORITY ===> YES (YES to retain user list)
14 CURRENT SERVER ........... ===> (Location name)
15 INCLUDE PATH? ............ ===> (NO or YES)

Figure 51. The Bind Plan panel

The following explains the functions on the Bind Plan panel and how to fill the
necessary fields in order to bind your program.
1 MEMBER
Lets you specify the DBRMs to include in the plan. You can specify a name
from 1 to 8 characters. You must specify MEMBER or INCLUDE
PACKAGE LIST, or both. If you do not specify MEMBER, fields 2, 3, and 4
are ignored.
The default member name depends on the input data set.
v If the input data set is partitioned, the default name is the member name
of the input data set specified in field 1 of the DB2 Program Preparation
panel.
v If the input data set is sequential, the default name is the second
qualifier of this input data set.
If you reached this panel directly from the DB2I Primary Option Menu,
you must provide values for the MEMBER and LIBRARY fields.
If you plan to use more than one DBRM, you can include the library name
and member name of each DBRM in the MEMBER and LIBRARY fields,
separating entries with commas. You can also specify more DBRMs by
using the ADDITIONAL DBRMS? field on this panel.
2 PASSWORD
Lets you enter passwords for the libraries you list in the LIBRARY field.
You can use this field only if you reached the Bind Plan panel directly
from the DB2 Primary Option Menu.

970 Application Programming and SQL Guide

3 LIBRARY
Lets you specify the name of the library or libraries that contain the
DBRMs to use for the bind process. You can specify a name up to 44
characters long.
4 ADDITIONAL DBRMS?
Lets you specify more DBRM entries if you need more room. Or, if you
reached this panel as part of the program preparation process, you can
include more DBRMs by entering YES in this field. A separate panel then
displays, where you can enter more DBRM library and member names; see
“Panels for entering lists of values” on page 981.
5 PLAN NAME
Lets you name the application plan to create. You can specify a name from
1 to 8 characters, and the first character must be alphabetic. If there are no
errors, the bind process prepares the plan and enters its description into
the EXPLAIN table.
If you reached this panel through the DB2 Program Preparation panel, the
default for this field depends on the value you entered in the INPUT
DATA SET NAME field of that panel.
If you reached this panel directly from the DB2 Primary Option Menu, you
must include a plan name if you want to create an application plan. The
default name for this field depends on the input data set:
v If the input data set is partitioned, the default name is the member
name.
v If the input data set is sequential, the default name is the second
qualifier of the data set name.
6 CHANGE CURRENT DEFAULTS?
Lets you specify whether to change the current defaults for binding plans.
If you enter YES in this field, you see the Defaults for Bind Plan panel as
your next step. You can enter your new preferences there.
7 ENABLE/DISABLE CONNECTIONS?
Lets you specify whether you want to enable and disable system
connections types to use with this package. This is valid only if the
LOCATION NAME field names your local DB2 system.
Placing YES in this field displays a panel (shown in Figure 54 on page 980)
that lets you specify whether various system connections are valid for this
application. You can specify connection names to further identify enabled
connections within a connection type. A connection name is valid only
when you also specify its corresponding connection type.
The default enables all connection types.
8 INCLUDE PACKAGE LIST?
Lets you include a list of packages in the plan. If you specify YES, a
separate panel displays on which you must enter the package location,
collection name, and package name for each package to include in the plan
(see “Panels for entering lists of values” on page 981). This list is optional
if you use the MEMBER field.
| You can specify a location name from 1 to 16 characters, a collection ID
| from 1 to 18 characters, and a package ID from 1 to 8 characters. If you
| specify a location name, which is optional, it must be in the catalog table
| SYSIBM.LOCATIONS; the default location is the local DBMS.

Chapter 17. Preparing an application to run on DB2 for z/OS 971

You must specify INCLUDE PACKAGE LIST? or MEMBER, or both, as
input to the bind plan.
9 OWNER OF PLAN (AUTHID)
Lets you specify the primary authorization ID of the owner of the new
plan. That ID is the name owning the plan, and the name associated with
all accounting and trace records produced by the plan.
The owner must have the privileges required to run SQL statements
contained in the plan.
10 QUALIFIER
| Lets you specify the default schema for unqualified tables, views and
| aliases. You can specify a schema name from 1 to 8 characters, which must
| conform to the rules for SQL identifiers. If you leave this field blank, the
| default qualifier is the authorization ID of the plan owner.
11 CACHESIZE
Lets you specify the size (in bytes) of the authorization cache. Valid values
are in the range 0 to 4096. Values that are not multiples of 256 round up to
the next highest multiple of 256. A value of 0 indicates that DB2 does not
use an authorization cache. The default is 1024.
Each concurrent user of a plan requires 8 bytes of storage, with an
additional 32 bytes for overhead.
12 ACTION ON PLAN
Lets you specify whether this is a new or changed application plan. Use:
REPLACE (default) to replace the plan named in the PLAN NAME
field if it already exists, and add the plan if it does not exist.
ADD to add the plan named in the PLAN NAME field, only if it does
not already exist.
13 RETAIN EXECUTION AUTHORITY
Lets you choose whether or not those users with the authority to bind or
run the existing plan are to keep that authority over the changed plan. This
applies only when you are replacing an existing plan.
If the plan ownership changes and you specify YES, the new owner grants
BIND and EXECUTE authority to the previous plan owner.
If the plan ownership changes and you do not specify YES, then everyone
but the new plan owner loses EXECUTE authority (but not BIND
authority), and the new plan owner grants BIND authority to the previous
plan owner.
14 CURRENT SERVER
Lets you specify the initial server to receive and process SQL statements in
this plan. You can specify a name from 1 to 16 characters, which you must
previously define in the catalog table SYSIBM.LOCATIONS.
If you specify a remote server, DB2 connects to that server when the first
SQL statement executes. The default is the name of the local DB2
subsystem.
15 INCLUDE PATH?
Indicates whether you will supply a list of schema names that DB2
searches when it resolves unqualified distinct type, user-defined function,
and stored procedure names in SQL statements. The default is NO. If you
specify YES, DB2 displays a panel in which you specify the names of
schemas for DB2 to search.

972 Application Programming and SQL Guide

When you finish making changes to this panel, press ENTER to go to the second
of the program preparation panels, Program Prep: Compile, Link, and Run.
Related concepts
“Authorization cache” on page 934
Related reference
“Defaults for Bind Plan panel” on page 976
BIND and REBIND options (DB2 Command Reference)

Defaults for Bind Package panel

This panel lets you change your defaults for BIND PACKAGE options.

On this panel, enter new defaults for binding the package.

With a few minor exceptions, the options on this panel are the same as the options
for the defaults for rebinding a package. However, the defaults for REBIND
PACKAGE are different from those shown in the preceding figure, and you can
specify SAME in any field to specify the values used the last time the package was
bound. For rebinding, the default value for all fields is SAME.

DSNEBP10 DEFAULTS FOR BIND PACKAGE SSID: DSN

COMMAND ===> _

Change default options as necessary:

1 ISOLATION LEVEL ......... ===> (RR, RS, CS, UR, or NC)

2 VALIDATION TIME ......... ===> (RUN or BIND)
3 RESOURCE RELEASE TIME ... ===> (COMMIT or DEALLOCATE)
4 EXPLAIN PATH SELECTION .. ===> (NO or YES)
5 DATA CURRENCY ........... ===> (NO or YES)
6 PARALLEL DEGREE ......... ===> (1 or ANY)
7 SQLERROR PROCESSING ..... ===> (NOPACKAGE or CONTINUE)
8 REOPTIMIZE FOR INPUT VARS ===> (ALWAYS, NONE, or ONCE)
9 DEFER PREPARE ........... ===> (NO OR YES)
10 KEEP DYN SQL PAST COMMIT ===> (NO or YES)
11 DBPROTOCOL .............. ===> (DRDA OR PRIVATE)
12 APPLICATION ENCODING ... ===> (Blank, ASCII, EBCDIC,
UNICODE, or ccsid)
13 OPTIMIZATION HINT ...... ===> (Blank or 'hint-id')
14 IMMEDIATE WRITE ......... ===> (YES, NO)
15 DYNAMIC RULES ........... ===> (RUN, BIND, DEFINE,
or INVOKE)

Figure 52. The Defaults for Bind Package panel

1 ISOLATION LEVEL
Lets you specify how far to isolate your application from the effects of
other running applications. The default is the value used for the old plan
or package if you are replacing an existing one.
2 PLAN VALIDATION TIME
Lets you specify RUN or BIND to tell whether to check authorization at
run time or at bind time. The default is that used for the old plan or
package, if you are replacing it.
3 RESOURCE RELEASE TIME
Lets you specify COMMIT or DEALLOCATE to tell when to release locks
on resources. The default is that used for the old plan or package, if you
are replacing it.

Chapter 17. Preparing an application to run on DB2 for z/OS 973

4 EXPLAIN PATH SELECTION
Lets you specify YES or NO for whether to obtain EXPLAIN information
about how SQL statements in the package execute. The default is NO.
The bind process inserts information into the table owner.PLAN_TABLE,
where owner is the authorization ID of the plan or package owner. If you
defined owner.DSN_STATEMNT_TABLE, DB2 also inserts information
about the cost of statement execution into that table. If you specify YES in
this field and BIND in the VALIDATION TIME field, and if you do not
correctly define PLAN_TABLE, the bind fails.
5 DATA CURRENCY
Lets you specify YES or NO for whether you need data currency for
ambiguous cursors opened at remote locations.
Data is current if the data within the host structure is identical to the data
within the base table. Data is always current for local processing.
6 PARALLEL DEGREE
Lets you specify ANY to run queries using parallel processing (when
possible) or 1 to request that DB2 not execute queries in parallel.
7 SQLERROR PROCESSING
Lets you specify CONTINUE to continue to create a package after finding
SQL errors, or NOPACKAGE to avoid creating a package after finding SQL
errors.
8 REOPTIMIZE FOR INPUT VARS
Specifies whether DB2 determines access paths at bind time and again at
execution time for statements that contain:
v Input host variables
v Parameter markers
v Special registers
If you specify ALWAYS, DB2 determines the access paths again at
execution time. When you specify ALWAYS for this option, you must also
specify YES for DEFER PREPARE, or you will receive a bind error. If you
specify ONCE, DB2 determines the access path at the first execution or
open time. It saves and continues to use that access path for that specific
statement until the statement is invalidated or removed from the dynamic
statement cache or until the statement needs to be prepared again. The
default, NONE, specifies that DB2 does not determine the access path at
bind time using input host variables, parameter markers, or special
registers.
9 DEFER PREPARE
Lets you defer preparation of dynamic SQL statements until DB2
encounters the first OPEN, DESCRIBE, or EXECUTE statement that refers
to those statements. Specify YES to defer preparation of the statement.
10 KEEP DYN SQL PAST COMMIT
Specifies whether DB2 keeps dynamic SQL statements after commit points.
YES causes DB2 to keep dynamic SQL statements after commit points. An
application can execute a PREPARE statement for a dynamic SQL
statement once and execute that statement after later commit points
without executing PREPARE again.
11 DBPROTOCOL
Specifies whether DB2 uses DRDA protocol or DB2 private protocol to
execute statements that contain 3-part names.

974 Application Programming and SQL Guide

12 APPLICATION ENCODING
Specifies the application encoding scheme to be used:
blank Indicates that all host variables in static SQL statements are
encoded using the encoding scheme in the DEF ENCODING
SCHEME field of installation panel DSNTIPF.
ASCII Indicates that the CCSIDs for all host variables in static SQL
statements are determined by the values in the ASCII CODED
CHAR SET and MIXED DATA fields of installation panel
DSNTIPF.
EBCDIC
Indicates that the CCSIDs for all host variables in static SQL
statements are determined by the values in the EBCDIC CODED
CHAR SET and MIXED DATA fields of installation panel
DSNTIPF.
UNICODE
Indicates that the CCSIDs of all host variables in static SQL
statements are determined by the value in the UNICODE CCSID
field of installation panel DSNTIPF.
ccsid Specifies a CCSID that determines the set of CCSIDs that are used
for all host variables in static SQL statements. If you specify ccsid,
this value should be a mixed CCSID. For Unicode, the mixed
CCSID is a UTF-8 CCSID. DB2 derives the SBCS and DBCS
CCSIDs.
13 OPTIMIZATION HINT
Specifies whether you want to use optimization hints to determine access
paths. Specify hint-id to indicate that you want DB2 to use the optimization
hints in owner.PLAN_TABLE, where owner is the authorization ID of the
plan or package owner. hint-id is a delimited string of up to 8 characters
that DB2 compares to the value of OPTHINT in owner.PLAN_TABLE to
determine the rows to use for optimization hints. If you specify a nonblank
value for hint-id, DB2 uses optimization hints only if the value of field
OPTIMIZATION HINTS on installation panel DSNTIP8 is YES.
Blank means that you do not want DB2 to use optimization hints. This is
the default.
14 IMMEDIATE WRITE
Specifies when DB2 writes the changes for updated group buffer
pool-dependent pages. This field applies only to a data sharing
environment. The values that you can specify are:
NO Write the changes at or before phase 1 of the commit process. If the
transaction is rolled back later, write the additional changes that
are caused by the rollback at the end of the abort process. NO is
the default.
PH1 is equivalent to NO.
YES Write the changes immediately after group buffer pool-dependent
pages are updated.
15 DYNAMIC RULES
For plans, lets you specify whether run-time (RUN) or bind-time (BIND)
rules apply to dynamic SQL statements at run time.

Chapter 17. Preparing an application to run on DB2 for z/OS 975

For packages, lets you specify whether run-time (RUN) or bind-time
(BIND) rules apply to dynamic SQL statements at run time. For packages
that run under an active user-defined function or stored procedure
environment, the INVOKEBIND, INVOKERUN, DEFINEBIND, and
DEFINERUN options indicate who must have authority to execute
dynamic SQL statements in the package.
For packages, the default rules for a package on the local server are the
same as the rules for the plan to which the package appends at run time.
For a package on the remote server, the default is RUN.
If you specify rules for a package that are different from the rules for the
plan, the SQL statements for the package use the rules you specify for that
package. If a package that is bound with DEFINEBIND or INVOKEBIND
is not executing under an active stored procedure or user-defined function
environment, SQL statements for that package use BIND rules. If a package
that is bound with DEFINERUN or INVOKERUN is not executing under
an active stored procedure or user-defined function environment, SQL
statements for that package use RUN rules.
Related concepts
“DYNAMICRULES bind option” on page 932
Giving optimization hints to (DB2 Performance)
Parallel processing (DB2 Performance)
Using EXPLAIN to capture information about SQL statements. (DB2
Performance)
Related tasks
“Setting the isolation level of SQL statements in a REXX procedure” on page 411
Choosing ACQUIRE and RELEASE options (DB2 Performance)
Related reference
BIND and REBIND options (DB2 Command Reference)

Defaults for Bind Plan panel

This panel lets you change your defaults for options of BIND PLAN.

On this panel, enter new defaults for binding your plan.

The options on this panel are mostly the same as the options for the defaults for
rebinding a package. However, for REBIND PLAN defaults, you can specify SAME
in any field to specify the values used the last time the plan was bound. For
rebinding, the default value for all fields is SAME.

976 Application Programming and SQL Guide

DSNEBP10 DEFAULTS FOR BIND PLAN SSID: DSN
COMMAND ===>

Change default options as necessary:

1 ISOLATION LEVEL ......... ===> RR (RR, RS, CS, or UR)

2 VALIDATION TIME ......... ===> RUN (RUN or BIND)
3 RESOURCE RELEASE TIME ... ===> COMMIT (COMMIT or DEALLOCATE)
4 EXPLAIN PATH SELECTION .. ===> NO (NO or YES)
5 DATA CURRENCY ........... ===> NO (NO or YES)
6 PARALLEL DEGREE ......... ===> 1 (1 or ANY)
7 RESOURCE ACQUISITION TIME ===> USE (USE or ALLOCATE)
8 REOPTIMIZE FOR INPUT VARS ===> NONE (ALWAYS, NONE, ONCE)
9 DEFER PREPARE ........... ===> NO (NO or YES)
10 KEEP DYN SQL PAST COMMIT. ===> NO (NO or YES)
11 DBPROTOCOL .............. ===> (Blank, DRDA, OR PRIVATE)
12 APPLICATION ENCODING ... ===> (Blank, ASCII, EBCDIC,
UNICODE, or ccsid)
13 OPTIMIZATION HINT ...... ===> (Blank or 'hint-id')
14 IMMEDIATE WRITE ......... ===> NO (YES, NO)
15 DYNAMIC RULES ........... ===> RUN (RUN or BIND)
16 SQLRULES................. ===> DB2 (DB2 or STD)
17 DISCONNECT .............. ===> EXPLICIT (EXPLICIT, AUTOMATIC,
or CONDITIONAL)

Figure 53. The Defaults for Bind Plan panel

1 ISOLATION LEVEL
Lets you specify how far to isolate your application from the effects of
other running applications. The default is the value used for the old plan
or package if you are replacing an existing one.
2 VALIDATION TIME
Lets you specify RUN or BIND to tell whether to check authorization at
run time or at bind time. The default is that used for the old plan or
package, if you are replacing it.
3 RESOURCE RELEASE TIME
Lets you specify COMMIT or DEALLOCATE to tell when to release locks
on resources. The default is that used for the old plan or package, if you
are replacing it.
4 EXPLAIN PATH SELECTION
Lets you specify YES or NO for whether to obtain EXPLAIN information
about how SQL statements in the package execute. The default is NO.
The bind process inserts information into the table owner.PLAN_TABLE,
where owner is the authorization ID of the plan or package owner. If you
defined owner.DSN_STATEMNT_TABLE, DB2 also inserts information
about the cost of statement execution into that table. If you specify YES in
this field and BIND in the VALIDATION TIME field, and if you do not
correctly define PLAN_TABLE, the bind fails.
5 DATA CURRENCY
Lets you specify YES or NO for whether you need data currency for
ambiguous cursors opened at remote locations.
Data is current if the data within the host structure is identical to the data
within the base table. Data is always current for local processing.
6 PARALLEL DEGREE
Lets you specify ANY to run queries using parallel processing (when
possible) or 1 to request that DB2 not execute queries in parallel.
7 RESOURCE ACQUISITION TIME
Lets you specify when to acquire locks on resources. Use:
Chapter 17. Preparing an application to run on DB2 for z/OS 977
USE (default) to open table spaces and acquire locks only when the
program bound to the plan first uses them.
ALLOCATE to open all table spaces and acquire all locks when you
allocate the plan. This value has no effect on dynamic SQL.
8 REOPTIMIZE FOR INPUT VARS
Specifies whether DB2 determines access paths at bind time and again at
execution time for statements that contain:
v Input host variables
v Parameter markers
v Special registers
If you specify ALWAYS, DB2 determines the access paths again at
execution time. When you specify ALWAYS for this option, you must also
specify YES for DEFER PREPARE, or you will receive a bind error. If you
specify ONCE, DB2 determines the access path at the first execution or
open time. It saves and continues to use that access path for that specific
statement until the statement is invalidated or removed from the dynamic
statement cache or until the statement needs to be prepared again. The
default, NONE, specifies that DB2 does not determine the access path at
bind time using input host variables, parameter markers, or special
registers.
9 DEFER PREPARE
Lets you defer preparation of dynamic SQL statements until DB2
encounters the first OPEN, DESCRIBE, or EXECUTE statement that refers
to those statements. Specify YES to defer preparation of the statement.
10 KEEP DYN SQL PAST COMMIT
Specifies whether DB2 keeps dynamic SQL statements after commit points.
YES causes DB2 to keep dynamic SQL statements after commit points. An
application can execute a PREPARE statement for a dynamic SQL
statement once and execute that statement after later commit points
without executing PREPARE again.
11 DBPROTOCOL
Specifies whether DB2 uses DRDA protocol or DB2 private protocol to
execute statements that contain 3-part names.
12 APPLICATION ENCODING
Specifies the application encoding scheme to be used:
blank Indicates that all host variables in static SQL statements are
encoded using the encoding scheme in the DEF ENCODING
SCHEME field of installation panel DSNTIPF.
ASCII Indicates that the CCSIDs for all host variables in static SQL
statements are determined by the values in the ASCII CODED
CHAR SET and MIXED DATA fields of installation panel
DSNTIPF.
EBCDIC
Indicates that the CCSIDs for all host variables in static SQL
statements are determined by the values in the EBCDIC CODED
CHAR SET and MIXED DATA fields of installation panel
DSNTIPF.
UNICODE
Indicates that the CCSIDs of all host variables in static SQL
statements are determined by the value in the UNICODE CCSID
field of installation panel DSNTIPF.

978 Application Programming and SQL Guide

ccsid Specifies a CCSID that determines the set of CCSIDs that are used
for all host variables in static SQL statements. If you specify ccsid,
this value should be a mixed CCSID. For Unicode, the mixed
CCSID is a UTF-8 CCSID. DB2 derives the SBCS and DBCS
CCSIDs.
13 OPTIMIZATION HINT
Specifies whether you want to use optimization hints to determine access
paths. Specify hint-id to indicate that you want DB2 to use the optimization
hints in owner.PLAN_TABLE, where owner is the authorization ID of the
plan or package owner. hint-id is a delimited string of up to 8 characters
that DB2 compares to the value of OPTHINT in owner.PLAN_TABLE to
determine the rows to use for optimization hints. If you specify a nonblank
value for hint-id, DB2 uses optimization hints only if the value of field
OPTIMIZATION HINTS on installation panel DSNTIP8 is YES.
Blank means that you do not want DB2 to use optimization hints. This is
the default.
14 IMMEDIATE WRITE
Specifies when DB2 writes the changes for updated group buffer
pool-dependent pages. This field applies only to a data sharing
environment. The values that you can specify are:
NO Write the changes at or before phase 1 of the commit process. If the
transaction is rolled back later, write the additional changes that
are caused by the rollback at the end of the abort process. NO is
the default.
PH1 is equivalent to NO.
YES Write the changes immediately after group buffer pool-dependent
pages are updated.
15 DYNAMIC RULES
For plans, lets you specify whether run-time (RUN) or bind-time (BIND)
rules apply to dynamic SQL statements at run time.
For packages, lets you specify whether run-time (RUN) or bind-time
(BIND) rules apply to dynamic SQL statements at run time. For packages
that run under an active user-defined function or stored procedure
environment, the INVOKEBIND, INVOKERUN, DEFINEBIND, and
DEFINERUN options indicate who must have authority to execute
dynamic SQL statements in the package.
For packages, the default rules for a package on the local server are the
same as the rules for the plan to which the package appends at run time.
For a package on the remote server, the default is RUN.
If you specify rules for a package that are different from the rules for the
plan, the SQL statements for the package use the rules you specify for that
package. If a package that is bound with DEFINEBIND or INVOKEBIND
is not executing under an active stored procedure or user-defined function
environment, SQL statements for that package use BIND rules. If a package
that is bound with DEFINERUN or INVOKERUN is not executing under
an active stored procedure or user-defined function environment, SQL
statements for that package use RUN rules.
16 SQLRULES
Lets you specify whether a CONNECT (Type 2) statement executes
according to DB2 rules (DB2) or the SQL standard (STD).

Chapter 17. Preparing an application to run on DB2 for z/OS 979

17 DISCONNECT
Lets you specify which remote connections end during a commit or a
rollback. Regardless of what you specify, all connections in the
released-pending state end during commit.
Use:
EXPLICIT to end connections in the release-pending state only at
COMMIT or ROLLBACK
AUTOMATIC to end all remote connections
CONDITIONAL to end remote connections that have no open cursors
WITH HOLD associated with them.
Related concepts
“Authorization cache” on page 934
“DYNAMICRULES bind option” on page 932
Parallel processing (DB2 Performance)
Using EXPLAIN to capture information about SQL statements. (DB2
Performance)
Related tasks
“Setting the isolation level of SQL statements in a REXX procedure” on page 411
“Specifying the rules that apply to SQL behavior at run time” on page 946
Choosing ACQUIRE and RELEASE options (DB2 Performance)

System Connection Types panel

The System Connection Types panel lets you specify which types of connections
can use a plan or package.

This panel displays if you enter YES for ENABLE/DISABLE CONNECTIONS? on

the Bind or Rebind Package or Plan panels. For the Bind or Rebind Package panel,
the REMOTE option does not display as it does in the following panel.

DSNEBP13 SYSTEM CONNECTION TYPES FOR BIND ... SSID: DSN

COMMAND ===>

Select system connection types to be Enabled/Disabled:

1 ENABLE ALL CONNECTION TYPES? ===> (* to enable all types)

or
2 ENABLE/DISABLE SPECIFIC CONNECTION TYPES ===> (E/D)

BATCH ....... ===> (Y/N) SPECIFY CONNECTION NAMES?

DB2CALL ..... ===> (Y/N)
RRSAF ....... ===> (Y/N)
CICS ........ ===> (Y/N) ===> N (Y/N)
IMS ......... ===> (Y/N)
DLIBATCH .... ===> (Y/N) ===> N (Y/N)
IMSBMP ...... ===> (Y/N) ===> N (Y/N)
IMSMPP ...... ===> (Y/N) ===> N (Y/N)
REMOTE ...... ===> (Y/N) ===> N (Y/N)

Figure 54. The System Connection Types panel

To enable or disable connection types (that is, allow or prevent the connection from
running the package or plan), enter the following information.

980 Application Programming and SQL Guide

1 ENABLE ALL CONNECTION TYPES?
Lets you enter an asterisk (*) to enable all connections. After that entry, you
can ignore the rest of the panel.
2 ENABLE/DISABLE SPECIFIC CONNECTION TYPES
Lets you specify a list of types to enable or disable; you cannot enable
some types and disable others in the same operation. If you list types to
enable, enter E; that disables all other connection types. If you list types to
disable, enter D; that enables all other connection types. For more
information about this option, see information about the ENABLE and
DISABLE bind options in the topic “BIND and REBIND options” in DB2
Command Reference.
For each connection type that follows, enter Y (yes) if it is on your list, N
(no) if it is not. The connection types are:
v BATCH for a TSO connection
v DB2CALL for a CAF connection
v RRSAF for an RRSAF connection
v CICS for a CICS connection
v IMS for all IMS connections: DLIBATCH, IMSBMP, and IMSMPP
v DLIBATCH for a DL/I Batch Support Facility connection
v IMSBMP for an IMS connection to a BMP region
v IMSMPP for an IMS connection to an MPP or IFP region
v REMOTE for remote location names and LU names
For each connection type that has a second arrow, under SPECIFY
CONNECTION NAMES?, enter Y if you want to list specific connection
names of that type. Leave N (the default) if you do not. If you use Y in
any of those fields, you see another panel on which you can enter the
connection names. For more information, see “Panels for entering lists of
values.”

If you use the DISPLAY command under TSO on this panel, you can determine
what you have currently defined as “enabled” or “disabled” in your ISPF
DSNSPFT library (member DSNCONNS). The information does not reflect the
current state of the DB2 Catalog.

If you type DISPLAY ENABLED on the command line, you get the connection
names that are currently enabled for your TSO connection types. For example:
Display OF ALL connection name(s) to be ENABLED

CONNECTION SUBSYSTEM
CICS1 ENABLED
CICS2 ENABLED
CICS3 ENABLED
CICS4 ENABLED
DLI1 ENABLED
DLI2 ENABLED
DLI3 ENABLED
DLI4 ENABLED
DLI5 ENABLED

Panels for entering lists of values

Some fields in DB2I panels are associated with command keywords that accept
multiple values. Those fields lead you to a list panel that lets you enter or modify
an unlimited number of values.

A list panel looks like an ISPF edit session and lets you scroll and use a limited set
of commands.

Chapter 17. Preparing an application to run on DB2 for z/OS 981

The format of each list panel varies, depending on the content and purpose for the
panel. The following figure shows a generic sample of a list panel:

panelid Specific subcommand function SSID: DSN

COMMAND ===>_ SCROLL ===>

Subcommand operand values:

CMD
"""" value ...
"""" value ...
""""
""""
""""
""""

Figure 55. Generic example of a DB2I list panel

All of the list panels let you enter limited commands in two places:
v On the system command line, prefixed by ====>
v In a special command area, identified by ″″″″

On the system command line, you can use:

END Saves all entered variables, exits the table, and continues to process.
CANCEL
Discards all entered variables, terminates processing, and returns to the
previous panel.
SAVE Saves all entered variables and remains in the table.

In the special command area, you can use:

Inn Insert nn lines after this one.
Dnn Delete this and the following lines for nn lines.
Rnn Repeat this line nn number of times.

The default for nn is 1.

When you finish with a list panel, specify END to same the current panel values
and continue processing.

Program Preparation: Compile, Link, and Run panel

The Compile, Link, and Run panel lets you perform the last two steps in the
program preparation process (compile and link-edit), as well as the PL/I MACRO
PHASE for programs requiring this option.

For TSO programs, the panel also lets you run programs.

982 Application Programming and SQL Guide

DSNEPP02 PROGRAM PREP: COMPILE, PRELINK, LINK, AND RUN SSID: DSN
COMMAND ===>_

Enter compiler or assembler options:

1 INCLUDE LIBRARY ===> SRCLIB.DATA
2 INCLUDE LIBRARY ===>
3 OPTIONS ....... ===> NUM, OPTIMIZE, ADV

Enter linkage editor options:

4 INCLUDE LIBRARY ===> SAMPLIB.COBOL
5 INCLUDE LIBRARY ===>
6 INCLUDE LIBRARY ===>
7 LOAD LIBRARY .. ===> RUNLIB.LOAD
8 PRELINK OPTIONS ===>
9 LINK OPTIONS... ===>
Enter run options:
10 PARAMETERS .... ===> D01, D02, D03/
11 SYSIN DATA SET ===> TERM
12 SYSPRINT DS ... ===> TERM

Figure 56. The Program Preparation: Compile, Link, and Run panel

1,2 INCLUDE LIBRARY

Lets you specify up to two libraries containing members for the compiler
to include. The members can also be output from DCLGEN. You can leave
these fields blank if you wish. There is no default.
3 OPTIONS
Lets you specify compiler, assembler, or PL/I macro processor options. You
can also enter a list of compiler or assembler options by separating entries
with commas, blanks, or both. You can leave these fields blank if you wish.
There is no default.
4,5,6 INCLUDE LIBRARY
Lets you enter the names of up to three libraries containing members for
the linkage editor to include. You can leave these fields blank if you wish.
There is no default.
7 LOAD LIBRARY
Lets you specify the name of the library to hold the load module. The
default value is RUNLIB.LOAD.
If the load library specified is a PDS, and the input data set is a PDS, the
member name specified in INPUT DATA SET NAME field of the Program
Preparation panel is the load module name. If the input data set is
sequential, the second qualifier of the input data set is the load module
name.
You must fill in this field if you request LINK or RUN on the Program
Preparation panel.
8 PRELINK OPTIONS
Lets you enter a list of prelinker options. Separate items in the list with
commas, blanks, or both. You can leave this field blank if you wish. There
is no default.
The prelink utility applies only to programs using C, C++, and Enterprise
COBOL for z/OS. For more information about prelinker options, see z/OS
Language Environment Programming Guide.
9 LINK OPTIONS
Lets you enter a list of link-edit options. Separate items in the list with
commas, blanks, or both.

Chapter 17. Preparing an application to run on DB2 for z/OS 983

To prepare a program that uses 31-bit addressing and runs above the
16-megabyte line, specify the following link-edit options: AMODE=31,
RMODE=ANY.
10 PARAMETERS
Lets you specify a list of parameters you want to pass either to your host
language run-time processor, or to your application. Separate items in the
list with commas, blanks, or both. You can leave this field blank.
If you are preparing an IMS or CICS program, you must leave this field
blank; you cannot use DB2I to run IMS and CICS programs.
Use a slash (/) to separate the options for your run-time processor from
those for your program.
v For PL/I and Fortran, run-time processor parameters must appear on
the left of the slash, and the application parameters must appear on the
right.
run-time processor parameters / application parameters
v For COBOL, reverse this order. Run-time processor parameters must
appear on the right of the slash, and the application parameters must
appear on the left.
v For assembler and C, there is no supported run-time environment, and
you need not use a slash to pass parameters to the application program.
11 SYSIN DATA SET
Lets you specify the name of a SYSIN (or in Fortran, FT05F001) data set for
your application program, if it needs one. If you do not enclose the data
set name in apostrophes, a standard TSO prefix (user ID) and suffix is
added to it. The default for this field is TERM.
If you are preparing an IMS or CICS program, you must leave this field
blank; you cannot use DB2I to run IMS and CICS programs.
12 SYSPRINT DS
Lets you specify the names of a SYSPRINT (or in Fortran, FT06F001) data
set for your application program, if it needs one. If you do not enclose the
data set name in apostrophes, a standard TSO prefix (user ID) and suffix is
added to it. The default for this field is TERM.
If you are preparing an IMS or CICS program, you must leave this field
blank; you cannot use DB2I to run IMS and CICS programs.

Your application could need other data sets besides SYSIN and SYSPRINT. If so,
remember to catalog and allocate them before you run your program.

When you press ENTER after entering values in this panel, DB2 compiles and
link-edits the application. If you specified in the DB2 Program Preparation panel
that you want to run the application, DB2 also runs the application.

DB2I panels that are used to rebind and free plans and packages
A set of DB2I panels lets you bind, rebind, or free packages.

Table 161 on page 985 describes additional panels that you can use to Rebind and
Free packages and plans. It also describes the Run panel, which you can use to run
application programs that have already been prepared.

984 Application Programming and SQL Guide

Table 161. DB2I panels used to rebind and free plans and packages and used to Run
application programs
Panel Panel description
“Bind/Rebind/Free The BIND/REBIND/FREE panel lets you select the BIND,
Selection panel” REBIND, or FREE, PLAN, PACKAGE, or TRIGGER PACKAGE
process that you need.
“Rebind Package panel” The Rebind Package panel lets you change options when you
on page 986 rebind a package.
“Rebind Trigger Package The Rebind Trigger Package panel lets you change options when
panel” on page 988 you rebind a trigger package.
“Rebind Plan panel” on The Rebind Plan panel lets you change options when you
page 990 rebind an application plan.
“Free Package panel” on The Free Package panel lets you change options when you free a
page 992 package.
“Free Plan panel” on page The Free Plan panel lets you change options when you free an
993 application plan.
“DB2I Run panel” on The Run panel lets you start an application program. You
page 996 should use this panel if you have already prepared the program
and you only want to run it.

You can also run a program by using the ″Program Prep:

Compile, Prelink, Link, and Run″ panel.

Bind/Rebind/Free Selection panel

The Bind/Rebind/Free selection panel lets choose whether to bind, rebind, or free
plans and packages.

DSNEBP01 BIND/REBIND/FREE SSID: DSN

COMMAND ===>_

Select one of the following and press ENTER:

1 BIND PLAN (Add or replace an application plan)

2 REBIND PLAN (Rebind existing application plan or plans)

3 FREE PLAN (Erase application plan or plans)

4 BIND PACKAGE (Add or replace a package)

5 REBIND PACKAGE (Rebind existing package or packages)

6 REBIND TRIGGER PACKAGE (Rebind existing package or packages)

7 FREE PACKAGE (Erase a package or packages)

Figure 57. The Bind/Rebind/Free selection panel

This panel lets you select the process you need.

1 BIND PLAN
Lets you build an application plan. You must have an application plan to
allocate DB2 resources and support SQL requests during run time. If you
select this option, the Bind Plan panel displays. For more information, see
“Bind Plan panel” on page 969.

Chapter 17. Preparing an application to run on DB2 for z/OS 985

2 REBIND PLAN
Lets you rebuild an application plan when changes to it affect the plan but
the SQL statements in the program are the same. For example, you should
rebind when you change authorizations, create a new index that the plan
uses, or use RUNSTATS. If you select this option, the Rebind Plan panel
displays. For more information, see “Rebind Plan panel” on page 990.
3 FREE PLAN
Lets you delete plans from DB2. If you select this option, the Free Plan
panel displays. For more information, see “Free Plan panel” on page 993.
4 BIND PACKAGE
Lets you build a package. If you select this option, the Bind Package panel
displays. For more information, see “Bind Package panel” on page 967.
5 REBIND PACKAGE
Lets you rebuild a package when changes to it affect the package but the
SQL statements in the program are the same. For example, you should
rebind when you change authorizations, create a new index that the
package uses, or use RUNSTATS. If you select this option, the Rebind
Package panel displays. For more information, see “Rebind Package
panel.”
6 REBIND TRIGGER PACKAGE
Lets you rebuild a trigger package when you need to change options for
the package. When you execute CREATE TRIGGER, DB2 binds a trigger
package using a set of default options. You can use REBIND TRIGGER
PACKAGE to change those options. For example, you can use REBIND
TRIGGER PACKAGE to change the isolation level for the trigger package.
If you select this option, the Rebind Trigger Package panel displays. For
more information, see “Rebind Trigger Package panel” on page 988.
7 FREE PACKAGE
Lets you delete a specific version of a package, all versions of a package,
or whole collections of packages from DB2. If you select this option, the
Free Package panel displays. For more information, see “Free Package
panel” on page 992.

Rebind Package panel

The Rebind Package panel is the first of two panels that you use to rebind a
package. It specifies options for rebinding the package.

Figure 58 on page 987 shows the rebind package options.

986 Application Programming and SQL Guide

DSNEBP08 REBIND PACKAGE SSID: DSN
COMMAND ===>_

1 Rebind all local packages ===> (* to rebind all packages)

or
Enter package name(s) to be rebound:
2 LOCATION NAME ............. ===> (Defaults to local)
3 COLLECTION-ID ............. ===> (Required)
4 PACKAGE-ID ................ ===> (Required)
5 VERSION-ID ................ ===>
(*, Blank, (), or version-id)
6 ADDITIONAL PACKAGES? ...... ===> (Yes to include more packages)

Enter options as desired ...... ===>

7 CHANGE CURRENT DEFAULTS?... ===> (NO or YES)
8 OWNER OF PACKAGE (AUTHID).. ===> (SAME, new OWNER)
9 QUALIFIER ................. ===> (SAME, new QUALIFIER)
10 ENABLE/DISABLE CONNECTIONS? ===> (NO or YES)
11 INCLUDE PATH? ............. ===> (SAME, DEFAULT, or YES)

Figure 58. The Rebind Package panel

This panel lets you choose options for rebinding a package. For information about
the rebind options that these fields represent, see the topic “BIND and REBIND
options” in DB2 Command Reference.
1 Rebind all local packages
Lets you rebind all packages on the local DBMS. To do so, place an asterisk
(*) in this field; otherwise, leave it blank.
2 LOCATION NAME
Lets you specify where to bind the package. If you specify a location name,
you should use from 1 to 16 characters, and you must have defined it in
the catalog table SYSIBM.LOCATIONS.
3 COLLECTION-ID
| Lets you specify the collection of the package to rebind. You must specify a
| collection ID from 1 to 8 characters, or an asterisk (*) to rebind all
| collections in the local DB2 system. You cannot use the asterisk to rebind a
| remote collection.
4 PACKAGE-ID
Lets you specify the name of the package to rebind. You must specify a
package ID from 1 to 8 characters, or an asterisk (*) to rebind all packages
in the specified collections in the local DB2 system. You cannot use the
asterisk to rebind a remote package.
5 VERSION-ID
Lets you specify the version of the package to rebind. You must specify a
version ID from 1 to 64 characters, or an asterisk (*) to rebind all versions
in the specified collections and packages in the local DB2 system. You
cannot use the asterisk to rebind a remote version.
6 ADDITIONAL PACKAGES?
Lets you indicate whether to name more packages to rebind. Use YES to
specify more packages on an additional panel, described on “Panels for
entering lists of values” on page 981. The default is NO.
7 CHANGE CURRENT DEFAULTS?
Lets you indicate whether to change the binding defaults. Use:
NO (default) to retain the binding defaults of the previous package.

Chapter 17. Preparing an application to run on DB2 for z/OS 987

YES to change the binding defaults from the previous package. For
information about the defaults for binding packages, see “Defaults for
Bind Package panel” on page 973.
8 OWNER OF PACKAGE (AUTHID)
Lets you change the authorization ID for the package owner. The owner
must have the required privileges to execute the SQL statements in the
package. The default is the existing package owner.
9 QUALIFIER
| Lets you specify the default schema for all unqualified table names, views,
| indexes, and aliases in the package. You can specify a schema name from 1
| to 8 characters, which must conform to the rules for the SQL short
| identifier. The default is the existing qualifier name.
10 ENABLE/DISABLE CONNECTIONS?
Lets you specify whether you want to enable and disable system
connections types to use with this package. This is valid only if the
LOCATION NAME field names your local DB2 system.
Placing YES in this field displays a panel (shown in Figure 54 on page 980)
that lets you specify whether various system connections are valid for this
application.
The default is the values used for the previous package.
11 INCLUDE PATH?
Indicates which one of the following actions you want to perform:
v Request that DB2 uses the same schema names as when the package was
bound for resolving unqualified distinct type, user-defined function, and
stored procedure names in SQL statements. Choose SAME to perform
this action. This is the default.
v Supply a list of schema names that DB2 searches when it resolves
unqualified distinct type, user-defined function, and stored procedure
names in SQL statements. Choose YES to perform this action.
v Request that DB2 resets the SQL path to SYSIBM, SYSFUN, SYSPROC,
and the package owner. Choose DEFAULT to perform this action.
If you specify YES, DB2 displays a panel in which you specify the names
of schemas for DB2 to search.

Rebind Trigger Package panel

The Rebind Trigger Package panel specifies options for rebinding a trigger
package.

Figure 59 on page 989 shows those options.

988 Application Programming and SQL Guide

DSNEBP19 REBIND TRIGGER PACKAGE SSID: DSN
COMMAND ===>_

1 Rebind all trigger packages ===> (* to rebind all packages)

or
Enter trigger package name(s) to be rebound:
2 LOCATION NAME ............. ===> (Defaults to local)
3 COLLECTION-ID (SCHEMA NAME) ===> (Required)
4 PACKAGE-ID (TRIGGER NAME).. ===> (Required)

Enter options as desired ...... ===>

5 ISOLATION LEVEL ........... ===> SAME (SAME, RR, RS, CS, UR, or NC)
6 RESOURCE RELEASE TIME ..... ===> SAME (SAME, DEALLOCATE, or COMMIT)
7 EXPLAIN PATH SELECTION .... ===> SAME (SAME, NO, or YES)
8 DATA CURRENCY ............. ===> SAME (SAME, NO, or YES)
9 IMMEDIATE WRITE OPTION .... ===> SAME (SAME, NO, YES)

Figure 59. The Rebind Trigger Package panel

This panel lets you choose options for rebinding a trigger package. For information
about the rebind options that these fields represent, see the topic “BIND and
REBIND options” in DB2 Command Reference.
1 Rebind all trigger packages
Lets you rebind all packages on the local DBMS. To do so, place an asterisk
(*) in this field; otherwise, leave it blank.
2 LOCATION NAME
Lets you specify where to bind the trigger package. If you specify a
location name, you should use from 1 to 16 characters, and you must have
defined it in the catalog table SYSIBM.LOCATIONS.
3 COLLECTION-ID (SCHEMA NAME)
| Lets you specify the collection of the trigger package to rebind. You must
| specify a collection ID from 1 to 8 characters, or an asterisk (*) to rebind all
| collections in the local DB2 system. You cannot use the asterisk to rebind a
| remote collection.
4 PACKAGE-ID
Lets you specify the name of the trigger package to rebind. You must
specify a package ID from 1 to 8 characters, or an asterisk (*) to rebind all
trigger packages in the specified collections in the local DB2 system. You
cannot use the asterisk to rebind a remote trigger package.
5 ISOLATION LEVEL
Lets you specify how far to isolate your application from the effects of
other running applications. The default is the value used for the old trigger
package.
6 RESOURCE RELEASE TIME
Lets you specify COMMIT or DEALLOCATE to tell when to release locks
on resources. The default is that used for the old trigger package.
7 EXPLAIN PATH SELECTION
Lets you specify YES or NO for whether to obtain EXPLAIN information
about how SQL statements in the package execute. The default is the value
used for the old trigger package.
The bind process inserts information into the table owner.PLAN_TABLE,
where owner is the authorization ID of the plan or package owner. If you
defined owner.DSN_STATEMNT_TABLE, DB2 also inserts information
about the cost of statement execution into that table. If you specify YES in

Chapter 17. Preparing an application to run on DB2 for z/OS 989

this field and BIND in the VALIDATION TIME field, and if you do not
correctly define PLAN_TABLE, the bind fails.
8 DATA CURRENCY
Lets you specify YES or NO for whether you need data currency for
ambiguous cursors opened at remote locations. The default is the value
used for the old trigger package.
Data is current if the data within the host structure is identical to the data
within the base table. Data is always current for local processing.
9 IMMEDIATE WRITE OPTION
Specifies when DB2 writes the changes for updated group buffer
pool-dependent pages. This field applies only to a data sharing
environment. The values that you can specify are:
SAME Choose the value of IMMEDIATE WRITE that you specified when
you bound the trigger package. SAME is the default.
NO Write the changes at or before phase 1 of the commit process. If the
transaction is rolled back later, write the additional changes that
are caused by the rollback at the end of the abort process.
PH1 is equivalent to NO.
YES Write the changes immediately after group buffer pool-dependent
pages are updated.
For more information about the IMMEDIATE WRITE option, see
information about the IMMEDWRITE bind option in the topic “BIND and
REBIND options” in DB2 Command Reference.

Rebind Plan panel

The Rebind Plan panel is the first of two panels that you use to rebind a plan. It
specifies options for rebinding the plan.

The following figure shows the rebind plan options.

DSNEBP03 REBIND PLAN SSID: DSN

COMMAND ===>_

Enter plan name(s) to be rebound:

1 PLAN NAME ................. ===> (* to rebind all plans)
2 ADDITIONAL PLANS? ......... ===> NO (Yes to include more plans)

Enter options as desired:

3 CHANGE CURRENT DEFAULTS?... ===> NO (NO or YES)
4 OWNER OF PLAN (AUTHID)..... ===> SAME (SAME, new OWNER)
5 QUALIFIER ................. ===> SAME (SAME, new QUALIFIER)
6 CACHESIZE ................. ===> SAME (SAME, or value 0-4096)
7 ENABLE/DISABLE CONNECTIONS? ===> NO (NO or YES)
8 INCLUDE PACKAGE LIST?...... ===> SAME (SAME, NO, or YES)
9 CURRENT SERVER ............ ===> (Location name)
10 INCLUDE PATH? ............. ===> SAME (SAME, DEFAULT, or YES)

Figure 60. The Rebind Plan panel

This panel lets you specify options for rebinding your plan.
1 PLAN NAME
Lets you name the application plan to rebind. You can specify a name from
1 to 8 characters, and the first character must be alphabetic. Do not begin

990 Application Programming and SQL Guide

the name with DSN, because it could create name conflicts with DB2. If
there are no errors, the bind process prepares the plan and enters its
description into the EXPLAIN table.
If you leave this field blank, the bind process occurs but produces no plan.
2 ADDITIONAL PLANS?
Lets you indicate whether to name more plans to rebind. Use YES to
specify more plans on an additional panel, described at “Panels for
entering lists of values” on page 981. The default is NO.
3 CHANGE CURRENT DEFAULTS?
Lets you indicate whether to change the binding defaults. Use:
NO (default) to retain the binding defaults of the previous plan.
YES to change the binding defaults from the previous plan.
4 OWNER OF PLAN (AUTHID)
Lets you change the authorization ID for the plan owner. The owner must
have the required privileges to execute the SQL statements in the plan. The
default is the existing plan owner.
5 QUALIFIER
| Lets you specify the default schema for all unqualified table names, views,
| indexes, and aliases in the plan. You can specify a schema name from 1 to
| 8 characters, which must conform to the rules for the SQL identifier. The
| default is the authorization ID.
6 CACHESIZE
Lets you specify the size (in bytes) of the authorization cache. Valid values
are in the range 0 to 4096. Values that are not multiples of 256 round up to
the next highest multiple of 256. A value of 0 indicates that DB2 does not
use an authorization cache. The default is the cache size specified for the
previous plan.
Each concurrent user of a plan requires 8 bytes of storage, with an
additional 32 bytes for overhead.
7 ENABLE/DISABLE CONNECTIONS?
Lets you specify whether you want to enable and disable system
connections types to use with this plan. This is valid only for rebinding on
your local DB2 system.
Placing YES in this field displays a panel (shown in Figure 54 on page 980)
that lets you specify whether various system connections are valid for this
application.
The default is the values used for the previous plan.
8 INCLUDE PACKAGE LIST?
Lets you include a list of collections and packages in the plan. If you
specify YES, a separate panel displays on which you must enter the
package location, collection name, and package name for each package to
include in the plan (see “Panels for entering lists of values” on page 981).
This field can either add a package list to a plan that did not have one, or
replace an existing package list.
| You can specify a location name from 1 to 16 characters, a collection ID
| from 1 to 18 characters, and a package ID from 1 to 8 characters. Separate
| two or more package list parameters with a comma. If you specify a
| location name, it must be in the catalog table SYSIBM.LOCATIONS. The
| default location is the package list used for the previous plan.

Chapter 17. Preparing an application to run on DB2 for z/OS 991

9 CURRENT SERVER
Lets you specify the initial server to receive and process SQL statements in
this plan. You can specify a name from 1 to 16 characters, which you must
previously define in the catalog table SYSIBM.LOCATIONS.
If you specify a remote server, DB2 connects to that server when the first
SQL statement executes. The default is the name of the local DB2
subsystem.
10 INCLUDE PATH?
Indicates which one of the following actions you want to perform:
v Request that DB2 uses the same schema names as when the plan was
bound for resolving unqualified distinct type, user-defined function, and
stored procedure names in SQL statements. Choose SAME to perform
this action. This is the default.
v Supply a list of schema names that DB2 searches when it resolves
unqualified distinct type, user-defined function, and stored procedure
names in SQL statements. Choose YES to perform this action.
v Request that DB2 resets the SQL path to SYSIBM, SYSFUN, SYSPROC,
and the plan owner. Choose DEFAULT to perform this action.
If you specify YES, DB2 displays a panel in which you specify the names
of schemas for DB2 to search.
Related reference
“Defaults for Bind Plan panel” on page 976
BIND and REBIND options (DB2 Command Reference)

Free Package panel

The Free Package panel is the first of two panels through which you can specify
options for freeing an application package.

The following figure shows the free package options.

DSNEBP18 FREE PACKAGE SSID: DSN

COMMAND ===>_

1 Free ALL packages ......... ===> (* to free authorized packages)

or
Enter package name(s) to be freed:
2 LOCATION NAME ............. ===> (Defaults to local)
3 COLLECTION-ID ............. ===> (Required)
4 PACKAGE-ID ................ ===> (* to free all packages)
5 VERSION-ID ................ ===>
(*, Blank, (), or version-id)
6 ADDITIONAL PACKAGES?....... ===> (Yes to include more packages)

Figure 61. The Free Package panel

This panel lets you specify options for erasing packages.

1 Free ALL packages
Lets you free (erase) all packages for which you have authorization or to
which you have BINDAGENT authority. To do so, place an asterisk (*) in
this field; otherwise, leave it blank.

992 Application Programming and SQL Guide

2 LOCATION NAME
Lets you specify the location name of the DBMS to free the package. You
can specify a name from 1 to 16 characters.
3 COLLECTION-ID
| Lets you specify the collection from which you want to delete packages for
| which you own or have BINDAGENT privileges. You can specify a name
| from 1 to 18 characters, or an asterisk (*) to free all collections in the local
| DB2 system. You cannot use the asterisk to free a remote collection.
4 PACKAGE-ID
Lets you specify the name of the package to free. You can specify a name
from 1 to 8 characters, or an asterisk (*) to free all packages in the specified
collections in the local DB2 system. You cannot use the asterisk to free a
remote package. The name you specify must be in the DB2 catalog tables.
5 VERSION-ID
Lets you specify the version of the package to free. You can specify an
identifier from 1 to 64 characters, or an asterisk (*) to free all versions of
the specified collections and packages in the local DB2 system. You cannot
use the asterisk to free a remote version.
6 ADDITIONAL PACKAGES?
Lets you indicate whether to name more packages to free. Use YES to
specify more packages on an additional panel, described in “Panels for
entering lists of values” on page 981. The default is NO.

Free Plan panel

The Free Plan panel is the first of two panels through which you can specify
options for freeing an application plan.

Figure 62 shows the free plan options.

DSNEBP09 FREE PLAN SSID: DSN

COMMAND ===>_

Enter plan name(s) to be freed:

1 PLAN NAME ............ ===> (* to free all authorized plans)
2 ADDITIONAL PLANS? .... ===> (Yes to include more plans)

Figure 62. The Free Plan panel

This panel lets you specify options for freeing plans.

1 PLAN NAME
Lets you name the application plan to delete from DB2. Use an asterisk to
free all plans for which you have BIND authority. You can specify a name
from 1 to 8 characters, and the first character must be alphabetic.
If there are errors, the free process terminates for that plan and continues
with the next plan.
2 ADDITIONAL PLANS?
Lets you indicate whether to name more plans to free. Use YES to specify
more plans on an additional panel, described in “Panels for entering lists
of values” on page 981. The default is NO.

Chapter 17. Preparing an application to run on DB2 for z/OS 993

994 Application Programming and SQL Guide
Chapter 18. Running an application on DB2 for z/OS
You can run your application after you have processed the SQL statements,
compiled and link-edited the application, and bound the application.

At run time, DB2 verifies that the information in the application plan and its
associated packages is consistent with the corresponding information in the DB2
catalog. If any destructive changes, such as DROP or REVOKE, occur (either to the
data structures that your application accesses or to the binder’s authority to access
those data structures), DB2 automatically rebinds packages or the plan as needed.

Establishing a test environment: This topic describes how to design a test data
structure and how to fill tables with test data.

CICSBefore you run an application, ensure that the following two conditions are
met:
v The corresponding entries in the SNT and RACF control areas authorize your
application to run.
v The program and its transaction code are defined in the CICS CSD.
The system administrator is responsible for these functions.

DSN command processor

The DSN command processor is a TSO command processor that runs in TSO
foreground or under TSO in JES-initiated batch.

It uses the TSO attachment facility to access DB2. The DSN command processor
provides an alternative method for running programs that access DB2 in a TSO
environment.

| When you run an application by using the DSN command processor, that
| application can run in a trusted connection if DB2 finds a matching trusted context.

You can use the DSN command processor implicitly during program development
for functions such as:
v Using the declarations generator (DCLGEN)
v Running the BIND, REBIND, and FREE subcommands on DB2 plans and
packages for your program
v Using SPUFI (SQL Processor Using File Input) to test some of the SQL functions
in the program

The DSN command processor runs with the TSO terminal monitor program (TMP).
Because the TMP runs in either foreground or background, DSN applications run
interactively or as batch jobs.

The DSN command processor can provide these services to a program that runs
under it:
v Automatic connection to DB2
v Attention key support
v Translation of return codes into error messages

© Copyright IBM Corp. 1983, 2009 995

Limitations of the DSN command processor:

When using DSN services, your application runs under the control of DSN.
Because TSO executes the ATTACH macro to start DSN, and DSN executes the
ATTACH macro to start a part of itself, your application gains control that is two
task levels below TSO.

Because your program depends on DSN to manage your connection to DB2:

v If DB2 is down, your application cannot begin to run.
v If DB2 terminates, your application also terminates.
v An application can use only one plan.

If these limitations are too severe, consider having your application use the call
attachment facility or Resource Recovery Services attachment facility. For more
information about these attachment facilities, see “Call attachment facility” on page
49 and “Resource Recovery Services attachment facility” on page 79.

DSN return code processing: At the end of a DSN session, register 15 contains the
highest value that is placed there by any DSN subcommand that is used in the
session or by any program that is run by the RUN subcommand. Your run-time
environment might format that value as a return code. The value does not,
however, originate in DSN.

DB2I Run panel

The Run panel lets you start an application program that can contain SQL
statements.

You can reach the Run panel only through the DB2I Primary Options Menu. You
can accomplish the same task using the “Program Preparation: Compile, Link, and
Run” panel. You should use this panel if you have already prepared the program
and simply want to run it. Figure 63 shows the run options.

DSNERP01 RUN SSID: DSN

COMMAND ===>_

Enter the name of the program you want to run:

1 DATA SET NAME ===>
2 PASSWORD..... ===> (Required if data set is password protected)

Enter the following as desired:

3 PARAMETERS .. ===>
4 PLAN NAME ... ===> (Required if different from program name)
5 WHERE TO RUN ===> (FOREGROUND, BACKGROUND, or EDITJCL)

Figure 63. The Run panel

This panel lets you run existing application programs.

1 DATA SET NAME
Lets you specify the name of the partitioned data set that contains the load
module. If the module is in a data set that the operating system can find,
you can specify the member name only. There is no default.
If you do not enclose the name in apostrophes, a standard TSO prefix (user
ID) and suffix (.LOAD) is added.
2 PASSWORD
Lets you specify the data set password if needed. The RUN processor does

996 Application Programming and SQL Guide

not check whether you need a password. If you do not enter a required
password, your program does not run.
3 PARAMETERS
Lets you specify a list of parameters you want to pass either to your host
language run-time processor, or to your application. You should separate
items in the list with commas, blanks, or both. You can leave this field
blank.
Use a slash (/) to separate the options for your run-time processor from
those for your program.
v For PL/I and Fortran, run-time processor parameters must appear on
the left of the slash, and the application parameters must appear on the
right.
run-time processor parameters / application parameters
v For COBOL, reverse this order. Run-time processor parameters must
appear on the right of the slash, and the application parameters must
appear on the left.
v For assembler and C, there is no supported run-time environment, and
you need not use the slash to pass parameters to the application
program.
4 PLAN NAME
Lets you specify the name of the plan to which the program is bound. The
default is the member name of the program.
5 WHERE TO RUN
Lets you indicate whether to run in the foreground or background. You can
also specify EDITJCL, in which case you are able to edit the job control
statement before you run the program. Use:
FOREGROUND to immediately run the program in the foreground
with the specified values.
BACKGROUND to create and immediately submit to run a file
containing a DSNH CLIST using the JOB control statement from either
DB2I Defaults Panel 2 or your site’s SUBMIT exit. The program runs in
the background.
EDITJCL to create and open a file containing a DSNH CLIST in edit
mode. You can then submit the CLIST or save it. The program runs in
the background.
Running command processors
To run a command processor (CP), use the following commands from the
TSO ready prompt or as a TSO TMP:
DSN SYSTEM (DB2-subsystem-name)
RUN CP PLAN (plan-name)

The RUN subcommand prompts you for more input. The end the DSN
processor, use the END command.

Running a program in TSO foreground

Use the DB2I RUN panel to run a program in TSO foreground. As an alternative to
the RUN panel, you can issue the DSN command followed by the RUN
subcommand of DSN.

Before running the program, be sure to allocate any data sets that your program
needs.

Chapter 18. Running an application on DB2 for z/OS 997

The following example shows how to start a TSO foreground application. The
name of the application is SAMPPGM, and ssid is the system ID:
TSO Prompt: READY
Enter: DSN SYSTEM(ssid)
DSN Prompt: DSN
Enter: RUN PROGRAM(SAMPPGM) -
PLAN(SAMPLAN) -
LIB(SAMPPROJ.SAMPLIB) -
. PARMS('/D01 D02 D03')
.
.
(Here the program runs and might prompt you for input)
DSN Prompt: DSN
Enter: END
TSO Prompt: READY

This sequence also works in ISPF option 6. You can package this sequence in a
CLIST. DB2 does not support access to multiple DB2 subsystems from a single
address space.

The PARMS keyword of the RUN subcommand enables you to pass parameters to
the run-time processor and to your application program:
PARMS ('/D01, D02, D03')

The slash (/) indicates that you are passing parameters. For some languages, you
pass parameters and run-time options in the form PARMS(’parameters/run-time-
options). An example of the PARMS keyword might be:
PARMS ('D01, D02, D03/')

Check your host language publications for the correct form of the PARMS option.

Running a DB2 REXX application

You run DB2 REXX applications under TSO. You do not precompile, compile,
link-edit, or bind DB2 REXX applications before you run them.

In a batch environment, you might use statements like these to invoke application
REXXPROG:
//RUNREXX EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSEXEC DD DISP=SHR,DSN=SYSADM.REXX.EXEC
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
%REXXPROG parameters

The SYSEXEC data set contains your REXX application, and the SYSTSIN data set
contains the command that you use to invoke the application.

Invoking programs through the Interactive System Productivity Facility

You can use ISPF to invoke programs that connect to DB2 through the call
attachment facility (CAF).

The ISPF/CAF sample connection manager programs (DSN8SPM and DSN8SCM)

take advantage of the ISPLINK SELECT services, letting each routine make its own
connection to DB2 and establish its own thread and plan.

998 Application Programming and SQL Guide

With the same modular structure as in the previous example, using CAF is likely
to provide greater efficiency by reducing the number of CLISTs. This does not
mean, however, that any DB2 function executes more quickly.

Disadvantages: Compared to the modular structure using DSN, the structure using
CAF is likely to require a more complex program, which in turn might require
assembler language subroutines. For more information, see “Call attachment
facility” on page 49.

ISPF
The Interactive System Productivity Facility (ISPF) helps you to construct and
execute dialogs. DB2 includes a sample application that illustrates how to use ISPF
through the call attachment facility (CAF).

For more information about the ISPF/CAF sample application, see the topic
“Running dynamic SQL and the ISPF/CAF application” in DB2 Installation Guide.

For more information about using the sample applications, see “DB2 sample
applications” on page 1069.

For more information about printing the listing sample applications, see the topic
“Printing the sample application listings” in DB2 Installation Guide.

Each scenario has advantages and disadvantages in terms of efficiency, ease of

coding, ease of maintenance, and overall flexibility.

Using ISPF and the DSN command processor:

There are some restrictions on how you make and break connections to DB2 in any
structure. If you use the PGM option of ISPF SELECT, ISPF passes control to your
load module by the LINK macro; if you use CMD, ISPF passes control by the
ATTACH macro.

The DSN command processor (see “DSN command processor” on page 995)
permits only single task control block (TCB) connections. Take care not to change
the TCB after the first SQL statement. ISPF SELECT services change the TCB if you
started DSN under ISPF, so you cannot use these to pass control from load module
to load module. Instead, use LINK, XCTL, or LOAD.

The following figure shows the task control blocks that result from attaching the
DSN command processor below TSO or ISPF.

Chapter 18. Running an application on DB2 for z/OS 999

TSO or ISPF

ATTACH

DSN initialization
load module
Alias=DSN

ATTACH

Ordinary
DSN main load LINK
application
module
program
(See Note 2)
ATTACH

Application
command
processor
(See Note 1)

Figure 64. DSN task structure

Notes:
1. The RUN command with the CP option causes DSN to attach your program
and create a new TCB.
2. The RUN command without the CP option causes DSN to link to your
program.

If you are in ISPF and running under DSN, you can perform an ISPLINK to
another program, which calls a CLIST. In turn, the CLIST uses DSN and another
application. Each such use of DSN creates a separate unit of recovery (process or
transaction) in DB2.

All such initiated DSN work units are unrelated, with regard to isolation (locking)
and recovery (commit). It is possible to deadlock with yourself; that is, one unit
(DSN) can request a serialized resource (a data page, for example) that another
unit (DSN) holds incompatibly.

A COMMIT in one program applies only to that process. There is no facility for
coordinating the processes.

Invoking a single SQL program through ISPF and DSN

When a user invokes a single SQL program through ISPF and DSN, the user first
invokes ISPF, which displays the data and selection panels. When the user selects
the program on the selection panel, ISPF calls a CLIST that runs the program.

A corresponding CLIST might contain:

DSN
RUN PROGRAM(MYPROG) PLAN(MYPLAN)
END

The application has one large load module and one plan.

Disadvantages: For large programs of this type, you want a more modular design,
making the plan more flexible and easier to maintain. If you have one large plan,

1000 Application Programming and SQL Guide

you must rebind the entire plan whenever you change a module that includes SQL
statements. To achieve a more modular construction when all parts of the program
use SQL, consider using packages. See “DB2 program preparation overview” on
page 947 You cannot pass control to another load module that makes SQL calls by
using ISPLINK; rather, you must use LINK, XCTL, or LOAD and BALR.

If you want to use ISPLINK, then call ISPF to run under DSN:
DSN
RUN PROGRAM(ISPF) PLAN(MYPLAN)
END

You then need to leave ISPF before you can start your application.

Furthermore, the entire program is dependent on DB2; if DB2 is not running, no

part of the program can begin or continue to run.

Invoking multiple SQL programs through ISPF and DSN

You can break a large application into several different functions, each
communicating through a common pool of shared variables controlled by ISPF.

You might write some functions as separately compiled and loaded programs,
others as EXECs or CLISTs. You can start any of those programs or functions
through the ISPF SELECT service, and you can start that from a program, a CLIST,
or an ISPF selection panel.

When you use the ISPF SELECT service, you can specify whether ISPF should
create a new ISPF variable pool before calling the function. You can also break a
large application into several independent parts, each with its own ISPF variable
pool.

You can call different parts of the program in different ways. For example, you can
use the PGM option of ISPF SELECT:
PGM(program-name) PARM(parameters)

Alternatively, you can use the CMD option:

CMD(command)

For a part that accesses DB2, the command can name a CLIST that starts DSN:
DSN
RUN PROGRAM(PART1) PLAN(PLAN1) PARM(input from panel)
END

Breaking the application into separate modules makes it more flexible and easier to
maintain. Furthermore, some of the application might be independent of DB2;
portions of the application that do not call DB2 can run, even if DB2 is not
running. A stopped DB2 database does not interfere with parts of the program that
refer only to other databases.

Disadvantages: The modular application, on the whole, has to do more work. It

calls several CLISTs, and each one must be located, loaded, parsed, interpreted,
and executed. It also makes and breaks connections to DB2 more often than the
single load module. As a result, you might lose some efficiency.

Chapter 18. Running an application on DB2 for z/OS 1001

Loading and running a batch program
You can run a DL/I batch program by running module DSNMTV01, which loads
your application, or by running the application program directly.

To run a program using DB2, you need a DB2 plan. The bind process creates the
DB2 plan. DB2 first verifies whether the DL/I batch job step can connect to batch
job DB2. Then DB2 verifies whether the application program can access DB2 and
enforce user identification of batch jobs accessing DB2.

The two ways to submit DL/I batch applications to DB2 are:

v The DL/I batch procedure can run module DSNMTV01 as the application
program. DSNMTV01 loads the “real” application program.
v The DL/I batch procedure can run your application program without using
module DSNMTV01. To accomplish this, perform the following actions:
– Specify SSM= in the DL/I batch procedure.
– In the batch region of your application JCL, specify the following information:
- MBR=application-name
- SSM=DB2 subsystem name

Submitting a DL/I batch application using DSNMTV01: The following skeleton

JCL example illustrates a COBOL application program, IVP8CP22, that runs using
DB2 DL/I batch support.
v The first step uses the standard DLIBATCH IMS procedure.
v The second step shows how to use the DFSERA10 IMS program to print the
contents of the DDOTV02 output data set.
| //ISOCS04 JOB 3000,ISOIR,MSGLEVEL=(1,1),NOTIFY=ISOIR,
| // MSGCLASS=T,CLASS=A
| //JOBLIB DD DISP=SHR,
| // DSN=prefix.SDSNLOAD
| //* ******************************************************************
| //*
| //* THE FOLLOWING STEP SUBMITS COBOL JOB IVP8CP22, WHICH UPDATES
| //* BOTH DB2 AND DL/I DATABASES.
| //*
| //* ******************************************************************
| //UPDTE EXEC DLIBATCH,DBRC=Y,LOGT=SYSDA,COND=EVEN,
| // MBR=DSNMTV01,PSB=IVP8CA,BKO=Y,IRLM=N//G.STEPLIB DD
| // DD
| // DD DSN=prefix.SDSNLOAD,DISP=SHR
| // DD DSN=prefix.RUNLIB.LOAD,DISP=SHR
| // DD DSN=SYS1.COB2LIB,DISP=SHR
| // DD DSN=IMS.PGMLIB,DISP=SHR
| //G.DDOTV02 DD DSN=&TEMP1,DISP=(NEW,PASS,DELETE),
| // SPACE=(TRK,(1,1),RLSE),UNIT=SYSDA,
| // DCB=(RECFM=VB,BLKSIZE=4096,LRECL=4092)
| //G.DDITV02 DD *
| SSDQ,SYS1,DSNMIN10,,A,-,BATCH001,,IVP8CP22
| /*
| //***************************************************************
| //*** ALWAYS ATTEMPT TO PRINT OUT THE DDOTV02 DATA SET ***
| //***************************************************************
| //STEP3 EXEC PGM=DFSERA10,COND=EVEN
| //STEPLIB DD DSN=IMS.RESLIB,DISP=SHR
| //SYSPRINT DD SYSOUT=A
| //SYSUT1 DD DSNAME=&TEMP1,DISP=(OLD,DELETE)
| //SYSIN DD *

1002 Application Programming and SQL Guide

| CONTROL CNTL K=000,H=8000
| OPTION PRINT
| /*
| //

Submitting a DL/I batch application without using DSNMTV01: The skeleton

JCL in the following example illustrates a COBOL application program, IVP8CP22,
that runs using DB2 DL/I batch support.
//TEPCTEST JOB 'USER=ADMF001',MSGCLASS=A,MSGLEVEL=(1,1),
// TIME=1440,CLASS=A,USER=SYSADM,PASSWORD=SYSADM
//*******************************
//BATCH EXEC DLIBATCH,PSB=IVP8CA,MBR=IVP8CP22,
// BKO=Y,DBRC=N,IRLM=N,SSM=SSDQ
//*******************************
//SYSPRINT DD SYSOUT=A
//REPORT DD SYSOUT=*
//G.DDOTV02 DD DSN=&TEMP,DISP=(NEW,PASS,DELETE),
// SPACE=(CYL,(10,1),RLSE),
// UNIT=SYSDA,DCB=(RECFM=VB,BLKSIZE=4096,LRECL=4092)
//G.DDITV02 DD *
SSDQ,SYS1,DSNMIN10,,Q,",DSNMTES1,,IVP8CP22
//G.SYSIN DD *
/*
//****************************************************
//* ALWAYS ATTEMPT TO PRINT OUT THE DDOTV02 DATA SET
//****************************************************
//PRTLOG EXEC PGM=DFSERA10,COND=EVEN
//STEPLIB DD DSN=IMS.RESLIB,DISP=SHR
//SYSPRINT DD SYSOUT=*
//SYSOUT DD SYSOUT=*
//SYSUT1 DD DSN=&TEMP,DISP=(OLD,DELETE)
//SYSIN DD *
CONTROL CNTL K=000,H=8000
OPTION PRINT
/*

Authorization for running a batch DL/I program

When a DL/I batch application tries to run the first SQL statement, DB2 checks
whether the authorization ID has the EXECUTE privilege for the plan. DB2 uses
the same ID for later authorization checks and also identifies records from the
accounting and performance traces.

The primary authorization ID is the value of the USER parameter on the job
statement, if that is available. If that parameter is not available, the primary
authorization ID is the TSO logon name if the job is submitted. Otherwise, the
primary authorization ID is the IMS PSB name. In that case, however, the ID must
not begin with the string “SYSADM” because this string causes the job to
abnormally terminate. The batch job is rejected if you try to change the
authorization ID in an exit routine.

Restarting a batch program

To restart a batch program that updates data, you must first run the IMS batch
backout utility, followed by a restart job indicating the last successful checkpoint
ID.

For guidelines on finding the last successful checkpoint, see “Finding the DL/I
batch checkpoint ID” on page 1005.

JCL example of a batch backoutThe skeleton JCL example that follows illustrates a
batch backout for PSB=IVP8CA.

Chapter 18. Running an application on DB2 for z/OS 1003

| //ISOCS04 JOB 3000,ISOIR,MSGLEVEL=(1,1),NOTIFY=ISOIR,
| // MSGCLASS=T,CLASS=A
| //* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
| //* *
| //* BACKOUT TO LAST CHKPT. *
| //* IF RC=0028 LOG WITH NO-UPDATE *
| //* *
| //* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *
| //BACKOUT EXEC PGM=DFSRRC00,
| // PARM='DLI,DFSBBO00,IVP8CA,,,,,,,,,,,Y,N,,Y',
| // REGION=2600K,COND=EVEN |
| //* ---> DBRC ON
| //STEPLIB DD DSN=IMS.RESLIB,DISP=SHR
| //IMS DD DSN=IMS.PSBLIB,DISP=SHR
| // DD DSN=IMS.DBDLIB,DISP=SHR
| //*
| //* IMSLOGR DD data set is required
| //* IEFRDER DD data set is required
| //DFSVSAMP DD *
| OPTIONS,LTWA=YES
| 2048,7
| 1024,7
| /*
| //SYSIN DD DUMMY
| /*

JCL example of restarting a DL/I batch job: Operational procedures can restart a
DL/I batch job step for an application program using IMS XRST and symbolic
CHKP calls.

You cannot restart a BMP application program in a DB2 DL/I batch environment.
The symbolic checkpoint records are not accessed, causing an IMS user abend
U0102.

To restart a batch job that terminated abnormally or prematurely, find the

checkpoint ID for the job on the z/OS system log or from the SYSOUT listing of
the failing job. Before you restart the job step, place the checkpoint ID in the
CKPTID=value option of the DLIBATCH procedure, submit the job. If the default
connection name is used (that is, you did not specify the connection name option
in the DDITV02 input data set), the job name of the restart job must be the same as
the failing job. Refer to the following skeleton example, in which the last
checkpoint ID value was IVP80002:
| //ISOCS04 JOB 3000,OJALA,MSGLEVEL=(1,1),NOTIFY=OJALA,
| // MSGCLASS=T,CLASS=A
| //* ******************************************************************
| //*
| //* THE FOLLOWING STEP RESTARTS COBOL PROGRAM IVP8CP22, WHICH UPDATES
| //* BOTH DB2 AND DL/I DATABASES, FROM CKPTID=IVP80002.
| //*
| //* ******************************************************************
| //RSTRT EXEC DLIBATCH,DBRC=Y,COND=EVEN,LOGT=SYSDA,
| // MBR=DSNMTV01,PSB=IVP8CA,BKO=Y,IRLM=N,CKPTID=IVP80002
| //G.STEPLIB DD
| // DD
| // DD DSN=prefix.SDSNLOAD,DISP=SHR
| // DD DSN=prefix.RUNLIB.LOAD,DISP=SHR
| // DD DSN=SYS1.COB2LIB,DISP=SHR
| // DD DSN=IMS.PGMLIB,DISP=SHR
| //* other program libraries
| //* G.IEFRDER data set required
| //* G.IMSLOGR data set required
| //G.DDOTV02 DD DSN=&TEMP2,DISP=(NEW,PASS,DELETE),
| // SPACE=(TRK,(1,1),RLSE),UNIT=SYSDA,

1004 Application Programming and SQL Guide

| // DCB=(RECFM=VB,BLKSIZE=4096,LRECL=4092)
| //G.DDITV02 DD *
| DB2X,SYS1,DSNMIN10,,A,-,BATCH001,,IVP8CP22
| /*
| //***************************************************************
| //*** ALWAYS ATTEMPT TO PRINT OUT THE DDOTV02 DATA SET ***
| //***************************************************************
| //STEP8 EXEC PGM=DFSERA10,COND=EVEN
| //STEPLIB DD DSN=IMS.RESLIB,DISP=SHR
| //SYSPRINT DD SYSOUT=A
| //SYSUT1 DD DSNAME=&TEMP2,DISP=(OLD,DELETE)
| //SYSIN DD *
| CONTROL CNTL K=000,H=8000
| OPTION PRINT
| /*
| //

Finding the DL/I batch checkpoint ID

When an application program issues an IMS CHKP call, IMS sends the checkpoint
ID to the z/OS console and the SYSOUT listing in message DFS0540I.

IMS also records the checkpoint ID in the type X’41’ IMS log record. Symbolic
CHKP calls also create one or more type X’18’ records on the IMS log. XRST uses
the type X’18’ log records to reposition DL/I databases and return information to
the application program.

During the commit process the application program checkpoint ID is passed to

DB2. If a failure occurs during the commit process, creating an indoubt work unit,
DB2 remembers the checkpoint ID. You can use the following techniques to find
the last checkpoint ID:
v Look at the SYSOUT listing for the job step to find message DFS0540I, which
contains the checkpoint IDs that are issued. Use the last listed checkpoint ID.
v Look at the z/OS console log to find message DFS0540I that contains the
checkpoint ID that is issued for this batch program. Use the last listed
checkpoint ID.
v Submit the IMS Batch Backout utility to back out the DL/I databases to the last
(default) checkpoint ID. When the batch backout finishes, message DFS395I
provides the last valid IMS checkpoint ID. Use this checkpoint ID on restart.
v When restarting DB2, issue the command -DISPLAY THREAD(*) TYPE(INDOUBT) to
obtain a possible indoubt unit of work (connection name and checkpoint ID). If
you restarted the application program from this checkpoint ID, the program
could work because the checkpoint is recorded on the IMS log; however, the
program could fail with an IMS user abend U102 because IMS did not finish
logging the information before the failure. In that case, restart the application
program from the previous checkpoint ID.

DB2 performs one of two actions automatically when restarted, if the failure occurs
outside the indoubt period: it either backs out the work unit to the prior
checkpoint, or it commits the data without any assistance. If the operator then
issues the following command, no work unit information is displayed:
-DISPLAY THREAD(*) TYPE(INDOUBT)

Chapter 18. Running an application on DB2 for z/OS 1005

| Running stored procedures from the command line processor
| As an alternative to calling a stored procedure from an application program, you
| can use the command line processor to invoke stored procedures.

| To run a stored procedure from the command line processor:

| 1. Invoke the command line processor and connect to the appropriate DB2
| subsystem. For more information about how to perform these tasks, see the
| topic Command Line Processor (DB2 Command Reference).
| 2. Specify the CALL statement in the form that is acceptable for the command line
| processor. For more information about the CALL statement for the command
| line processor, see “Command line processor CALL statement.”
| Related tasks
| Implementing DB2 stored procedures (DB2 Administration Guide)

| Command line processor CALL statement

| Use the command line processor CALL statement to invoke stored procedures from
| the command line processor.

| Use the following syntax for the command line processor CALL statement.

| (1)


CALL procedure-name ( )

,
(2) (3) (4)
 parameter
|
| Notes:
| 1 If you specify an unqualified stored procedure name, DB2 searches the
| schema list in the CURRENT PATH special register. DB2 searches this list for
| a stored procedure with the specified number of input and output
| parameters.
| 2 Specify a question mark (?) as a placeholder for each output parameter.
| 3 For non-numeric, BLOB, or CLOB input parameters, enclose each value in
| single quotation marks (’). The exception is if the data is a BLOB or CLOB
| value that is to be read from a file. In that case, use the notation file://fully
| qualified file name.
| 4 Specify the input and output parameters in the order that they are specified
| in the signature for the stored procedure.

| Example: Assume that the TEST.DEPT_MEDIAN stored procedure was created

| with the following statement:
| CREATE PROCEDURE TEST.DEPT_MEDIAN
| (IN DEPTNUMBER SMALLINT, OUT MEDIANSALARY INT)

| To invoke the stored procedure from the command line processor, you can specify
| the following CALL statement:
| CALL TEST.DEPT_MEDIAN(51, ?)

| Assume that the stored procedure returns a value of 25,000. The following
| information is displayed by the command line processor:

1006 Application Programming and SQL Guide

| Value of output parameters
| --------------------------
| Parameter Name : MEDIANSALARY
| Parameter Value : 25000

| Example: Suppose that stored procedure TEST.BLOBSP is defined with one input
| parameter of type BLOB and one output parameter. You can invoke this stored
| procedure from the command line processor with the following statement:
| CALL TEST.BLOBSP(file:///tmp/photo.bmp,?)

| The command line processor reads the contents from /tmp/photo.bmp as the
| input parameter. Alternatively, you can invoke this stored procedure by specifying
| the input parameter in the CALL statement itself, as in the following example:
| CALL TEST.BLOBSP('abcdef',?)
|
Example of running a batch DB2 application in TSO
Most application programs that are written for the batch environment run under
the TSO Terminal Monitor Program (TMP) in background mode.

The following figure shows the JCL statements that you need in order to start such
a job. The list that follows explains each statement.
//jobname JOB USER=MY DB2ID
//GO EXEC PGM=IKJEFT01,DYNAMNBR=20
//STEPLIB DD DSN=prefix.SDSNEXIT,DISP=SHR
//
. DD DSN=prefix.SDSNLOAD,DISP=SHR
.
.
//SYSTSPRT DD SYSOUT=A
//SYSTSIN DD *
DSN SYSTEM (ssid)
RUN PROG (SAMPPGM) -
PLAN (SAMPLAN) -
LIB (SAMPPROJ.SAMPLIB) -
PARMS ('/D01 D02 D03')
END
/*
v The JOB option identifies this as a job card. The USER option specifies the DB2
authorization ID of the user.
v The EXEC statement calls the TSO Terminal Monitor Program (TMP).
v The STEPLIB statement specifies the library in which the DSN Command
Processor load modules and the default application programming defaults
module, DSNHDECP, reside. It can also reference the libraries in which user
applications, exit routines, and the customized DSNHDECP module reside. The
customized DSNHDECP module is created during installation.
v Subsequent DD statements define additional files that are needed by your
program.
v The DSN command connects the application to a particular DB2 subsystem.
v The RUN subcommand specifies the name of the application program to run.
v The PLAN keyword specifies plan name.
v The LIB keyword specifies the library that the application should access.
v The PARMS keyword passes parameters to the run-time processor and the
application program.
v END ends the DSN command processor.

Usage notes:

Chapter 18. Running an application on DB2 for z/OS 1007

v Keep DSN job steps short.
v Recommendation: Do not use DSN to call the EXEC command processor to run
CLISTs that contain ISPEXEC statements; results are unpredictable.
v If your program abends or gives you a non-zero return code, DSN terminates.
v You can use a group attachment name instead of a specific ssid to connect to a
member of a data sharing group.
For more information about using the TSO TMP in batch mode, see z/OS TSO/E
User’s Guide.

Example of calling applications in a command procedure

As an alternative to foreground or batch calls to an application, you can run a TSO
or batch application using a command procedure (CLIST).

The following CLIST calls a DB2 application program named MYPROG. ssid
represents the DB2 subsystem name or group attachment name.
PROC 0 /* INVOCATION OF DSN FROM A CLIST */
DSN SYSTEM(ssid) /* INVOKE DB2 SUBSYSTEM ssid */
IF &LASTCC = 0 THEN /* BE SURE DSN COMMAND WAS SUCCESSFUL */
DO /* IF SO THEN DO DSN RUN SUBCOMMAND */
DATA /* ELSE OMIT THE FOLLOWING: */
RUN PROGRAM(MYPROG)
END
ENDDATA /* THE RUN AND THE END ARE FOR DSN */
END
EXIT

IMS: To run a message-driven program

First, ensure that you can respond to the program’s interactive requests for data
and that you can recognize the expected results. Then, enter the transaction code
that is associated with the program. Users of the transaction code must be
authorized to run the program.

To run a non-message-driven program

CICSTo run a program

First, ensure that the corresponding entries in the SNT and RACF control areas
allow run authorization for your application. The system administrator is
responsible for these functions.

Submit the job control statements that are needed to run the program.

Also, be sure to define to CICS the transaction code that is assigned to your
program and the program itself.

Make a new copy of the program

Issue the NEWCOPY command if CICS has not been reinitialized since the
program was last bound and compiled.

1008 Application Programming and SQL Guide

Chapter 19. Testing and debugging an application program on
DB2 for z/OS
Depending on the situation, testing your application program might involve setting
up a test environment, testing SQL statements, debugging your programs and
reading output from the precompiler.

Designing a test data structure

When you test an application that accesses DB2 data, you should have DB2 data
available for testing. To do this, you can create test tables and views.
v Test views of existing tables: If your application does not change a set of DB2
data and the data exists in one or more production-level tables, you might
consider using a view of existing tables.
v Test tables: To create a test table, you need a database and table space. Talk with
your DBA to make sure that a database and table spaces are available for your
use.
If the data that you want to change already exists in a table, consider using the
LIKE clause of CREATE TABLE. If you want others besides yourself to have
ownership of a table for test purposes, you can specify a secondary ID as the
owner of the table. You can do this with the SET CURRENT SQLID statement.
For more information about this statement, see the topic “SET CURRENT
SQLID” in DB2 SQL Reference. For more information about authorization IDs, see
the topic “Authorization IDs”in DB2 Administration Guide .

If your location has a separate DB2 system for testing, you can create the test
tables and views on the test system and then test your program thoroughly on that
system. This information assumes that you do all testing on a separate system, and
that the person who created the test tables and views has an authorization ID of
TEST. The table names are TEST.EMP, TEST.PROJ and TEST.DEPT.

Analyzing application data needs

To design tests of an application, you need to determine the type of data that the
application uses, and how the application accesses that data.

This information assumes that you do all testing on a separate system, and that the
person who created the test tables and views has an authorization ID of TEST. The
table names are TEST.EMP, TEST.PROJ and TEST.DEPT.

To design test tables and views, first analyze the data needs of your application.
1. List the data that your application accesses and describe how it accesses each
data item. For example, suppose that you are testing an application that
accesses the DSN8910.EMP, DSN8910.DEPT, and DSN8910.PROJ tables. You
might record the information about the data as shown in Table 162 on page
1010.

© Copyright IBM Corp. 1983, 2009 1009

Table 162. Description of the application data
Update
Table or view name Insert rows? Delete rows? Column name Data type access?
DSN8910.EMP No No EMPNO CHAR(6) No
LASTNAME VARCHAR(15) No
WORKDEPT CHAR(3) Yes
PHONENO CHAR(4) Yes
JOB DECIMAL(3) Yes
DSN8910.DEPT No No DEPTNO CHAR(3) No
MGRNO CHAR (6) No
DSN8910.PROJ Yes Yes PROJNO CHAR(6) No
DEPTNO CHAR(3) Yes
RESPEMP CHAR(6) Yes
PRSTAFF DECIMAL(5,2) Yes
PRSTDATE DECIMAL(6) Yes
PRENDATE DECIMAL(6) Yes

2. Determine the test tables and views that you need to test your application.
Create a test table on your list when either of the following conditions exists:
v The application modifies data in the table.
v You need to create a view that is based on a test table because your
application modifies data in the view.
To continue the example, create these test tables:
v TEST.EMP, with the following format:

EMPNO LASTNAME WORKDEPT PHONENO JOB

. . . . .
. . . . .
. . . . .

v TEST.PROJ, with the same columns and format as DSN8910.PROJ, because

the application inserts rows into the DSN8910.PROJ table.
To support the example, create a test view of the DSN8910.DEPT table.
v TEST.DEPT view, with the following format:

DEPTNO MGRNO
. .
. .
. .

Because the application does not change any data in the DSN8910.DEPT table,
you can base the view on the table itself (rather than on a test table). However,
a safer approach is to have a complete set of test tables and to test the program
thoroughly using only test data.

Authorization for test tables and applications

Before you can create a table, you need to be authorized to create tables and to use
the table space in which the table is to reside. You must also have authority to
bind and run programs you want to test.

1010 Application Programming and SQL Guide

Your DBA can grant you the necessary authorization to create and access tables
and to bind and run programs.

If you intend to use existing tables and views (either directly or as the basis for a
view), you need privileges to access those tables and views. Your DBA can grant
those privileges.

To create a view, you must have authorization for each table and view on which
you base the view. You then have the same privileges over the view that you have
over the tables and views on which you based the view. Before trying the
examples, have your DBA grant you the privileges to create new tables and views
and to access existing tables. Obtain the names of tables and views that you are
authorized to access (as well as the privileges you have for each table) from your
DBA.

Example SQL statements to create a comprehensive test

structure
You need to create a storage group, database, table space, and table to use as a test
structure for your SQL application.

The following SQL statements show how to create a complete test structure to
contain a small table named SPUFINUM. The test structure consists of:
v A storage group named SPUFISG
v A database named SPUFIDB
v A table space named SPUFITS in database SPUFIDB and using storage group
SPUFISG
v A table named SPUFINUM within the table space SPUFITS
CREATE STOGROUP SPUFISG
VOLUMES (user-volume-number)
VCAT DSNCAT ;

CREATE DATABASE SPUFIDB ;

CREATE TABLESPACE SPUFITS

IN SPUFIDB
USING STOGROUP SPUFISG ;

CREATE TABLE SPUFINUM

( XVAL CHAR(12) NOT NULL,
ISFLOAT FLOAT,
DEC30 DECIMAL(3,0),
DEC31 DECIMAL(3,1),
DEC32 DECIMAL(3,2),
DEC33 DECIMAL(3,3),
DEC10 DECIMAL(1,0),
DEC11 DECIMAL(1,1),
DEC150 DECIMAL(15,0),
DEC151 DECIMAL(15,1),
DEC1515 DECIMAL(15,15) )
IN SPUFIDB.SPUFITS ;

For more information about the syntax of each CREATE statement, see the topics
“CREATE STOGROUP”, “CREATE DATABASE”“CREATE TABLESPACE” and
“CREATE TABLE” in DB2 SQL Reference.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1011
Populating the test tables with data
To populate test tables, use SQL INSERT statements or the LOAD utility.

You can put test data into a table in several ways:

v INSERT ... VALUES (an SQL statement) puts one row into a table each time the
statement executes. For information about the INSERT statement, see “Inserting
rows by using the INSERT statement” on page 605.
v INSERT ... SELECT (an SQL statement) obtains data from an existing table
(based on a SELECT clause) and puts it into the table that is identified in the
INSERT statement. For information about this technique, see “Inserting rows
into a table from another table” on page 607.
| v MERGE (an SQL statement) puts new data into a table and updates existing
| data. For more information about the MERGE statement, see “Inserting data and
| updating data in a single operation” on page 611.
v The LOAD utility obtains data from a sequential file (a non-DB2 file), formats it
for a table, and puts it into a table. For more information about the LOAD
utility, see the topic “LOAD” in DB2 Utility Guide and Reference.
v The DB2 sample UNLOAD program (DSNTIAUL) can unload data from a table
or view and build control statements for the LOAD utility. For more information
about the sample UNLOAD program, see “DB2 sample applications” on page
1069.
v The UNLOAD utility can unload data from a table and build control statements
for the LOAD utility. For more information about the UNLOAD utility, see the
topic “UNLOAD” in DB2 Utility Guide and Reference.

Methods for testing SQL statements

You can test your SQL statements by using SPUFI or the command line processor.

Test with SPUFI:You can use SPUFI (an interface between ISPF and DB2) to test
SQL statements in a TSO/ISPF environment. With SPUFI panels, you can put SQL
statements into a data set that DB2 subsequently executes. The SPUFI Main panel
has several functions that enable you to:
v Name an input data set to hold the SQL statements that are passed to DB2 for
execution
v Name an output data set to contain the results of executing the SQL statements
v Specify SPUFI processing options
For more information about how to use SPUFI, see “Executing SQL by using
SPUFI” on page 1013.

| Test with the command line processor: You can use the command line processor
| to test SQL statements from UNIX System Services on z/OS. For more information
| about how to use the command line processor and which statements you can run,
| see the topic “Working with DB2 Commands” in DB2 Command Reference.

| SQL statements that are executed under SPUFI or the command line processor
| operate on actual tables (in this case, the tables that you created for testing).
| Consequently, before you access DB2 data:
| v Make sure that all tables and views that your SQL statements refer to exist.

1012 Application Programming and SQL Guide

| v If the tables or views do not exist, create them (or have your database
| administrator create them). You can use SPUFI or the command line processor to
| issue the CREATE statements that are used to create the tables and views that
| you need for testing.

Executing SQL by using SPUFI

You can execute SQL statements in a TSO session by using the SPUFI (SQL
processor using file input) facility.

Before you use SPUFI, allocate an input data set to store the SQL statements that
you want to execute, if such a data set does not already exist. For information
about allocating data sets, see z/OS ISPF User’s Guide Volumes 1 and 2.

Important: Ensure that the TSO terminal CCSID matches the DB2 CCSID. If these
CCSIDs do not match, data corruption can occur. If SPUFI issues the warning
message DSNE345I, terminate your SPUFI session and notify the system
administrator.

Before you begin this task, you can specify whether TSO message IDs are
displayed by using the TSO PROFILE command. To view message IDs, type TSO
PROFILE MSGID on the ISPF command line. To suppress message IDs, type TSO
PROFILE NOMSGID.

These instructions assume that ISPF is available to you.

To execute SQL by using SPUFI:

1. Open SPUFI and specify the initial options.
2. Optional: “Changing SPUFI defaults” on page 1019
3. Enter SQL statements in SPUFI.
4. Process SQL statements with SPUFI.

Opening SPUFI and specifying initial options:

To being using SPUFI, you need to open and fill out the SPUFI panel.

To open SPUFI and specify initial options:

1. Select SPUFI from the DB2I Primary Option Menu as shown in Figure 45 on
page 955.The SPUFI panel is displayed.
2. Specify the input data set name and output data set name.An example of a
SPUFI panel in which an input data set and output data set have been specified
is shown in the following figure.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1013
DSNESP01 SPUFI SSID: DSN
===>
Enter the input data set name: (Can be sequential or partitioned)
1 DATA SET NAME..... ===> EXAMPLES(XMP1)
2 VOLUME SERIAL..... ===> (Enter if not cataloged)
3 DATA SET PASSWORD. ===> (Enter if password protected)

Enter the output data set name: (Must be a sequential data set)
4 DATA SET NAME..... ===> RESULT

Specify processing options:

5 CHANGE DEFAULTS... ===> Y (Y/N - Display SPUFI defaults panel?)
6 EDIT INPUT........ ===> Y (Y/N - Enter SQL statements?)
7 EXECUTE........... ===> Y (Y/N - Execute SQL statements?)
8 AUTOCOMMIT........ ===> Y (Y/N - Commit after successful run?)
9 BROWSE OUTPUT..... ===> Y (Y/N - Browse output data set?)

For remote SQL processing:

10 CONNECT LOCATION ===>

PRESS: ENTER to process END to exit HELP for more information

Figure 65. The SPUFI panel filled in

3. Optional: Specify new values in any of the other fields on the SPUFI panel. For
more information about these fields, see “The SPUFI panel” on page 1017.

Entering SQL statements in SPUFI:

After you open SPUFI, specify the initial options, and optionally change any SPUFI
defaults, you can enter one or more SQL statements to execute.

Before you begin this task, you must complete the task ″Opening SPUFI and
specifying initial options.″

If the input data set that you specified on the SPUFI panel already contains all of
the SQL statements that you want to execute, you can bypass this editing step by
specifying NO for the EDIT INPUT field on the SPUFI panel.

To enter SQL statements by using SPUFI:

1. If the EDIT panel is not already open, on the SPUFI panel, specify Y in the
EDIT INPUT field and press ENTER. If the input data set that you specified is
empty, an empty EDIT panel opens. Otherwise, if the input data set contained
SQL statements, those SQL statements are displayed in an EDIT panel.
2. On the EDIT panel, use the ISPF EDIT program to enter or edit any SQL
statements that you want to execute. Move the cursor to the first blank input
line, and enter the first part of an SQL statement. You can enter the rest of the
SQL statement on subsequent lines, as shown in the following figure:

EDIT --------userid.EXAMPLES(XMP1) --------------------- COLUMNS 001 072

COMMAND INPUT ===> SAVE SCROLL ===> PAGE
********************************** TOP OF DATA ***********************
000100 SELECT LASTNAME, FIRSTNME, PHONENO
000200 FROM DSN8910.EMP
000300 WHERE WORKDEPT= 'D11'
000400 ORDER BY LASTNAME;
********************************* BOTTOM OF DATA *********************

Figure 66. The edit panel: After entering an SQL statement

1014 Application Programming and SQL Guide

Consider the following rules and recommendations when editing this input
data set:
v Indent your lines and enter your statements on several lines to make your
statements easier to read. Entering your statements on multiple lines does
not change how your statements are processed.
v Do not put more than one SQL statement on a single line. If you do, the first
statement executes, but DB2 ignores the other SQL statements on the same
line. You can put more than one SQL statement in the input data set. DB2
executes the statements in the order in which you placed them in the data
set.
v End each SQL statement with the statement terminator that you specified on
the CURRENT SPUFI DEFAULTS panel.
v Save the data set every 10 minutes or so by entering the SAVE command.
3. Press the END PF key. The data set is saved, and the SPUFI panel is displayed.

Processing SQL statements with SPUFI

You can use SPUFI to submit the SQL statements in a data set to DB2.

Before you begin this task, you must:

v Complete the task ″Opening SPUFI and specifying initial options.″
v Ensure that the input data set contains the SQL statements that you want to
execute.

To process SQL statements by using SPUFI:

1. On the SPUFI panel, specify YES in the EXECUTE field.
2. If you did not just finish using the EDIT panel to edit the input data set as
described in ″Entering SQL statements in SPUFI,″ specify NO In the EDIT
INPUT field.
3. Press Enter.
SPUFI passes the input data set to DB2 for processing. DB2 executes the SQL
statement in the input data set and sends the output to the output data set.
The output data set opens.
Your SQL statement might take a long time to execute, depending on how large
a table DB2 must search, or on how many rows DB2 must process. In this case,
you can interrupt the processing by pressing the PA1 key. Then respond to the
message that asks you if you really want to stop processing. This action cancels
the executing SQL statement. Depending on how much of the input data set
DB2 was able to process before you interrupted its processing, DB2 might not
have opened the output data set yet, or the output data set might contain all or
part of the results data that are produced so far.

For information about how to interpret the output in the output data set, see
“Output from SPUFI” on page 1025.

SQL statements that exceed resource limit thresholds:

Your system administrator might use the DB2 resource limit facility (governor) to
set time limits for processing SQL statements in SPUFI. Those limits can be error
limits or warning limits.

If you execute an SQL statement through SPUFI that runs longer than this error
time limit, SPUFI terminates processing of that SQL statement and all statements

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1015
that follow in the SPUFI input data set. SPUFI displays a panel that lets you
commit or roll back the previously uncommitted changes that you have made.
That panel is shown in the following figure.

DSNESP04 SQL STATEMENT RESOURCE LIMIT EXCEEDED SSID: DSN

===>

The following SQL statement has encountered an SQLCODE of -905 or -495:

Statement text

Your SQL statement has exceeded the resource utilization threshold set
by your site administrator.

You must ROLLBACK or COMMIT all the changes made since the last COMMIT.
SPUFI processing for the current input file will terminate immediately
after the COMMIT or ROLLBACK is executed.

1 NEXT ACTION ===> (Enter COMMIT or ROLLBACK)

PRESS: ENTER to process HELP for more information

Figure 67. The resource limit facility error panel

If you execute an SQL statement through SPUFI that runs longer than the warning
time limit for predictive governing, SPUFI displays the SQL STATEMENT
RESOURCE LIMIT EXCEEDED panel. On this panel, you can tell DB2 to continue
executing that statement, or stop processing that statement and continue to the
next statement in the SPUFI input data set. That panel is shown in the following
figure.

DSNESP05 SQL STATEMENT RESOURCE LIMIT EXCEEDED SSID: DSN

===>

The following SQL statement has encountered an SQLCODE of 495:

Statement text

You can now either CONTINUE executing this statement or BYPASS the execution
of this statement. SPUFI processing for the current input file will continue
after the CONTINUE or BYPASS processing is completed.

1 NEXT ACTION ===> (Enter CONTINUE or BYPASS)

PRESS: ENTER to process HELP for more information

Figure 68. The resource limit facility warning panel

For information about the DB2 governor and how to set error and warning time
limits, see the topic “Controlling resource usage” in DB2 Administration Guide.

SPUFI
You can use SPUFI to execute SQL statements dynamically.

1016 Application Programming and SQL Guide

SPUFI can execute SQL statements that retrieve Unicode UTF-16 graphic data.
However, SPUFI might not be able to display some characters, if those characters
have no mapping in the target SBCS EBCDIC CCSID.

Content of a SPUFI input data set

A SPUFI input data set can contain SQL statements, comments, and SPUFI control
statements.

You can put comments about SQL statements either on separate lines or on the
same line. In either case, use two hyphens (--) to begin a comment. Specify any
text other than #SET TERMINATOR or #SET TOLWARN after the comment
marker. DB2 ignores everything else to the right of the two hyphens.

The SPUFI panel

The SPUFI panel is the first panel that you need to fill out to run the SPUFI
application.

After you complete any fields on the SPUFI panel and press Enter, those settings
are saved. When the SPUFI panel displays again, the data entry fields on the panel
contain the values that you previously entered. You can specify data set names and
processing options each time the SPUFI panel is displayed, as needed. Values that
you do not change remain in effect.

The following descriptions explain the fields that are available on the SPUFI panel.
1,2,3 INPUT DATA SET NAME
Identify the input data set in fields 1 through 3. This data set contains one
or more SQL statements that you want to execute. Allocate this data set
before you use SPUFI, if one does not already exist. Consider the following
rules:
v The name of the data set must conform to standard TSO naming
conventions.
v The data set can be empty before you begin the session. You can then
add the SQL statements by editing the data set from SPUFI.
v The data set can be either sequential or partitioned, but it must have the
following DCB characteristics:
– A record format (RECFM) of either F or FB.
– A logical record length (LRECL) of either 79 or 80. Use 80 for any
data set that the EXPORT command of DB2 QMF did not create.
v Data in the data set can begin in column 1. It can extend to column 71 if
the logical record length is 79, and to column 72 if the logical record
length is 80. SPUFI assumes that the last 8 bytes of each record are for
sequence numbers.
If you use this panel a second time, the name of the data set you
previously used displays in the field DATA SET NAME. To create a new
member of an existing partitioned data set, change only the member name.
4 OUTPUT DATA SET NAME
Enter the name of a data set to receive the output of the SQL statement.
You do not need to allocate the data set before you do this.
If the data set exists, the new output replaces its content. If the data set
does not exist, DB2 allocates a data set on the device type specified on the
CURRENT SPUFI DEFAULTS panel and then catalogs the new data set.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1017
The device must be a direct-access storage device, and you must be
authorized to allocate space on that device.
Attributes required for the output data set are:
v Organization: sequential
v Record format: F, FB, FBA, V, VB, or VBA
v Record length: 80 to 32768 bytes, not less than the input data set
“Executing SQL by using SPUFI” on page 1013 shows the simplest choice,
entering RESULT. SPUFI allocates a data set named userid.RESULT and
sends all output to that data set. If a data set named userid.RESULT already
exists, SPUFI sends DB2 output to it, replacing all existing data.
5 CHANGE DEFAULTS
Enables you to change control values and characteristics of the output data
set and format of your SPUFI session. If you specify Y(YES) you can look
at the SPUFI defaults panel. See “Changing SPUFI defaults” on page 1019
for more information about the values you can specify and how they affect
SPUFI processing and output characteristics. You do not need to change
the SPUFI defaults for this example.
6 EDIT INPUT
To edit the input data set, leave Y(YES) on line 6. You can use the ISPF
editor to create a new member of the input data set and enter SQL
statements in it. (To process a data set that already contains a set of SQL
statements you want to execute immediately, enter N (NO). Specifying N
bypasses the step 3 described in “Executing SQL by using SPUFI” on page
1013.)
7 EXECUTE
To execute SQL statements contained in the input data set, leave Y(YES) on
line 7.
SPUFI handles the SQL statements that can be dynamically prepared.
8 AUTOCOMMIT
To make changes to the DB2 data permanent, leave Y(YES) on line 8.
Specifying Y makes SPUFI issue COMMIT if all statements execute
successfully. If all statements do not execute successfully, SPUFI issues a
ROLLBACK statement, which deletes changes already made to the file
(back to the last commit point). For information about the COMMIT
statement, see the topic “COMMIT” in DB2 SQL Reference. For information
about the ROLLBACK statement, see the topic “ROLLBACK” in DB2 SQL
Reference.
If you specify N, DB2 displays the SPUFI COMMIT OR ROLLBACK panel
after it executes the SQL in your input data set. That panel prompts you to
COMMIT, ROLLBACK, or DEFER any updates made by the SQL. If you
enter DEFER, you neither commit nor roll back your changes.
9 BROWSE OUTPUT
To look at the results of your query, leave Y(YES) on line 9. SPUFI saves
the results in the output data set. You can look at them at any time, until
you delete or write over the data set.
10 CONNECT LOCATION
Specify the name of the database server, if applicable, to which you want
to submit SQL statements. SPUFI then issues a type 2 CONNECT
statement to this server.

1018 Application Programming and SQL Guide

SPUFI is a locally bound package. SQL statements in the input data set can
process only if the CONNECT statement is successful. If the connect
request fails, the output data set contains the resulting SQL return codes
and error messages.

Changing SPUFI defaults

Before you execute SQL statements in SPUFI, you can change the default execution
behavior, such as the SQL terminator and the isolation level.

SPUFI provides default values the first time that you use SPUFI for all options
except the DB2 subsystem name. Any changes that you make to these values
remain in effect until you change the values again.

To change the SPUFI defaults:

1. On the SPUFI panel, specify YES in the CHANGE DEFAULTS field.
2. Press Enter. The CURRENT SPUFI DEFAULTS panel opens. The following
figure shows the initial default values.

| DSNESP02 CURRENT SPUFI DEFAULTS SSID: DSN

| ===>
| Enter the following to control your SPUFI session:
| 1 SQL TERMINATOR .. ===> ; (SQL Statement Terminator)
| 2 ISOLATION LEVEL ===> RR (RR=Repeatable Read, CS=Cursor Stability)
| UR=Uncommitted Read)
| 3 MAX SELECT LINES ===> 250 (Maximum lines to be returned from a SELECT)
| 4 ALLOW SQL WARNINGS===> NO (Continue fetching after SQL warning)
| 5 CHANGE PLAN NAMES ===> NO (Change the plan names used by SPUFI)
| 6 SQL FORMAT ...... ===> SQL (SQL, SQLCOMNT, or SQLPL)
| Output data set characteristics:
| 7 SPACE UNIT ...... ===> TRK (TRK or CYL)
| 8 PRIMARY SPACE ... ===> 5 (Primary space allocation 1-999)
| 9 SECONDARY SPACE . ===> 6 (Secondary space allocation 0-999)
| 10 RECORD LENGTH ... ===> 4092 (LRECL= logical record length)
| 11 BLOCKSIZE ....... ===> 4096 (Size of one block)
| 12 RECORD FORMAT.... ===> VB (RECFM= F, FB, FBA, V, VB, or VB)
| 13 DEVICE TYPE...... ===> SYSDA (Must be a DASD unit name)
| Output format characteristics:
| 14 MAX NUMERIC FIELD ===> 33 (Maximum width for numeric field)
| 15 MAX CHAR FIELD .. ===> 80 (Maximum width for character field)
| 16 COLUMN HEADING .. ===> NAMES (NAMES, LABELS, ANY, or BOTH)
| 17 FOR BIT DATA .... ===> ASIS (ASIS or HEX)
|
|
|
| PRESS: ENTER to process END to exit HELP for more information
||
| Figure 69. The SPUFI defaults panel
|
3. Specify any new values in the fields of this panel. All fields must contain a
value. For more information about these values, see “CURRENT SPUFI
DEFAULTS panel” on page 1020.
4. Press Enter. SPUFI saves your changes and one of the following panels or data
sets open:
v The CURRENT SPUFI DEFAULTS - PANEL 2 panel. This panel opens if you
specified YES in the CHANGE PLAN NAMES field.
v EDIT panel. This panel opens if you specified YES in the EDIT INPUT field
on the SPUFI panel.
v Output data set. This data set opens if you specified NO in the EDIT INPUT
field on the SPUFI panel.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1019
v SPUFI panel. This panel opens if you specified NO for all of the processing
options on the SPUFI panel.
If you press the END key on the CURRENT SPUFI DEFAULTS panel, the
SPUFI panel is displayed, and you lose all the changes that you made on the
CURRENT SPUFI DEFAULTS panel.
5. If the CURRENT SPUFI DEFAULTS - PANEL 2 panel opens, specify values for
the fields on that panel and press Enter. All fields must contain a value. For
more information about these values, see “CURRENT SPUFI DEFAULTS -
PANEL 2 panel” on page 1023.

Important: If you specify an invalid or incorrect plan name, SPUFI might

experience operational errors or your data might be contaminated.

SPUFI saves your changes and one of the following panels or data sets open:
v EDIT panel. This panel opens if you specified YES in the EDIT INPUT field
on the SPUFI panel.
v Output data set. This data set opens if you specified NO in the EDIT INPUT
field on the SPUFI panel.
v SPUFI panel. This panel opens if you specified NO for all of the processing
options on the SPUFI panel.

Next, continue with one of the following tasks:

v If you want to add SQL statements to the input data set or edit the SQL
statements in the input data set, enter SQL statements in SPUFI.
v Otherwise if the input data set already contains the SQL statements that you
want to execute, process SQL statements with SPUFI.

CURRENT SPUFI DEFAULTS panel

Use the CURRENT SPUFI DEFAULTS panel to specify SPUFI defaults.

The following descriptions explain the information on the CURRENT SPUFI

DEFAULTS panel.
1 SQL TERMINATOR
Specify the character that you use to end each SQL statement. You can
specify any character except the characters listed in Table 163. A semicolon
(;) is the default SQL terminator.
Table 163. Invalid special characters for the SQL terminator
Hexadecimal
Name Character representation
blank X’40’
comma , X’5E’
double quote ″ X’7F’
left parenthesis ( X’4D’
right parenthesis ) X’5D’
single quote ’ X’7D’
underscore _ X’6D’

Use a character other than a semicolon if you plan to execute a statement

that contains embedded semicolons. For example, suppose you choose the

1020 Application Programming and SQL Guide

character # as the statement terminator. Then a CREATE TRIGGER
statement with embedded semicolons looks like the following statement:
CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END#
A CREATE PROCEDURE statement with embedded semicolons looks like
the following statement:
CREATE PROCEDURE PROC1 (IN PARM1 INT, OUT SCODE INT)
LANGUAGE SQL
BEGIN
DECLARE SQLCODE INT;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
SET SCODE = SQLCODE;
UPDATE TBL1 SET COL1 = PARM1;
END #
Be careful to choose a character for the SQL terminator that is not used
within the statement.
You can also set or change the SQL terminator within a SPUFI input data
set by using the --#SET TERMINATOR statement. See “Executing SQL by
using SPUFI” on page 1013 for details.
2 ISOLATION LEVEL
Specify the isolation level for your SQL statements.
3 MAX SELECT LINES
The maximum number of rows that a SELECT statement can return. To
limit the number of rows retrieved, enter another maximum number
greater than 1.
4 ALLOW SQL WARNINGS
| Enter YES (the default) or NO to indicate whether SPUFI will continue to
process an SQL statement after receiving SQL warnings:
YES If a warning occurs when SPUFI executes an OPEN or FETCH for
a SELECT statement, SPUFI continues to process the SELECT
statement.
NO If a warning occurs when SPUFI executes an OPEN or FETCH for
a SELECT statement, SPUFI stops processing the SELECT
statement. If SQLCODE +802 occurs when SPUFI executes a
FETCH for a SELECT statement, SPUFI continues to process the
SELECT statement.
| You can also specify how SPUFI pre-processes the SQL input by using the
| --#SET TOLWARN statement. For more information about how to enter this
| statement, see “Executing SQL by using SPUFI” on page 1013.
5 CHANGE PLAN NAMES
If you enter YES in this field, you can change plan names on a subsequent
SPUFI defaults panel, DSNESP07. Enter YES in this field only if you are
certain that you want to change the plan names that are used by SPUFI.
Consult with your DB2 system administrator if you are uncertain whether
you want to change the plan names. Using an invalid or incorrect plan
name might cause SPUFI to experience operational errors or it might cause
data contamination.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1021
| 6 SQL FORMAT
| Specify how SPUFI pre-processes the SQL input before passing it to DB2.
| Select one of the following options:
| SQL This is the preferred mode for SQL statements other than SQL
| procedural language. When you use this option, which is the
| default, SPUFI collapses each line of an SQL statement into a single
| line before passing the statement to DB2. SPUFI also discards all
| SQL comments.
| SQLCOMNT
| This mode is suitable for all SQL, but it is intended primarily for
| SQL procedural language processing. When this option is in effect,
| behavior is similar to SQL mode, except that SPUFI does not
| discard SQL comments. Instead, it automatically terminates each
| SQL comment with a line feed character (hex 25), unless the
| comment is already terminated by one or more line formatting
| characters. Use this option to process SQL procedural language
| with minimal modification by SPUFI.
| SQLPL
| This mode is suitable for all SQL, but it is intended primarily for
| SQL procedural language processing. When this option is in effect,
| SPUFI retains SQL comments and terminates each line of an SQL
| statement with a line feed character (hex 25) before passing the
| statement to DB2. Lines that end with a split token are not
| terminated with a line feed character. Use this mode to obtain
| improved diagnostics and debugging of SQL procedural language.
| You can also specify how SPUFI pre-processes the SQL input by using the
| --#SET SQLFORMAT statement. For more information about how to enter this
| statement, see “Executing SQL by using SPUFI” on page 1013.
| 7 SPACE UNIT
| Specify how space for the SPUFI output data set is to be allocated.
| TRK Track
| CYL Cylinder
| 8 PRIMARY SPACE
| Specify how many tracks or cylinders of primary space are to be allocated.
| 9 SECONDARY SPACE
| Specify how many tracks or cylinders of secondary space are to be
| allocated.
| 10 RECORD LENGTH
The record length must be at least 80 bytes. The maximum record length
| depends on the device type you use. The default value allows a 32756-byte
record.
Each record can hold a single line of output. If a line is longer than a
record, the output is truncated, and SPUFI discards fields that extend
beyond the record length.
| 11 BLOCKSIZE
Follow the normal rules for selecting the block size. For record format F,
the block size is equal to the record length. For FB and FBA, choose a
block size that is an even multiple of LRECL. For VB and VBA only, the
block size must be 4 bytes larger than the block size for FB or FBA.

1022 Application Programming and SQL Guide

| 12 RECORD FORMAT
Specify F, FB, FBA, V, VB, or VBA. FBA and VBA formats insert a printer
control character after the number of lines specified in the LINES/PAGE
OF LISTING field on the DB2I Defaults panel. The record format default is
VB (variable-length blocked).
| 13 DEVICE TYPE
Specify a standard z/OS name for direct-access storage device types. The
default is SYSDA. SYSDA specifies that z/OS is to select an appropriate
direct access storage device.
| 14 MAX NUMERIC FIELD
The maximum width of a numeric value column in your output. Choose a
value greater than 0. The default is 33. For more information, see “Output
from SPUFI” on page 1025.
| 15 MAX CHAR FIELD
The maximum width of a character value column in your output.
DATETIME and GRAPHIC data strings are externally represented as
characters, and SPUFI includes their defaults with the default values for
character fields. Choose a value greater than 0. The IBM-supplied default is
| 250. For more information, see “Output from SPUFI” on page 1025.
| 16 COLUMN HEADING
You can specify NAMES, LABELS, ANY, or BOTH for column headings.
| v NAMES uses column names only.
| v LABELS (default) uses column labels. Leave the title blank if no label
| exists.
v ANY uses existing column labels or column names.
v BOTH creates two title lines, one with names and one with labels.
Column names are the column identifiers that you can use in SQL
statements. If an SQL statement has an AS clause for a column, SPUFI
displays the contents of the AS clause in the heading, rather than the
column name. You define column labels with LABEL statements.
17 FOR BIT DATA
Specify how SPUFI is to display the data from FOR BIT DATA columns.
ASIS SPUFI displays the data from FOR BIT DATA columns as it is
stored. The default is ASIS.
If you specify ASIS when a graphic character set is in effect, SPUFI
replaces all occurrences of the shift-out (X’0E’) and shift-in (X’0F’)
characters in the output of the FOR BIT DATA columns with a
substitution character of ’.’ (X’4B’). To avoid this substitution,
specify HEX.
HEX SPUFI displays the data from FOR BIT DATA columns in
hexadecimal format.

CURRENT SPUFI DEFAULTS - PANEL 2 panel

Use the CURRENT SPUFI DEFAULTS - PANEL 2 panel to specify default plan
name information.

This panel opens if you specify YES in the CHANGE PLAN NAMES field of the
CURRENT SPUFI DEFAULTS panel.

Figure 70 on page 1024 shows the initial default values.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1023
| DSNESP07 CURRENT SPUFI DEFAULTS - PANEL 2 SSID: DSN
| ===>
| Enter the following to control your SPUFI session:
| 1 CS ISOLATION PLAN ===> DSNESPCS (Name of plan for CS isolation level)
| 2 RR ISOLATION PLAN ===> DSNESPRR (Name of plan for RR isolation level)
| 3 UR ISOLATION PLAN ===> DSNESPUR (Name of plan for UR isolation level)
|
| Indicate warning message status:
| 4 BLANK CCSID WARNING ===> YES (Show warning if terminal CCSID is blank)
|
|
|
|
|
|
|
|
|
|
|
|
|
| PRESS: ENTER to process END to exit HELP for more information
|
|
| Figure 70. CURRENT SPUFI DEFAULTS - PANEL 2
|
The following descriptions explain the information on the CURRENT SPUFI
DEFAULTS - PANEL 2 panel.
1 CS ISOLATION PLAN
Specify the name of the plan that SPUFI uses when you specify an
isolation level of cursor stability (CS). By default, this name is DSNESPCS.
2 RR ISOLATION PLAN
Specify the name of the plan that SPUFI uses when you specify an
isolation level of repeatable read (RR). By default, this name is DSNESPRR.
3 UR ISOLATION PLAN
Specify the name of the plan that SPUFI uses when you specify an
isolation level of uncommitted read (UR). By default, this name is
DSNESPUR.
4 BLANK CCSID ALERT
Indicate whether to receive message DSNE345I when the terminal CCSID
setting is blank. A blank terminal CCSID setting occurs when the terminal
code page and character set cannot be queried or if they are not supported
by ISPF.
Recommendation: To avoid possible data contamination use the default
setting of YES, unless you are specifically directed by your DB2 system
administrator to use NO.

Setting the SQL terminator character in a SPUFI input data set

In the SPUFI input data set, you can override the SQL terminator character that is
specified on the CURRENT SPUFI DEFAULTS panel. The default SQL terminator is
a semicolon (;).

Overriding the default SQL termination character is useful if you need to use a
different SQL terminator character for one particular SQL statement.

To set the SQL terminator character in a SPUFI input data set, specify the text
--#SET TERMINATOR character before that SQL statement to which you want this
character to apply. This text specifies that SPUFI is to interpret character as a

1024 Application Programming and SQL Guide

statement terminator. You can specify any single-byte character except the
characters that are listed in Table 164. Choose a character for the SQL terminator
that is not used within the statement. The terminator that you specify overrides a
terminator that you specified in option 1 of the CURRENT SPUFI DEFAULTS
panel or in a previous --#SET TERMINATOR statement.
Table 164. Invalid special characters for the SQL terminator
Hexadecimal
Name Character representation
blank X’40’
comma , X’5E’
double quote ″ X’7F’
left parenthesis ( X’4D’
right parenthesis ) X’5D’
single quote ’ X’7D’
underscore _ X’6D’

Use a character other than a semicolon if you plan to execute a statement that
contains embedded semicolons. For example, suppose that you choose the
character # as the statement terminator. In this case, a CREATE TRIGGER
statement with embedded semicolons looks like this:
CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END#

Controlling toleration of warnings in SPUFI

When you use SPUFI, you can specify the action that SPUFI is to take when a
warning occurs.

To control the toleration of warnings, specify one of the following TOLWARN

control statements:
--#SET TOLWARN NO
If a warning occurs when SPUFI executes an OPEN or FETCH for SELECT
statement, SPUFI stops processing the SELECT statement. If SQLCODE
+802 occurs when SPUFI executes a FETCH for a SELECT statement,
SPUFI continues to process the SELECT statement.
--#SET TOLWARN YES
If a warning occurs when SPUFI executes an OPEN or FETCH for SELECT
statement, SPUFI continues to process the SELECT statement.

Example: The following example activates and then deactivates toleration of SQL
warnings:
SELECT * FROM MY.T1;
--#SET TOLWARN YES
SELECT * FROM YOUR.T1;
--#SET TOLWARN NO

Output from SPUFI

SPUFI formats and displays the output data set using the ISPF Browse program.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1025
Figure 71 shows the output from the sample program. An output data set contains
the following items for each SQL statement that DB2 executes:
v The executed SQL statement, copied from the input data set
v The results of executing the SQL statement
v The formatted SQLCA, if an error occurs during statement execution

At the end of the data set are summary statistics that describe the processing of the
input data set as a whole.

For SELECT statements that are executed with SPUFI, the message “SQLCODE IS
100” indicates an error-free result. If the message SQLCODE IS 100 is the only
result, DB2 is unable to find any rows that satisfy the condition that is specified in
the statement.

For all other types of SQL statements that are executed with SPUFI, the message
“SQLCODE IS 0” indicates an error-free result.

BROWSE-- userid.RESULT COLUMNS 001 072

COMMAND INPUT ===> SCROLL ===> PAGE
--------+---------+---------+---------+---------+---------+---------+---------+
SELECT LASTNAME, FIRSTNME, PHONENO 00010000
FROM DSN8910.EMP 00020000
WHERE WORKDEPT = 'D11' 00030000
ORDER BY LASTNAME; 00040000
---------+---------+---------+---------+---------+---------+---------+---------+
LASTNAME FIRSTNME PHONENO
ADAMSON BRUCE 4510
BROWN DAVID 4501
JOHN REBA 0672
JONES WILLIAM 0942
LUTZ JENNIFER 0672
PIANKA ELIZABETH 3782
SCOUTTEN MARILYN 1682
STERN IRVING 6423
WALKER JAMES 2986
YAMAMOTO KIYOSHI 2890
YOSHIMURA MASATOSHI 2890
DSNE610I NUMBER OF ROWS DISPLAYED IS 11
DSNE616I STATEMENT EXECUTION WAS SUCCESSFUL, SQLCODE IS 100
---------+---------+---------+---------+---------+---------+----
---------+---------+---------+---------+---------+---------+----
DSNE617I COMMIT PERFORMED, SQLCODE IS 0
DSNE616I STATEMENT EXECUTION WAS SUCCESSFUL, SQLCODE IS 0
---------+---------+---------+---------+---------+---------+----
DSNE601I SQL STATEMENTS ASSUMED TO BE BETWEEN COLUMNS 1 AND 72
DSNE620I NUMBER OF SQL STATEMENTS PROCESSED IS 1
DSNE621I NUMBER OF INPUT RECORDS READ IS 4
DSNE622I NUMBER OF OUTPUT RECORDS WRITTEN IS 30

Figure 71. Result data set from the sample problem

Formatting rules for SELECT statement results in SPUFI:

The results of SELECT statements follow these rules:

v If numeric or character data of a column cannot be displayed completely:
| – Character values and binary values that are too wide truncate on the right.
– Numeric values that are too wide display as asterisks (*).
| – For columns other than LOB and XML columns, if truncation occurs, the
| output data set contains a warning message. Because LOB and XML columns
| are generally longer than the value you choose for field MAX CHAR FIELD
| on panel CURRENT SPUFI DEFAULTS, SPUFI displays no warning message
| when it truncates LOB or XML column output.

1026 Application Programming and SQL Guide

You can change the amount of data that is displayed for numeric and character
columns by changing values on the CURRENT SPUFI DEFAULTS panel, as
described in “Changing SPUFI defaults” on page 1019.
v A null value is displayed as a series of hyphens (-).
| v A ROWID, BLOB, BINARY, or VARBINARY column value is displayed in
| hexadecimal.
v A CLOB column value is displayed in the same way as a VARCHAR column
value.
v A DBCLOB column value is displayed in the same way as a VARGRAPHIC
column value.
| v An XML column is displayed in the same way as a LOB column.
v A heading identifies each selected column, and is repeated at the top of each
output page. The contents of the heading depend on the value that you specified
in the COLUMN HEADING field of the CURRENT SPUFI DEFAULTS panel.

Content of the messages from SPUFI:

Each SPUFI message contains the following:

v The SQLCODE, if the statement executes successfully.
v The formatted SQLCA, if the statement executes unsuccessfully.
v What character positions of the input data set that SPUFI scanned to find SQL
statements. This information helps you check the assumptions that SPUFI made
about the location of line numbers (if any) in your input data set.
v Some overall statistics:
– Number of SQL statements that are processed
– Number of input records that are read (from the input data set)
– Number of output records that are written (to the output data set).

Other messages that you could receive from the processing of SQL statements
include:
v The number of rows that DB2 processed, that either:
– Your select operation retrieved
– Your update operation modified
– Your insert operation added to a table
– Your delete operation deleted from a table
v Which columns display truncated data because the data was too wide

Testing an external user-defined function

Some commonly used debugging tools, such as TSO TEST, are not available in the
environment where user-defined functions run. You need to use alternative testing
strategies.

Testing a user-defined function by using the Debug Tool for

z/OS
You can use the Debug Tool for z/OS, which works with Language Environment,
to test DB2 for z/OS user-defined functions written in any of the supported
languages.

You can use the Debug Tool either interactively or in batch mode.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1027
Using the Debug Tool interactively: To test a user-defined function interactively
using the Debug Tool, you must have the Debug Tool installed on the z/OS system
where the user-defined function runs. To debug your user-defined function using
the Debug Tool, do the following:
1. Compile the user-defined function with the TEST option. This places
information in the program that the Debug Tool uses.
2. Invoke the Debug Tool. One way to do that is to specify the Language
Environment run-time TEST option. The TEST option controls when and how
the Debug Tool is invoked. The most convenient place to specify run-time
options is with the RUN OPTIONS clause of CREATE FUNCTION or ALTER
FUNCTION. See “Components of a user-defined function definition” on page
485 for more information about the RUN OPTIONS clause. For example,
suppose that you code this option:
TEST(ALL,*,PROMPT,JBJONES%SESSNA:)

The parameter values cause the following things to happen:

ALL
The Debug Tool gains control when an attention interrupt, abend, or
program or Language Environment condition of Severity 1 and above
occurs.
* Debug commands will be entered from the terminal.
PROMPT
The Debug Tool is invoked immediately after Language Environment
initialization.
JBJONES%SESSNA:
The Debug Tool initiates a session on a workstation identified to APPC as
JBJONES with a session ID of SESSNA.
3. If you want to save the output from your debugging session, issue a command
that names a log file. For example, the following command starts logging to a
file on the workstation called dbgtool.log.
SET LOG ON FILE dbgtool.log;

This should be the first command that you enter from the terminal or include
in your commands file.

Using the Debug Tool in batch mode: To test your user-defined function in batch
mode, you must have the Debug Tool installed on the z/OS system where the
user-defined function runs. To debug your user-defined function in batch mode
using the Debug Tool, do the following:
1. If you plan to use the Language Environment run-time TEST option to invoke
the Debug Tool, compile the user-defined function with the TEST option. This
places information in the program that the Debug Tool uses during a
debugging session.
2. Allocate a log data set to receive the output from the Debug Tool. Put a DD
statement for the log data set in the startup procedure for the stored procedures
address space.
3. Enter commands in a data set that you want the Debug Tool to execute. Put a
DD statement for that data set in the startup procedure for the stored
procedures address space. To define the data set that contains the commands to
the Debug Tool, specify its data set name or DD name in the TEST run-time
option. For example, this option tells the Debug Tool to look for the commands
in the data set that is associated with DD name TESTDD:

1028 Application Programming and SQL Guide

TEST(ALL,TESTDD,PROMPT,*)
The first command in the commands data set should be:
SET LOG ON FILE ddname;
This command directs output from your debugging session to the log data set
you defined in step 2. For example, if you defined a log data set with DD name
INSPLOG in the start-up procedure for the stored procedures address space,
the first command should be:
SET LOG ON FILE INSPLOG;
4. Invoke the Debug Tool. The following are two possible methods for invoking
the Debug Tool:
v Specify the Language Environment run-time TEST option. The most
convenient place to do that is in the RUN OPTIONS parameter of CREATE
FUNCTION or ALTER FUNCTION.
v Put CEETEST calls in the user-defined function source code. If you use this
approach for an existing user-defined function, you must compile, link-edit,
and bind the user-defined function again. Then you must issue the STOP
FUNCTION SPECIFIC and START FUNCTION SPECIFIC commands to
reload the user-defined function.
You can combine the Language Environment run-time TEST option with
CEETEST calls. For example, you might want to use TEST to name the
commands data set but use CEETEST calls to control when the Debug Tool
takes control.
You can combine the Language Environment run-time TEST option with
CEETEST calls. For example, you might want to use TEST to name the
commands data set but use CEETEST calls to control when the Debug Tool
takes control.

For more information about the Debug Tool, see Debug Tool User’s Guide and
Reference.

Testing a user-defined function by routing the debugging

messages to SYSPRINT
You can include simple print statements in your user-defined function code that
you route to SYSPRINT. Then use System Display and Search Facility (SDSF) to
examine the SYSPRINT contents while the WLM-established stored procedure
address space is running.

You can serialize I/O by running the WLM-established stored procedure address
space with NUMTCB=1.

Testing a user-defined function by using driver applications

You can write a small driver application that calls a user-defined function as a
subprogram and passes the parameter list for the user-defined function. You can
then test and debug the user-defined function as a normal DB2 application under
TSO.

You can then use TSO TEST and other commonly used debugging tools.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1029
Testing a user-defined function by using SQL INSERT
statements
You can use SQL to insert debugging information into a DB2 table. This allows
other machines in the network (such as workstations) to easily access the data in
the table using DRDA access.

DB2 discards the debugging information if the application executes the

ROLLBACK statement. To prevent the loss of the debugging data, code the calling
application so that it retrieves the diagnostic data before executing the ROLLBACK
statement.

| Debugging stored procedures

| When debugging stored procedures, you might need to use different techniques
| than you would use for regular application programs. For example, some
| commonly used debugging tools, such as TSO TEST, are not available in the
| environment where stored procedures run.

| To debug a stored procedure, perform one or more of the following actions:

| v Use the DISPLAY command to view information about particular stored
| procedures, including statistics and thread information.
| v Look at the diagnostic information in CEEDUMP if your stored procedures
| address space has the CEEDUMP data set allocated.
| For COBOL stored procedures, compile the stored procedure with the option
| TEST(SYM) if you want a formatted local variable dump included in the
| CEEDUMP output.
| v Debug the stored procedure as a stand-alone program on a workstation.
| If you have debugging support on a workstation, you might choose to do most
| of your development and testing on a workstation before installing a stored
| procedure on z/OS. This technique results in very little debugging activity on
| z/OS.
| v Record stored procedure debugging messages to a disk file or JES spool file.
| v Issue DISPLAY statements in the procedure to find information about the started
| task that is associated with the address space for the WLM application
| environment. You can view the DISPLAY results in the SDSF output.
| v Store debugging information in a table. This technique is useful for remote
| stored procedures.
| v For native SQL procedures, external SQL procedures, and Java stored
| procedures, use the Unified Debugger.
| v For COBOL, C, and C++ stored procedures, use the Debug Tool for z/OS.
| v For external stored procedures, use a driver application.
| v Ensure that the stored procedure is written to handle any SQL errors.
| v For external stored procedures, create or alter the stored procedure definition to
| include the PARAMETER STYLE SQL option. This option enables the stored
| procedure to share any error information with the calling application. Ensure
| that your procedure follows linkage conventions for stored procedures.
| v If you changed a stored procedure or a startup JCL procedure for a WLM
| application environment, determine whether you need to refresh the WLM
| environment. You must refresh the WLM environment for certain stored
| procedure changes to be implemented.

1030 Application Programming and SQL Guide

| v If necessary, use the STOP PROCEDURE command to stop calls to one or more
| problematic stored procedures. You can restart them later.
| Related concepts
| “Linkage conventions for stored procedures” on page 741
| Related tasks
| “Handling SQL conditions in an SQL procedure” on page 540
| Displaying information about stored procedures with DB2 commands (DB2
| Administration Guide)
| Refreshing a WLM application environment for stored procedures (DB2
| Administration Guide)
| Implementing DB2 stored procedures (DB2 Administration Guide)
| Related reference
| Debugging COBOL, PL/I, and C/C++ procedures on z/OS (DB2 9 for z/OS
| Stored Procedures: Through the CALL and Beyond)
| Debugging SQL procedures on z/OS, Linux, UNIX, and Windows (DB2 9 for
| z/OS Stored Procedures: Through the CALL and Beyond)
| -START PROCEDURE (DB2) (DB2 Command Reference)
| -STOP PROCEDURE (DB2) (DB2 Command Reference)

| Debugging stored procedures with the Debug Tool and IBM

| VisualAge COBOL
| If you have VisualAge® COBOL installed on your workstation and the Debug Tool
| installed on your z/OS system, you can use the VisualAge COBOL
| Edit/Compile/Debug component with the Debug Tool to debug COBOL stored
| procedures that run in a WLM-established stored procedures address space.

| For detailed information about the Debug Tool, see Debug Tool User’s Guide and
| Reference.

| Before you begin debugging, write your COBOL stored procedure and set up the
| WLM environment.

| To debug with the Debug Tool and IBM VisualAge COBOL:

| 1. When you compile the stored procedure, specify the TEST and SOURCE
| options. Ensure that the source listing is stored in a permanent data set.
| VisualAge COBOL displays the source listing during the debug session.
| 2. When you define the stored procedure, include run-time option TEST with the
| suboption VADTCPIP&ipaddr in your RUN OPTIONS argument.
| VADTCPIP& tells the Debug Tool that it is interfacing with a workstation that
| runs VisualAge COBOL and is configured for TCP/IP communication with
| your z/OS system. ipaddr is the IP address of the workstation on which you
| display your debug information. For example, the RUN OPTIONS value in the
| following stored procedure definition indicates that debug information should
| go to the workstation with IP address 9.63.51.17:
| CREATE PROCEDURE WLMCOB
| (IN INTEGER, INOUT VARCHAR(3000), INOUT INTEGER)
| MODIFIES SQL DATA
| LANGUAGE COBOL EXTERNAL

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1031
| PROGRAM TYPE MAIN
| WLM ENVIRONMENT WLMENV1
| RUN OPTIONS 'POSIX(ON),TEST(,,,VADTCPIP&9.63.51.17:*)'
| 3. In the JCL startup procedure for WLM-established stored procedures address
| space, add the data set name of the Debug Tool load library to the STEPLIB
| concatenation. For example, suppose that ENV1PROC is the JCL procedure for
| application environment WLMENV1. The modified JCL for ENV1PROC might
| look like this:
| //DSNWLM PROC RGN=0K,APPLENV=WLMENV1,DB2SSN=DSN,NUMTCB=8
| //IEFPROC EXEC PGM=DSNX9WLM,REGION=&RGN,TIME=NOLIMIT,
| // PARM='&DB2SSN,&NUMTCB,&APPLENV'
| //STEPLIB DD DISP=SHR,DSN=DSN910.RUNLIB.LOAD
| // DD DISP=SHR,DSN=CEE.SCEERUN
| // DD DISP=SHR,DSN=DSN910.SDSNLOAD
| // DD DISP=SHR,DSN=EQAW.SEQAMOD <== DEBUG TOOL
| 4. On the workstation, start the VisualAge Remote Debugger daemon. This
| daemon waits for incoming requests from TCP/IP.
| 5. Call the stored procedure. When the stored procedure starts, a window that
| contains the debug session is displayed on the workstation. You can then
| execute Debug Tool commands to debug the stored procedure.

| Debugging a C language stored procedure with the Debug

| Tool and C/C++ Productivity Tools for z/OS
| If you have the C/C++ Productivity Tools for z/OS installed on your workstation
| and the Debug Tool installed on your z/OS system, you can debug a C or C++
| stored procedure that runs in a WLM-established stored procedures address space.

| The code against which you run the debug tools is the C source program that is
| produced by the program preparation process for the stored procedure. For
| detailed information about the Debug Tool, see Debug Tool User’s Guide and
| Reference.

| Before you begin debugging, write your C++ stored procedure and set up the
| WLM environment.

| To test the stored procedure with the Distributed Debugger feature of the C/C++
| Productivity Tools for z/OS and the Debug Tool:
| 1. When you define the stored procedure, include run-time option TEST with the
| suboption VADTCPIP&ipaddr in your RUN OPTIONS argument.
| VADTCPIP& tells the Debug Tool that it is interfacing with a workstation that
| runs VisualAge C++ and is configured for TCP/IP communication with your
| z/OS system. ipaddr is the IP address of the workstation on which you display
| your debug information. For example, this RUN OPTIONS value in a stored
| procedure definition indicates that debug information should go to the
| workstation with IP address 9.63.51.17:
| RUN OPTIONS 'POSIX(ON),TEST(,,,VADTCPIP&9.63.51.17:*)'
| 2. Precompile the stored procedure. Ensure that the modified source program that
| is the output from the precompile step is in a permanent, catalogued data set.
| 3. Compile the output from the precompile step. Specify the TEST, SOURCE, and
| OPT(0) compiler options.
| 4. In the JCL startup procedure for the stored procedures address space, add the
| data set name of the Debug Tool load library to the STEPLIB concatenation. For

1032 Application Programming and SQL Guide

| example, suppose that ENV1PROC is the JCL procedure for application
| environment WLMENV1. The modified JCL for ENV1PROC might look like
| this:
| //DSNWLM PROC RGN=0K,APPLENV=WLMENV1,DB2SSN=DSN,NUMTCB=8
| //IEFPROC EXEC PGM=DSNX9WLM,REGION=&RGN,TIME=NOLIMIT,
| // PARM='&DB2SSN,&NUMTCB,&APPLENV'
| //STEPLIB DD DISP=SHR,DSN=DSN910.RUNLIB.LOAD
| // DD DISP=SHR,DSN=CEE.SCEERUN
| // DD DISP=SHR,DSN=DSN910.SDSNLOAD
| // DD DISP=SHR,DSN=EQAW.SEQAMOD <== DEBUG TOOL
| 5. On the workstation, start the Distributed Debugger daemon. This daemon waits
| for incoming requests from TCP/IP.
| 6. Call the stored procedure. When the stored procedure starts, a window that
| contains the debug session is displayed on the workstation. You can then
| execute Debug Tool commands to debug the stored procedure.

| Debugging stored procedures by using the Unified Debugger

| You can use the Unified Debugger to remotely debug native SQL procedures,
| external SQL procedures, and Java stored procedures that execute on DB2 for z/OS
| servers. The Unified Debugger also supports debugging nested stored procedure
| calls.

| With the Unified Debugger, you can observe the execution of the procedure code,
| set breakpoints for lines, and view or modify variable values.

| To debug stored procedures by using the Unified Debugger:

| 1. Set up the Unified Debugger by performing the following steps:
| a. Customize and run the post installation job DSNTIJSD program in data set
| DSN910.SDSNSAMP. This JCL defines to DB2 the stored procedures that
| provide server support for the Unified Debugger.
| b. Define the debug mode characteristics for the stored procedure that you
| want to debug by completing one of the following actions:
| v For a native SQL procedure, define the procedure with the ALLOW
| DEBUG MODE option and the WLM ENVIRONMENT FOR DEBUG
| MODE option. If the procedure already exists, you can use the ALTER
| PROCEDURE statement to specify these options.
| v For an external SQL procedure, use DSNTPSMP or IBM Optim
| Development Studio to build the SQL procedure with the BUILD_DEBUG
| option.
| v For a Java stored procedure, define the procedure with the ALLOW
| DEBUG MODE option, select an appropriate WLM environment for Java
| debugging, and compile the Java code with the -G option.
| c. Grant the DEBUGSESSION privilege to the user who runs the debug client.
| 2. Include breakpoints in your routines or executable files.
| 3. Follow the instructions for debugging stored procedures in the information for
| IBM Optim Development Studio.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1033
| Related concepts
| Java stored procedures and user-defined functions (Programming for Java)
| Related tasks
| “Creating an external SQL procedure by using DSNTPSMP” on page 565
| Related reference
| “Sample programs to help you prepare and run external SQL procedures” on page
| 576
| The Unified Debugger (DB2 9 for z/OS Stored Procedures: Through the CALL
| and Beyond)
| Integrated Data Management Information Center
| ALTER PROCEDURE (SQL - native) (SQL Reference)
| CREATE PROCEDURE (SQL - native) (SQL Reference)

| Debugging stored procedures with the Debug Tool for z/OS

| You can use the Debug Tool for z/OS to test z/OS stored procedures that are
| written in any of the compiled languages that the Debug Tool supports. You can
| test these procedures either interactively or in batch mode.

| Using Debug Tool interactively: To test a stored procedure interactively using the
| Debug Tool, you must have the Debug Tool installed on the z/OS system where
| the stored procedure runs.

| To debug your stored procedure using the Debug Tool:

| 1. Compile the stored procedure with option TEST. This places information in the
| program that the Debug Tool uses during a debugging session.
| 2. Invoke the Debug Tool. One way to do that is to specify the Language
| Environment run-time option TEST. The TEST option controls when and how
| the Debug Tool is invoked. The most convenient place to specify run-time
| options is in the RUN OPTIONS parameter of the CREATE PROCEDURE or
| ALTER PROCEDURE statement for the stored procedure.
| For example, you can code the TEST option using the following parameters:
| TEST(ALL,*,PROMPT,JBJONES%SESSNA:)
| Table 165 lists the effects each parameter has on the Debug Tool:
| Table 165. Effects of the TEST option parameters on the Debug Tool
| Parameter value Effect on the Debug Tool
| ALL The Debug Tool gains control when an
| attention interrupt, ABEND, or program or
| Language Environment condition of Severity
| 1 and above occurs.

| Debug commands will be entered from the

| terminal.
| PROMPT The Debug Tool is invoked immediately after
| Language Environment initialization.
| JBJONES%SESSNA: The Debug Tool initiates a session on a
| workstation identified to APPC/MVS as
| JBJONES with a session ID of SESSNA.
|

1034 Application Programming and SQL Guide

| 3. If you want to save the output from your debugging session, issue the
| following command:
| SET LOG ON FILE dbgtool.log;

| This command saves a log of your debugging session to a file on the

| workstation called dbgtool.log. This should be the first command that you
| enter from the terminal or include in your commands file.

| Using Debug Tool in batch mode: To test your stored procedure in batch mode, you
| must have the Debug Tool installed on the z/OS system where the stored
| procedure runs. To debug your stored procedure in batch mode using the Debug
| Tool, do the following:
| v Compile the stored procedure with option TEST, if you plan to use the Language
| Environment run-time option TEST to invoke the Debug Tool. This places
| information in the program that the Debug Tool uses during a debugging
| session.
| v Allocate a log data set to receive the output from the Debug Tool. Put a DD
| statement for the log data set in the start-up procedure for the stored procedures
| address space.
| v Enter commands in a data set that you want the Debug Tool to execute. Put a
| DD statement for that data set in the start-up procedure for the stored
| procedures address space. To define the commands data set to the Debug Tool,
| specify the commands data set name or DD name in the TEST run-time option.
| For example, to specify that the Debug Tool use the commands that are in the
| data set that is associated with the DD name TESTDD, include the following
| parameter in the TEST option:
| TEST(ALL,TESTDD,PROMPT,*)
| The first command in the commands data set should be:
| SET LOG ON FILE ddname;
| This command directs output from your debugging session to the log data set
| that you defined in the previous step. For example, if you defined a log data set
| with DD name INSPLOG in the stored procedures address space start-up
| procedure, the first command should be the following command:
| SET LOG ON FILE INSPLOG;
| v Invoke the Debug Tool. The following are two possible methods for invoking the
| Debug Tool:
| – Specify the run-time option TEST. The most convenient place to do that is in
| the RUN OPTIONS parameter of the CREATE PROCEDURE or ALTER
| PROCEDURE statement for the stored procedure.
| – Put CEETEST calls in the stored procedure source code. If you use this
| approach for an existing stored procedure, you must recompile, re-link, and
| bind it, and issue the STOP PROCEDURE and START PROCEDURE
| commands to reload the stored procedure.
| You can combine the run-time option TEST with CEETEST calls. For example,
| you might want to use TEST to name the commands data set but use
| CEETEST calls to control when the Debug Tool takes control.

| For more information about using the Debug Tool for z/OS, see Debug Tool User’s
| Guide and Reference.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1035
| Recording stored procedure debugging messages in a file
| You can debug external stored procedures and external SQL procedures by
| recording debugging messages in a disk file or JES spool file. You cannot use this
| debugging technique for native SQL procedures or Java stored procedures.

| To record stored procedure debugging messages in a file:

| 1. Specify the Language Environment (LE) MSGFILE runtime option for the
| stored procedure. This option identifies where LE is to write the debugging
| messages. To specify this option, include the RUN OPTIONS clause in either
| the CREATE PROCEDURE statement or an ALTER PROCEDURE statement.
| Specify the following MSGFILE parameters:
| v Use the first MSGFILE parameter to specify the JCL DD statement that
| identifies the data set for the debugging messages. You can direct debugging
| messages to a disk file or JES spool file. To prevent multiple procedures from
| sharing a data set, ensure that you specify a unique DD statement.
| v Use the ENQ option to serialize I/O to the message file. This action is
| necessary, because multiple TCBs can be active in the stored procedure
| address space. Alternatively, if you debug your applications infrequently or
| on a DB2 test system, you can serialize I/O by temporarily running the
| stored procedures address space with NUMTCB=1 in the stored procedures
| address space start-up procedure.
| 2. For each instance of MSGFILE that you specify, add a DD statement to the JCL
| procedure that is used to start the stored procedures address space.
| Related reference
| ALTER PROCEDURE (external) (SQL Reference)
| ALTER PROCEDURE (SQL - external) (SQL Reference)
| CREATE PROCEDURE (SQL - external) (SQL Reference)
| CREATE PROCEDURE (external) (SQL Reference)
| GRANT (system privileges) (SQL Reference)
| Related information
| Language Environment information

| Driver applications for debugging procedures

| You can write a small driver application that calls the stored procedure as a
| subprogram and passes the parameter list supported by the stored procedure. You
| can then test and debug the stored procedure as a normal DB2 application under
| TSO.

| Using this method, you can use TSO TEST and other commonly used debugging
| tools.

| Restriction: You cannot use this technique for SQL procedures

| DB2 tables that contain debugging information

| You can use SQL statements to insert debugging information into a DB2 table.
| Inserting this information into a table enables other machines in the network (such
| as a workstation) to easily access the data in the table using DRDA access.

1036 Application Programming and SQL Guide

| DB2 discards the debugging information if the application executes the
| ROLLBACK statement. To prevent the loss of the debugging data, code the calling
| application so that it retrieves the diagnostic data before executing the ROLLBACK
| statement.

Debugging an application program

Many sites have guidelines regarding what to do if your program abnormally
terminates.

The following topics suggest some common guidelines:

v “Techniques for debugging programs in TSO” on page 1042
v “Techniques for debugging programs in IMS” on page 1042
v “Techniques for debugging programs in CICS” on page 1043

For information about the compiler or assembler test facilities, see the publications
for the compiler or CODE/370. The compiler publications include information
about the appropriate debugger for the language you are using.

You can also use ISPF Dialog Test to debug your program. You can run all or
portions of your application, examine the results, make changes, and rerun it. Fore
more information about ISPF Dialog Test, see z/OS ISPF User’s Guide Volumes 1 and
2.

Locating the problem in an application

If your program does not run correctly, you need to isolate the problem. If DB2 did
not invalidate the application plan for the program, you should check several
items.

Those items are:

v Output from the precompiler, which consists of errors and warnings. Ensure that
you have resolved all errors and warnings.
v Output from the compiler or assembler. Ensure that you have resolved all error
messages.
v Output from the linkage editor.
– Have you resolved all external references?
– Have you included all necessary modules in the correct order?
– Did you include the correct language interface module? The correct language
interface module is:
- DSNELI for TSO
- DFSLI000 for IMS
- DSNCLI for CICS
- DSNALI for the call attachment facility
– Did you specify the correct entry point to your program?
v Output from the bind process.
– Have you resolved all error messages?
– Did you specify a plan name? If not, the bind process assumes that you want
to process the DBRM for diagnostic purposes, but that you do not want to
produce an application plan.
– Have you specified all the DBRMs and packages that are associated with the
programs that make up the application and their partitioned data set (PDS)
names in a single application plan?

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1037
v Your JCL.
IMS
– If you are using IMS, have you included the DL/I option statement in the
correct format?
– Have you included the region size parameter in the EXEC statement? Does it
specify a region size that is large enough for the required storage for the DB2
interface, the TSO, IMS, or CICS system, and your program?
– Have you included the names of all data sets (DB2 and non-DB2) that the
program requires?
v Your program.
You can also use dumps to help localize problems in your program. For
example, one of the more common error situations occurs when your program is
running and you receive a message that it abended. In this situation, your test
procedure might be to capture a TSO dump. To do so, you must allocate a
SYSUDUMP or SYSABEND dump data set before calling DB2. When you press
the ENTER key (after the error message and READY message), the system
requests a dump. You then need to use the FREE command to deallocate the
dump data set.

Error and warning messages from the precompiler

Under some circumstances, the statements that the DB2 precompiler generates can
produce compiler or assembly error messages. You must know why the messages
occur when you compile DB2-produced source statements.

SYSTERM output from the precompiler

The SYSTERM output provides a brief summary of the results from the
precompiler, all error messages that the precompiler generated, and the statement
that is in error, when possible.

The DB2 precompiler provides SYSTERM output when you allocate the DD name
SYSTERM. If you use the program preparation panels to prepare and run your
program, DB2I allocates SYSTERM according to the TERM option that you specify.

You can use the line number that is provided in each error message in the
SYSTERM output to locate the failing source statement.

Figure 72 shows the format of SYSTERM output.

DB2 SQL PRECOMPILER MESSAGES

DSNH104I E DSNHPARS LINE 32 COL 26 ILLEGAL SYMBOL "X" VALID SYMBOLS ARE:, FROM1
SELECT VALUE INTO HIPPO X;2

DB2 SQL PRECOMPILER STATISTICS

SOURCE STATISTICS3
SOURCE LINES READ: 36
NUMBER OF SYMBOLS: 15
SYMBOL TABLE BYTES EXCLUDING ATTRIBUTES: 1848
THERE WERE 1 MESSAGES FOR THIS PROGRAM.4
THERE WERE 0 MESSAGES SUPPRESSED BY THE FLAG OPTION.5
111664 BYTES OF STORAGE WERE USED BY THE PRECOMPILER.6
RETURN CODE IS 87

Figure 72. DB2 precompiler SYSTERM output

Notes:
1. Error message.

1038 Application Programming and SQL Guide

2. Source SQL statement.
3. Summary statements of source statistics.
4. Summary statement of the number of errors that were detected.
5. Summary statement that indicates the number of errors that were detected but
not printed. This situation might occur if you specify a FLAG option other than
I.
6. Storage requirement statement that indicates how many bytes of working
storage that the DB2 precompiler actually used to process your source
statements. That value helps you determine the storage allocation requirements
for your program.
7. Return code: 0 = success, 4 = warning, 8 = error, 12 = severe error, and 16 =
unrecoverable error.

SYSPRINT output from the precompiler

SYSPRINT output from the DB2 precompiler shows the results of the precompile
operation. This output can also include a list of the options that were used, a
source code listing, and a host variable cross-reference listing.

When you use the program preparation panels to prepare and run your program,
DB2 allocates SYSPRINT according to TERM option that you specify (on line 12 of
the PROGRAM PREPARATION: COMPILE, PRELINK, LINK, AND RUN panel).
As an alternative, when you use the DSNH command procedure (CLIST), you can
specify PRINT(TERM) to obtain SYSPRINT output at your terminal, or you can
specify PRINT(qualifier) to place the SYSPRINT output into a data set named
authorizationID.qualifier.PCLIST. Assuming that you do not specify PRINT as
LEAVE, NONE, or TERM, DB2 issues a message when the precompiler finishes,
telling you where to find your precompiler listings. This helps you locate your
diagnostics quickly and easily.

The SYSPRINT output can provide information about your precompiled source
module if you specify the options SOURCE and XREF when you start the DB2
precompiler.

The format of SYSPRINT output is as follows:

v A list of the DB2 precompiler options that are in effect during the
precompilation (if you did not specify NOOPTIONS).
v A list of your source statements (only if you specified the SOURCE option). An
example is shown in Figure 73 on page 1040.
v A list of the symbolic names used in SQL statements (this listing appears only if
you specify the XREF option). An example is show in Figure 74 on page 1041.
v A summary of the errors that are detected by the DB2 precompiler and a list of
the error messages that are generated by the precompiler. An example is shown
in

The following code shows an example list of DB2 precompiler options as it is

displayed in the SYSPRINT output.
| DB2 SQL PRECOMPILER VERSION 9 REL. 1.0
| OPTIONS SPECIFIED: HOST(PLI),SOURCE,XREF
| DSNHDECP LOADED FROM - (USER99.RELK.TESTLIB(DSNHDECP))
| OPTIONS USED - SPECIFIED OR DEFAULTED
| APOST
| APOSTSQL
| ATTACH(TSO)
| CCSID(37)
| NOPADNTSTR

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1039
| CONNECT(2)
| DEC(15)
| FLAG(I)
| HOST(PLI)
| FLOAT(S390)
| LINECOUNT(60)
| MARGINS(2,72)
| NEWFUN(YES)
| ONEPASS
| OPTIONS
| PERIOD
| SOURCE
| STDSQL(NO)
| SQL(DB2)
| XREF

Notes:
1. This section lists the options that are specified at precompilation time. This list
does not appear if one of the precompiler option is NOOPTIONS.
2. This section lists the options that are in effect, including defaults, forced values,
and options that you specified. The DB2 precompiler overrides or ignores any
options that you specify that are inappropriate for the host language.

The following figure shows an example list of source statements as it is displayed

in the SYSPRINT output.

DB2 SQL PRECOMPILER TMN5P40:PROCEDURE OPTIONS (MAIN): PAGE 2

1 TMN5P40:PROCEDURE OPTIONS(MAIN) ; 00000100

2 /*******************************************************00000200
3 * program description and prologue 00000300
..
.
1324 /*************************************************/ 00132400
1325 /* GET INFORMATION ABOUT THE PROJECT FROM THE */ 00132500
1326 /* PROJECT TABLE. */ 00132600
1327 /*************************************************/ 00132700
1328 EXEC SQL SELECT ACTNO, PREQPROJ, PREQACT 00132800
1329 INTO PROJ_DATA 00132900
1330 FROM TPREREQ 00133000
1331 WHERE PROJNO = :PROJ_NO; 00133100
1332 00133200
1333 /*************************************************/ 00133300
1334 /* PROJECT IS FINISHED. DELETE IT. */ 00133400
1335 /*************************************************/ 00133500
1336 00133600
1337 EXEC SQL DELETE FROM PROJ 00133700
1338 WHERE PROJNO = :PROJ_NO; 00133800
..
.
1523 END; 00152300

Figure 73. DB2 precompiler SYSPRINT output: Source statements section

Notes:
v The left column of sequence numbers, which the DB2 precompiler generates, is
for use with the symbol cross-reference listing, the precompiler error messages,
and the BIND error messages.
v The right column shows sequence numbers that come from the sequence
numbers that are supplied with your source statements.

1040 Application Programming and SQL Guide

The following figure shows an example list of symbolic names as it is displayed in
the SYSPRINT output.

DB2 SQL PRECOMPILER SYMBOL CROSS-REFERENCE LISTING PAGE 29

DATA NAMES DEFN REFERENCE

"ACTNO" **** FIELD

1328
"PREQACT" **** FIELD
1328
"PREQPROJ" **** FIELD
1328
"PROJNO" **** FIELD
1331 1338

...

PROJ_DATA 495 CHARACTER(35)

1329
PROJ_NO 496 CHARACTER(3)
1331 1338
"TPREREQ" **** TABLE
1330 1337

Figure 74. DB2 precompiler SYSPRINT output: Symbol cross-reference section

Notes:
DATA NAMES
Identifies the symbolic names that are used in source statements. Names
enclosed in double quotation marks (″) or apostrophes (’) are names of SQL
entities such as tables, columns, and authorization IDs. Other names are host
variables.
DEFN
Is the number of the line that the precompiler generates to define the name.
**** means that the object was not defined, or the precompiler did not
recognize the declarations.
REFERENCE
Contains two kinds of information: the symbolic name, which the source
program defines, and which lines refer to the symbolic name. If the symbolic
name refers to a valid host variable, the list also identifies the data type or the
word STRUCTURE.

The following code shows an example summary report of errors as it is displayed

in the SYSPRINT output.
DB2 SQL PRECOMPILER STATISTICS

SOURCE STATISTICS
SOURCE LINES READ: 15231
NUMBER OF SYMBOLS: 1282
SYMBOL TABLE BYTES EXCLUDING ATTRIBUTES: 64323

THERE WERE 1 MESSAGES FOR THIS PROGRAM.4

THERE WERE 0 MESSAGES SUPPRESSED.5
65536 BYTES OF STORAGE WERE USED BY THE PRECOMPILER.6
RETURN CODE IS 8.7
DSNH104I E LINE 590 COL 64 ILLEGAL SYMBOL: 'X'; VALID SYMBOLS ARE:,FROM8

Notes:
1. Summary statement that indicates the number of source lines.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1041
2. Summary statement that indicates the number of symbolic names in the symbol
table (SQL names and host names).
3. Storage requirement statement that indicates the number of bytes for the
symbol table.
4. Summary statement that indicates the number of messages that are printed.
5. Summary statement that indicates the number of errors that are detected but
not printed. You might get this statement if you specify the option FLAG.
6. Storage requirement statement that indicates the number of bytes of working
storage that are actually used by the DB2 precompiler to process your source
statements.
7. Return code 0 = success, 4 = warning, 8 = error, 12 = severe error, and 16 =
unrecoverable error.
8. Error messages (this example detects only one error).

Techniques for debugging programs in TSO

Documenting the errors that are identified during testing of a TSO application
helps you investigate and correct problems in the program.

The following information can be useful:

v The application plan name of the program
v The input data that is being processed
v The failing SQL statement and its function
v The contents of the SQLCA (SQL communication area) and, if your program
accepts dynamic SQL statements, the SQLDA (SQL descriptor area)
v The date and time of day
v The abend code and any error messages

When your program encounters an error that does not result in an abend, it can
pass all the required error information to a standard error routine. Online
programs might also send an error message to the terminal.

The TSO TEST command:

The TSO TEST command is especially useful for debugging assembler programs.

The following example is a command procedure (CLIST) that runs a DB2

application named MYPROG under TSO TEST, and sets an address stop at the
entry to the program. The DB2 subsystem name in this example is DB4.
PROC 0
TEST 'prefix.SDSNLOAD(DSN)' CP
DSN SYSTEM(DB4)
AT MYPROG.MYPROG.+0 DEFER
GO
RUN PROGRAM(MYPROG) LIBRARY('L186331.RUNLIB.LOAD(MYPROG)')

For more information about the TEST command, see z/OS TSO/E Command
Reference.

Techniques for debugging programs in IMS

Documenting the errors that are identified during testing of an IMS application
helps you investigate and correct problems in the program.

The following information can be useful:

1042 Application Programming and SQL Guide

v The application plan name for the program
v The input message that is being processed
v The name of the originating logical terminal
v The failing statement and its function
v The contents of the SQLCA (SQL communication area) and, if your program
accepts dynamic SQL statements, the SQLDA (SQL descriptor area)
v The date and time of day
v The PSB name for the program
v The transaction code that the program was processing
v The call function (that is, the name of a DL/I function)
v The contents of the PCB that the program call refers to
v If a DL/I database call was running, the SSAs, if any, that the call used
v The abend completion code, abend reason code, and any dump error messages

When your program encounters an error, it can pass all the required error
information to a standard error routine. Online programs can also send an error
message to the originating logical terminal.

An interactive program also can send a message to the master terminal operator
giving information about the termination of the program. To do that, the program
places the logical terminal name of the master terminal in an express PCB and
issues one or more ISRT calls.

Some organizations run a BMP at the end of the day to list all the errors that
occurred during the day. If your organization does this, you can send a message by
using an express PCB that has its destination set for that BMP.

Batch Terminal Simulator: The Batch Terminal Simulator (BTS) enables you to test
IMS application programs. BTS traces application program DL/I calls and SQL
statements, and it simulates data communication functions. It can make a TSO
terminal appear as an IMS terminal to the terminal operator, which enables the end
user to interact with the application as though it were an online application. The
user can use any application program that is under the user’s control to access any
database (whether DL/I or DB2) that is under the user’s control. Access to DB2
databases requires BTS to operate in batch BMP or TSO BMP mode.

Techniques for debugging programs in CICS

Documenting the errors that are identified during testing of a CICS application
helps you investigate and correct problems in the program.

The following information can be useful:

v The application plan name of the program
v The input data that is being processed
v The ID of the originating logical terminal
v The failing SQL statement and its function
v The contents of the SQLCA (SQL communication area) and, if your program
accepts dynamic SQL statements, the SQLDA (SQL descriptor area)
v The date and time of day
v Data that is peculiar to CICS that you should record
v Abend code and dump error messages

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1043
v Transaction dump, if produced

Using CICS facilities, you can have a printed error record; you can also print the
SQLCA and SQLDA contents.

Debugging aids for CICS:

CICS provides the following aids to the testing, monitoring, and debugging of
application programs:
v Execution (Command Level) Diagnostic Facility (EDF). EDF shows CICS
commands for all releases of CICS.
v Abend recovery. You can use the HANDLE ABEND command to deal with
abend conditions. You can use the ABEND command to cause a task to abend.
v Trace facility. A trace table can contain entries showing the execution of various
CICS commands, SQL statements, and entries that are generated by application
programs; you can have these entries written to main storage and, optionally, to
an auxiliary storage device.
v Dump facility. You can specify areas of main storage to dump onto a sequential
data set, either tape or disk, for subsequent offline formatting and printing with
a CICS utility program.
v Journals. For statistical or monitoring purposes, facilities can create entries in
special data sets called journals. The system log is a journal.
v Recovery. When an abend occurs, CICS restores certain resources to their
original state so that the operator can easily resubmit a transaction for restart.
You can use the SYNCPOINT command to subdivide a program so that you
only need to resubmit the uncompleted part of a transaction.

For more details about each of these topics, see CICS Transaction Server for z/OS
Application Programming Reference.

CICS execution diagnostic facility:

The CICS execution diagnostic facility (EDF) traces SQL statements in an

interactive debugging mode, enabling application programmers to test and debug
programs online without changing the program or the program preparation
procedure.

EDF intercepts the running application program at various points and displays
helpful information about the statement type, input and output variables, and any
error conditions after the statement executes. It also displays any screens that the
application program sends, so that you can converse with the application program
during testing just as a user would on a production system.

EDF displays essential information before and after an SQL statement runs, while
the task is in EDF mode. This can be a significant aid in debugging CICS
transaction programs that contains SQL statements. The SQL information that EDF
displays is helpful for debugging programs and for error analysis after an SQL
error or warning. Using this facility reduces the amount of work that you need to
do to write special error handlers.

EDF before execution: The following figure shows an example of an EDF screen
before it executes an SQL statement. The names of the key information fields on
this panel are in boldface.

1044 Application Programming and SQL Guide

TRANSACTION: XC05 PROGRAM: TESTC05 TASK NUMBER: 0000668 DISPLAY: 00
STATUS: ABOUT TO EXECUTE COMMAND
CALL TO RESOURCE MANAGER DSNCSQL
EXEC SQL INSERT
DBRM=TESTC05, STMT=00368, SECT=00004
IVAR 001: TYPE=CHAR, LEN=00007, IND=000 AT X'03C92810'
DATA=X'F0F0F9F4F3F4F2'
IVAR 002: TYPE=CHAR, LEN=00007, IND=000 AT X'03C92817'
DATA=X'F0F1F3F3F7F5F1'
IVAR 003: TYPE=CHAR, LEN=00004, IND=000 AT X'03C9281E'
DATA=X'E7C3F0F5'
IVAR 004: TYPE=CHAR, LEN=00040, IND=000 AT X'03C92822'
DATA=X'E3C5E2E3C3F0F540E2C9D4D7D3C540C4C2F240C9D5E2C5D9E3404040'...
IVAR 005: TYPE=SMALLINT, LEN=00002, IND=000 AT X'03C9284A'
DATA=X'0001'

OFFSET:X'001ECE' LINE:UNKNOWN EIBFN=X'1002'

ENTER: CONTINUE
PF1 : UNDEFINED PF2 : UNDEFINED PF3 : UNDEFINED
PF4 : SUPPRESS DISPLAYS PF5 : WORKING STORAGE PF6 : USER DISPLAY
PF7 : SCROLL BACK PF8 : SCROLL FORWARD PF9 : STOP CONDITIONS
PF10: PREVIOUS DISPLAY PF11: UNDEFINED PF12: ABEND USER TASK

Figure 75. EDF screen before a DB2 SQL statement

The DB2 SQL information in this screen is as follows:

v EXEC SQL statement type
This is the type of SQL statement to execute. The SQL statement can be any
valid SQL statement.
v DBRM=dbrm name
The name of the database request module (DBRM) that is currently processing.
The DBRM, created by the DB2 precompiler, contains information about an SQL
statement.
v STMT=statement number
This is the DB2 precompiler-generated statement number. The source and error
message listings from the precompiler use this statement number, and you can
use the statement number to determine which statement is processing. This
number is a source line counter that includes host language statements. A
statement number that is greater than 32 767 displays as 0.
v SECT=section number
The section number of the plan that the SQL statement uses.

SQL statements that contain input host variables: The IVAR (input host variables)
section and its attendant fields appear only when the executing statement contains
input host variables.

The host variables section includes the variables from predicates, the values used
for inserting or updating, and the text of dynamic SQL statements that are being
prepared. The address of the input variable is AT X’nnnnnnnn’.

Additional host variable information:

v TYPE=data type
Specifies the data type for this host variable. The basic data types include
character string, graphic string, binary integer, floating-point, decimal, date,
time, and timestamp. For more information about these data types, see “Data
types” on page 426.
v LEN=length

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1045
Specifies the length of the host variable.
v IND=indicator variable status number
Specifies the indicator variable that is associated with this particular host
variable. A value of zero indicates that no indicator variable exists. If the value
for the selected column is null, DB2 puts a negative value in the indicator
variable for this host variable. For more information indicator variables, see
“Indicator variables, arrays, and structures” on page 145.
v DATA=host variable data
Specifies the data, displayed in hexadecimal format, that is associated with this
host variable. If the data exceeds what can display on a single line, three periods
(...) appear at the far right to indicate that more data is present.

EDF after execution:The following figure shows an example of the first EDF screen
that is displayed after the executing an SQL statement. The names of the key
information fields on this panel are in boldface.

TRANSACTION: XC05 PROGRAM: TESTC05 TASK NUMBER: 0000698 DISPLAY: 00

STATUS: COMMAND EXECUTION COMPLETE
CALL TO RESOURCE MANAGER DSNCSQL
EXEC SQL FETCH P.AUTH=SYSADM , S.AUTH=
PLAN=TESTC05, DBRM=TESTC05, STMT=00346, SECT=00001
SQL COMMUNICATION AREA:
SQLCABC = 136 AT X'03C92789'
SQLCODE = 000 AT X'03C9278D'
SQLERRML = 000 AT X'03C92791'
SQLERRMC = '' AT X'03C92793'
SQLERRP = 'DSN' AT X'03C927D9'
SQLERRD(1-6) = 000, 000, 00000, -1, 00000, 000 AT X'03C927E1'
SQLWARN(0-A) = '_ _ _ _ _ _ _ _ _ _ _' AT X'03C927F9'
SQLSTATE = 00000 AT X'03C92804'
+ OVAR 001: TYPE=INTEGER, LEN=00004, IND=000 AT X'03C920A0'
DATA=X'00000001'
OFFSET:X'001D14' LINE:UNKNOWN EIBFN=X'1802'

ENTER: CONTINUE
PF1 : UNDEFINED PF2 : UNDEFINED PF3 : END EDF SESSION
PF4 : SUPPRESS DISPLAYS PF5 : WORKING STORAGE PF6 : USER DISPLAY
PF7 : SCROLL BACK PF8 : SCROLL FORWARD PF9 : STOP CONDITIONS
PF10: PREVIOUS DISPLAY PF11: UNDEFINED PF12: ABEND USER TASK

Figure 76. EDF screen after a DB2 SQL statement

The DB2 SQL information in this screen is as follows:

v P.AUTH=primary authorization ID
The primary DB2 authorization ID.
v S.AUTH=secondary authorization ID
The secondary authorization ID. If the RACF list of group options is not active,
DB2 uses the connected group name that the CICS attachment facility supplies
as the secondary authorization ID. If the RACF list of group options is active,
DB2 ignores the connected group name that the CICS attachment facility
supplies, but the value is displayed in the DB2 list of secondary authorization
IDs.
v PLAN=plan name
The name of the plan that is currently running. The PLAN represents the control
structure that is produced during the bind process and that is used by DB2 to
process SQL statements that are encountered while the application is running.
v SQL Communication Area (SQLCA)

1046 Application Programming and SQL Guide

Information in the SQLCA. The SQLCA contains information about errors, if any
occur. DB2 uses the SQLCA to give an application program information about
the executing SQL statements.

Plus signs (+) on the left of the screen indicate that you can see additional EDF
output by using PF keys to scroll the screen forward or back.

The OVAR (output host variables) section and its attendant fields are displayed
only when the executing statement returns output host variables.

The following figure contains the rest of the EDF output for this example.

TRANSACTION: XC05 PROGRAM: TESTC05 TASK NUMBER: 0000698 DISPLAY: 00

STATUS: COMMAND EXECUTION COMPLETE
CALL TO RESOURCE MANAGER DSNCSQL
+ OVAR 002: TYPE=CHAR, LEN=00008, IND=000 AT X'03C920B0'
DATA=X'C8F3E3E3C1C2D3C5'
OVAR 003: TYPE=CHAR, LEN=00040, IND=000 AT X'03C920B8'
DATA=X'C9D5C9E3C9C1D340D3D6C1C440404040404040404040404040404040'...

OFFSET:X'001D14' LINE:UNKNOWN EIBFN=X'1802'

ENTER: CONTINUE
PF1 : UNDEFINED PF2 : UNDEFINED PF3 : END EDF SESSION
PF4 : SUPPRESS DISPLAYS PF5 : WORKING STORAGE PF6 : USER DISPLAY
PF7 : SCROLL BACK PF8 : SCROLL FORWARD PF9 : STOP CONDITIONS
PF10: PREVIOUS DISPLAY PF11: UNDEFINED PF12: ABEND USER TASK

Figure 77. EDF screen after a DB2 SQL statement, continued

The attachment facility automatically displays SQL information while in the EDF
mode. (You can start EDF as outlined in the appropriate CICS application
programmer’s reference manual.) If this information is not displayed, contact the
person that is responsible for installing and migrating DB2.

Finding a violated referential or check constraint

When you receive an SQL error because of a constraint violation, look at the
SQLCA for specific information.

Question: When a referential or check constraint has been violated, how do I

determine which one it is?

Answer: When you receive an SQL error because of a constraint violation, print out
the SQLCA. You can use the DSNTIAR routine described in “Displaying SQLCA
fields by calling DSNTIAR” on page 204 to format the SQLCA for you. Check the
SQL error message insertion text (SQLERRM) for the name of the constraint. For
information about possible violations, see SQLCODEs -530 through -548 in the
topic “Error SQL codes” in DB2 Codes.

Chapter 19. Testing and debugging an application program on DB2 for z/OS 1047
1048 Application Programming and SQL Guide
Chapter 20. DB2 sample applications and data
DB2 provides sample data and applications that you can use to learn about DB2
capabilities or as models for your own situations.
Related reference
DB2 sample tables (Introduction to DB2 for z/OS)

DB2 sample tables

Much of the DB2 information refers to or relies on the DB2 sample tables. As a
group, the tables include information that describes employees, departments,
projects, and activities, and they make up a sample application that exemplifies
many of the features of DB2.

The sample storage group, databases, table spaces, tables, and views are
created when you run the installation sample jobs DSNTEJ1 and DSNTEJ7. DB2
sample objects that include LOBs are created in job DSNTEJ7. All other sample
objects are created in job DSNTEJ1. The CREATE INDEX statements for the sample
tables are not shown here; they, too, are created by the DSNTEJ1 and DSNTEJ7
sample jobs.

Authorization on all sample objects is given to PUBLIC in order to make the

sample programs easier to run. You can review the contents of any table by
executing an SQL statement, for example SELECT * FROM DSN8910.PROJ. For
convenience in interpreting the examples, the department and employee tables are
listed in full.

Activity table (DSN8910.ACT)

The activity table describes the activities that can be performed during a project.

The activity table resides in database DSN8D91A and is created with the
following statement:
CREATE TABLE DSN8910.ACT
(ACTNO SMALLINT NOT NULL,
ACTKWD CHAR(6) NOT NULL,
ACTDESC VARCHAR(20) NOT NULL,
PRIMARY KEY (ACTNO) )
IN DSN8D91A.DSN8S91P
CCSID EBCDIC;

Content of the activity table

The following table shows the content of the columns in the activity table.
Table 166. Columns of the activity table
Column Column name Description
1 ACTNO Activity ID (the primary key)
2 ACTKWD Activity keyword (up to six characters)
3 ACTDESC Activity description

© Copyright IBM Corp. 1983, 2009 1049

The activity table has the following indexes.
Table 167. Indexes of the activity table
Name On column Type of index
DSN8910.XACT1 ACTNO Primary, ascending
DSN8910.XACT2 ACTKWD Unique, ascending

Relationship to other tables

The activity table is a parent table of the project activity table, through a foreign
key on column ACTNO.

Department table (DSN8910.DEPT)

The department table describes each department in the enterprise and identifies its
manager and the department to which it reports.

The department table resides in table space DSN8D91A.DSN8S91D and is

created with the following statement:
CREATE TABLE DSN8910.DEPT
(DEPTNO CHAR(3) NOT NULL,
DEPTNAME VARCHAR(36) NOT NULL,
MGRNO CHAR(6) ,
ADMRDEPT CHAR(3) NOT NULL,
LOCATION CHAR(16) ,
PRIMARY KEY (DEPTNO) )
IN DSN8D91A.DSN8S91D
CCSID EBCDIC;

Because the department table is self-referencing, and also is part of a cycle of

dependencies, its foreign keys must be added later with the following statements:
ALTER TABLE DSN8910.DEPT
FOREIGN KEY RDD (ADMRDEPT) REFERENCES DSN8910.DEPT
ON DELETE CASCADE;

ALTER TABLE DSN8910.DEPT

FOREIGN KEY RDE (MGRNO) REFERENCES DSN8910.EMP
ON DELETE SET NULL;

Content of the department table

The following table shows the content of the columns in the department table.
Table 168. Columns of the department table
Column Column name Description
1 DEPTNO Department ID, the primary key.
2 DEPTNAME A name that describes the general activities of the
department.
3 MGRNO Employee number (EMPNO) of the department
manager.
4 ADMRDEPT ID of the department to which this department
reports; the department at the highest level reports
to itself.
5 LOCATION The remote location name.

1050 Application Programming and SQL Guide

The following table shows the indexes of the department table.
Table 169. Indexes of the department table
Name On column Type of index
DSN8910.XDEPT1 DEPTNO Primary, ascending
DSN8910.XDEPT2 MGRNO Ascending
DSN8910.XDEPT3 ADMRDEPT Ascending

The following table shows the content of the department table.

Table 170. DSN8910.DEPT: department table
DEPTNO DEPTNAME MGRNO ADMRDEPT LOCATION

A00 SPIFFY COMPUTER SERVICE 000010 A00 ----------------

DIV.
B01 PLANNING 000020 A00 ----------------
C01 INFORMATION CENTER 000030 A00 ----------------
D01 DEVELOPMENT CENTER ------ A00 ----------------
E01 SUPPORT SERVICES 000050 A00 ----------------
D11 MANUFACTURING SYSTEMS 000060 D01 ----------------
D21 ADMINISTRATION SYSTEMS 000070 D01 ----------------
E11 OPERATIONS 000090 E01 ----------------
E21 SOFTWARE SUPPORT 000100 E01 ----------------
F22 BRANCH OFFICE F2 ------ E01 ----------------
G22 BRANCH OFFICE G2 ------ E01 ----------------
H22 BRANCH OFFICE H2 ------ E01 ----------------
I22 BRANCH OFFICE I2 ------ E01 ----------------
J22 BRANCH OFFICE J2 ------ E01 ----------------

The LOCATION column contains null values until sample job DSNTEJ6 updates
this column with the location name.

Relationship to other tables

The department table is self-referencing: the value of the administering department
must be a valid department ID.

The department table is a parent table of the following :

v The employee table, through a foreign key on column WORKDEPT
v The project table, through a foreign key on column DEPTNO

The department table is a dependent of the employee table, through its foreign key
on column MGRNO.

Employee table (DSN8910.EMP)

The employee table identifies all employees by an employee number and lists basic
personnel information.

The employee table resides in the partitioned table space

DSN8D91A.DSN8S91E. Because this table has a foreign key that references DEPT,
that table and the index on its primary key must be created first. Then EMP is
created with the following statement:

Chapter 20. DB2 sample applications and data 1051

CREATE TABLE DSN8910.EMP
(EMPNO CHAR(6) NOT NULL,
FIRSTNME VARCHAR(12) NOT NULL,
MIDINIT CHAR(1) NOT NULL,
LASTNAME VARCHAR(15) NOT NULL,
WORKDEPT CHAR(3) ,
PHONENO CHAR(4) CONSTRAINT NUMBER CHECK
(PHONENO >= '0000' AND
PHONENO <= '9999') ,
HIREDATE DATE ,
JOB CHAR(8) ,
EDLEVEL SMALLINT ,
SEX CHAR(1) ,
BIRTHDATE DATE ,
SALARY DECIMAL(9,2) ,
BONUS DECIMAL(9,2) ,
COMM DECIMAL(9,2) ,
PRIMARY KEY (EMPNO) ,
FOREIGN KEY RED (WORKDEPT) REFERENCES DSN8910.DEPT
ON DELETE SET NULL )
EDITPROC DSN8EAE1
IN DSN8D91A.DSN8S91E
CCSID EBCDIC;

Content of the employee table

The following table shows the type of content of each of the columns in the
employee table. The table has a check constraint, NUMBER, which checks that the
four-digit phone number is in the numeric range 0000 to 9999.
Table 171. Columns of the employee table
Column Column name Description
1 EMPNO Employee number (the primary key)
2 FIRSTNME First name of employee
3 MIDINIT Middle initial of employee
4 LASTNAME Last name of employee
5 WORKDEPT ID of department in which the employee works
6 PHONENO Employee telephone number
7 HIREDATE Date of hire
8 JOB Job held by the employee
9 EDLEVEL Number of years of formal education
10 SEX Sex of the employee (M or F)
11 BIRTHDATE Date of birth
12 SALARY Yearly salary in dollars
13 BONUS Yearly bonus in dollars
14 COMM Yearly commission in dollars

The following table shows the indexes of the employee table.

Table 172. Indexes of the employee table
Name On column Type of index
DSN8910.XEMP1 EMPNO Primary, partitioned, ascending
DSN8910.XEMP2 WORKDEPT Ascending

1052 Application Programming and SQL Guide

The following table shows the first half (left side) of the content of the employee
table. (Table 174 on page 1054 shows the remaining content (right side) of the
employee table.)
Table 173. Left half of DSN8910.EMP: employee table. Note that a blank in the MIDINIT column is an actual value of
″ ″ rather than null.
EMPNO FIRSTNME MIDINIT LASTNAME WORKDEPT PHONENO HIREDATE

000010 CHRISTINE I HAAS A00 3978 1965-01-01

000020 MICHAEL L THOMPSON B01 3476 1973-10-10
000030 SALLY A KWAN C01 4738 1975-04-05
000050 JOHN B GEYER E01 6789 1949-08-17
000060 IRVING F STERN D11 6423 1973-09-14
000070 EVA D PULASKI D21 7831 1980-09-30
000090 EILEEN W HENDERSON E11 5498 1970-08-15
000100 THEODORE Q SPENSER E21 0972 1980-06-19
000110 VINCENZO G LUCCHESSI A00 3490 1958-05-16
000120 SEAN O’CONNELL A00 2167 1963-12-05
000130 DOLORES M QUINTANA C01 4578 1971-07-28
000140 HEATHER A NICHOLLS C01 1793 1976-12-15
000150 BRUCE ADAMSON D11 4510 1972-02-12
000160 ELIZABETH R PIANKA D11 3782 1977-10-11
000170 MASATOSHI J YOSHIMURA D11 2890 1978-09-15
000180 MARILYN S SCOUTTEN D11 1682 1973-07-07
000190 JAMES H WALKER D11 2986 1974-07-26
000200 DAVID BROWN D11 4501 1966-03-03
000210 WILLIAM T JONES D11 0942 1979-04-11
000220 JENNIFER K LUTZ D11 0672 1968-08-29
000230 JAMES J JEFFERSON D21 2094 1966-11-21
000240 SALVATORE M MARINO D21 3780 1979-12-05
000250 DANIEL S SMITH D21 0961 1969-10-30
000260 SYBIL P JOHNSON D21 8953 1975-09-11
000270 MARIA L PEREZ D21 9001 1980-09-30
000280 ETHEL R SCHNEIDER E11 8997 1967-03-24
000290 JOHN R PARKER E11 4502 1980-05-30
000300 PHILIP X SMITH E11 2095 1972-06-19
000310 MAUDE F SETRIGHT E11 3332 1964-09-12
000320 RAMLAL V MEHTA E21 9990 1965-07-07
000330 WING LEE E21 2103 1976-02-23
000340 JASON R GOUNOT E21 5698 1947-05-05
200010 DIAN J HEMMINGER A00 3978 1965-01-01
200120 GREG ORLANDO A00 2167 1972-05-05
200140 KIM N NATZ C01 1793 1976-12-15
200170 KIYOSHI YAMAMOTO D11 2890 1978-09-15
200220 REBA K JOHN D11 0672 1968-08-29
200240 ROBERT M MONTEVERDE D21 3780 1979-12-05
200280 EILEEN R SCHWARTZ E11 8997 1967-03-24
200310 MICHELLE F SPRINGER E11 3332 1964-09-12
200330 HELENA WONG E21 2103 1976-02-23
200340 ROY R ALONZO E21 5698 1947-05-05

(Table 173 shows the first half (right side) of the content of employee table.)

Chapter 20. DB2 sample applications and data 1053

Table 174. Right half of DSN8910.EMP: employee table
(EMPNO) JOB EDLEVEL SEX BIRTHDATE SALARY BONUS COMM

(000010) PRES 18 F 1933-08-14 52750.00 1000.00 4220.00

(000020) MANAGER 18 M 1948-02-02 41250.00 800.00 3300.00
(000030) MANAGER 20 F 1941-05-11 38250.00 800.00 3060.00
(000050) MANAGER 16 M 1925-09-15 40175.00 800.00 3214.00
(000060) MANAGER 16 M 1945-07-07 32250.00 600.00 2580.00
(000070) MANAGER 16 F 1953-05-26 36170.00 700.00 2893.00
(000090) MANAGER 16 F 1941-05-15 29750.00 600.00 2380.00
(000100) MANAGER 14 M 1956-12-18 26150.00 500.00 2092.00
(000110) SALESREP 19 M 1929-11-05 46500.00 900.00 3720.00
(000120) CLERK 14 M 1942-10-18 29250.00 600.00 2340.00
(000130) ANALYST 16 F 1925-09-15 23800.00 500.00 1904.00
(000140) ANALYST 18 F 1946-01-19 28420.00 600.00 2274.00
(000150) DESIGNER 16 M 1947-05-17 25280.00 500.00 2022.00
(000160) DESIGNER 17 F 1955-04-12 22250.00 400.00 1780.00
(000170) DESIGNER 16 M 1951-01-05 24680.00 500.00 1974.00
(000180) DESIGNER 17 F 1949-02-21 21340.00 500.00 1707.00
(000190) DESIGNER 16 M 1952-06-25 20450.00 400.00 1636.00
(000200) DESIGNER 16 M 1941-05-29 27740.00 600.00 2217.00
(000210) DESIGNER 17 M 1953-02-23 18270.00 400.00 1462.00
(000220) DESIGNER 18 F 1948-03-19 29840.00 600.00 2387.00
(000230) CLERK 14 M 1935-05-30 22180.00 400.00 1774.00
(000240) CLERK 17 M 1954-03-31 28760.00 600.00 2301.00
(000250) CLERK 15 M 1939-11-12 19180.00 400.00 1534.00
(000260) CLERK 16 F 1936-10-05 17250.00 300.00 1380.00
(000270) CLERK 15 F 1953-05-26 27380.00 500.00 2190.00
(000280) OPERATOR 17 F 1936-03-28 26250.00 500.00 2100.00
(000290) OPERATOR 12 M 1946-07-09 15340.00 300.00 1227.00
(000300) OPERATOR 14 M 1936-10-27 17750.00 400.00 1420.00
(000310) OPERATOR 12 F 1931-04-21 15900.00 300.00 1272.00
(000320) FIELDREP 16 M 1932-08-11 19950.00 400.00 1596.00
(000330) FIELDREP 14 M 1941-07-18 25370.00 500.00 2030.00
(000340) FIELDREP 16 M 1926-05-17 23840.00 500.00 1907.00
(200010) SALESREP 18 F 1933-08-14 46500.00 1000.00 4220.00
(200120) CLERK 14 M 1942-10-18 29250.00 600.00 2340.00
(200140) ANALYST 18 F 1946-01-19 28420.00 600.00 2274.00
(200170) DESIGNER 16 M 1951-01-05 24680.00 500.00 1974.00
(200220) DESIGNER 18 F 1948-03-19 29840.00 600.00 2387.00
(200240) CLERK 17 M 1954-03-31 28760.00 600.00 2301.00
(200280) OPERATOR 17 F 1936-03-28 26250.00 500.00 2100.00
(200310) OPERATOR 12 F 1931-04-21 15900.00 300.00 1272.00
(200330) FIELDREP 14 F 1941-07-18 25370.00 500.00 2030.00
(200340) FIELDREP 16 M 1926-05-17 23840.00 500.00 1907.00

Relationship to other tables

The employee table is a parent table of:

v The department table, through a foreign key on column MGRNO
v The project table, through a foreign key on column RESPEMP

The employee table is a dependent of the department table, through its foreign key
on column WORKDEPT.

1054 Application Programming and SQL Guide

Employee photo and resume table
(DSN8910.EMP_PHOTO_RESUME)
The employee photo and resume table complements the employee table.

Each row of the photo and resume table contains a photo of the employee,
in two formats, and the employee’s resume. The photo and resume table resides in
table space DSN8D91A.DSN8S91E. The following statement creates the table:
CREATE TABLE DSN8910.EMP_PHOTO_RESUME
(EMPNO CHAR(06) NOT NULL,
EMP_ROWID ROWID NOT NULL GENERATED ALWAYS,
PSEG_PHOTO BLOB(500K),
BMP_PHOTO BLOB(100K),
RESUME CLOB(5K))
PRIMARY KEY (EMPNO)
IN DSN8D91L.DSN8S91B
CCSID EBCDIC;

DB2 requires an auxiliary table for each LOB column in a table. The following
statements define the auxiliary tables for the three LOB columns in
DSN8910.EMP_PHOTO_RESUME:
CREATE AUX TABLE DSN8910.AUX_BMP_PHOTO
IN DSN8D91L.DSN8S91M
STORES DSN8910.EMP_PHOTO_RESUME
COLUMN BMP_PHOTO;

CREATE AUX TABLE DSN8910.AUX_PSEG_PHOTO

IN DSN8D91L.DSN8S91L
STORES DSN8910.EMP_PHOTO_RESUME
COLUMN PSEG_PHOTO;

CREATE AUX TABLE DSN8910.AUX_EMP_RESUME

IN DSN8D91L.DSN8S91N
STORES DSN8910.EMP_PHOTO_RESUME
COLUMN RESUME;

Content of the employee photo and resume table

The following table shows the content of the columns in the employee photo and
resume table.
Table 175. Columns of the employee photo and resume table
Column Column name Description
1 EMPNO Employee ID (the primary key).
2 EMP_ROWID Row ID to uniquely identify each row of the table.
DB2 supplies the values of this column.
3 PSEG_PHOTO Employee photo, in PSEG format.
4 BMP_PHOTO Employee photo, in BMP format.
5 RESUME Employee resume.

The following table shows the indexes for the employee photo and resume table.
Table 176. Indexes of the employee photo and resume table
Name On column Type of index
DSN8910.XEMP_PHOTO_RESUME EMPNO Primary, ascending

Chapter 20. DB2 sample applications and data 1055

The following table shows the indexes for the auxiliary tables that support the
employee photo and resume table.
Table 177. Indexes of the auxiliary tables for the employee photo and resume table
Name On table Type of index
DSN8910.XAUX_BMP_PHOTO DSN8910.AUX_BMP_PHOTO Unique
DSN8910.XAUX_PSEG_PHOTO DSN8910.AUX_PSEG_PHOTO Unique
DSN8910.XAUX_EMP_RESUME DSN8910.AUX_EMP_RESUME Unique

Relationship to other tables

The employee photo and resume table is a parent table of the project table,
through a foreign key on column RESPEMP.

Project table (DSN8910.PROJ)

The project table describes each project that the business is currently undertaking.
Data that is contained in each row of the table includes the project number, name,
person responsible, and schedule dates.

The project table resides in database DSN8D91A. Because this table has
foreign keys that reference DEPT and EMP, those tables and the indexes on their
primary keys must be created first. Then PROJ is created with the following
statement:
CREATE TABLE DSN8910.PROJ
(PROJNO CHAR(6) PRIMARY KEY NOT NULL,
PROJNAME VARCHAR(24) NOT NULL WITH DEFAULT
'PROJECT NAME UNDEFINED',
DEPTNO CHAR(3) NOT NULL REFERENCES
DSN8910.DEPT ON DELETE RESTRICT,
RESPEMP CHAR(6) NOT NULL REFERENCES
DSN8910.EMP ON DELETE RESTRICT,
PRSTAFF DECIMAL(5, 2) ,
PRSTDATE DATE ,
PRENDATE DATE ,
MAJPROJ CHAR(6))
IN DSN8D91A.DSN8S91P
CCSID EBCDIC;

Because the project table is self-referencing, the foreign key for that constraint must
be added later with the following statement:
ALTER TABLE DSN8910.PROJ
FOREIGN KEY RPP (MAJPROJ) REFERENCES DSN8910.PROJ
ON DELETE CASCADE;

Content of the project table

The following table shows the content of the columns of the project table.
Table 178. Columns of the project table
Column Column name Description
1 PROJNO Project ID (the primary key)
2 PROJNAME Project name
3 DEPTNO ID of department responsible for the project

1056 Application Programming and SQL Guide

Table 178. Columns of the project table (continued)
Column Column name Description
4 RESPEMP ID of employee responsible for the project
5 PRSTAFF Estimated mean number of persons that are
needed between PRSTDATE and PRENDATE to
complete the whole project, including any
subprojects
6 PRSTDATE Estimated project start date
7 PRENDATE Estimated project end date
8 MAJPROJ ID of any project of which this project is a part

The following table shows the indexes for the project table:
Table 179. Indexes of the project table
Name On column Type of index
DSN8910.XPROJ1 PROJNO Primary, ascending
DSN8910.XPROJ2 RESPEMP Ascending

Relationship to other tables

The table is self-referencing: a non-null value of MAJPROJ must be a valid project

number. The table is a parent table of the project activity table, through a foreign
key on column PROJNO. It is a dependent of the following tables:
v The department table, through its foreign key on DEPTNO
v The employee table, through its foreign key on RESPEMP

Project activity table (DSN8910.PROJACT)

The project activity table lists the activities that are performed for each project.

The project activity table resides in database DSN8D91A. Because this table
has foreign keys that reference PROJ and ACT, those tables and the indexes on
their primary keys must be created first. Then PROJACT is created with the
following statement:
CREATE TABLE DSN8910.PROJACT
(PROJNO CHAR(6) NOT NULL,
ACTNO SMALLINT NOT NULL,
ACSTAFF DECIMAL(5,2) ,
ACSTDATE DATE NOT NULL,
ACENDATE DATE ,
PRIMARY KEY (PROJNO, ACTNO, ACSTDATE),
FOREIGN KEY RPAP (PROJNO) REFERENCES DSN8910.PROJ
ON DELETE RESTRICT,
FOREIGN KEY RPAA (ACTNO) REFERENCES DSN8910.ACT
ON DELETE RESTRICT)
IN DSN8D91A.DSN8S91P
CCSID EBCDIC;

Chapter 20. DB2 sample applications and data 1057

Content of the project activity table

The following table shows the content of the columns of the project activity table.
Table 180. Columns of the project activity table
Column Column name Description
1 PROJNO Project ID
2 ACTNO Activity ID
3 ACSTAFF Estimated mean number of employees that are
needed to staff the activity
4 ACSTDATE Estimated activity start date
5 ACENDATE Estimated activity completion date

The following table shows the index of the project activity table:
Table 181. Index of the project activity table
Name On columns Type of index
DSN8910.XPROJAC1 PROJNO, ACTNO, primary, ascending
ACSTDATE

Relationship to other tables

The project activity table is a parent table of the employee to project activity table,
through a foreign key on columns PROJNO, ACTNO, and EMSTDATE. It is a
dependent of the following tables:
v The activity table, through its foreign key on column ACTNO
v The project table, through its foreign key on column PROJNO

Related reference
“Project table (DSN8910.PROJ)” on page 1056
“Activity table (DSN8910.ACT)” on page 1049

Employee to project activity table (DSN8910.EMPPROJACT)

The employee to project activity table identifies the employee who performs an
activity for a project, tells the proportion of the employee’s time required, and
gives a schedule for the activity.

The employee to project activity table resides in database DSN8D91A.

Because this table has foreign keys that reference EMP and PROJACT, those tables
and the indexes on their primary keys must be created first. Then EMPPROJACT is
created with the following statement:
CREATE TABLE DSN8910.EMPPROJACT
(EMPNO CHAR(6) NOT NULL,
PROJNO CHAR(6) NOT NULL,
ACTNO SMALLINT NOT NULL,
EMPTIME DECIMAL(5,2) ,
EMSTDATE DATE ,
EMENDATE DATE ,
FOREIGN KEY REPAPA (PROJNO, ACTNO, EMSTDATE)
REFERENCES DSN8910.PROJACT
ON DELETE RESTRICT,

1058 Application Programming and SQL Guide

FOREIGN KEY REPAE (EMPNO) REFERENCES DSN8910.EMP
ON DELETE RESTRICT)
IN DSN8D91A.DSN8S91P
CCSID EBCDIC;

Content of the employee to project activity table

The following table shows the content of the columns in the employee to project
activity table.
Table 182. Columns of the employee to project activity table
Column Column name Description
1 EMPNO Employee ID number
2 PROJNO Project ID of the project
3 ACTNO ID of the activity within the project
4 EMPTIME A proportion of the employee’s full time (between
0.00 and 1.00) that is to be spent on the activity
5 EMSTDATE Date the activity starts
6 EMENDATE Date the activity ends

The following table shows the indexes for the employee to project activity table:
Table 183. Indexes of the employee to project activity table
Name On columns Type of index
DSN8910.XEMPPROJACT1 PROJNO, ACTNO, Unique, ascending
EMSTDATE, EMPNO
DSN8910.XEMPPROJACT2 EMPNO Ascending

Relationship to other tables

The employee to project activity table is a dependent of the following tables:

v The employee table, through its foreign key on column EMPNO
v The project activity table, through its foreign key on columns PROJNO, ACTNO,
and EMSTDATE.
Related reference
“Project activity table (DSN8910.PROJACT)” on page 1057
“Employee table (DSN8910.EMP)” on page 1051

Unicode sample table (DSN8910.DEMO_UNICODE)

The Unicode sample table is used to verify that data conversions to and from
EBCDIC and Unicode are working as expected.

The table resides in database DSN8D91A, and is defined with the following
statement:
CREATE TABLE DSN8910.DEMO_UNICODE
(LOWER_A_TO_Z CHAR(26) ,
UPPER_A_TO_Z CHAR(26) ,
ZERO_TO_NINE CHAR(10) ,
X00_TO_XFF VARCHAR(256) FOR BIT DATA)
IN DSN8D81E.DSN8S81U
CCSID UNICODE;

Chapter 20. DB2 sample applications and data 1059

Content of the Unicode sample table

The following table shows the content of the columns in the Unicode sample table:
Table 184. Columns of the Unicode sample table
Column Column Name Description
1 LOWER_A_TO_Z Array of characters, ’a’ to ’z’
2 UPPER_A_TO_Z Array of characters, ’A’ to ’Z’
3 ZERO_TO_NINE Array of characters, ’0’ to ’9’
4 X00_TO_XFF Array of characters, x’00’ to x’FF’

This table has no indexes.

Relationship to other tables

This table has no relationship to other tables.

Relationships among the sample tables

Relationships among the sample tables are established by foreign keys in
dependent tables that reference primary keys in parent tables.

The following figure shows relationships among the sample tables. You can
find descriptions of the columns with the descriptions of the tables.

CASCADE
DEPT

SET SET
NULL NULL

RESTRICT EMP
RESTRICT
RESTRICT EMP_PHOTO_RESUME

RESTRICT
CASCADE ACT

PROJ RESTRICT
RESTRICT

PROJACT
RESTRICT

RESTRICT

EMPPROJACT

Figure 78. Relationships among tables in the sample application

1060 Application Programming and SQL Guide

Related reference
“Activity table (DSN8910.ACT)” on page 1049
“Department table (DSN8910.DEPT)” on page 1050
“Employee table (DSN8910.EMP)” on page 1051
“Employee photo and resume table (DSN8910.EMP_PHOTO_RESUME)” on page
1055
“Project table (DSN8910.PROJ)” on page 1056
“Project activity table (DSN8910.PROJACT)” on page 1057
“Employee to project activity table (DSN8910.EMPPROJACT)” on page 1058
“Unicode sample table (DSN8910.DEMO_UNICODE)” on page 1059

Views on the sample tables

DB2 creates a number of views on the sample tables for use in the sample
applications.

The following table indicates the tables on which each view is defined and
the sample applications that use the view. All view names have the qualifier
DSN8910.
Table 185. Views on sample tables
View name On tables or views Used in application
VDEPT DEPT
Organization
Project
VHDEPT DEPT Distributed organization
VEMP EMP
Distributed organization
Organization
Project
VPROJ PROJ Project
VACT ACT Project
VPROJACT PROJACT Project
VEMPPROJACT EMPPROJACT Project
VDEPMG1 Organization
DEPT
EMP
VEMPDPT1 Organization
DEPT
EMP
VASTRDE1 DEPT
VASTRDE2 Organization
VDEPMG1
EMP
VPROJRE1 Project
PROJ
EMP
VPSTRDE1 Project
VPROJRE1
VPROJRE2

Chapter 20. DB2 sample applications and data 1061

Table 185. Views on sample tables (continued)
View name On tables or views Used in application
VPSTRDE2 VPROJRE1 Project
VFORPLA Project
VPROJRE1
EMPPROJACT
VSTAFAC1 Project
PROJACT
ACT
VSTAFAC2 Project
EMPPROJACT
ACT
EMP
VPHONE Phone
EMP
DEPT
VEMPLP EMP Phone

The following SQL statement creates the view named VDEPT.

CREATE VIEW DSN8910.VDEPT
AS SELECT ALL DEPTNO ,
DEPTNAME,
MGRNO ,
ADMRDEPT
FROM DSN8910.DEPT;

The following SQL statement creates the view named VHDEPT.

CREATE VIEW DSN8910.VHDEPT
AS SELECT ALL DEPTNO ,
DEPTNAME,
MGRNO ,
ADMRDEPT,
LOCATION
FROM DSN8910.DEPT;

The following SQL statement creates the view named VEMP.

CREATE VIEW DSN8910.VEMP
AS SELECT ALL EMPNO ,
FIRSTNME,
MIDINIT ,
LASTNAME,
WORKDEPT
FROM DSN8910.EMP;

The following SQL statement creates the view named VPROJ.

CREATE VIEW DSN8910.VPROJ
AS SELECT ALL
PROJNO, PROJNAME, DEPTNO, RESPEMP, PRSTAFF,
PRSTDATE, PRENDATE, MAJPROJ
FROM DSN8910.PROJ ;

The following SQL statement creates the view named VACT.

1062 Application Programming and SQL Guide

CREATE VIEW DSN8910.VACT
AS SELECT ALL ACTNO ,
ACTKWD ,
ACTDESC
FROM DSN8910.ACT ;

The following SQL statement creates the view named VPROJACT.

CREATE VIEW DSN8910.VPROJACT
AS SELECT ALL
PROJNO,ACTNO, ACSTAFF, ACSTDATE, ACENDATE
FROM DSN8910.PROJACT ;

The following SQL statement creates the view named VEMPPROJACT.

CREATE VIEW DSN8910.VEMPPROJACT
AS SELECT ALL
EMPNO, PROJNO, ACTNO, EMPTIME, EMSTDATE, EMENDATE
FROM DSN8910.EMPPROJACT ;

The following SQL statement creates the view named VDEPMG1.

CREATE VIEW DSN8910.VDEPMG1
(DEPTNO, DEPTNAME, MGRNO, FIRSTNME, MIDINIT,
LASTNAME, ADMRDEPT)
AS SELECT ALL
DEPTNO, DEPTNAME, EMPNO, FIRSTNME, MIDINIT,
LASTNAME, ADMRDEPT
FROM DSN8910.DEPT LEFT OUTER JOIN DSN8910.EMP
ON MGRNO = EMPNO ;

The following SQL statement creates the view named VEMPDPT1.

CREATE VIEW DSN8910.VEMPDPT1
(DEPTNO, DEPTNAME, EMPNO, FRSTINIT, MIDINIT,
LASTNAME, WORKDEPT)
AS SELECT ALL
DEPTNO, DEPTNAME, EMPNO, SUBSTR(FIRSTNME, 1, 1), MIDINIT,
LASTNAME, WORKDEPT
FROM DSN8910.DEPT RIGHT OUTER JOIN DSN8910.EMP
ON WORKDEPT = DEPTNO ;

The following SQL statement creates the view named VASTRDE1.

CREATE VIEW DSN8910.VASTRDE1
(DEPT1NO,DEPT1NAM,EMP1NO,EMP1FN,EMP1MI,EMP1LN,TYPE2,
DEPT2NO,DEPT2NAM,EMP2NO,EMP2FN,EMP2MI,EMP2LN)
AS SELECT ALL
D1.DEPTNO,D1.DEPTNAME,D1.MGRNO,D1.FIRSTNME,D1.MIDINIT,
D1.LASTNAME, '1',
D2.DEPTNO,D2.DEPTNAME,D2.MGRNO,D2.FIRSTNME,D2.MIDINIT,
D2.LASTNAME
FROM DSN8910.VDEPMG1 D1, DSN8910.VDEPMG1 D2
WHERE D1.DEPTNO = D2.ADMRDEPT ;

The following SQL statement creates the view named VASTRDE2.

CREATE VIEW DSN8910.VASTRDE2
(DEPT1NO,DEPT1NAM,EMP1NO,EMP1FN,EMP1MI,EMP1LN,TYPE2,
DEPT2NO,DEPT2NAM,EMP2NO,EMP2FN,EMP2MI,EMP2LN)
AS SELECT ALL
D1.DEPTNO,D1.DEPTNAME,D1.MGRNO,D1.FIRSTNME,D1.MIDINIT,
D1.LASTNAME,'2',
D1.DEPTNO,D1.DEPTNAME,E2.EMPNO,E2.FIRSTNME,E2.MIDINIT,
E2.LASTNAME
FROM DSN8910.VDEPMG1 D1, DSN8910.EMP E2
WHERE D1.DEPTNO = E2.WORKDEPT;

Chapter 20. DB2 sample applications and data 1063

The following figure shows the SQL statement that creates the view named
VPROJRE1.

CREATE VIEW DSN8910.VPROJRE1

(PROJNO,PROJNAME,PROJDEP,RESPEMP,FIRSTNME,MIDINIT,
LASTNAME,MAJPROJ)
AS SELECT ALL
PROJNO,PROJNAME,DEPTNO,EMPNO,FIRSTNME,MIDINIT,
LASTNAME,MAJPROJ
FROM DSN8910.PROJ, DSN8910.EMP
WHERE RESPEMP = EMPNO ;

Figure 79. VPROJRE1

The following SQL statement creates the view named VPSTRDE1.

CREATE VIEW DSN8910.VPSTRDE1
(PROJ1NO,PROJ1NAME,RESP1NO,RESP1FN,RESP1MI,RESP1LN,
PROJ2NO,PROJ2NAME,RESP2NO,RESP2FN,RESP2MI,RESP2LN)
AS SELECT ALL
P1.PROJNO,P1.PROJNAME,P1.RESPEMP,P1.FIRSTNME,P1.MIDINIT,
P1.LASTNAME,
P2.PROJNO,P2.PROJNAME,P2.RESPEMP,P2.FIRSTNME,P2.MIDINIT,
P2.LASTNAME
FROM DSN8910.VPROJRE1 P1,
DSN8910.VPROJRE1 P2
WHERE P1.PROJNO = P2.MAJPROJ ;

The following SQL statement creates the view named VPSTRDE2.

CREATE VIEW DSN8910.VPSTRDE2
(PROJ1NO,PROJ1NAME,RESP1NO,RESP1FN,RESP1MI,RESP1LN,
PROJ2NO,PROJ2NAME,RESP2NO,RESP2FN,RESP2MI,RESP2LN)
AS SELECT ALL
P1.PROJNO,P1.PROJNAME,P1.RESPEMP,P1.FIRSTNME,P1.MIDINIT,
P1.LASTNAME,
P1.PROJNO,P1.PROJNAME,P1.RESPEMP,P1.FIRSTNME,P1.MIDINIT,
P1.LASTNAME
FROM DSN8910.VPROJRE1 P1
WHERE NOT EXISTS
(SELECT * FROM DSN8910.VPROJRE1 P2
WHERE P1.PROJNO = P2.MAJPROJ) ;

The following SQL statement creates the view named VFORPLA.

CREATE VIEW DSN8910.VFORPLA
(PROJNO,PROJNAME,RESPEMP,PROJDEP,FRSTINIT,MIDINIT,LASTNAME)
AS SELECT ALL
F1.PROJNO,PROJNAME,RESPEMP,PROJDEP, SUBSTR(FIRSTNME, 1, 1),
MIDINIT, LASTNAME
FROM DSN8910.VPROJRE1 F1 LEFT OUTER JOIN DSN8910.EMPPROJACT F2
ON F1.PROJNO = F2.PROJNO;

The following SQL statement creates the view named VSTAFAC1.

CREATE VIEW DSN8910.VSTAFAC1
(PROJNO, ACTNO, ACTDESC, EMPNO, FIRSTNME, MIDINIT, LASTNAME,
EMPTIME,STDATE,ENDATE, TYPE)
AS SELECT ALL
PA.PROJNO, PA.ACTNO, AC.ACTDESC,' ', ' ', ' ', ' ',
PA.ACSTAFF, PA.ACSTDATE,
PA.ACENDATE,'1'
FROM DSN8910.PROJACT PA, DSN8910.ACT AC
WHERE PA.ACTNO = AC.ACTNO ;

The following SQL statement creates the view named VSTAFAC2.

1064 Application Programming and SQL Guide

CREATE VIEW DSN8910.VSTAFAC2
(PROJNO, ACTNO, ACTDESC, EMPNO, FIRSTNME, MIDINIT, LASTNAME,
EMPTIME,STDATE, ENDATE, TYPE)
AS SELECT ALL
EP.PROJNO, EP.ACTNO, AC.ACTDESC, EP.EMPNO,EM.FIRSTNME,
EM.MIDINIT, EM.LASTNAME, EP.EMPTIME, EP.EMSTDATE,
EP.EMENDATE,'2'
FROM DSN8910.EMPPROJACT EP, DSN8910.ACT AC, DSN8910.EMP EM
WHERE EP.ACTNO = AC.ACTNO AND EP.EMPNO = EM.EMPNO ;

The following SQL statement creates the view named VPHONE.

CREATE VIEW DSN8910.VPHONE
(LASTNAME,
FIRSTNAME,
MIDDLEINITIAL,
PHONENUMBER,
EMPLOYEENUMBER,
DEPTNUMBER,
DEPTNAME)
AS SELECT ALL LASTNAME,
FIRSTNME,
MIDINIT ,
VALUE(PHONENO,' '),
EMPNO,
DEPTNO,
DEPTNAME
FROM DSN8910.EMP, DSN8910.DEPT
WHERE WORKDEPT = DEPTNO;

The following SQL statement creates the view named VEMPLP.

CREATE VIEW DSN8910.VEMPLP
(EMPLOYEENUMBER,
PHONENUMBER)
AS SELECT ALL EMPNO ,
PHONENO
FROM DSN8910.EMP ;

Storage of sample application tables

Normally, related data is stored in the same database.

The following figure shows how the sample tables are related to databases
and storage groups. Two databases are used to illustrate the possibility.

Chapter 20. DB2 sample applications and data 1065

Storage group: DSN8Gvr0

DSN8DvrA DSN8DvrL DSN8DvrP

Databases: LOB application common for
application
data data programming
tables

Table
spaces: Separate
LOB spaces
spaces for DSN8SvrP
for employee
DSN8SvrD DSN8SvrE other common for
photo and
department employee application programming
resume table
table table tables tables

vr is a 2-digit version identifer.

Figure 80. Relationship among sample databases and table spaces

In addition to the storage group and databases that are shown in the preceding
figure, the storage group DSN8G91U and database DSN8D91U are created when
you run DSNTEJ2A.

Storage group for sample application data

Sample application data is stored in storage group DSN8G910. The default storage
group, SYSDEFLT, which is created when DB2 is installed, is not used to store
sample application data.

The storage group that is used to store sample application data is defined
by the following statement:
CREATE STOGROUP DSN8G910
VOLUMES (DSNV01)
VCAT DSNC910;

Databases for sample application data

Sample application data is stored in several different databases. The default
database that is created when DB2 is installed is not used to store the sample
application data.

DSN8D91P is the database that is used for tables that are related to
programs. The other databases are used for tables that are related to applications.
The databases are defined by the following statements:
| CREATE DATABASE DSN8D91A
| STOGROUP DSN8G910
| BUFFERPOOL BP0
| CCSID EBCDIC;
|
| CREATE DATABASE DSN8D91P
| STOGROUP DSN8G910
| BUFFERPOOL BP0
| CCSID EBCDIC;
|
| CREATE DATABASE DSN8D91L
| STOGROUP DSN8G910

1066 Application Programming and SQL Guide

| BUFFERPOOL BP0
| CCSID EBCDIC;
|
| CREATE DATABASE DSN8D91E
| STOGROUP DSN8G910
| BUFFERPOOL BP0
| CCSID UNICODE;
|
| CREATE DATABASE DSN8D91U
| STOGROUP DSN8G91U
| CCSID EBCDIC;

Table spaces for sample application data

The table spaces that are not explicitly defined are created implicitly in the
DSN8D91A database, using the default space attributes.

The following SQL statements explicitly define a series of table spaces.

CREATE TABLESPACE DSN8S91D
IN DSN8D91A
USING STOGROUP DSN8G910
PRIQTY 20
SECQTY 20
ERASE NO
LOCKSIZE PAGE LOCKMAX SYSTEM
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;

CREATE TABLESPACE DSN8S91E

IN DSN8D91A
USING STOGROUP DSN8G910
PRIQTY 20
SECQTY 20
ERASE NO
NUMPARTS 4
(PART 1 USING STOGROUP DSN8G910
PRIQTY 12
SECQTY 12,
PART 3 USING STOGROUP DSN8G910
PRIQTY 12
SECQTY 12)
LOCKSIZE PAGE LOCKMAX SYSTEM
BUFFERPOOL BP0
CLOSE NO
COMPRESS YES
CCSID EBCDIC;
CREATE TABLESPACE DSN8S91B
IN DSN8D91L
USING STOGROUP DSN8G910
PRIQTY 20
SECQTY 20
ERASE NO
LOCKSIZE PAGE
LOCKMAX SYSTEM
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;
CREATE LOB TABLESPACE DSN8S91M
IN DSN8D91L
LOG NO;

Chapter 20. DB2 sample applications and data 1067

CREATE LOB TABLESPACE DSN8S91L
IN DSN8D91L
LOG NO;

CREATE LOB TABLESPACE DSN8S91N

IN DSN8D91L
LOG NO;
CREATE TABLESPACE DSN8S91C
IN DSN8D91P
USING STOGROUP DSN8G910
PRIQTY 160
SECQTY 80
SEGSIZE 4
LOCKSIZE TABLE
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;

CREATE TABLESPACE DSN8S91P

IN DSN8D91A
USING STOGROUP DSN8G910
PRIQTY 160
SECQTY 80
SEGSIZE 4
LOCKSIZE ROW
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;
CREATE TABLESPACE DSN8S91R
IN DSN8D91A
USING STOGROUP DSN8G910
PRIQTY 20
SECQTY 20
ERASE NO
LOCKSIZE PAGE LOCKMAX SYSTEM
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;
CREATE TABLESPACE DSN8S91S
IN DSN8D91A
USING STOGROUP DSN8G910
PRIQTY 20
SECQTY 20
ERASE NO
LOCKSIZE PAGE LOCKMAX SYSTEM
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;
CREATE TABLESPACE DSN8S81Q
IN DSN8D81P
USING STOGROUP DSN8G810
PRIQTY 160
SECQTY 80
SEGSIZE 4
LOCKSIZE PAGE
BUFFERPOOL BP0
CLOSE NO
CCSID EBCDIC;
CREATE TABLESPACE DSN8S81U
IN DSN8D81E
USING STOGROUP DSN8G810
PRIQTY 5
SECQTY 5
ERASE NO

1068 Application Programming and SQL Guide

LOCKSIZE PAGE LOCKMAX SYSTEM
BUFFERPOOL BP0
CLOSE NO
CCSID UNICODE;

DB2 sample applications

Several sample applications come with DB2 to help you with DB2 programming
techniques and coding practices within each of the four environments: batch, TSO,
IMS, and CICS. The sample applications contain various applications that might
apply to managing a company.

This topic describes the DB2 sample applications and the environments under
which each application runs. It also provides information on how to use the
applications, and how to print the application listings.

You can examine the source code for the sample application programs in the online
sample library included with the DB2 product. The name of this sample library is
prefix.SDSNSAMP.

Using the sample applications

You can use the applications interactively by accessing data in the sample tables on
screen displays (panels). You can also access the sample tables in batch when using
the phone applications. All sample objects have PUBLIC authorization, which
makes the samples easier to run.

Productivity-aid sample programs:

DB2 provides four sample programs that many users find helpful as productivity
aids. These programs are shipped as source code, so you can modify them to meet
your needs. The programs are:
DSNTIAUL
The sample unload program. This program, which is written in assembler
language, is a simple alternative to the UNLOAD utility. It unloads some
or all rows from up to 100 DB2 tables. With DSNTIAUL, you can unload
data of any DB2 built-in data type or distinct type. DSNTIAUL unloads the
rows in a form that is compatible with the LOAD utility and generates
utility control statements for LOAD. DSNTIAUL also lets you execute any
SQL non-SELECT statement that can be executed dynamically.
DSNTIAD
A sample dynamic SQL program that is written in assembler language.
With this program, you can execute any SQL statement that can be
executed dynamically, except a SELECT statement.
DSNTEP2
A sample dynamic SQL program that is written in the PL/I language. With
this program, you can execute any SQL statement that can be executed
dynamically. You can use the source version of DSNTEP2 and modify it to
meet your needs, or, if you do not have a PL/I compiler at your
installation, you can use the object code version of DSNTEP2.
DSNTEP4
A sample dynamic SQL program that is written in the PL/I language. This

Chapter 20. DB2 sample applications and data 1069

program is identical to DSNTEP2 except DSNTEP4 uses multi-row fetch for
increased performance. You can use the source version of DSNTEP4 and
modify it to meet your needs, or, if you do not have a PL/I compiler at
your installation, you can use the object code version of DSNTEP4.

Because these four programs also accept the static SQL statements CONNECT, SET
CONNECTION, and RELEASE, you can use the programs to access DB2 tables at
remote locations.

Retrieval of UTF-16 Unicode data:

You can use DSNTEP2, DSNTEP4, and DSNTIAUL to retrieve Unicode UTF-16
graphic data. However, these programs might not be able to display some
characters, if those characters have no mapping in the target SBCS EBCDIC CCSID.

DSNTIAUL and DSNTIAD are shipped only as source code, so you must
precompile, assemble, link, and bind them before you can use them. If you want to
use the source code version of DSNTEP2 or DSNTEP4, you must precompile,
compile, link, and bind it. You need to bind the object code version of DSNTEP2 or
DSNTEP4 before you can use it. Usually a system administrator prepares the
programs as part of the installation process. The following table indicates which
installation job prepares each sample program. All installation jobs are in data set
DSN910.SDSNSAMP.
Table 186. Jobs that prepare DSNTIAUL, DSNTIAD, DSNTEP2, and DSNTEP4
Program name Program preparation job
DSNTIAUL DSNTEJ2A
DSNTIAD DSNTIJTM
DSNTEP2 (source) DSNTEJ1P
DSNTEP2 (object) DSNTEJ1L
DSNTEP4 (source) DSNTEJ1P
DSNTEP4 (object) DSNTEJ1L

To run the sample programs, use the DSN RUN command.

The following table lists the load module name and plan name that you must
specify, and the parameters that you can specify when you run each program. See
the following topics for the meaning of each parameter.
Table 187. DSN RUN option values for DSNTIAUL, DSNTIAD, DSNTEP2, and DSNTEP4
Program name Load module Plan Parameters
DSNTIAUL DSNTIAUL DSNTIB91 SQL
number of rows per fetch
TOLWARN(NO|YES)
DSNTIAD DSNTIAD DSNTIA91 RC0
SQLTERM(termchar)
DSNTEP2 DSNTEP2 DSNTEP91 ALIGN(MID)
or ALIGN(LHS)
NOMIXED or MIXED
SQLTERM(termchar)
TOLWARN(NO|YES)
| PREPWARN

1070 Application Programming and SQL Guide

Table 187. DSN RUN option values for DSNTIAUL, DSNTIAD, DSNTEP2, and
DSNTEP4 (continued)
Program name Load module Plan Parameters
DSNTEP4 DSNTEP4 DSNTP491 ALIGN(MID)
or ALIGN(LHS)
NOMIXED or MIXED
SQLTERM(termchar)
TOLWARN(NO|YES)
| PREPWARN

The remainder of this section contains the following information about running
each program:
v Descriptions of the input parameters
v Data sets that you must allocate before you run the program
v Return codes from the program
v Examples of invocation
Related reference
RUN (DSN) (DB2 Command Reference)

Types of sample applications

DB2 provides a number of sample applications that manage sample company
information. These applications also demonstrate how to use stored procedures,
user-defined functions, and LOBs.

Organization application:

The organization application manages the following company information:

v Department administrative structure
v Individual departments
v Individual employees.

Management of information about department administrative structures involves

how departments relate to other departments. You can view or change the
organizational structure of an individual department, and the information about
individual employees in any department. The organization application runs
interactively in the ISPF/TSO, IMS, and CICS environments and is available in
PL/I and COBOL.

Project application:

The project application manages information about a company’s project activities,

including the following:
v Project structures
v Project activity listings
v Individual project processing
v Individual project activity estimate processing
v Individual project staffing processing.

Each department works on projects that contain sets of related activities.

Information available about these activities includes staffing assignments,
completion-time estimates for the project as a whole, and individual activities
within a project. The project application runs interactively in IMS and CICS and is
available in PL/I only.

Chapter 20. DB2 sample applications and data 1071

Phone application:

The phone application lets you view or update individual employee phone
numbers. There are different versions of the application for ISPF/TSO, CICS, IMS,
and batch:
v ISPF/TSO applications use COBOL and PL/I.
v CICS and IMS applications use PL/I.
v Batch applications use C, C++, COBOL, FORTRAN, and PL/I.

Stored procedure applications:

There are three sets of stored procedure applications:

IFI applications
These applications let you pass DB2 commands from a client program to a
stored procedure, which runs the commands at a DB2 server using the
instrumentation facility interface (IFI). There are two sets of client
programs and stored procedures. One set has a PL/I client and stored
procedure; the other set has a C client and stored procedure.
ODBA application
This application demonstrates how you can use the IMS ODBA interface to
access IMS databases from stored procedures. The stored procedure
accesses the IMS sample DL/I database. The client program and the stored
procedure are written in COBOL.
Utilities stored procedure application
This application demonstrates how to call the utilities stored procedure.
SQL procedure applications
| Sample applications are available for both external SQL procedures and
| native SQL procedures:
v The applications for external SQL procedures demonstrate how to write,
prepare, and invoke such procedures. One set of applications
demonstrates how to prepare SQL procedures using JCL. The other set
of applications shows how to prepare SQL procedures using the SQL
procedure processor. The client programs are written in C.
v The sample job for a native SQL procedure shows how to prepare a
native SQL procedure, how to manage versions of native SQL
procedures, and optionally, how to deploy a native SQL procedure to a
remote server. The sample also prepares and executes a sample caller in
the C language
WLM refresh application
This application is a client program that calls the DB2–supplied stored
procedure WLM_REFRESH to refresh a WLM environment. This program
is written in C.
System parameter reporting application
This application is a client program that calls the DB2–supplied stored
procedure DSNWZP to display the current settings of system parameters.
This program is written in C.

All stored procedure applications run in the TSO batch environment.

1072 Application Programming and SQL Guide

User-defined function applications:

The user-defined function applications consist of a client program that invokes the
sample user-defined functions and a set of user-defined functions that perform the
following functions:
v Convert the current date to a user-specified format
v Convert a date from one format to another
v Convert the current time to a user-specified format
v Convert a date from one format to another
v Return the day of the week for a user-specified date
v Return the month for a user-specified date
v Format a floating point number as a currency value
v Return the table name for a table, view, or alias
v Return the qualifier for a table, view or alias
v Return the location for a table, view or alias
v Return a table of weather information

All programs are written in C or C++ and run in the TSO batch environment.

LOB application:

The LOB application demonstrates how to perform the following tasks:

v Define DB2 objects to hold LOB data
v Populate DB2 tables with LOB data using the LOAD utility, or using INSERT
and UPDATE statements when the data is too large for use with the LOAD
utility
v Manipulate the LOB data using LOB locators

The programs that create and populate the LOB objects use DSNTIAD and run in
the TSO batch environment. The program that manipulates the LOB data is written
in C and runs under ISPF/TSO.

Application languages and environments for the sample

applications
The sample applications demonstrate how to run DB2 applications in the TSO,
IMS, or CICS environments.

The following table shows the environments under which each application runs,
and the languages the applications use for each environment.
Table 188. Application languages and environments
Programs ISPF/TSO IMS CICS Batch SPUFI
Dynamic SQL Assembler
programs PL/I
Exit routines Assembler Assembler Assembler Assembler Assembler
Organization COBOL COBOL COBOL
PL/I PL/I

Chapter 20. DB2 sample applications and data 1073

Table 188. Application languages and environments (continued)
Programs ISPF/TSO IMS CICS Batch SPUFI
Phone COBOL PL/I PL/I COBOL
PL/I FORTRAN
Assembler1 PL/I
C
C++
Project PL/I PL/I
SQLCA Assembler Assembler Assembler Assembler
formatting
routines
Stored COBOL PL/I
procedures C
SQL
User-defined C
functions C++
LOBs C
Notes:
1. Assembler subroutine DSN8CA.

Sample applications in TSO

A set of DB2 sample applications run in the TSO environment.
Table 189. Sample DB2 applications for TSO
Preparation
JCL member Attachment
Application Program name name facility Description
Phone DSN8BC3 DSNTEJ2C DSNELI This COBOL batch program lists employee
telephone numbers and updates them if
requested.
Phone DSN8BD3 DSNTEJ2D DSNELI This C batch program lists employee telephone
numbers and updates them if requested.
Phone DSN8BE3 DSNTEJ2E DSNELI This C++ batch program lists employee
telephone numbers and updates them if
requested.
Phone DSN8BP3 DSNTEJ2P DSNELI This PL/I batch program lists employee
telephone numbers and updates them if
requested.
Phone DSN8BF3 DSNTEJ2F DSNELI This FORTRAN program lists employee
telephone numbers and updates them if
requested.
Organization DSN8HC3 DSNTEJ3C or DSNALI This COBOL ISPF program displays and
DSNTEJ6 updates information about a local department. It
can also display and update information about
an employee at a local or remote location.
Phone DSN8SC3 DSNTEJ3C DSNALI This COBOL ISPF program lists employee
telephone numbers and updates them if
requested.
Phone DSN8SP3 DSNTEJ3P DSNALI This PL/I ISPF program lists employee
telephone numbers and updates them if
requested.

1074 Application Programming and SQL Guide

Table 189. Sample DB2 applications for TSO (continued)
Preparation
JCL member Attachment
Application Program name name facility Description
UNLOAD DSNTIAUL DSNTEJ2A DSNELI This assembler language program unloads the
data from a table or view and to produce LOAD
utility control statements for the data.
Dynamic SQL DSNTIAD DSNTIJTM DSNELI This assembler language program dynamically
executes non-SELECT statements read in from
SYSIN; that is, it uses dynamic SQL to execute
non-SELECT SQL statements.
Dynamic SQL DSNTEP2 DSNTEJ1P or DSNELI This PL/I program dynamically executes SQL
DSNTEJ1L statements read in from SYSIN. Unlike
DSNTIAD, this application can also execute
SELECT statements.
Stored DSN8EP1 DSNTEJ6P DSNELI The jobs DSNTEJ6P and DSNTEJ6S prepare a
procedures1 PL/I version of the application. This sample
executes DB2 commands using the
| Stored DSN8EP2 DSNTEJ6S DSNRLI
instrumentation facility interface (IFI).
procedure1
Stored DSN8EPU DSNTEJ6U DSNELI The sample that is prepared by job DSNTEJ6U
procedures1 invokes the utilities stored procedure.
Stored DSN8ED1 DSNTEJ6D DSNELI The jobs DSNTEJ6D and DSNTEJ6T prepare a C
procedures1 version of the application. The C stored
procedure uses result sets to return commands
| Stored DSN8ED2 DSNTEJ6T DSNRLI to the client. This sample executes DB2
procedures1 commands using the instrumentation facility
interface (IFI).
| Stored DSN8EC1 DSNTEJ61 DSNRLI The sample that is prepared by jobs DSNTEJ61
procedures1 and DSNTEJ62 demonstrates a stored procedure
that accesses IMS databases through the ODBA
Stored DSN8EC2 DSNTEJ62 DSNELI
interface.
procedures1
| Stored DSN8ES1 DSNTEJ63 DSNRLI The sample that is prepared by jobs DSNTEJ63
procedures1 and DSNTEJ64 demonstrates how to prepare an
SQL procedure using JCL.
Stored DSN8ED3 DSNTEJ64 DSNELI
procedures1
| Stored DSN8ES2 DSNTEJ65 DSNRLI The sample that is prepared by job DSNTEJ65
procedures1 demonstrates how to prepare an SQL procedure
using the SQL procedure processor.
Stored DSN8ED6 DSNTEJ6W DSNELI The sample that is prepared by job DSNTEJ6W
procedures1 demonstrates how to prepare and run a client
program that calls a DB2–supplied stored
procedure to refresh a WLM environment.
Stored DSN8ED7 DSNTEJ6Z DSNELI The sample that is prepared by job DSNTEJ6Z
procedures1 demonstrates how to prepare and run a client
program that calls a DB2–supplied stored
procedure to display the current settings of
system parameters.

Chapter 20. DB2 sample applications and data 1075

Table 189. Sample DB2 applications for TSO (continued)
Preparation
JCL member Attachment
Application Program name name facility Description
| Stored DSN8ED9 DSNTEJ66 DSNELI The sample that is prepared by job DSNTEJ66
| procedures1 demonstrates how to prepare and run a client
| program that calls a native SQL procedure,
| manages versions of that procedure, and
|| Stored DSN8ES3 DSNTEJ66 not applicable optionally, deploys that procedure to a remote
|| procedures1 server. DSN8ES3 is the sample native SQL
| procedure and DSN8ED9 is the sample C
| language caller of DSN8ES3.
| User-defined DSN8DUAD DSNTEJ2U DSNRLI These C applications consist of a set of
functions user-defined scalar functions that can be
invoked through SPUFI or DSNTEP2.
| User-defined DSN8DUAT DSNTEJ2U DSNRLI
functions
| User-defined DSN8DUCD DSNTEJ2U DSNRLI
functions
| User-defined DSN8DUCT DSNTEJ2U DSNRLI
functions
| User-defined DSN8DUCY DSNTEJ2U DSNRLI
functions
| User-defined DSN8DUTI DSNTEJ2U DSNRLI
functions
| User-defined DSN8DUWC DSNTEJ2U DSNRLI The user-defined table function DSN8DUWF
functions can be invoked by the C client program
DSN8DUWC.
| User-defined DSN8DUWF DSNTEJ2U DSNRLI
functions
| User-defined DSN8EUDN DSNTEJ2U DSNRLI These C++ applications consist of a set of
functions user-defined scalar functions that can be
invoked through SPUFI or DSNTEP2.
| User-defined DSN8EUMN DSNTEJ2U DSNRLI
functions
LOBs DSN8DLPL DSNTEJ71 DSNELI These applications demonstrate how to populate
a LOB column that is greater than 32 KB,
LOBs DSN8DLCT DSNTEJ71 DSNELI
manipulate the data using the POSSTR and
LOBs DSN8DLRV DSNTEJ73 DSNELI SUBSTR built-in functions, and display the data
LOBs DSN8DLPV DSNTEJ75 DSNELI in ISPF using GDDM®.

Note:
1. All of the stored procedure applications consist of a calling program, a stored
procedure program, or both.
Related reference
“Data sets that the precompiler uses” on page 893

Sample applications in IMS

A set of DB2 sample applications run in the IMS environment.

1076 Application Programming and SQL Guide

Table 190. Sample DB2 applications for IMS
Application Program name JCL member name Description
Organization DSN8IC0 DSNTEJ4C IMS COBOL
DSN8IC1 Organization
DSN8IC2 Application
Organization DSN8IP0 DSNTEJ4P IMS PL/I
DSN8IP1 Organization
DSN8IP2 Application
Project DSN8IP6 DSNTEJ4P IMS PL/I Project
DSN8IP7 Application
DSN8IP8
Phone DSN8IP3 DSNTEJ4P IMS PL/I Phone
Application. This
program lists
employee telephone
numbers and updates
them if requested.

Related reference
“Data sets that the precompiler uses” on page 893

Sample applications in CICS

A set of DB2 sample applications run in the CICS environment.
Table 191. Sample DB2 applications for CICS
Application Program name JCL member name Description
Organization DSN8CC0 DSNTEJ5C CICS COBOL
DSN8CC1 Organization
DSN8CC2 Application
Organization DSN8CP0 DSNTEJ5P CICS PL/I
DSN8CP1 Organization
DSN8CP2 Application
Project DSN8CP6 DSNTEJ5P CICS PL/I Project
DSN8CP7 Application
DSN8CP8
Phone DSN8CP3 DSNTEJ5P CICS PL/I Phone
Application. This
program lists
employee telephone
numbers and updates
them if requested.

Related reference
“Data sets that the precompiler uses” on page 893

DSNTIAUL
Use the DSNTIAUL program to unload data from DB2 tables into sequential data
sets.

This topic contains information that you need when you run DSNTIAUL,
including parameters, data sets, return codes, and invocation examples.

Chapter 20. DB2 sample applications and data 1077

To retrieve data from a remote site by using the multi-row fetch capability for
enhanced performance, bind DSNTIAUL with the DBPROTOCOL(DRDA) option.
To run DSNTIAUL remotely when it is bound with the DBPROTOCOL(PRIVATE)
option, switch DSNTIAUL to single-row fetch mode by specifying 1 for the
number of rows per fetch parameter.

DSNTIAUL parameters:
SQL
Specify SQL to indicate that your input data set contains one or more complete
SQL statements, each of which ends with a semicolon. You can include any
SQL statement that can be executed dynamically in your input data set. In
addition, you can include the static SQL statements CONNECT, SET
CONNECTION, or RELEASE. DSNTIAUL uses the SELECT statements to
determine which tables to unload and dynamically executes all other
statements except CONNECT, SET CONNECTION, and RELEASE. DSNTIAUL
executes CONNECT, SET CONNECTION, and RELEASE statically to connect
to remote locations.
number of rows per fetch
Specify a number from 1 to 32767 to specify the number of rows per fetch that
DSNTIAUL retrieves. If you do not specify this number, DSNTIAUL retrieves
100 rows per fetch. This parameter can be specified with the SQL parameter.
Specify 1 to retrieve data from a remote site when DSNTIAUL is bound with
the DBPROTOCOL(PRIVATE) option.
TOLWARN
Specify NO (the default) or YES to indicate whether DSNTIAUL continues to
retrieve rows after receiving an SQL warning:
NO If a warning occurs when DSNTIAUL executes an OPEN or FETCH to
retrieve rows, DSNTIAUL stops retrieving rows. If the SQLWARN1,
SQLWARN2, SQLWARN6, or SQLWARN7 flag is set when DSNTIAUL
executes a FETCH to retrieve rows, DSNTIAUL continues to retrieve
rows.
YES If a warning occurs when DSNTIAUL executes an OPEN or FETCH to
retrieve rows, DSNTIAUL continues to retrieve rows.
| LOBFILE(prefix)
| Specify LOBFILE to indicate that you want DSNTIAUL to dynamically allocate
| data sets, each to receive the full content of a LOB cell. (A LOB cell is the
| intersection of a row and a LOB column.) If you do not specify the LOBFILE
| option, you can unload up to only 32 KB of data from a LOB column.
| prefix
| Specify a high-level qualifier for these dynamically allocated data sets. You
| can specify up to 17 characters. The qualifier must conform with the rules
| for TSO data set names.

| DSNTIAUL uses a naming convention for these dynamically allocated data sets
| of prefix.Qiiiiiii.Cjjjjjjj.Rkkkkkkk, where these qualifiers have the following
| values:
| prefix
| The high-level qualifier that you specify in the LOBFILE option.
| Qiiiiiii
| The sequence number (starting from 0) of a query that returns one or more
| LOB columns

1078 Application Programming and SQL Guide

| Cjjjjjjj
| The sequence number (starting from 0) of a column in a query that returns
| one or more LOB columns
| Rkkkkkkk
| The sequence number (starting from 0) of a row of a result set that has one
| or more LOB columns.
| The generated LOAD statement contains LOB file reference variables that can
| be used to load data from these dynamically allocated data sets.

If you do not specify the SQL parameter, your input data set must contain one or
more single-line statements (without a semicolon) that use the following syntax:
table or view name [WHERE conditions] [ORDER BY columns]

Each input statement must be a valid SQL SELECT statement with the clause
SELECT * FROM omitted and with no ending semicolon. DSNTIAUL generates a
SELECT statement for each input statement by appending your input line to
SELECT * FROM, then uses the result to determine which tables to unload. For this
input format, the text for each table specification can be a maximum of 72 bytes
and must not span multiple lines.

You can use the input statements to specify SELECT statements that join two or
more tables or select specific columns from a table. If you specify columns, you
need to modify the LOAD statement that DSNTIAUL generates.

DSNTIAUL data sets:

Data set
Description
SYSIN
Input data set.
You cannot enter comments in DSNTIAUL input.
The record length for the input data set must be at least 72 bytes.
DSNTIAUL reads only the first 72 bytes of each record.
SYSPRINT
Output data set. DSNTIAUL writes informational and error messages in
this data set.
The record length for the SYSPRINT data set is 121 bytes.
SYSPUNCH
Output data set. DSNTIAUL writes the LOAD utility control statements in
this data set.
SYSRECnn
Output data sets. The value nn ranges from 00 to 99. You can have a
maximum of 100 output data sets for a single execution of DSNTIAUL.
Each data set contains the data that is unloaded when DSNTIAUL
processes a SELECT statement from the input data set. Therefore, the
number of output data sets must match the number of SELECT statements
(if you specify parameter SQL) or table specifications in your input data
set.

Define all data sets as sequential data sets. You can specify the record length and
block size of the SYSPUNCH and SYSRECnn data sets. The maximum record
length for the SYSPUNCH and SYSRECnn data sets is 32760 bytes.

Chapter 20. DB2 sample applications and data 1079

DSNTIAUL return codes:
Table 192. DSNTIAUL return codes
Return code Meaning
0 Successful completion.
| 4 An SQL statement received a warning code.
| v If TOLWARN(YES) is specified, and the warning occurred on a FETCH
| or OPEN during the processing of a SELECT statement, DB2 performs
| the unload operation.
| v Otherwise if the SQL statement was a SELECT statement, DB2 did not
| perform the associated unload operation.
| If DB2 returns a +394, which indicates that it is using optimization hints,
| or a +395, which indicates one or more invalid optimization hints, DB2
| performs the unload operation.
| 8 An SQL statement received an error code. If the SQL statement was a
| SELECT statement, DB2 did not perform the associated unload operation
| or did not complete it.
| 12 DSNTIAUL could not open a data set, an SQL statement returned a
| severe error code (-144, -302, -804, -805, -818, -902, -906, -911, -913, -922,
| -923, -924, or -927), or an error occurred in the SQL message formatting
| routine.

Example of using DSNTIAUL to unload a subset of rows in a

table:

Suppose that you want to unload the rows for department D01 from the project
table. Because you can fit the table specification on one line, and you do not want
to execute any non-SELECT statements, you do not need the SQL parameter. Your
invocation looks like the one that is shown in the following figure:
//UNLOAD EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB91) -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSREC00 DD DSN=DSN8UNLD.SYSREC00,
// UNIT=SYSDA,SPACE=(32760,(1000,500)),DISP=(,CATLG),
// VOL=SER=SCR03
//SYSPUNCH DD DSN=DSN8UNLD.SYSPUNCH,
// UNIT=SYSDA,SPACE=(800,(15,15)),DISP=(,CATLG),
// VOL=SER=SCR03,RECFM=FB,LRECL=120,BLKSIZE=1200
//SYSIN DD *DSN8910
.PROJ WHERE DEPTNO='D01'

Example of using DSNTIAUL to unload rows in more than one

table:

Suppose that you also want to use DSNTIAUL to perform the following actions:
v Unload all rows from the project table
v Unload only rows from the employee table for employees in departments with
department numbers that begin with D, and order the unloaded rows by
employee number
v Lock both tables in share mode before you unload them

1080 Application Programming and SQL Guide

v Retrieve 250 rows per fetch

For these activities, you must specify the SQL parameter and specify the number of
rows per fetch when you run DSNTIAUL. Your DSNTIAUL invocation is shown in
the following figure:
//UNLOAD EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB91) PARMS('SQL,250') -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSREC00 DD DSN=DSN8UNLD.SYSREC00,
// UNIT=SYSDA,SPACE=(32760,(1000,500)),DISP=(,CATLG),
// VOL=SER=SCR03
//SYSREC01 DD DSN=DSN8UNLD.SYSREC01,
// UNIT=SYSDA,SPACE=(32760,(1000,500)),DISP=(,CATLG),
// VOL=SER=SCR03
//SYSPUNCH DD DSN=DSN8UNLD.SYSPUNCH,
// UNIT=SYSDA,SPACE=(800,(15,15)),DISP=(,CATLG),
// VOL=SER=SCR03,RECFM=FB,LRECL=120,BLKSIZE=1200
//SYSIN DD *
LOCK TABLE DSN8910.EMP IN SHARE MODE;
LOCK TABLE DSN8910.PROJ IN SHARE MODE;
SELECT * FROM DSN8910.PROJ;
SELECT * FROM DSN8910.EMP
WHERE WORKDEPT LIKE 'D%'
ORDER BY EMPNO;

Example of using DSNTIAUL to obtain LOAD utility control

statements:

If you want to obtain the LOAD utility control statements for loading rows into a
table, but you do not want to unload the rows, you can set the data set names for
the SYSRECnn data sets to DUMMY. For example, to obtain the utility control
statements for loading rows into the department table, you invoke DSNTIAUL as
shown in the following figure:
//UNLOAD EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB91) -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSREC00 DD DUMMY
//SYSPUNCH DD DSN=DSN8UNLD.SYSPUNCH,
// UNIT=SYSDA,SPACE=(800,(15,15)),DISP=(,CATLG),
// VOL=SER=SCR03,RECFM=FB,LRECL=120,BLKSIZE=1200
//SYSIN DD *DSN8910
.DEPT

Example of using DSNTIAUL to unload LOB data:

| This example uses the sample LOB table with the following structure:
CREATE TABLE DSN8910.EMP_PHOTO_RESUME
( EMPNO CHAR(06) NOT NULL,
EMP_ROWID ROWID NOT NULL GENERATED ALWAYS,
PSEG_PHOTO BLOB(500K),
BMP_PHOTO BLOB(100K),

Chapter 20. DB2 sample applications and data 1081

RESUME CLOB(5K),
PRIMARY KEY (EMPNO))
IN DSN8D91L.DSN8S91B
CCSID EBCDIC;

The following call to DSNTIAUL unloads the sample LOB table. The parameters
for DSNTIAUL indicate the following options:
v The input data set (SYSIN) contains SQL.
v DSNTIAUL is to retrieve 2 rows per fetch.
v DSNTIAUL places the LOB data in data sets with a high-level qualifier of
DSN8UNLD.
//UNLOAD EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAUL) PLAN(DSNTIB91) -
PARMS('SQL,2,LOBFILE(DSN8UNLD)') -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSREC00 DD DSN=DSN8UNLD.SYSREC00,
// UNIT=SYSDA,SPACE=(800,(15,15)),DISP=(,CATLG),
// VOL=SER=SCR03,RECFM=FB
//SYSPUNCH DD DSN=DSN8UNLD.SYSPUNCH,
// UNIT=SYSDA,SPACE=(800,(15,15)),DISP=(,CATLG),
// VOL=SER=SCR03,RECFM=FB
//SYSIN DD *
SELECT * FROM DSN8910.EMP_PHOTO_RESUME;

Given that the sample LOB table has 4 rows of data, DSNTIAUL produces the
following output:
v Data for columns EMPNO and EMP_ROWID are placed in the data set that is
allocated according to the SYSREC00 DD statement. The data set name is
DSN8UNLD.SYSREC00
v A generated LOAD statement is placed in the data set that is allocated according
to the SYSPUNCH DD statement. The data set name is DSN8UNLD.SYSPUNCH
v The following data sets are dynamically created to store LOB data:
– DSN8UNLD.Q0000000.C0000002.R0000000
– DSN8UNLD.Q0000000.C0000002.R0000001
– DSN8UNLD.Q0000000.C0000002.R0000002
– DSN8UNLD.Q0000000.C0000002.R0000003
– DSN8UNLD.Q0000000.C0000003.R0000000
– DSN8UNLD.Q0000000.C0000003.R0000001
– DSN8UNLD.Q0000000.C0000003.R0000002
– DSN8UNLD.Q0000000.C0000003.R0000003
– DSN8UNLD.Q0000000.C0000004.R0000000
– DSN8UNLD.Q0000000.C0000004.R0000001
– DSN8UNLD.Q0000000.C0000004.R0000002
– DSN8UNLD.Q0000000.C0000004.R0000003
For example, DSN8UNLD.Q0000000.C0000004.R0000001 means that the data set
contains data that is unloaded from the second row (R0000001) and the fifth
column (C0000004) of the result set for the first query (Q0000000).

1082 Application Programming and SQL Guide

DSNTIAD
Use the DSNTIAD program to execute SQL statements other than SELECT
statements dynamically.

DSNTIAD parameters:
RC0
If you specify this parameter, DSNTIAD ends with return code 0, even if the
program encounters SQL errors. If you do not specify RC0, DSNTIAD ends
with a return code that reflects the severity of the errors that occur. Without
RC0, DSNTIAD terminates if more than 10 SQL errors occur during a single
execution.
SQLTERM(termchar)
Specify this parameter to indicate the character that you use to end each SQL
statement. You can use any special character except one of those listed in the
following table. SQLTERM(;) is the default.
Table 193. Invalid special characters for the SQL terminator
Name Character Hexadecimal representation
blank X’40’
comma , X’6B’
double quotation mark ″ X’7F’
left parenthesis ( X’4D’
right parenthesis ) X’5D’
single quotation mark ’ X’7D’
underscore _ X’6D’

Use a character other than a semicolon if you plan to execute a statement that
contains embedded semicolons.

example:

Suppose that you specify the parameter SQLTERM(#) to indicate that the
character # is the statement terminator. Then a CREATE TRIGGER statement
with embedded semicolons looks like this:
CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END#

A CREATE PROCEDURE statement with embedded semicolons looks like the

following statement:
CREATE PROCEDURE PROC1 (IN PARM1 INT, OUT SCODE INT)
LANGUAGE SQL
BEGIN
DECLARE SQLCODE INT;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
SET SCODE = SQLCODE;
UPDATE TBL1 SET COL1 = PARM1;
END #

Chapter 20. DB2 sample applications and data 1083

Be careful to choose a character for the statement terminator that is not used
within the statement.

DSNTIAD data sets:

Data set
Description
SYSIN
Input data set. In this data set, you can enter any number of non-SELECT
SQL statements, each terminated with a semicolon. A statement can span
multiple lines, but DSNTIAD reads only the first 72 bytes of each line.
You cannot enter comments in DSNTIAD input.
SYSPRINT
Output data set. DSNTIAD writes informational and error messages in this
data set. DSNTIAD sets the record length of this data set to 121 bytes and
the block size to 1210 bytes.

Define all data sets as sequential data sets.

DSNTIAD return codes:

Table 194. DSNTIAD return codes
Return code Meaning
0 Successful completion, or the user-specified parameter RC0.
4 An SQL statement received a warning code.
8 An SQL statement received an error code.
12 DSNTIAD could not open a data set, the length of an SQL statement was
more than 32760 bytes, an SQL statement returned a severe error code
(-8nn or -9nn), or an error occurred in the SQL message formatting
routine.

Example of DSNTIAD invocation:

Suppose that you want to execute 20 UPDATE statements, and you do not want
DSNTIAD to terminate if more than 10 errors occur. Your invocation looks like the
one that is shown in the following figure:
//RUNTIAD EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTIAD) PLAN(DSNTIA91) PARMS('RC0') -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSIN DD *
UPDATE DSN8910.PROJ SET DEPTNO='J01' WHERE DEPTNO='A01';
UPDATE
. DSN8910.PROJ SET DEPTNO='J02' WHERE DEPTNO='A02';
.
.
UPDATE DSN8910.PROJ SET DEPTNO='J20' WHERE DEPTNO='A20';

DSNTEP2 and DSNTEP4

Use the DSNTEP2 or DSNTEP4 programs to execute SQL statements dynamically.

1084 Application Programming and SQL Guide

| DSNTEP2 and DSNTEP4 write their results to the data set that is defined by the
| SYSPRINT DD statement. SYSPRINT data must have a logical record length of 133
| bytes (LRECL=133). Otherwise, the program issues return code 12 with abend
| U4038 and reason code 1. This abend occurs due to the PL/I file exception error
| IBM0201S ONCODE=81. The following error message is issued:
| The UNDEFINEDFILE condition was raised because of conflicting DECLARE
| and OPEN attributes (FILE= SYSPRINT).

| Important: When you allocate a new data set with the SYSPRINT DD statement,
| either specify a DCB with LRECL=133, or do not specify the DCB parameter.

DSNTEP2 and DSNTEP4 parameters:

ALIGN(MID) or ALIGN(LHS)
Specifies the alignment.
ALIGN(MID)
Specifies that DSNTEP2 or DSNTEP4 output should be centered.
ALIGN(MID) is the default.
ALIGN(LHS)
Specifies that the DSNTEP2 or DSNTEP4 output should be left-justified.
NOMIXED or MIXED
Specifies whether DSNTEP2 or DSNTEP4 contains any DBCS characters.
NOMIXED
Specifies that the DSNTEP2 or DSNTEP4 input contains no DBCS
characters. NOMIXED is the default.
MIXED
Specifies that the DSNTEP2 or DSNTEP4 input contains some DBCS
characters.
| PREPWARN
| Specifies that DSNTEP2 or DSNTEP4 is to display the PREPARE
| SQLWARNING message and set the return code to 4 when an SQLWARNING
| is encountered at PREPARE.
| SQLFORMAT
| Specifies how DSNTEP2 or DSNTEP4 pre-processes SQL statements before
| passing them to DB2. Select one of the following options:
| SQL This is the preferred mode for SQL statements other than SQL
| procedural language. When you use this option, which is the default,
| DSNTEP2 or DSNTEP4 collapses each line of an SQL statement into a
| single line before passing the statement to DB2. DSNTEP2 or DSNTEP4
| also discards all SQL comments.
| SQLCOMNT
| This mode is suitable for all SQL, but it is intended primarily for SQL
| procedural language processing. When this option is in effect, behavior
| is similar to SQL mode, except that DSNTEP2 or DSNTEP4 does not
| discard SQL comments. Instead, it automatically terminates each SQL
| comment with a line feed character (hex 25), unless the comment is
| already terminated by one or more line formatting characters. Use this
| option to process SQL procedural language with minimal modification
| by DSNTEP2 or DSNTEP4.
| SQLPL
| This mode is suitable for all SQL, but it is intended primarily for SQL

Chapter 20. DB2 sample applications and data 1085

| procedural language processing. When this option is in effect,
| DSNTEP2 or DSNTEP4 retains SQL comments and terminates each line
| of an SQL statement with a line feed character (hex 25) before passing
| the statement to DB2. Lines that end with a split token are not
| terminated with a line feed character. Use this mode to obtain
| improved diagnostics and debugging of SQL procedural language.
SQLTERM(termchar)
Specifies the character that you use to end each SQL statement. You can use
any character except one of those that are listed in Table 193 on page 1083.
SQLTERM(;) is the default.
Use a character other than a semicolon if you plan to execute a statement that
contains embedded semicolons.
Example: Suppose that you specify the parameter SQLTERM(#) to indicate that
the character # is the statement terminator. Then a CREATE TRIGGER
statement with embedded semicolons looks like this:
CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END#

A CREATE PROCEDURE statement with embedded semicolons looks like the

following statement:
CREATE PROCEDURE PROC1 (IN PARM1 INT, OUT SCODE INT)
LANGUAGE SQL
BEGIN
DECLARE SQLCODE INT;
DECLARE EXIT HANDLER FOR SQLEXCEPTION
SET SCODE = SQLCODE;
UPDATE TBL1 SET COL1 = PARM1;
END #

Be careful to choose a character for the statement terminator that is not used
within the statement.
If you want to change the SQL terminator within a series of SQL statements,
you can use the --#SET TERMINATOR control statement.
Example: Suppose that you have an existing set of SQL statements to which
you want to add a CREATE TRIGGER statement that has embedded
semicolons. You can use the default SQLTERM value, which is a semicolon, for
all of the existing SQL statements. Before you execute the CREATE TRIGGER
statement, include the --#SET TERMINATOR # control statement to change the
SQL terminator to the character #:
SELECT * FROM DEPT;
SELECT * FROM ACT;
SELECT * FROM EMPPROJACT;
SELECT * FROM PROJ;
SELECT * FROM PROJACT;
--#SET TERMINATOR #
CREATE TRIGGER NEW_HIRE
AFTER INSERT ON EMP
FOR EACH ROW MODE DB2SQL
BEGIN ATOMIC
UPDATE COMPANY_STATS SET NBEMP = NBEMP + 1;
END#

1086 Application Programming and SQL Guide

See the following discussion of the SYSIN data set for more information about
the --#SET control statement.
TOLWARN
Specify NO (the default) or YES to indicate whether DSNTEP2 or DSNTEP4
continues to process SQL SELECT statements after receiving an SQL warning:
NO If a warning occurs when DSNTEP2 or DSNTEP4 executes an OPEN or
FETCH for a SELECT statement, DSNTEP2 or DSNTEP4 stops
processing the SELECT statement. If SQLCODE +445 or SQLCODE
+595 occurs when DSNTEP2 or DSNTEP4 executes a FETCH for a
SELECT statement, DSNTEP2 or DSNTEP4 continues to process the
SELECT statement. If SQLCODE +802 occurs when DSNTEP2 or
DSNTEP4 executes a FETCH for a SELECT statement, DSNTEP2 or
DSNTEP4 continues to process the SELECT statement if the
TOLARTHWRN control statement is set to YES.
YES If a warning occurs when DSNTEP2 or DSNTEP4 executes an OPEN or
FETCH for a SELECT statement, DSNTEP2 or DSNTEP4 continues to
process the SELECT statement.

DSNTEP2 and DSNTEP4 data sets:

Data Set
Description
SYSIN
Input data set. In this data set, you can enter any number of SQL
statements, each terminated with a semicolon. A statement can span
multiple lines, but DSNTEP2 or DSNTEP4 reads only the first 72 bytes of
each line.
You can enter comments in DSNTEP2 or DSNTEP4 input with an asterisk
(*) in column 1 or two hyphens (--) anywhere on a line. Text that follows
the asterisk is considered to be comment text. Text that follows two
| hyphens can be comment text or a control statement. Comments are not
| considered in dynamic statement caching. Comments and control
statements cannot span lines.
You can enter control statements of the following form in the DSNTEP2
and DSNTEP4 input data set:
--#SET control-option value

The control options are:

TERMINATOR
The SQL statement terminator. value is any single-byte character other
than one of those that are listed in Table 193 on page 1083. The default
is the value of the SQLTERM parameter.
ROWS_FETCH
The number of rows that are to be fetched from the result table. value
is a numeric literal between -1 and the number of rows in the result
table. -1 means that all rows are to be fetched. The default is -1.
ROWS_OUT
The number of fetched rows that are to be sent to the output data set.
value is a numeric literal between -1 and the number of fetched rows.
-1 means that all fetched rows are to be sent to the output data set. The
default is -1.

Chapter 20. DB2 sample applications and data 1087

MULT_FETCH
This option is valid only for DSNTEP4. Use MULT_FETCH to specify
the number of rows that are to be fetched at one time from the result
table. The default fetch amount for DSNTEP4 is 100 rows, but you can
specify from 1 to 32676 rows.
TOLWARN
Indicates whether DSNTEP2 and DSNTEP4 continue to process an SQL
SELECT statement after an SQL warning is returned. value is either NO
(the default) or YES.
| TOLARTHWRN
| Indicates whether DSNTEP2 and DSNTEP4 continue to process an SQL
| SELECT statement after an arithmetic SQL warning (SQLCODE +802)
| is returned. value is either NO (the default) or YES.
| PREPWARN
| Indicates how DSNTEP2 and DSNTEP4 is to handle a PREPARE
| SQLWARNING message.
| NO
| Indicates that DSNTEP2 and DSNTEP4 does not display the
| PREPARE SQLWARNING message and does not set the return
| code to 4 when an SQLWARNING is encountered at PREPARE.
| The default is NO.
| YES
| Indicates that DSNTEP2 and DSNTEP4 displays the PREPARE
| SQLWARNING message and sets the return code to 4 when an
| SQLWARNING is encountered at PREPARE.
| SQLFORMAT
| Specifies how DSNTEP2 or DSNTEP4 pre-processes SQL statements
| before passing them to DB2. Select one of the following options:
| SQL This is the preferred mode for SQL statements other than SQL
| procedural language. When you use this option, which is the
| default, DSNTEP2 or DSNTEP4 collapses each line of an SQL
| statement into a single line before passing the statement to
| DB2. DSNTEP2 or DSNTEP4 also discards all SQL comments.
| SQLCOMNT
| This mode is suitable for all SQL, but it is intended primarily
| for SQL procedural language processing. When this option is in
| effect, behavior is similar to SQL mode, except that DSNTEP2
| or DSNTEP4 does not discard SQL comments. Instead, it
| automatically terminates each SQL comment with a line feed
| character (hex 25), unless the comment is already terminated
| by one or more line formatting characters. Use this option to
| process SQL procedural language with minimal modification
| by DSNTEP2 or DSNTEP4.
| SQLPL
| This mode is suitable for all SQL, but it is intended primarily
| for SQL procedural language processing. When this option is in
| effect, DSNTEP2 or DSNTEP4 retains SQL comments and
| terminates each line of an SQL statement with a line feed
| character (hex 25) before passing the statement to DB2. Lines
| that end with a split token are not terminated with a line feed

1088 Application Programming and SQL Guide

| character. Use this mode to obtain improved diagnostics and
| debugging of SQL procedural language.
| MAXERRORS
| Specifies that number of errors that DSNTEP2 and DSNTEP4 handle
| before processing stops. The default is 10.
SYSPRINT
Output data set. DSNTEP2 and DSNTEP4 write informational and error
messages in this data set. DSNTEP2 and DSNTEP4 write output records of
no more than 133 bytes.

Define all data sets as sequential data sets.

DSNTEP2 and DSNTEP4 return codes

Table 195. DSNTEP2 and DSNTEP4 return codes
Return code Meaning
0 Successful completion.
4 An SQL statement received a warning code.
8 An SQL statement received an error code.
12 The length of an SQL statement was more than 32760 bytes, an SQL
statement returned a severe error code (-8nn or -9nn), or an error
occurred in the SQL message formatting routine.

Example of DSNTEP2 invocation

Suppose that you want to use DSNTEP2 to execute SQL SELECT statements that
might contain DBCS characters. You also want left-aligned output. Your invocation
looks like the one in the following figure.
//RUNTEP2 EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTEP2) PLAN(DSNTEP91) PARMS('/ALIGN(LHS) MIXED TOLWARN(YES)') -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSIN DD *
SELECT * FROM DSN8910.PROJ;

Example of DSNTEP4 invocation

Suppose that you want to use DSNTEP4 to execute SQL SELECT statements that
might contain DBCS characters, and you want center-aligned output. You also
want DSNTEP4 to fetch 250 rows at a time. Your invocation looks like the one in
the following figure:
//RUNTEP2 EXEC PGM=IKJEFT01,DYNAMNBR=20
//SYSTSPRT DD SYSOUT=*
//SYSTSIN DD *
DSN SYSTEM(DSN)
RUN PROGRAM(DSNTEP4) PLAN(DSNTEP481) PARMS('/ALIGN(MID) MIXED') -
LIB('DSN910.RUNLIB.LOAD')
//SYSPRINT DD SYSOUT=*
//SYSUDUMP DD SYSOUT=*
//SYSIN DD *
--#SET MULT_FETCH 250
SELECT * FROM DSN8910.EMP;

Chapter 20. DB2 sample applications and data 1089

1090 Application Programming and SQL Guide
Information resources for DB2 for z/OS and related products
Many information resources are available to help you use DB2 for z/OS and many
related products. A large amount of technical information about IBM products is
now available online in information centers or on library Web sites.

Disclaimer: Any Web addresses that are included here are accurate at the time this
information is being published. However, Web addresses sometimes change. If you
visit a Web address that is listed here but that is no longer valid, you can try to
find the current Web address for the product information that you are looking for
at either of the following sites:
v http://www.ibm.com/support/publications/us/library/index.shtml, which lists
the IBM information centers that are available for various IBM products
v http://www.elink.ibmlink.ibm.com/public/applications/publications/cgibin/
pbi.cgi, which is the IBM Publications Center, where you can download online
PDF books or order printed books for various IBM products

DB2 for z/OS product information

The primary place to find and use information about DB2 for z/OS is the
Information Management Software for z/OS Solutions Information Center
(http://publib.boulder.ibm.com/infocenter/imzic), which also contains information
about IMS, QMF, and many DB2 and IMS Tools products. This information center
is also available as an installable information center that can run on a local system
or on an intranet server. You can order the Information Management for z/OS
Solutions Information Center DVD (SK5T-7377) for a low cost from the IBM
Publications Center (www.ibm.com/shop/publications/order).

The majority of the DB2 for z/OS information in this information center is also
available in the books that are identified in the following table. You can access
these books at the DB2 for z/OS library Web site (http://www.ibm.com/software/
data/db2/zos/library.html) or at the IBM Publications Center
(http://www.ibm.com/shop/publications/order).
Table 196. DB2 Version 9.1 for z/OS book titles
Available in Available in
Publication information Available in BookManager® Available in
Title number center PDF format printed book
DB2 Version 9.1 for z/OS SC18-9840 X X X X
Administration Guide
DB2 Version 9.1 for z/OS Application SC18-9841 X X X X
Programming & SQL Guide
DB2 Version 9.1 for z/OS Application SC18-9842 X X X X
Programming Guide and Reference for
Java
DB2 Version 9.1 for z/OS Codes GC18-9843 X X X X
DB2 Version 9.1 for z/OS Command SC18-9844 X X X X
Reference
DB2 Version 9.1 for z/OS Data Sharing: SC18-9845 X X X X
Planning and Administration

© Copyright IBM Corp. 1983, 2009 1091

Table 196. DB2 Version 9.1 for z/OS book titles (continued)
Available in Available in
Publication information Available in BookManager® Available in
Title number center PDF format printed book
DB2 Version 9.1 for z/OS Diagnosis LY37-3218 X X X
Guide and Reference 1
DB2 Version 9.1 for z/OS Diagnostic LY37-3219 X
Quick Reference
DB2 Version 9.1 for z/OS Installation GC18-9846 X X X X
Guide
DB2 Version 9.1 for z/OS Introduction to SC18-9847 X X X X
DB2
DB2 Version 9.1 for z/OS Licensed GC18-9848 X X
Program Specifications
DB2 Version 9.1 for z/OS Messages GC18-9849 X X X X
DB2 Version 9.1 for z/OS ODBC Guide SC18-9850 X X X X
and Reference
DB2 Version 9.1 for z/OS Performance SC18-9851 X X X X
Monitoring and Tuning Guide
DB2 Version 9.1 for z/OS Optimization X
Service Center
DB2 Version 9.1 for z/OS Program GI10-8737 X X
Directory
DB2 Version 9.1 for z/OS RACF Access SC18-9852 X X X
Control Module Guide
DB2 Version 9.1 for z/OS Reference for SC18-9853 X X X
Remote DRDA Requesters and Servers
DB2 Version 9.1 for z/OS Reference SX26-3854 X
Summary
DB2 Version 9.1 for z/OS SQL Reference SC18-9854 X X X X
DB2 Version 9.1 for z/OS Utility Guide SC18-9855 X X X X
and Reference
DB2 Version 9.1 for z/OS What’s New? GC18-9856 X X X
DB2 Version 9.1 for z/OS XML Extender SC18-9857 X X X X
Administration and Programming
DB2 Version 9.1 for z/OS XML Guide SC18-9858 X X X X
IRLM Messages and Codes for IMS and GC19-2666 X X X
DB2 for z/OS
Note:
1. DB2 Version 9.1 for z/OS Diagnosis Guide and Reference is available in PDF and BookManager formats on the DB2
Version 9.1 for z/OS Licensed Collection kit, LK3T-7195. You can order this License Collection kit on the IBM
Publications Center site (http://www.elink.ibmlink.ibm.com/public/applications/publications/cgibin/pbi.cgi).
This book is also available in online format in DB2 data set DSN910.SDSNIVPD(DSNDR).

Information resources for related products

In the following table, related product names are listed in alphabetic order, and the
associated Web addresses of product information centers or library Web pages are
indicated.

1092 Application Programming and SQL Guide

Table 197. Related product information resource locations
Related product Information resources
C/C++ for z/OS Library Web site: http://www.ibm.com/software/awdtools/czos/library/

This product is now called z/OS XL C/C++.

CICS Transaction Server for Information center: http://publib.boulder.ibm.com/infocenter/cicsts/v3r1/index.jsp
z/OS
COBOL Information center: http://publib.boulder.ibm.com/infocenter/pdthelp/v1r1/index.jsp

This product is now called Enterprise COBOL for z/OS.

® ™
DB2 Connect Information center: http://publib.boulder.ibm.com/infocenter/db2luw/v9/index.jsp

This resource is for DB2 Connect 9.

DB2 Database for Linux, Information center: http://publib.boulder.ibm.com/infocenter/db2luw/v9/index.jsp
UNIX, and Windows
This resource is for DB2 9 for Linux, UNIX, and Windows.
DB2 Query Management Information center: http://publib.boulder.ibm.com/infocenter/imzic
Facility
DB2 Server for VSE & VM One of the following locations:
v For VSE: http://www.ibm.com/support/docview.wss?rs=66&uid=swg27003758
v For VM: http://www.ibm.com/support/docview.wss?rs=66&uid=swg27003759
DB2 Tools One of the following locations:
v Information center: http://publib.boulder.ibm.com/infocenter/imzic
v Library Web site: http://www.ibm.com/software/data/db2imstools/library.html

These resources include information about the following products and others:
v DB2 Administration Tool
v DB2 Automation Tool
v DB2 Log Analysis Tool
v DB2 Object Restore Tool
v DB2 Query Management Facility
v DB2 SQL Performance Analyzer
DB2 Universal Database Information center: http://www.ibm.com/systems/i/infocenter/
for iSeries
Debug Tool for z/OS Information center: http://publib.boulder.ibm.com/infocenter/pdthelp/v1r1/index.jsp
Enterprise COBOL for Information center: http://publib.boulder.ibm.com/infocenter/pdthelp/v1r1/index.jsp
z/OS
Enterprise PL/I for z/OS Information center: http://publib.boulder.ibm.com/infocenter/pdthelp/v1r1/index.jsp
IMS Information center: http://publib.boulder.ibm.com/infocenter/imzic

Information resources for DB2 for z/OS and related products 1093
Table 197. Related product information resource locations (continued)
Related product Information resources
IMS Tools One of the following locations:
v Information center: http://publib.boulder.ibm.com/infocenter/imzic
v Library Web site: http://www.ibm.com/software/data/db2imstools/library.html

These resources have information about the following products and others:
v IMS Batch Terminal Simulator for z/OS
v IMS Connect
v IMS HALDB Conversion and Maintenance Aid
v IMS High Performance Utility products
v IMS DataPropagator
v IMS Online Reorganization Facility
v IMS Performance Analyzer
Integrated Data Information center: http://publib.boulder.ibm.com/infocenter/idm/v2r2/index.jsp
Management products
This information center has information about the following products and others:
v IBM Data Studio
v InfoSphere™ Data Architect
v InfoSphere Warehouse
v Optim™ Database Administrator
v Optim Development Studio
v Optim Query Tuner
PL/I Information center: http://publib.boulder.ibm.com/infocenter/pdthelp/v1r1/index.jsp

This product is now called Enterprise PL/I for z/OS.

System z http://publib.boulder.ibm.com/infocenter/eserver/v1r2/index.jsp
| Tivoli OMEGAMONXE for Information center: http://publib.boulder.ibm.com/infocenter/tivihelp/v15r1/
| DB2 Performance Expert index.jsp?topic=/com.ibm.ko2pe.doc/ko2welcome.htm
| on z/OS
In earlier releases, this product was called DB2 Performance Expert for z/OS.
WebSphere Application Information center: http://publib.boulder.ibm.com/infocenter/wasinfo/v6r0/index.jsp
Server
WebSphere Message Broker Information center: http://publib.boulder.ibm.com/infocenter/wmbhelp/v6r0m0/
with Rules and Formatter index.jsp
Extension
The product is also known as WebSphere MQ Integrator Broker.
WebSphere MQ Information center: http://publib.boulder.ibm.com/infocenter/wmqv6/v6r0/index.jsp

The resource includes information about MQSeries.

WebSphere Replication Either of the following locations:
Server for z/OS v Information center: http://publib.boulder.ibm.com/infocenter/imzic
v Library Web site: http://www.ibm.com/software/data/db2imstools/library.html

This product is also known as DB2 DataPropagator.

z/Architecture Library Center site: http://www.ibm.com/servers/eserver/zseries/zos/bkserv/

1094 Application Programming and SQL Guide

Table 197. Related product information resource locations (continued)
Related product Information resources
z/OS Library Center site: http://www.ibm.com/servers/eserver/zseries/zos/bkserv/

This resource includes information about the following z/OS elements and components:
v Character Data Representation Architecture
v Device Support Facilities
v DFSORT
v Fortran
v High Level Assembler
v NetView®
v SMP/E for z/OS
v SNA
v TCP/IP
v TotalStorage® Enterprise Storage Server®
v VTAM
v z/OS C/C++
v z/OS Communications Server
v z/OS DCE
v z/OS DFSMS™
v z/OS DFSMS Access Method Services
v z/OS DFSMSdss™
v z/OS DFSMShsm™
v z/OS DFSMSdfp
v z/OS ICSF
v z/OS ISPF
v z/OS JES3
v z/OS Language Environment
v z/OS Managed System Infrastructure
v z/OS MVS
v z/OS MVS JCL
v z/OS Parallel Sysplex
v z/OS RMF™
v z/OS Security Server
v z/OS UNIX System Services
z/OS XL C/C++ http://www.ibm.com/software/awdtools/czos/library/

The following information resources from IBM are not necessarily specific to a
single product:
v The DB2 for z/OS Information Roadmap; available at: http://www.ibm.com/
software/data/db2/zos/roadmap.html
v DB2 Redbooks® and Redbooks about related products; available at:
http://www.ibm.com/redbooks
v IBM Educational resources:
– Information about IBM educational offerings is available on the Web at:
http://www.ibm.com/software/sw-training/

Information resources for DB2 for z/OS and related products 1095
– A collection of glossaries of IBM terms in multiple languages is available on
the IBM Terminology Web site at: http://www.ibm.com/software/
globalization/terminology/index.jsp
v National Language Support information; available at the IBM Publications
Center at: http://www.elink.ibmlink.ibm.com/public/applications/publications/
cgibin/pbi.cgi
v SQL Reference for Cross-Platform Development; available at the following
developerWorks® site: http://www.ibm.com/developerworks/db2/library/
techarticle/0206sqlref/0206sqlref.html

The following information resources are not published by IBM but can be useful to
users of DB2 for z/OS and related products:
v Database design topics:
– DB2 for z/OS and OS/390 Development for Performance Volume I, by Gabrielle
Wiorkowski, Gabrielle & Associates, ISBN 0-96684-605-2
– DB2 for z/OS and OS/390 Development for Performance Volume II, by Gabrielle
Wiorkowski, Gabrielle & Associates, ISBN 0-96684-606-0
– Handbook of Relational Database Design, by C. Fleming and B. Von Halle,
Addison Wesley, ISBN 0-20111-434-8
v Distributed Relational Database Architecture (DRDA) specifications;
http://www.opengroup.org
v Domain Name System: DNS and BIND, Third Edition, Paul Albitz and Cricket
Liu, O’Reilly, ISBN 0-59600-158-4
v Microsoft® Open Database Connectivity (ODBC) information;
http://msdn.microsoft.com/library/
v Unicode information; http://www.unicode.org

1096 Application Programming and SQL Guide

How to obtain DB2 information
You can access the official information about the DB2 product in a number of
ways.
v “DB2 on the Web”
v “DB2 product information”
v “DB2 education” on page 1098
v “How to order the DB2 library” on page 1098

DB2 on the Web

Stay current with the latest information about DB2 by visiting the DB2 home page
on the Web:

www.ibm.com/software/db2zos

On the DB2 home page, you can find links to a wide variety of information
resources about DB2. You can read news items that keep you informed about the
latest enhancements to the product. Product announcements, press releases, fact
sheets, and technical articles help you plan and implement your database
management strategy.

DB2 product information

The official DB2 for z/OS information is available in various formats and delivery
methods. IBM provides mid-version updates to the information in the information
center and in softcopy updates that are available on the Web and on CD-ROM.
Information Management Software for z/OS Solutions Information Center
DB2 product information is viewable in the information center, which is
the primary delivery vehicle for information about DB2 for z/OS, IMS,
QMF, and related tools. This information center enables you to search
across related product information in multiple languages for data
management solutions for the z/OS environment and print individual
topics or sets of related topics. You can also access, download, and print
PDFs of the publications that are associated with the information center
topics. Product technical information is provided in a format that offers
more options and tools for accessing, integrating, and customizing
information resources. The information center is based on Eclipse open
source technology.
The Information Management Software for z/OS Solutions Information
Center is viewable at the following Web site:

http://publib.boulder.ibm.com/infocenter/imzic
CD-ROMs and DVD
Books for DB2 are available on a CD-ROM that is included with your
product shipment:
v DB2 V9.1 for z/OS Licensed Library Collection, LK3T-7195, in English
The CD-ROM contains the collection of books for DB2 V9.1 for z/OS in
PDF and BookManager formats. Periodically, IBM refreshes the books on
subsequent editions of this CD-ROM.
© Copyright IBM Corp. 1983, 2009 1097
The books for DB2 for z/OS are also available on the following CD-ROM
and DVD collection kits, which contain online books for many IBM
products:
v IBM z/OS Software Products Collection , SK3T-4270, in English
v IBM z/OS Software Products DVD Collection , SK3T–4271, in English
PDF format
Many of the DB2 books are available in PDF (Portable Document Format)
for viewing or printing from CD-ROM or the DB2 home page on the Web
or from the information center. Download the PDF books to your intranet
for distribution throughout your enterprise.
BookManager format
You can use online books on CD-ROM to read, search across books, print
portions of the text, and make notes in these BookManager books. Using
the IBM Softcopy Reader, appropriate IBM Library Readers, or the
BookManager Read product, you can view these books in the z/OS,
Windows, and VM environments. You can also view and search many of
the DB2 BookManager books on the Web.

DB2 education

IBM Education and Training offers a wide variety of classroom courses to help you
quickly and efficiently gain DB2 expertise. IBM schedules classes are in cities all
over the world. You can find class information, by country, at the IBM Learning
Services Web site:

www.ibm.com/services/learning

IBM also offers classes at your location, at a time that suits your needs. IBM can
customize courses to meet your exact requirements. For more information,
including the current local schedule, contact your IBM representative.

How to order the DB2 library

To order books, visit the IBM Publication Center on the Web:

www.elink.ibmlink.ibm.com/public/applications/publications/cgibin/pbi.cgi

From the IBM Publication Center, you can go to the Publication Notification
System (PNS). PNS users receive electronic notifications of updated publications in
their profiles. You have the option of ordering the updates by using the
publications direct ordering application or any other IBM publication ordering
channel. The PNS application does not send automatic shipments of publications.
You will receive updated publications and a bill for them if you respond to the
electronic notification.

You can also order DB2 publications and CD-ROMs from your IBM representative
or the IBM branch office that serves your locality. If your location is within the
United States or Canada, you can place your order by calling one of the toll-free
numbers:
v In the U.S., call 1-800-879-2755.
v In Canada, call 1-800-426-4968.

To order additional copies of licensed publications, specify the SOFTWARE option.

To order additional publications or CD-ROMs, specify the PUBLICATIONS option.

1098 Application Programming and SQL Guide

Be prepared to give your customer number, the product number, and either the
feature codes or order numbers that you want.

How to obtain DB2 information 1099

1100 Application Programming and SQL Guide
How to use the DB2 library
Titles of books in the library begin with DB2 Version 9.1 for z/OS. However,
references from one book in the library to another are shortened and do not
include the product name, version, and release. Instead, they point directly to the
section that holds the information. The primary place to find and use information
about DB2 for z/OS is the Information Management Software for z/OS Solutions
Information Center (http://publib.boulder.ibm.com/infocenter/imzic).

| If you are new to DB2 for z/OS, Introduction to DB2 for z/OS provides a
| comprehensive introduction to DB2 Version 9.1 for z/OS. Topics included in this
| book explain the basic concepts that are associated with relational database
| management systems in general, and with DB2 for z/OS in particular.

The most rewarding task associated with a database management system is asking
questions of it and getting answers, the task called end use. Other tasks are also
necessary—defining the parameters of the system, putting the data in place, and so
on. The tasks that are associated with DB2 are grouped into the following major
categories.

Installation

If you are involved with installing DB2, you will need to use a variety of resources,
such as:
v DB2 Program Directory
v DB2 Installation Guide
v DB2 Administration Guide
v DB2 Application Programming Guide and Reference for Java
v DB2 Codes
v DB2 Internationalization Guide
v DB2 Messages
v DB2 Performance Monitoring and Tuning Guide
v DB2 RACF Access Control Module Guide
v DB2 Utility Guide and Reference

If you will be using data sharing capabilities you also need DB2 Data Sharing:
Planning and Administration, which describes installation considerations for data
sharing.

If you will be installing and configuring DB2 ODBC, you will need DB2 ODBC
Guide and Reference.

If you are installing IBM Spatial Support for DB2 for z/OS, you will need IBM
Spatial Support for DB2 for z/OS User’s Guide and Reference.

If you are installing IBM OmniFind® Text Search Server for DB2 for z/OS, you will
need IBM OmniFind Text Search Server for DB2 for z/OS Installation, Administration,
and Reference.

© Copyright IBM Corp. 1983, 2009 1101

End use

End users issue SQL statements to retrieve data. They can also insert, update, or
delete data, with SQL statements. They might need an introduction to SQL,
detailed instructions for using SPUFI, and an alphabetized reference to the types of
SQL statements. This information is found in DB2 Application Programming and SQL
Guide, and DB2 SQL Reference.

End users can also issue SQL statements through the DB2 Query Management
Facility (QMF) or some other program, and the library for that licensed program
might provide all the instruction or reference material they need. For a list of the
titles in the DB2 QMF library, see the bibliography at the end of this book.

Application programming

Some users access DB2 without knowing it, using programs that contain SQL
statements. DB2 application programmers write those programs. Because they
write SQL statements, they need the same resources that end users do.

Application programmers also need instructions for many other topics:

v How to transfer data between DB2 and a host program—written in Java, C, or
COBOL, for example
v How to prepare to compile a program that embeds SQL statements
v How to process data from two systems simultaneously, for example, DB2 and
IMS or DB2 and CICS
v How to write distributed applications across operating systems
v How to write applications that use Open Database Connectivity (ODBC) to
access DB2 servers
| v How to write applications that use JDBC and SQLJ with the Java programming
| language to access DB2 servers
| v How to write applications to store XML data on DB2 servers and retrieve XML
| data from DB2 servers.

The material needed for writing a host program containing SQL is in DB2
Application Programming and SQL Guide.

| The material needed for writing applications that use JDBC and SQLJ to access
| DB2 servers is in DB2 Application Programming Guide and Reference for Java. The
| material needed for writing applications that use DB2 CLI or ODBC to access DB2
| servers is in DB2 ODBC Guide and Reference. The material needed for working with
| XML data in DB2 is in DB2 XML Guide. For handling errors, see DB2 Messages and
| DB2 Codes.

If you are a software vendor implementing DRDA clients and servers, you will
need DB2 Reference for Remote DRDA Requesters and Servers.

Information about writing applications across operating systems can be found in

IBM DB2 SQL Reference for Cross-Platform Development.

System and database administration

Administration covers almost everything else. DB2 Administration Guide divides

some of those tasks among the following sections:

1102 Application Programming and SQL Guide

v DB2 concepts: Introduces DB2 structures, the DB2 environment, and high
availability.
v Designing a database: Discusses the decisions that must be made when
designing a database and tells how to implement the design by creating and
altering DB2 objects, loading data, and adjusting to changes.
v Security and auditing: Describes ways of controlling access to the DB2 system
and to data within DB2, to audit aspects of DB2 usage, and to answer other
security and auditing concerns.
v Operation and recovery: Describes the steps in normal day-to-day operation and
discusses the steps one should take to prepare for recovery in the event of some
failure.

DB2 Performance Monitoring and Tuning Guide explains how to monitor the
performance of the DB2 system and its parts. It also lists things that can be done to
make some parts run faster.

If you will be using the RACF access control module for DB2 authorization
checking, you will need DB2 RACF Access Control Module Guide.

If you are involved with DB2 only to design the database, or plan operational
procedures, you need DB2 Administration Guide. If you also want to carry out your
own plans by creating DB2 objects, granting privileges, running utility jobs, and so
on, you also need:
v DB2 SQL Reference, which describes the SQL statements you use to create, alter,
and drop objects and grant and revoke privileges
v DB2 Utility Guide and Reference, which explains how to run utilities
v DB2 Command Reference, which explains how to run commands

If you will be using data sharing, you need DB2 Data Sharing: Planning and
Administration, which describes how to plan for and implement data sharing.

Additional information about system and database administration can be found in

DB2 Messages and DB2 Codes, which list messages and codes issued by DB2, with
explanations and suggested responses.

Diagnosis

Diagnosticians detect and describe errors in the DB2 program. They might also
recommend or apply a remedy. The documentation for this task is in DB2 Diagnosis
Guide and Reference, DB2 Messages, and DB2 Codes.

How to use the DB2 library 1103

1104 Application Programming and SQL Guide
Notices
This information was developed for products and services offered in the U.S.A.

IBM may not offer the products, services, or features discussed in this document in
other countries. Consult your local IBM representative for information on the
products and services currently available in your area. Any reference to an IBM
product, program, or service is not intended to state or imply that only that IBM
product, program, or service may be used. Any functionally equivalent product,
program, or service that does not infringe any IBM intellectual property right may
be used instead. However, it is the user’s responsibility to evaluate and verify the
operation of any non-IBM product, program, or service.

IBM may have patents or pending patent applications covering subject matter
described in this document. The furnishing of this document does not give you
any license to these patents. You can send license inquiries, in writing, to:

IBM Director of Licensing

IBM Corporation
North Castle Drive
Armonk, NY 10504-1785
U.S.A.

For license inquiries regarding double-byte (DBCS) information, contact the IBM
Intellectual Property Department in your country or send inquiries, in writing, to:

Intellectual Property Licensing

Legal and Intellectual Property Law
IBM Japan, Ltd.
3-2-12, Roppongi, Minato-ku
Tokyo 106-8711
Japan

The following paragraph does not apply to the United Kingdom or any other
country where such provisions are inconsistent with local law:
INTERNATIONAL BUSINESS MACHINES CORPORATION PROVIDES THIS
PUBLICATION ″AS IS″ WITHOUT WARRANTY OF ANY KIND, EITHER
EXPRESS OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE. Some states do not allow disclaimer of express or
implied warranties in certain transactions, therefore, this statement may not apply
to you.

This information could include technical inaccuracies or typographical errors.

Changes are periodically made to the information herein; these changes will be
incorporated in new editions of the publication. IBM may make improvements
and/or changes in the product(s) and/or the program(s) described in this
publication at any time without notice.

Any references in this information to non-IBM Web sites are provided for
convenience only and do not in any manner serve as an endorsement of those Web
sites. The materials at those Web sites are not part of the materials for this IBM
product and use of those Web sites is at your own risk.

© Copyright IBM Corp. 1983, 2009 1105

IBM may use or distribute any of the information you supply in any way it
believes appropriate without incurring any obligation to you.

Licensees of this program who wish to have information about it for the purpose
of enabling: (i) the exchange of information between independently created
programs and other programs (including this one) and (ii) the mutual use of the
information which has been exchanged, should contact:

IBM Corporation
J46A/G4
555 Bailey Avenue
San Jose, CA 95141-1003
U.S.A.

Such information may be available, subject to appropriate terms and conditions,

including in some cases, payment of a fee.

The licensed program described in this document and all licensed material
available for it are provided by IBM under terms of the IBM Customer Agreement,
IBM International Program License Agreement, or any equivalent agreement
between us.

This information contains examples of data and reports used in daily business
operations. To illustrate them as completely as possible, the examples include the
names of individuals, companies, brands, and products. All of these names are
fictitious and any similarity to the names and addresses used by an actual business
enterprise is entirely coincidental.

COPYRIGHT LICENSE:

This information contains sample application programs in source language, which

illustrate programming techniques on various operating platforms. You may copy,
modify, and distribute these sample programs in any form without payment to
IBM, for the purposes of developing, using, marketing or distributing application
programs conforming to the application programming interface for the operating
platform for which the sample programs are written. These examples have not
been thoroughly tested under all conditions. IBM, therefore, cannot guarantee or
imply reliability, serviceability, or function of these programs. The sample
programs are provided ″AS IS″, without warranty of any kind. IBM shall not be
liable for any damages arising out of your use of the sample programs.

If you are viewing this information softcopy, the photographs and color
illustrations may not appear.

Programming Interface Information

This information is intended to help you to write programs that contain SQL
statements. This book primarily documents General-use Programming Interface
and Associated Guidance Information provided by DB2 Version 9.1 for z/OS (DB2
V9.1 for z/OS). However, this book also documents Product-sensitive
Programming Interface and Associated Guidance Information.

1106 Application Programming and SQL Guide

General-use Programming Interface and Associated Guidance
Information
General-use Programming Interfaces allow the customer to write programs that
obtain the services of DB2 Version 9.1 for z/OS.

General-use Programming Interface and Associated Guidance Information is

identified where it occurs by the following markings:

General-use Programming Interface and Associated Guidance Information...

Product-sensitive Programming Interface and Associated

Guidance Information
Product-sensitive Programming Interfaces allow the customer installation to
perform tasks such as diagnosing, modifying, monitoring, repairing, tailoring, or
tuning of this IBM software product. Use of such interfaces creates dependencies
on the detailed design or implementation of the IBM software product.
Product-sensitive Programming Interfaces should be used only for these
specialized purposes. Because of their dependencies on detailed design and
implementation, it is to be expected that programs written to such interfaces may
need to be changed in order to run with new product releases or versions, or as a
result of service.

Product-sensitive Programming Interface and Associated Guidance Information is

identified where it occurs by the following markings:

PSPI Product-sensitive Programming Interface and Associated Guidance

Information... PSPI

Trademarks
IBM, the IBM logo, and ibm.com® are trademarks or registered marks of
International Business Machines Corp., registered in many jurisdictions worldwide.
Other product and service names might be trademarks of IBM or other companies.
A current list of IBM trademarks is available on the Web at http://www.ibm.com/
legal/copytrade.shtml.

Linux is a registered trademark of Linus Torvalds in the United States, other

countries, or both.

Microsoft, Windows, Windows NT, and the Windows logo are trademarks of
Microsoft Corporation in the United States, other countries, or both.

UNIX is a registered trademark of The Open Group in the United States and other
countries.

Java and all Java-based trademarks and logos are trademarks of Sun Microsystems,
Inc. in the United States, other countries, or both.

Notices 1107
1108 Application Programming and SQL Guide
Glossary
abend See abnormal end of task. aggregate function
An operation that derives its result by
abend reason code
using values from one or more rows.
A 4-byte hexadecimal code that uniquely
Contrast with scalar function.
identifies a problem with DB2.
| alias An alternative name that can be used in
abnormal end of task (abend)
| SQL statements to refer to a table or view
Termination of a task, job, or subsystem
| in the same or a remote DB2 subsystem.
because of an error condition that
| An alias can be qualified with a schema
recovery facilities cannot resolve during
| qualifier and can thereby be referenced by
execution.
| other users. Contrast with synonym.
access method services
allied address space
| The facility that is used to define, alter,
An area of storage that is external to DB2
| delete, print, and reproduce VSAM
and that is connected to DB2. An allied
| key-sequenced data sets.
address space can request DB2 services.
access path See also address space.
The path that is used to locate data that is
allied agent
specified in SQL statements. An access
An agent that represents work requests
path can be indexed or sequential.
that originate in allied address spaces. See
active log also system agent.
The portion of the DB2 log to which log
allied thread
records are written as they are generated.
A thread that originates at the local DB2
The active log always contains the most
subsystem and that can access data at a
recent log records. See also archive log.
remote DB2 subsystem.
address space
allocated cursor
| A range of virtual storage pages that is
A cursor that is defined for a stored
| identified by a number (ASID) and a
procedure result set by using the SQL
| collection of segment and page tables that
ALLOCATE CURSOR statement.
| map the virtual pages to real pages of the
| computer’s memory. ambiguous cursor
A database cursor for which DB2 cannot
address space connection
determine whether it is used for update
The result of connecting an allied address
or read-only purposes.
space to DB2. See also allied address
space and task control block. APAR See authorized program analysis report.
address space identifier (ASID) APF See authorized program facility.
A unique system-assigned identifier for
API See application programming interface.
an address space.
APPL A VTAM network definition statement
| AFTER trigger
that is used to define DB2 to VTAM as an
| A trigger that is specified to be activated
application program that uses SNA LU
| after a defined trigger event (an insert,
6.2 protocols.
| update, or delete operation on the table
| that is specified in a trigger definition). application
| Contrast with BEFORE trigger and A program or set of programs that
| INSTEAD OF trigger. performs a task; for example, a payroll
application.
agent In DB2, the structure that associates all
processes that are involved in a DB2 unit application plan
of work. See also allied agent and system The control structure that is produced
agent. during the bind process. DB2 uses the

© Copyright IBM Corp. 1983, 2009 1109

application plan to process SQL authorized program analysis report (APAR)
statements that it encounters during A report of a problem that is caused by a
statement execution. suspected defect in a current release of an
IBM supplied program.
application process
The unit to which resources and locks are authorized program facility (APF)
allocated. An application process involves | A facility that allows an installation to
the execution of one or more programs. | identify system or user programs that can
| use sensitive system functions.
application programming interface (API)
A functional interface that is supplied by automatic bind
the operating system or by a separately (More correctly automatic rebind.) A
orderable licensed program that allows an process by which SQL statements are
application program that is written in a bound automatically (without a user
high-level language to use specific data or issuing a BIND command) when an
functions of the operating system or application process begins execution and
licensed program. the bound application plan or package it
requires is not valid.
application requester
The component on a remote system that automatic query rewrite
generates DRDA requests for data on A process that examines an SQL statement
behalf of an application. that refers to one or more base tables or
materialized query tables, and, if
application server
appropriate, rewrites the query so that it
The target of a request from a remote
performs better.
application. In the DB2 environment, the
application server function is provided by auxiliary index
the distributed data facility and is used to | An index on an auxiliary table in which
access DB2 data from remote applications. | each index entry refers to a LOB or XML
| document.
archive log
The portion of the DB2 log that contains auxiliary table
log records that have been copied from A table that contains columns outside the
the active log. See also active log. actual table in which they are defined.
Auxiliary tables can contain either LOB or
ASCII An encoding scheme that is used to
XML data.
represent strings in many environments,
typically on PCs and workstations. backout
Contrast with EBCDIC and Unicode. The process of undoing uncommitted
changes that an application process made.
ASID See address space identifier.
A backout is often performed in the event
attachment facility of a failure on the part of an application
An interface between DB2 and TSO, IMS, process, or as a result of a deadlock
CICS, or batch address spaces. An situation.
attachment facility allows application
backward log recovery
programs to access DB2.
The final phase of restart processing
attribute during which DB2 scans the log in a
A characteristic of an entity. For example, backward direction to apply UNDO log
in database design, the phone number of records for all aborted changes.
an employee is an attribute of that
base table
employee.
A table that is created by the SQL
authorization ID CREATE TABLE statement and that holds
| A string that can be verified for persistent data. Contrast with clone table,
| connection to DB2 and to which a set of materialized query table, result table,
| privileges is allowed. An authorization ID temporary table, and transition table.
| can represent an individual or an
base table space
| organizational group.
A table space that contains base tables.

1110 Application Programming and SQL Guide

| basic row format | v A form of character data. Binary data is
| A row format in which values for | generally more highly recommended
| columns are stored in the row in the | than character-for-bit data.
| order in which the columns are defined
BLOB See binary large object.
| by the CREATE TABLE statement.
| Contrast with reordered row format. block fetch
| A capability in which DB2 can retrieve, or
basic sequential access method (BSAM)
| fetch, a large set of rows together. Using
An access method for storing or retrieving
| block fetch can significantly reduce the
data blocks in a continuous sequence,
| number of messages that are being sent
using either a sequential-access or a
| across the network. Block fetch applies
direct-access device.
| only to non-rowset cursors that do not
| BEFORE trigger | update data.
| A trigger that is specified to be activated
bootstrap data set (BSDS)
| before a defined trigger event (an insert,
A VSAM data set that contains name and
| an update, or a delete operation on the
status information for DB2 and RBA
| table that is specified in a trigger
range specifications for all active and
| definition). Contrast with AFTER trigger
archive log data sets. The BSDS also
| and INSTEAD OF trigger.
contains passwords for the DB2 directory
binary large object (BLOB) and catalog, and lists of conditional
| A binary string data type that contains a restart and checkpoint records.
| sequence of bytes that can range in size
BSAM
| from 0 bytes to 2 GB, less 1 byte. This
See basic sequential access method.
| string does not have an associated code
| page and character set. BLOBs can BSDS See bootstrap data set.
| contain, for example, image, audio, or
buffer pool
| video data. In general, BLOB values are
| An area of memory into which data pages
| used whenever a binary string might
| are read, modified, and held during
| exceed the limits of the VARBINARY
| processing.
| type.
built-in data type
binary string
| A data type that IBM supplies. Among
| A sequence of bytes that is not associated
| the built-in data types for DB2 for z/OS
| with a CCSID. Binary string data type can
| are string, numeric, XML, ROWID, and
| be further classified as BINARY,
| datetime. Contrast with distinct type.
| VARBINARY, or BLOB.
built-in function
| bind A process by which a usable control
| A function that is generated by DB2 and
| structure with SQL statements is
| that is in the SYSIBM schema. Contrast
| generated; the structure is often called an
| with user-defined function. See also
| access plan, an application plan, or a
| function, cast function, external function,
| package. During this bind process, access
| sourced function, and SQL function.
| paths to the data are selected, and some
| authorization checking is performed. See business dimension
| also automatic bind. A category of data, such as products or
time periods, that an organization might
bit data
want to analyze.
| v Data with character type CHAR or
| VARCHAR that is defined with the cache structure
| FOR BIT DATA clause. Note that using A coupling facility structure that stores
| BINARY or VARBINARY rather than data that can be available to all members
| FOR BIT DATA is highly of a Sysplex. A DB2 data sharing group
| recommended. uses cache structures as group buffer
pools.
| v Data with character type CHAR or
| VARCHAR that is defined with the CAF See call attachment facility.
| FOR BIT DATA clause.

DB2 glossary 1111

call attachment facility (CAF) central processor (CP)
A DB2 attachment facility for application The part of the computer that contains the
programs that run in TSO or z/OS batch. sequencing and processing facilities for
The CAF is an alternative to the DSN instruction execution, initial program
command processor and provides greater load, and other machine operations.
control over the execution environment.
CFRM See coupling facility resource
Contrast with Recoverable Resource
management.
Manager Services attachment facility.
CFRM policy
call-level interface (CLI)
The allocation rules for a coupling facility
A callable application programming
structure that are declared by a z/OS
interface (API) for database access, which
administrator.
is an alternative to using embedded SQL.
character conversion
cascade delete
The process of changing characters from
A process by which DB2 enforces
one encoding scheme to another.
referential constraints by deleting all
descendent rows of a deleted parent row. Character Data Representation Architecture
(CDRA)
CASE expression
An architecture that is used to achieve
An expression that is selected based on
consistent representation, processing, and
the evaluation of one or more conditions.
interchange of string data.
cast function
character large object (CLOB)
A function that is used to convert
| A character string data type that contains
instances of a (source) data type into
| a sequence of bytes that represent
instances of a different (target) data type.
| characters (single-byte, multibyte, or both)
castout | that can range in size from 0 bytes to 2
The DB2 process of writing changed | GB, less 1 byte. In general, CLOB values
pages from a group buffer pool to disk. | are used whenever a character string
| might exceed the limits of the VARCHAR
castout owner
| type.
The DB2 member that is responsible for
casting out a particular page set or character set
partition. A defined set of characters.
catalog character string
In DB2, a collection of tables that contains | A sequence of bytes that represent bit
descriptions of objects such as tables, | data, single-byte characters, or a mixture
views, and indexes. | of single-byte and multibyte characters.
| Character data can be further classified as
catalog table
| CHARACTER, VARCHAR, or CLOB.
Any table in the DB2 catalog.
check constraint
CCSID
A user-defined constraint that specifies
See coded character set identifier.
the values that specific columns of a base
CDB See communications database. table can contain.
CDRA check integrity
See Character Data Representation The condition that exists when each row
Architecture. in a table conforms to the check
constraints that are defined on that table.
CEC See central processor complex.
check pending
central electronic complex (CEC)
A state of a table space or partition that
See central processor complex.
prevents its use by some utilities and by
central processor complex (CPC) some SQL statements because of rows
A physical collection of hardware that that violate referential constraints, check
consists of main storage, one or more constraints, or both.
central processors, timers, and channels.

1112 Application Programming and SQL Guide

checkpoint | have separate underlying VSAM data
A point at which DB2 records status | sets, which are identified by their data set
information on the DB2 log; the recovery | instance numbers. Contrast with base
process uses this information if DB2 | table.
abnormally terminates.
closed application
child lock An application that requires exclusive use
For explicit hierarchical locking, a lock of certain statements on certain DB2
that is held on either a table, page, row, objects, so that the objects are managed
or a large object (LOB). Each child lock solely through the external interface of
has a parent lock. See also parent lock. that application.
CI See control interval. clustering index
An index that determines how rows are
CICS Represents (in this information): CICS
physically ordered (clustered) in a table
Transaction Server for z/OS: Customer
space. If a clustering index on a
Information Control System Transaction
partitioned table is not a partitioning
Server for z/OS.
index, the rows are ordered in cluster
CICS attachment facility sequence within each data partition
| A facility that provides a multithread instead of spanning partitions.
| connection to DB2 to allow applications
| CM See conversion mode.
| that run in the CICS environment to
| execute DB2 statements. | CM* See conversion mode*.
claim A notification to DB2 that an object is C++ member
being accessed. Claims prevent drains A data object or function in a structure,
from occurring until the claim is released, union, or class.
which usually occurs at a commit point.
C++ member function
Contrast with drain.
An operator or function that is declared
claim class as a member of a class. A member
A specific type of object access that can be function has access to the private and
one of the following isolation levels: protected data members and to the
v Cursor stability (CS) member functions of objects in its class.
Member functions are also called
v Repeatable read (RR)
methods.
v Write
C++ object
class of service A region of storage. An object is created
A VTAM term for a list of routes through when a variable is defined or a new
a network, arranged in an order of function is invoked.
preference for their use.
An instance of a class.
clause In SQL, a distinct part of a statement,
such as a SELECT clause or a WHERE coded character set
clause. A set of unambiguous rules that establish
a character set and the one-to-one
CLI See call-level interface. relationships between the characters of
client See requester. the set and their coded representations.

CLOB See character large object. coded character set identifier (CCSID)
A 16-bit number that uniquely identifies a
| clone object coded representation of graphic
| An object that is associated with a clone characters. It designates an encoding
| table, including the clone table itself and scheme identifier and one or more pairs
| check constraints, indexes, and BEFORE that consist of a character set identifier
| triggers on the clone table. and an associated code page identifier.
| clone table code page
| A table that is structurally identical to a A set of assignments of characters to code
| base table. The base and clone table each

DB2 glossary 1113

points. Within a code page, each code operator or an IMS subsystem user to
point has only one specific meaning. In route DB2 commands to specific DB2
EBCDIC, for example, the character A is subsystems.
assigned code point X’C1’, and character
command scope
B is assigned code point X’C2’.
The scope of command operation in a
code point data sharing group.
In CDRA, a unique bit pattern that
commit
represents a character in a code page.
The operation that ends a unit of work by
code unit releasing locks so that the database
The fundamental binary width in a changes that are made by that unit of
computer architecture that is used for work can be perceived by other processes.
representing character data, such as 7 bits, Contrast with rollback.
8 bits, 16 bits, or 32 bits. Depending on
commit point
the character encoding form that is used,
A point in time when data is considered
each code point in a coded character set
consistent.
can be represented by one or more code
units. common service area (CSA)
| In z/OS, a part of the common area that
coexistence
| contains data areas that are addressable
During migration, the period of time in
| by all address spaces. Most DB2 use is in
which two releases exist in the same data
| the extended CSA, which is above the
sharing group.
| 16-MB line.
cold start
communications database (CDB)
A process by which DB2 restarts without
A set of tables in the DB2 catalog that are
processing any log records. Contrast with
used to establish conversations with
warm start.
remote database management systems.
collection
comparison operator
A group of packages that have the same
A token (such as =, >, or <) that is used
qualifier.
to specify a relationship between two
column values.
The vertical component of a table. A
compatibility mode
column has a name and a particular data
| See conversion mode.
type (for example, character, decimal, or
integer). compatibility mode* (CM*)
See conversion mode*.
column function
See aggregate function. composite key
| An ordered set of key columns or
″come from″ checking
| expressions of the same table.
An LU 6.2 security option that defines a
list of authorization IDs that are allowed compression dictionary
to connect to DB2 from a partner LU. The dictionary that controls the process of
compression and decompression. This
command
dictionary is created from the data in the
A DB2 operator command or a DSN
table space or table space partition.
subcommand. A command is distinct
from an SQL statement. concurrency
The shared use of resources by more than
command prefix
one application process at the same time.
A 1- to 8-character command identifier.
The command prefix distinguishes the conditional restart
command as belonging to an application A DB2 restart that is directed by a
or subsystem rather than to z/OS. user-defined conditional restart control
record (CRCR).
command recognition character (CRC)
A character that permits a z/OS console

1114 Application Programming and SQL Guide

connection data; the converted string is shorter
In SNA, the existence of a communication because the shift codes are removed.
path between two partner LUs that allows
control interval (CI)
information to be exchanged (for example,
two DB2 subsystems that are connected v A unit of information that VSAM
and communicating by way of a transfers between virtual and auxiliary
conversation). storage.
v In a key-sequenced data set or file, the
connection context
set of records that an entry in the
In SQLJ, a Java object that represents a
sequence-set index record points to.
connection to a data source.
conversation
connection declaration clause
Communication, which is based on LU
In SQLJ, a statement that declares a
6.2 or Advanced Program-to-Program
connection to a data source.
Communication (APPC), between an
connection handle application and a remote transaction
The data object containing information program over an SNA logical
that is associated with a connection that unit-to-logical unit (LU-LU) session that
DB2 ODBC manages. This includes allows communication while processing a
general status information, transaction transaction.
status, and diagnostic information.
| conversion mode (CM)
connection ID | The first stage of the version-to-version
An identifier that is supplied by the | migration process. In a DB2 data sharing
attachment facility and that is associated | group, members in conversion mode can
with a specific address space connection. | coexist with members that are still at the
| prior version level. Fallback to the prior
consistency token
| version is also supported. When in
A timestamp that is used to generate the
| conversion mode, the DB2 subsystem
version identifier for an application. See
| cannot use most new functions of the new
also version.
| version. Contrast with conversion mode*,
constant | enabling-new-function mode,
A language element that specifies an | enabling-new-function mode*, and
unchanging value. Constants are classified | new-function mode.
as string constants or numeric constants.
| Previously known as compatibility mode
Contrast with variable.
| (CM).
constraint
| conversion mode* (CM*)
A rule that limits the values that can be
| A stage of the version-to-version
inserted, deleted, or updated in a table.
| migration process that applies to a DB2
See referential constraint, check constraint,
| subsystem or data sharing group that was
and unique constraint.
| in enabling-new-function mode (ENFM),
context | enabling-new-function mode* (ENFM*), or
An application’s logical connection to the | new-function mode (NFM) at one time.
data source and associated DB2 ODBC | Fallback to a prior version is not
connection information that allows the | supported. When in conversion mode*, a
application to direct its operations to a | DB2 data sharing group cannot coexist
data source. A DB2 ODBC context | with members that are still at the prior
represents a DB2 thread. | version level. Contrast with conversion
| mode, enabling-new-function mode,
contracting conversion
| enabling-new-function mode*, and
A process that occurs when the length of
| new-function mode.
a converted string is smaller than that of
the source string. For example, this | Previously known as compatibility mode*
process occurs when an EBCDIC | (CM*).
mixed-data string that contains DBCS
coordinator
characters is converted to ASCII mixed
The system component that coordinates

DB2 glossary 1115

the commit or rollback of a unit of work column of the DSN_STATEMNT_TABLE
that includes work that is done on one or when a statement is explained.
more other systems.
coupling facility
coprocessor | A special PR/SM logical partition (LPAR)
See SQL statement coprocessor. | that runs the coupling facility control
| program and provides high-speed
copy pool
| caching, list processing, and locking
| A collection of names of storage groups
| functions in a Parallel Sysplex.
| that are processed collectively for fast
| replication operations. coupling facility resource management (CFRM)
A component of z/OS that provides the
copy target
services to manage coupling facility
A named set of SMS storage groups that
resources in a Parallel Sysplex. This
are to be used as containers for copy pool
management includes the enforcement of
volume copies. A copy target is an SMS
CFRM policies to ensure that the coupling
construct that lets you define which
facility and structure requirements are
storage groups are to be used as
satisfied.
containers for volumes that are copied by
using FlashCopy functions. CP See central processor.
copy version CPC See central processor complex.
A point-in-time FlashCopy copy that is
CRC See command recognition character.
managed by HSM. Each copy pool has a
version parameter that specifies the created temporary table
number of copy versions to be maintained A persistent table that holds temporary
on disk. data and is defined with the SQL
statement CREATE GLOBAL
correlated columns
TEMPORARY TABLE. Information about
A relationship between the value of one
created temporary tables is stored in the
column and the value of another column.
DB2 catalog and can be shared across
correlated subquery application processes. Contrast with
A subquery (part of a WHERE or declared temporary table. See also
HAVING clause) that is applied to a row temporary table.
or group of rows of a table or view that is
cross-system coupling facility (XCF)
named in an outer subselect statement.
A component of z/OS that provides
correlation ID functions to support cooperation between
An identifier that is associated with a authorized programs that run within a
specific thread. In TSO, it is either an Sysplex.
authorization ID or the job name.
cross-system extended services (XES)
correlation name A set of z/OS services that allow multiple
| An identifier that is specified and used instances of an application or subsystem,
| within a single SQL statement as the running on different systems in a Sysplex
| exposed name for objects such as a table, environment, to implement
| view, table function reference, nested table high-performance, high-availability data
| expression, or result of a data change sharing by using a coupling facility.
| statement. Correlation names are useful in
CS See cursor stability.
| an SQL statement to allow two distinct
| references to the same base table and to CSA See common service area.
| allow an alternative name to be used to
CT See cursor table.
| represent an object.
current data
cost category
Data within a host structure that is
A category into which DB2 places cost
current with (identical to) the data within
estimates for SQL statements at the time
the base table.
the statement is bound. The cost category
is externalized in the COST_CATEGORY

1116 Application Programming and SQL Guide

current status rebuild database descriptor (DBD)
The second phase of restart processing An internal representation of a DB2
during which the status of the subsystem database definition, which reflects the
is reconstructed from information on the data definition that is in the DB2 catalog.
log. The objects that are defined in a database
descriptor are table spaces, tables,
cursor A control structure that an application
indexes, index spaces, relationships, check
program uses to point to a single row or
constraints, and triggers. A DBD also
multiple rows within some ordered set of
contains information about accessing
rows of a result table. A cursor can be
tables in the database.
used to retrieve, update, or delete rows
from a result table. database exception status
In a data sharing environment, an
cursor sensitivity
indication that something is wrong with a
The degree to which database updates are
database.
visible to the subsequent FETCH
statements in a cursor. database identifier (DBID)
An internal identifier of the database.
cursor stability (CS)
The isolation level that provides database management system (DBMS)
maximum concurrency without the ability A software system that controls the
to read uncommitted data. With cursor creation, organization, and modification of
stability, a unit of work holds locks only a database and the access to the data that
on its uncommitted changes and on the is stored within it.
current row of each of its cursors. See also
database request module (DBRM)
read stability, repeatable read, and
A data set member that is created by the
uncommitted read.
DB2 precompiler and that contains
cursor table (CT) information about SQL statements.
| The internal representation of a cursor. DBRMs are used in the bind process.
cycle A set of tables that can be ordered so that database server
each table is a descendent of the one The target of a request from a local
before it, and the first table is a application or a remote intermediate
descendent of the last table. A database server.
self-referencing table is a cycle with a
data currency
single member. See also referential cycle.
The state in which the data that is
database retrieved into a host variable in a
A collection of tables, or a collection of program is a copy of the data in the base
table spaces and index spaces. table.
database access thread (DBAT) data dictionary
A thread that accesses data at the local A repository of information about an
subsystem on behalf of a remote organization’s application programs,
subsystem. databases, logical data models, users, and
authorizations.
database administrator (DBA)
An individual who is responsible for data partition
designing, developing, operating, A VSAM data set that is contained within
safeguarding, maintaining, and using a a partitioned table space.
database.
data-partitioned secondary index (DPSI)
database alias A secondary index that is partitioned
The name of the target server if it is according to the underlying data.
different from the location name. The Contrast with nonpartitioned secondary
database alias is used to provide the index.
name of the database server as it is
| data set instance number
known to the network.
| A number that indicates the data set that
| contains the data for an object.

DB2 glossary 1117

data sharing DBCS See double-byte character set.
A function of DB2 for z/OS that enables
DBD See database descriptor.
applications on different DB2 subsystems
to read from and write to the same data DB2I See DB2 Interactive.
concurrently.
DBID See database identifier.
data sharing group
DB2 Interactive (DB2I)
A collection of one or more DB2
An interactive service within DB2 that
subsystems that directly access and
facilitates the execution of SQL
change the same data while maintaining
statements, DB2 (operator) commands,
data integrity.
and programmer commands, and the
data sharing member invocation of utilities.
A DB2 subsystem that is assigned by XCF
DBMS
services to a data sharing group.
See database management system.
data source
DBRM
A local or remote relational or
See database request module.
non-relational data manager that is
capable of supporting data access via an DB2 thread
ODBC driver that supports the ODBC | The database manager structure that
APIs. In the case of DB2 for z/OS, the | describes an application’s connection,
data sources are always relational | traces its progress, processes resource
database managers. | functions, and delimits its accessibility to
| the database manager resources and
data type
| services. Most DB2 for z/OS functions
An attribute of columns, constants,
| execute under a thread structure.
variables, parameters, special registers,
and the results of functions and DCLGEN
expressions. See declarations generator.
data warehouse DDF See distributed data facility.
A system that provides critical business
deadlock
information to an organization. The data
Unresolvable contention for the use of a
warehouse system cleanses the data for
resource, such as a table or an index.
accuracy and currency, and then presents
the data to decision makers so that they declarations generator (DCLGEN)
can interpret and use it effectively and A subcomponent of DB2 that generates
efficiently. SQL table declarations and COBOL, C, or
PL/I data structure declarations that
DBA See database administrator.
conform to the table. The declarations are
DBAT See database access thread. generated from DB2 system catalog
information.
DB2 catalog
A collection of tables that are maintained declared temporary table
by DB2 and contain descriptions of DB2 A non-persistent table that holds
objects, such as tables, views, and temporary data and is defined with the
indexes. SQL statement DECLARE GLOBAL
TEMPORARY TABLE. Information about
DBCLOB
declared temporary tables is not stored in
See double-byte character large object.
the DB2 catalog and can be used only by
DB2 command the application process that issued the
An instruction to the DB2 subsystem that DECLARE statement. Contrast with
a user enters to start or stop DB2, to created temporary table. See also
display information on current users, to temporary table.
start or stop databases, to display
default value
information on the status of databases,
| A predetermined value, attribute, or
and so on.
| option that is assumed when no other

1118 Application Programming and SQL Guide

| value is specified. A default value can be table space) of its parent. See also parent
| defined for column data in DB2 tables by row, parent table, and parent table space.
| specifying the DEFAULT keyword in an
dependent row
| SQL statement that changes data (such as
A row that contains a foreign key that
| INSERT, UPDATE, and MERGE).
matches the value of a primary key in the
deferred embedded SQL parent row.
SQL statements that are neither fully
dependent table
static nor fully dynamic. These statements
A table that is a dependent in at least one
are embedded within an application and
referential constraint.
are prepared during the execution of the
application. descendent
An object that is a dependent of an object
deferred write
or is the dependent of a descendent of an
The process of asynchronously writing
object.
changed data pages to disk.
descendent row
degree of parallelism
A row that is dependent on another row,
The number of concurrently executed
or a row that is a descendent of a
operations that are initiated to process a
dependent row.
query.
descendent table
delete hole
A table that is a dependent of another
The location on which a cursor is
table, or a table that is a descendent of a
positioned when a row in a result table is
dependent table.
refetched and the row no longer exists on
the base table. See also update hole. deterministic function
A user-defined function whose result is
delete rule
dependent on the values of the input
The rule that tells DB2 what to do to a
arguments. That is, successive invocations
dependent row when a parent row is
with the same input values produce the
deleted. Delete rules include CASCADE,
same answer. Sometimes referred to as a
RESTRICT, SET NULL, or NO ACTION.
not-variant function. Contrast with
delete trigger nondeterministic function (sometimes
A trigger that is defined with the called a variant function).
triggering delete SQL operation.
dimension
delimited identifier A data category such as time, products, or
A sequence of characters that are enclosed markets. The elements of a dimension are
within escape characters such as double referred to as members. See also
quotation marks (″). dimension table.
delimiter token dimension table
A string constant, a delimited identifier, The representation of a dimension in a
an operator symbol, or any of the special star schema. Each row in a dimension
characters that are shown in DB2 syntax table represents all of the attributes for a
diagrams. particular member of the dimension. See
also dimension, star schema, and star join.
denormalization
The intentional duplication of columns in directory
multiple tables to increase data The DB2 system database that contains
redundancy. Denormalization is internal objects such as database
sometimes necessary to minimize descriptors and skeleton cursor tables.
performance problems. Contrast with
disk A direct-access storage device that records
normalization.
data magnetically.
dependent
distinct type
An object (row, table, or table space) that
A user-defined data type that is
has at least one parent. The object is also
represented as an existing type (its source
said to be a dependent (row, table, or

DB2 glossary 1119

type), but is considered to be a separate national languages such as Japanese and
and incompatible type for semantic Chinese, that have more symbols than can
purposes. be represented by a single byte. Each
character is 2 bytes in length. Contrast
distributed data
with single-byte character set and
Data that resides on a DBMS other than
multibyte character set.
the local system.
double-precision floating point number
distributed data facility (DDF)
A 64-bit approximate representation of a
A set of DB2 components through which
real number.
DB2 communicates with another
relational database management system. DPSI See data-partitioned secondary index.
Distributed Relational Database Architecture drain The act of acquiring a locked resource by
(DRDA) quiescing access to that object. Contrast
A connection protocol for distributed with claim.
relational database processing that is used
drain lock
by IBM relational database products.
A lock on a claim class that prevents a
DRDA includes protocols for
claim from occurring.
communication between an application
and a remote relational database DRDA
management system, and for See Distributed Relational Database
communication between relational Architecture.
database management systems. See also
DRDA access
DRDA access.
An open method of accessing distributed
DNS See domain name server. data that you can use to connect to
another database server to execute
| DOCID
packages that were previously bound at
| See document ID.
the server location.
| document ID
DSN
| A value that uniquely identifies a row
| that contains an XML column. This value v The default DB2 subsystem name.
| is stored with the row and never changes. v The name of the TSO command
processor of DB2.
domain
The set of valid values for an attribute. v The first three characters of DB2
module and macro names.
domain name
The name by which TCP/IP applications dynamic cursor
refer to a TCP/IP host within a TCP/IP A named control structure that an
network. application program uses to change the
size of the result table and the order of its
domain name server (DNS) rows after the cursor is opened. Contrast
A special TCP/IP network server that with static cursor.
manages a distributed directory that is
used to map TCP/IP host names to IP dynamic dump
addresses. A dump that is issued during the
execution of a program, usually under the
double-byte character large object (DBCLOB) control of that program.
| A graphic string data type in which a
| sequence of bytes represent double-byte dynamic SQL
| characters that range in size from 0 bytes | SQL statements that are prepared and
| to 2 GB, less 1 byte. In general, DBCLOB | executed at run time. In dynamic SQL,
| values are used whenever a double-byte | the SQL statement is contained as a
| character string might exceed the limits of | character string in a host variable or as a
| the VARGRAPHIC type. | constant, and it is not precompiled.

double-byte character set (DBCS) EA-enabled table space

A set of characters, which are used by A table space or index space that is
enabled for extended addressability and

1120 Application Programming and SQL Guide

that contains individual partitions (or An enclave is similar to a program or run
pieces, for LOB table spaces) that are unit. See also WLM enclave.
greater than 4 GB.
encoding scheme
EB See exabyte. A set of rules to represent character data
(ASCII, EBCDIC, or Unicode).
EBCDIC
Extended binary coded decimal | ENFM See enabling-new-function mode.
interchange code. An encoding scheme
ENFM*
that is used to represent character data in
| See enabling-new-function mode*.
the z/OS, VM, VSE, and iSeries
environments. Contrast with ASCII and | entity A person, object, or concept about which
Unicode. | information is stored. In a relational
| database, entities are represented as
embedded SQL
| tables. A database includes information
SQL statements that are coded within an
| about the entities in an organization or
application program. See static SQL.
| business, and their relationships to each
| enabling-new-function mode (ENFM) | other.
| A transitional stage of the
enumerated list
| version-to-version migration process
A set of DB2 objects that are defined with
| during which the DB2 subsystem or data
a LISTDEF utility control statement in
| sharing group is preparing to use the new
which pattern-matching characters (*, %;,
| functions of the new version. When in
_, or ?) are not used.
| enabling-new-function mode, a DB2 data
| sharing group cannot coexist with environment
| members that are still at the prior version A collection of names of logical and
| level. Fallback to a prior version is not physical resources that are used to
| supported, and most new functions of the support the performance of a function.
| new version are not available for use in
environment handle
| enabling-new-function mode. Contrast
| A handle that identifies the global context
| with conversion mode, conversion mode*,
| for database access. All data that is
| enabling-new-function mode*, and
| pertinent to all objects in the environment
| new-function mode.
| is associated with this handle.
| enabling-new-function mode* (ENFM*)
equijoin
| A transitional stage of the
A join operation in which the
| version-to-version migration process that
join-condition has the form expression =
| applies to a DB2 subsystem or data
expression. See also join, full outer join,
| sharing group that was in new-function
inner join, left outer join, outer join, and
| mode (NFM) at one time. When in
right outer join.
| enabling-new-function mode*, a DB2
| subsystem or data sharing group is error page range
| preparing to use the new functions of the A range of pages that are considered to be
| new version but cannot yet use them. A physically damaged. DB2 does not allow
| data sharing group that is in users to access any pages that fall within
| enabling-new-function mode* cannot this range.
| coexist with members that are still at the
escape character
| prior version level. Fallback to a prior
The symbol, a double quotation (″) for
| version is not supported. Contrast with
example, that is used to enclose an SQL
| conversion mode, conversion mode*,
delimited identifier.
| enabling-new-function mode, and
| new-function mode. exabyte
A unit of measure for processor, real and
enclave
virtual storage capacities, and channel
In Language Environment , an
volume that has a value of 1 152 921 504
independent collection of routines, one of
606 846 976 bytes or 260.
which is designated as the main routine.

DB2 glossary 1121

exception exposed name
| An SQL operation that involves the A correlation name or a table or view
| EXCEPT set operator, which combines name for which a correlation name is not
| two result tables. The result of an specified.
| exception operation consists of all of the
expression
| rows that are in only one of the result
An operand or a collection of operators
| tables.
and operands that yields a single value.
exception table
Extended Recovery Facility (XRF)
A table that holds rows that violate
A facility that minimizes the effect of
referential constraints or check constraints
failures in z/OS, VTAM, the host
that the CHECK DATA utility finds.
processor, or high-availability applications
exclusive lock during sessions between high-availability
A lock that prevents concurrently applications and designated terminals.
executing application processes from This facility provides an alternative
reading or changing data. Contrast with subsystem to take over sessions from the
share lock. failing subsystem.
executable statement Extensible Markup Language (XML)
An SQL statement that can be embedded A standard metalanguage for defining
in an application program, dynamically markup languages that is a subset of
prepared and executed, or issued Standardized General Markup Language
interactively. (SGML).
execution context external function
In SQLJ, a Java object that can be used to | A function that has its functional logic
control the execution of SQL statements. | implemented in a programming language
| application that resides outside the
exit routine
| database, in the file system of the
A user-written (or IBM-provided default)
| database server. The association of the
program that receives control from DB2 to
| function with the external code
perform specific functions. Exit routines
| application is specified by the EXTERNAL
run as extensions of DB2.
| clause in the CREATE FUNCTION
expanding conversion | statement. External functions can be
A process that occurs when the length of | classified as external scalar functions and
a converted string is greater than that of | external table functions. Contrast with
the source string. For example, this | sourced function, built-in function, and
process occurs when an ASCII mixed-data | SQL function.
string that contains DBCS characters is
external procedure
converted to an EBCDIC mixed-data
| A procedure that has its procedural logic
string; the converted string is longer
| implemented in an external programming
because shift codes are added.
| language application. The association of
explicit hierarchical locking | the procedure with the external
Locking that is used to make the | application is specified by a CREATE
parent-child relationship between | PROCEDURE statement with a
resources known to IRLM. This kind of | LANGUAGE clause that has a value other
locking avoids global locking overhead | than SQL and an EXTERNAL clause that
when no inter-DB2 interest exists on a | implicitly or explicitly specifies the name
resource. | of the external application. Contrast with
| external SQL procedure and native SQL
explicit privilege
| procedure.
| A privilege that has a name and is held as
| the result of an SQL GRANT statement external routine
| and revoked as the result of an SQL A user-defined function or stored
| REVOKE statement. For example, the procedure that is based on code that is
| SELECT privilege. written in an external programming
language.

1122 Application Programming and SQL Guide

| external SQL procedure | orientation (for example, NEXT ROWSET,
| An SQL procedure that is processed using | LAST ROWSET, or ROWSET STARTING
| a generated C program that is a | AT ABSOLUTE n).
| representation of the procedure. When an
field procedure
| external SQL procedure is called, the C
A user-written exit routine that is
| program representation of the procedure
designed to receive a single value and
| is executed in a stored procedures address
transform (encode or decode) it in any
| space. Contrast with external procedure
way the user can specify.
| and native SQL procedure.
| file reference variable
failed member state
| A host variable that is declared with one
A state of a member of a data sharing
| of the derived data types (BLOB_FILE,
group in which the member’s task,
| CLOB_FILE, DBCLOB_FILE); file
address space, or z/OS system terminates
| reference variables direct the reading of a
before the state changes from active to
| LOB from a file or the writing of a LOB
quiesced.
| into a file.
fallback
filter factor
| The process of returning to a previous
A number between zero and one that
| release of DB2 after attempting or
estimates the proportion of rows in a
| completing migration to a current release.
table for which a predicate is true.
| Fallback is supported only from a
| subsystem that is in conversion mode. fixed-length string
| A character, graphic, or binary string
false global lock contention
| whose length is specified and cannot be
A contention indication from the coupling
| changed. Contrast with varying-length
facility that occurs when multiple lock
| string.
names are hashed to the same indicator
and when no real contention exists. FlashCopy
| A function on the IBM Enterprise Storage
fan set
| Server that can, in conjunction with the
A direct physical access path to data,
| BACKUP SYSTEM utility, create a
which is provided by an index, hash, or
| point-in-time copy of data while an
link; a fan set is the means by which DB2
| application is running.
supports the ordering of data.
foreign key
federated database
A column or set of columns in a
The combination of a DB2 server (in
dependent table of a constraint
Linux, UNIX, and Windows
relationship. The key must have the same
environments) and multiple data sources
number of columns, with the same
to which the server sends queries. In a
descriptions, as the primary key of the
federated database system, a client
parent table. Each foreign key value must
application can use a single SQL
either match a parent key value in the
statement to join data that is distributed
related parent table or be null.
across multiple database management
systems and can view the data as if it forest An ordered set of subtrees of XML nodes.
were local.
forward log recovery
fetch orientation The third phase of restart processing
| The specification of the desired placement during which DB2 processes the log in a
| of the cursor as part of a FETCH forward direction to apply all REDO log
| statement. The specification can be before records.
| or after the rows of the result table (with
free space
| BEFORE or AFTER). The specification can
The total amount of unused space in a
| also have either a single-row fetch
page; that is, the space that is not used to
| orientation (for example, NEXT, LAST, or
store records or control information is free
| ABSOLUTE n) or a rowset fetch
space.

DB2 glossary 1123

full outer join buffer pool. Either read/write interest is
The result of a join operation that active among DB2 subsystems for this
includes the matched rows of both tables page set, or the page set has changed
that are being joined and preserves the pages in the group buffer pool that have
unmatched rows of both tables. See also not yet been cast out to disk.
join, equijoin, inner join, left outer join,
generalized trace facility (GTF)
outer join, and right outer join.
A z/OS service program that records
| fullselect significant system events such as I/O
| A subselect, a fullselect in parentheses, or interrupts, SVC interrupts, program
| a number of both that are combined by interrupts, or external interrupts.
| set operators. Fullselect specifies a result
generic resource name
| table. If a set operator is not used, the
A name that VTAM uses to represent
| result of the fullselect is the result of the
several application programs that provide
| specified subselect or fullselect.
the same function in order to handle
fully escaped mapping session distribution and balancing in a
A mapping from an SQL identifier to an Sysplex environment.
XML name when the SQL identifier is a
getpage
column name.
An operation in which DB2 accesses a
function data page.
A mapping, which is embodied as a
global lock
program (the function body) that is
A lock that provides concurrency control
invocable by means of zero or more input
within and among DB2 subsystems. The
values (arguments) to a single value (the
scope of the lock is across all DB2
result). See also aggregate function and
subsystems of a data sharing group.
scalar function.
global lock contention
Functions can be user-defined, built-in, or
Conflicts on locking requests between
generated by DB2. (See also built-in
different DB2 members of a data sharing
function, cast function, external function,
group when those members are trying to
sourced function, SQL function, and
serialize shared resources.
user-defined function.)
governor
function definer
See resource limit facility.
The authorization ID of the owner of the
schema of the function that is specified in graphic string
the CREATE FUNCTION statement. | A sequence of DBCS characters. Graphic
| data can be further classified as
function package
| GRAPHIC, VARGRAPHIC, or DBCLOB.
A package that results from binding the
DBRM for a function program. | GRECP
| See group buffer pool recovery pending.
function package owner
The authorization ID of the user who gross lock
binds the function program’s DBRM into The shared, update, or exclusive mode locks
a function package. on a table, partition, or table space.
function signature group buffer pool duplexing
The logical concatenation of a fully The ability to write data to two instances
qualified function name with the data of a group buffer pool structure: a
types of all of its parameters. primary group buffer pool and a
secondary group buffer pool. z/OS
GB Gigabyte. A value of (1 073 741 824 bytes).
publications refer to these instances as the
GBP See group buffer pool. “old” (for primary) and “new” (for
secondary) structures.
GBP-dependent
The status of a page set or page set group buffer pool (GBP)
partition that is dependent on the group A coupling facility cache structure that is

1124 Application Programming and SQL Guide

used by a data sharing group to cache hole A row of the result table that cannot be
data and to ensure that the data is accessed because of a delete or an update
consistent for all members. that has been performed on the row. See
also delete hole and update hole.
| group buffer pool recovery pending (GRECP)
| The state that exists after the buffer pool home address space
| for a data sharing group is lost. When a The area of storage that z/OS currently
| page set is in this state, changes that are recognizes as dispatched.
| recorded in the log must be applied to the
host The set of programs and resources that
| affected page set before the page set can
are available on a given TCP/IP instance.
| be used.
host expression
group level
A Java variable or expression that is
The release level of a data sharing group,
referenced by SQL clauses in an SQLJ
which is established when the first
application program.
member migrates to a new release.
host identifier
group name
A name that is declared in the host
The z/OS XCF identifier for a data
program.
sharing group.
host language
group restart
A programming language in which you
A restart of at least one member of a data
can embed SQL statements.
sharing group after the loss of either locks
or the shared communications area. host program
An application program that is written in
GTF See generalized trace facility.
a host language and that contains
handle embedded SQL statements.
In DB2 ODBC, a variable that refers to a
host structure
data structure and associated resources.
In an application program, a structure
See also statement handle, connection
that is referenced by embedded SQL
handle, and environment handle.
statements.
help panel
host variable
A screen of information that presents
In an application program written in a
tutorial text to assist a user at the
host language, an application variable
workstation or terminal.
that is referenced by embedded SQL
heuristic damage statements.
The inconsistency in data between one or
host variable array
more participants that results when a
An array of elements, each of which
heuristic decision to resolve an indoubt
corresponds to a value for a column. The
LUW at one or more participants differs
dimension of the array determines the
from the decision that is recorded at the
maximum number of rows for which the
coordinator.
array can be used.
heuristic decision
IBM System z9 Integrated Processor (zIIP)
A decision that forces indoubt resolution
| A specialized processor that can be used
at a participant by means other than
| for some DB2 functions.
automatic resynchronization between
coordinator and participant. IDCAMS
An IBM program that is used to process
| histogram statistics
access method services commands. It can
| A way of summarizing data distribution.
be invoked as a job or jobstep, from a
| This technique divides up the range of
TSO terminal, or from within a user’s
| possible values in a data set into intervals,
application program.
| such that each interval contains
| approximately the same percentage of the
| values. A set of statistics are collected for
| each interval.

DB2 glossary 1125

IDCAMS LISTCAT index A set of pointers that are logically ordered
A facility for obtaining information that is by the values of a key. Indexes can
contained in the access method services provide faster access to data and can
catalog. enforce uniqueness on the rows in a table.
identity column index-controlled partitioning
| A column that provides a way for DB2 to A type of partitioning in which partition
| automatically generate a numeric value boundaries for a partitioned table are
| for each row. Identity columns are controlled by values that are specified on
| defined with the AS IDENTITY clause. the CREATE INDEX statement. Partition
| Uniqueness of values can be ensured by limits are saved in the LIMITKEY column
| defining a unique index that contains of the SYSIBM.SYSINDEXPART catalog
| only the identity column. A table can table.
| have no more than one identity column.
index key
IFCID See instrumentation facility component The set of columns in a table that is used
identifier. to determine the order of index entries.
IFI See instrumentation facility interface. index partition
A VSAM data set that is contained within
IFI call
a partitioning index space.
An invocation of the instrumentation
facility interface (IFI) by means of one of index space
its defined functions. A page set that is used to store the entries
of one index.
image copy
An exact reproduction of all or part of a indicator column
table space. DB2 provides utility A 4-byte value that is stored in a base
programs to make full image copies (to table in place of a LOB column.
copy the entire table space) or incremental
indicator variable
image copies (to copy only those pages
A variable that is used to represent the
that have been modified since the last
null value in an application program. If
image copy).
the value for the selected column is null,
IMS attachment facility a negative value is placed in the indicator
A DB2 subcomponent that uses z/OS variable.
subsystem interface (SSI) protocols and
indoubt
cross-memory linkage to process requests
A status of a unit of recovery. If DB2 fails
from IMS to DB2 and to coordinate
after it has finished its phase 1 commit
resource commitment.
processing and before it has started phase
in-abort 2, only the commit coordinator knows if
A status of a unit of recovery. If DB2 fails an individual unit of recovery is to be
after a unit of recovery begins to be rolled committed or rolled back. At restart, if
back, but before the process is completed, DB2 lacks the information it needs to
DB2 continues to back out the changes make this decision, the status of the unit
during restart. of recovery is indoubt until DB2 obtains
this information from the coordinator.
in-commit
More than one unit of recovery can be
A status of a unit of recovery. If DB2 fails
indoubt at restart.
after beginning its phase 2 commit
processing, it ″knows,″ when restarted, indoubt resolution
that changes made to data are consistent. The process of resolving the status of an
Such units of recovery are termed indoubt logical unit of work to either the
in-commit. committed or the rollback state.
independent inflight
An object (row, table, or table space) that A status of a unit of recovery. If DB2 fails
is neither a parent nor a dependent of before its unit of recovery completes
another object. phase 1 of the commit process, it merely

1126 Application Programming and SQL Guide

backs out the updates of its unit of instrumentation facility component identifier
recovery at restart. These units of (IFCID)
recovery are termed inflight. A value that names and identifies a trace
record of an event that can be traced. As a
inheritance
parameter on the START TRACE and
The passing downstream of class
MODIFY TRACE commands, it specifies
resources or attributes from a parent class
that the corresponding event is to be
in the class hierarchy to a child class.
traced.
initialization file
instrumentation facility interface (IFI)
For DB2 ODBC applications, a file
A programming interface that enables
containing values that can be set to adjust
programs to obtain online trace data
the performance of the database manager.
about DB2, to submit DB2 commands,
inline copy and to pass data to DB2.
A copy that is produced by the LOAD or
Interactive System Productivity Facility (ISPF)
REORG utility. The data set that the inline
An IBM licensed program that provides
copy produces is logically equivalent to a
interactive dialog services in a z/OS
full image copy that is produced by
environment.
running the COPY utility with read-only
access (SHRLEVEL REFERENCE). inter-DB2 R/W interest
A property of data in a table space, index,
inner join
or partition that has been opened by more
The result of a join operation that
than one member of a data sharing group
includes only the matched rows of both
and that has been opened for writing by
tables that are being joined. See also join,
at least one of those members.
equijoin, full outer join, left outer join,
outer join, and right outer join. intermediate database server
The target of a request from a local
inoperative package
application or a remote application
A package that cannot be used because
requester that is forwarded to another
one or more user-defined functions or
database server.
procedures that the package depends on
were dropped. Such a package must be internal resource lock manager (IRLM)
explicitly rebound. Contrast with invalid A z/OS subsystem that DB2 uses to
package. control communication and database
locking.
insensitive cursor
A cursor that is not sensitive to inserts, internationalization
updates, or deletes that are made to the The support for an encoding scheme that
underlying rows of a result table after the is able to represent the code points of
result table has been materialized. characters from many different
geographies and languages. To support all
insert trigger
geographies, the Unicode standard
A trigger that is defined with the
requires more than 1 byte to represent a
triggering SQL operation, an insert.
single character. See also Unicode.
install The process of preparing a DB2
| intersection
subsystem to operate as a z/OS
| An SQL operation that involves the
subsystem.
| INTERSECT set operator, which combines
| INSTEAD OF trigger | two result tables. The result of an
| A trigger that is associated with a single | intersection operation consists of all of the
| view and is activated by an insert, | rows that are in both result tables.
| update, or delete operation on the view
invalid package
| and that can define how to propagate the
A package that depends on an object
| insert, update, or delete operation on the
(other than a user-defined function) that
| view to the underlying tables of the view.
is dropped. Such a package is implicitly
| Contrast with BEFORE trigger and
rebound on invocation. Contrast with
| AFTER trigger.
inoperative package.

DB2 glossary 1127

IP address | columns, or an expression that is
| A value that uniquely identifies a TCP/IP | identified in the description of a table,
| host. | index, or referential constraint. The same
| column or expression can be part of more
IRLM See internal resource lock manager.
| than one key.
isolation level
key-sequenced data set (KSDS)
The degree to which a unit of work is
A VSAM file or data set whose records
isolated from the updating operations of
are loaded in key sequence and controlled
other units of work. See also cursor
by an index.
stability, read stability, repeatable read,
and uncommitted read. KSDS See key-sequenced data set.
ISPF See Interactive System Productivity large object (LOB)
Facility. A sequence of bytes representing bit data,
single-byte characters, double-byte
iterator
characters, or a mixture of single- and
In SQLJ, an object that contains the result
double-byte characters. A LOB can be up
set of a query. An iterator is equivalent to
to 2 GB minus 1 byte in length. See also
a cursor in other host languages.
binary large object, character large object,
iterator declaration clause and double-byte character large object.
In SQLJ, a statement that generates an
last agent optimization
iterator declaration class. An iterator is an
An optimized commit flow for either
object of an iterator declaration class.
presumed-nothing or presumed-abort
JAR See Java Archive. protocols in which the last agent, or final
participant, becomes the commit
Java Archive (JAR)
coordinator. This flow saves at least one
A file format that is used for aggregating
message.
many files into a single file.
latch A DB2 mechanism for controlling
JDBC A Sun Microsystems database application
concurrent events or the use of system
programming interface (API) for Java that
resources.
allows programs to access database
management systems by using callable LCID See log control interval definition.
SQL.
LDS See linear data set.
join A relational operation that allows retrieval
leaf page
of data from two or more tables based on
An index page that contains pairs of keys
matching column values. See also
and RIDs and that points to actual data.
equijoin, full outer join, inner join, left
Contrast with nonleaf page.
outer join, outer join, and right outer join.
left outer join
KB Kilobyte. A value of 1024 bytes.
The result of a join operation that
Kerberos includes the matched rows of both tables
A network authentication protocol that is that are being joined, and that preserves
designed to provide strong authentication the unmatched rows of the first table. See
for client/server applications by using also join, equijoin, full outer join, inner
secret-key cryptography. join, outer join, and right outer join.
Kerberos ticket limit key
A transparent application mechanism that The highest value of the index key for a
transmits the identity of an initiating partition.
principal to its target. A simple ticket
linear data set (LDS)
contains the principal’s identity, a session
A VSAM data set that contains data but
key, a timestamp, and other information,
no control information. A linear data set
which is sealed using the target’s secret
can be accessed as a byte-addressable
key.
string in virtual storage.
| key A column, an ordered collection of

1128 Application Programming and SQL Guide

linkage editor local lock
A computer program for creating load A lock that provides intra-DB2
modules from one or more object concurrency control, but not inter-DB2
modules or load modules by resolving concurrency control; that is, its scope is a
cross references among the modules and, single DB2.
if necessary, adjusting addresses.
local subsystem
link-edit The unique relational DBMS to which the
The action of creating a loadable user or application program is directly
computer program using a linkage editor. connected (in the case of DB2, by one of
the DB2 attachment facilities).
list A type of object, which DB2 utilities can
process, that identifies multiple table location
spaces, multiple index spaces, or both. A The unique name of a database server. An
list is defined with the LISTDEF utility application uses the location name to
control statement. access a DB2 database server. A database
alias can be used to override the location
list structure
name when accessing a remote server.
A coupling facility structure that lets data
be shared and manipulated as elements of location alias
a queue. Another name by which a database server
identifies itself in the network.
L-lock See logical lock.
Applications can use this name to access a
load module DB2 database server.
A program unit that is suitable for
lock A means of controlling concurrent events
loading into main storage for execution.
or access to data. DB2 locking is
The output of a linkage editor.
performed by the IRLM.
LOB See large object.
lock duration
LOB locator The interval over which a DB2 lock is
A mechanism that allows an application held.
program to manipulate a large object
lock escalation
value in the database system. A LOB
The promotion of a lock from a row, page,
locator is a fullword integer value that
or LOB lock to a table space lock because
represents a single LOB value. An
the number of page locks that are
application program retrieves a LOB
concurrently held on a given resource
locator into a host variable and can then
exceeds a preset limit.
apply SQL operations to the associated
LOB value using the locator. locking
The process by which the integrity of data
LOB lock
is ensured. Locking prevents concurrent
A lock on a LOB value.
users from accessing inconsistent data.
LOB table space See also claim, drain, and latch.
A table space that contains all the data for
lock mode
a particular LOB column in the related
A representation for the type of access
base table.
that concurrently running programs can
local A way of referring to any object that the have to a resource that a DB2 lock is
local DB2 subsystem maintains. A local holding.
table, for example, is a table that is
lock object
maintained by the local DB2 subsystem.
The resource that is controlled by a DB2
Contrast with remote.
lock.
locale The definition of a subset of a user’s
lock promotion
environment that combines a CCSID and
The process of changing the size or mode
characters that are defined for a specific
of a DB2 lock to a higher, more restrictive
language and country.
level.

DB2 glossary 1129

lock size logical recovery pending (LRECP)
The amount of data that is controlled by a The state in which the data and the index
DB2 lock on table data; the value can be a keys that reference the data are
row, a page, a LOB, a partition, a table, or inconsistent.
a table space.
logical unit (LU)
lock structure An access point through which an
A coupling facility data structure that is application program accesses the SNA
composed of a series of lock entries to network in order to communicate with
support shared and exclusive locking for another application program. See also LU
logical resources. name.
log A collection of records that describe the logical unit of work identifier (LUWID)
events that occur during DB2 execution A name that uniquely identifies a thread
and that indicate their sequence. The within a network. This name consists of a
information thus recorded is used for fully-qualified LU network name, an
recovery in the event of a failure during LUW instance number, and an LUW
DB2 execution. sequence number.
log control interval definition logical unit of work
A suffix of the physical log record that The processing that a program performs
tells how record segments are placed in between synchronization points.
the physical control interval.
log initialization
logical claim The first phase of restart processing
A claim on a logical partition of a during which DB2 attempts to locate the
nonpartitioning index. current end of the log.
logical index partition log record header (LRH)
The set of all keys that reference the same A prefix, in every log record, that contains
data partition. control information.
logical lock (L-lock) log record sequence number (LRSN)
The lock type that transactions use to An identifier for a log record that is
control intra- and inter-DB2 data associated with a data sharing member.
concurrency between transactions. DB2 uses the LRSN for recovery in the
Contrast with physical lock (P-lock). data sharing environment.
logically complete log truncation
A state in which the concurrent copy A process by which an explicit starting
process is finished with the initialization RBA is established. This RBA is the point
of the target objects that are being copied. at which the next byte of log data is to be
The target objects are available for written.
update.
LPL See logical page list.
logical page list (LPL)
LRECP
A list of pages that are in error and that
See logical recovery pending.
cannot be referenced by applications until
the pages are recovered. The page is in LRH See log record header.
logical error because the actual media
LRSN See log record sequence number.
(coupling facility or disk) might not
contain any errors. Usually a connection LU See logical unit.
to the media has been lost.
LU name
logical partition Logical unit name, which is the name by
A set of key or RID pairs in a which VTAM refers to a node in a
nonpartitioning index that are associated network.
with a particular partition.
LUW See logical unit of work.

1130 Application Programming and SQL Guide

LUWID physical and logical characteristics and
See logical unit of work identifier. attributes of a session.
mapping table modify locks
A table that the REORG utility uses to An L-lock or P-lock with a MODIFY
map the associations of the RIDs of data attribute. A list of these active locks is
records in the original copy and in the kept at all times in the coupling facility
shadow copy. This table is created by the lock structure. If the requesting DB2
user. subsystem fails, that DB2 subsystem’s
modify locks are converted to retained
mass delete
locks.
The deletion of all rows of a table.
multibyte character set (MBCS)
materialize
A character set that represents single
v The process of putting rows from a characters with more than a single byte.
view or nested table expression into a UTF-8 is an example of an MBCS.
work file for additional processing by a Characters in UTF-8 can range from 1 to 4
query. bytes in DB2. Contrast with single-byte
v The placement of a LOB value into character set and double-byte character
contiguous storage. Because LOB set. See also Unicode.
values can be very large, DB2 avoids
multidimensional analysis
materializing LOB data until doing so
The process of assessing and evaluating
becomes absolutely necessary.
an enterprise on more than one level.
materialized query table
Multiple Virtual Storage (MVS)
A table that is used to contain information
An element of the z/OS operating system.
that is derived and can be summarized
This element is also called the Base
from one or more source tables. Contrast
Control Program (BCP).
with base table.
multisite update
MB Megabyte (1 048 576 bytes).
Distributed relational database processing
MBCS See multibyte character set. in which data is updated in more than
one location within a single unit of work.
member name
The z/OS XCF identifier for a particular multithreading
DB2 subsystem in a data sharing group. Multiple TCBs that are executing one
copy of DB2 ODBC code concurrently
menu A displayed list of available functions for
(sharing a processor) or in parallel (on
selection by the operator. A menu is
separate central processors).
sometimes called a menu panel.
MVS See Multiple Virtual Storage.
metalanguage
A language that is used to create other | native SQL procedure
specialized languages. | An SQL procedure that is processed by
| converting the procedural statements to a
migration
| native representation that is stored in the
The process of converting a subsystem
| database directory, as is done with other
with a previous release of DB2 to an
| SQL statements. When a native SQL
updated or current release. In this
| procedure is called, the native
process, you can acquire the functions of
| representation is loaded from the
the updated or current release without
| directory, and DB2 executes the
losing the data that you created on the
| procedure. Contrast with external
previous release.
| procedure and external SQL procedure.
mixed data string
nested table expression
A character string that can contain both
A fullselect in a FROM clause
single-byte and double-byte characters.
(surrounded by parentheses).
mode name
network identifier (NID)
A VTAM name for the collection of
The network ID that is assigned by IMS

DB2 glossary 1131

or CICS, or if the connection type is forward direction. Nonscrollable cursors
RRSAF, the RRS unit of recovery ID are sometimes called forward-only cursors
(URID). or serial cursors.
| new-function mode (NFM) normalization
| The normal mode of operation that exists A key step in the task of building a
| after successful completion of a logical relational database design.
| version-to-version migration. At this Normalization helps you avoid
| stage, all new functions of the new redundancies and inconsistencies in your
| version are available for use. A DB2 data data. An entity is normalized if it meets a
| sharing group cannot coexist with set of constraints for a particular normal
| members that are still at the prior version form (first normal form, second normal
| level, and fallback to a prior version is form, and so on). Contrast with
| not supported. Contrast with conversion denormalization.
| mode, conversion mode*,
not-variant function
| enabling-new-function mode, and
See deterministic function.
| enabling-new-function mode*.
NPSI See nonpartitioned secondary index.
| NFM See new-function mode.
NUL The null character (’\0’), which is
NID See network identifier.
represented by the value X’00’. In C, this
| node ID index character denotes the end of a string.
| See XML node ID index.
null A special value that indicates the absence
nondeterministic function of information.
A user-defined function whose result is
null terminator
not solely dependent on the values of the
| In C, the value that indicates the end of a
input arguments. That is, successive
| string. For EBCDIC, ASCII, and Unicode
invocations with the same argument
| UTF-8 strings, the null terminator is a
values can produce a different answer.
| single-byte value (X’00’). For Unicode
This type of function is sometimes called
| UTF-16 or UCS-2 (wide) strings, the null
a variant function. Contrast with
| terminator is a double-byte value
deterministic function (sometimes called a
| (X’0000’).
not-variant function).
ODBC
nonleaf page
See Open Database Connectivity.
A page that contains keys and page
numbers of other pages in the index ODBC driver
(either leaf or nonleaf pages). Nonleaf A dynamically-linked library (DLL) that
pages never point to actual data. Contrast implements ODBC function calls and
with leaf page. interacts with a data source.
nonpartitioned index | OLAP See online analytical processing.
An index that is not physically
| online analytical processing (OLAP)
partitioned. Both partitioning indexes and
| The process of collecting data from one or
secondary indexes can be nonpartitioned.
| many sources; transforming and
nonpartitioned secondary index (NPSI) | analyzing the consolidated data quickly
An index on a partitioned table space that | and interactively; and examining the
is not the partitioning index and is not | results across different dimensions of the
partitioned. Contrast with | data by looking for patterns, trends, and
data-partitioned secondary index. | exceptions within complex relationships
| of that data.
nonpartitioning index
See secondary index. Open Database Connectivity (ODBC)
A Microsoft database application
nonscrollable cursor
programming interface (API) for C that
A cursor that can be moved only in a
allows access to database management
systems by using callable SQL. ODBC

1132 Application Programming and SQL Guide

does not require the use of an SQL | BIND PACKAGE or REBIND PACKAGE
preprocessor. In addition, ODBC provides | command. An SQL procedural language
an architecture that lets users add | package is created by a CREATE or
modules called database drivers, which link | ALTER PROCEDURE statement for a
the application to their choice of database | native SQL procedure. The name of a
management systems at run time. This | package consists of a location name, a
means that applications no longer need to | collection ID, a package ID, and a version
be directly linked to the modules of all | ID.
the database management systems that
| page A unit of storage within a table space (4
are supported.
| KB, 8 KB, 16 KB, or 32 KB) or index space
ordinary identifier | (4 KB, 8 KB, 16 KB, or 32 KB). In a table
An uppercase letter followed by zero or | space, a page contains one or more rows
more characters, each of which is an | of a table. In a LOB or XML table space, a
uppercase letter, a digit, or the underscore | LOB or XML value can span more than
character. An ordinary identifier must not | one page, but no more than one LOB or
be a reserved word. | XML value is stored on a page.
ordinary token page set
A numeric constant, an ordinary Another way to refer to a table space or
identifier, a host identifier, or a keyword. index space. Each page set consists of a
collection of VSAM data sets.
originating task
In a parallel group, the primary agent page set recovery pending (PSRCP)
that receives data from other execution A restrictive state of an index space. In
units (referred to as parallel tasks) that are this case, the entire page set must be
executing portions of the query in recovered. Recovery of a logical part is
parallel. prohibited.
outer join panel A predefined display image that defines
The result of a join operation that the locations and characteristics of display
includes the matched rows of both tables fields on a display surface (for example, a
that are being joined and preserves some menu panel).
or all of the unmatched rows of the tables
parallel complex
that are being joined. See also join,
A cluster of machines that work together
equijoin, full outer join, inner join, left
to handle multiple transactions and
outer join, and right outer join.
applications.
overloaded function
parallel group
A function name for which multiple
A set of consecutive operations that
function instances exist.
execute in parallel and that have the same
package number of parallel tasks.
An object containing a set of SQL
parallel I/O processing
statements that have been statically
A form of I/O processing in which DB2
bound and that is available for
initiates multiple concurrent requests for a
processing. A package is sometimes also
single user query and performs I/O
called an application package.
processing concurrently (in parallel) on
package list multiple data partitions.
An ordered list of package names that
parallelism assistant
may be used to extend an application
In Sysplex query parallelism, a DB2
plan.
subsystem that helps to process parts of a
package name parallel query that originates on another
| The name of an object that is used for an DB2 subsystem in the data sharing group.
| application package or an SQL procedure
| package. An application package is a
| bound version of a database request
| module (DBRM) that is created by a

DB2 glossary 1133

parallelism coordinator parent table space
In Sysplex query parallelism, the DB2 A table space that contains a parent table.
subsystem from which the parallel query A table space containing a dependent of
originates. that table is a dependent table space.
Parallel Sysplex participant
A set of z/OS systems that communicate An entity other than the commit
and cooperate with each other through coordinator that takes part in the commit
certain multisystem hardware components process. The term participant is
and software services to process customer synonymous with agent in SNA.
workloads.
partition
parallel task | A portion of a page set. Each partition
The execution unit that is dynamically | corresponds to a single, independently
created to process a query in parallel. A | extendable data set. The maximum size of
parallel task is implemented by a z/OS | a partition depends on the number of
service request block. | partitions in the partitioned page set. All
| partitions of a given page set have the
parameter marker
| same maximum size.
| A question mark (?) that appears in a
| statement string of a dynamic SQL | partition-by-growth table space
| statement. The question mark can appear | A table space whose size can grow to
| where a variable could appear if the | accommodate data growth. DB2 for z/OS
| statement string were a static SQL | manages partition-by-growth table spaces
| statement. | by automatically adding new data sets
| when the database needs more space to
parameter-name
| satisfy an insert operation. Contrast with
| An SQL identifier that designates a
| range-partitioned table space. See also
| parameter in a routine that is written by a
| universal table space.
| user. Parameter names are required for
| SQL procedures and SQL functions, and partitioned data set (PDS)
| they are used in the body of the routine | A data set in disk storage that is divided
| to refer to the values of the parameters. | into partitions, which are called members.
| Parameter names are optional for external | Each partition can contain a program,
| routines. | part of a program, or data. A program
| library is an example of a partitioned data
parent key
| set.
A primary key or unique key in the
parent table of a referential constraint. partitioned index
The values of a parent key determine the An index that is physically partitioned.
valid values of the foreign key in the Both partitioning indexes and secondary
referential constraint. indexes can be partitioned.
parent lock partitioned page set
For explicit hierarchical locking, a lock A partitioned table space or an index
that is held on a resource that might have space. Header pages, space map pages,
child locks that are lower in the hierarchy. data pages, and index pages reference
A parent lock is usually the table space data only within the scope of the
lock or the partition intent lock. See also partition.
child lock.
partitioned table space
parent row | A table space that is based on a single
A row whose primary key value is the | table and that is subdivided into
foreign key value of a dependent row. | partitions, each of which can be processed
| independently by utilities. Contrast with
parent table
| segmented table space and universal table
A table whose primary key is referenced
| space.
by the foreign key of a dependent table.
partitioning index
An index in which the leftmost columns

1134 Application Programming and SQL Guide

are the partitioning columns of the table. decimal number (called the size in the C
The index can be partitioned or language). In the C language, the number
nonpartitioned. of digits to the right of the decimal point
(called the scale in SQL). The DB2
partner logical unit
information uses the SQL terms.
An access point in the SNA network that
is connected to the local DB2 subsystem precompilation
by way of a VTAM conversation. A processing of application programs
containing SQL statements that takes
path See SQL path.
place before compilation. SQL statements
PDS See partitioned data set. are replaced with statements that are
recognized by the host language compiler.
physical consistency
Output from this precompilation includes
The state of a page that is not in a
source code that can be submitted to the
partially changed state.
compiler and the database request
physical lock (P-lock) module (DBRM) that is input to the bind
A type of lock that DB2 acquires to process.
provide consistency of data that is cached
predicate
in different DB2 subsystems. Physical
An element of a search condition that
locks are used only in data sharing
expresses or implies a comparison
environments. Contrast with logical lock
operation.
(L-lock).
prefix A code at the beginning of a message or
physically complete
record.
The state in which the concurrent copy
process is completed and the output data preformat
set has been created. | The process of preparing a VSAM linear
| data set for DB2 use, by writing specific
piece A data set of a nonpartitioned page set.
| data patterns.
plan See application plan.
prepare
plan allocation The first phase of a two-phase commit
The process of allocating DB2 resources to process in which all participants are
a plan in preparation for execution. requested to prepare for commit.
plan member prepared SQL statement
The bound copy of a DBRM that is A named object that is the executable
identified in the member clause. form of an SQL statement that has been
processed by the PREPARE statement.
plan name
The name of an application plan. primary authorization ID
The authorization ID that is used to
P-lock See physical lock.
identify the application process to DB2.
point of consistency
primary group buffer pool
A time when all recoverable data that an
For a duplexed group buffer pool, the
application accesses is consistent with
structure that is used to maintain the
other data. The term point of consistency
coherency of cached data. This structure
is synonymous with sync point or commit
is used for page registration and
point.
cross-invalidation. The z/OS equivalent is
policy See CFRM policy. old structure. Compare with secondary
group buffer pool.
postponed abort UR
A unit of recovery that was inflight or primary index
in-abort, was interrupted by system An index that enforces the uniqueness of
failure or cancellation, and did not a primary key.
complete backout during restart.
primary key
precision In a relational database, a unique, nonnull
In SQL, the total number of digits in a key that is part of the definition of a

DB2 glossary 1135

table. A table cannot be defined as a PSRCP
parent unless it has a unique key or See page set recovery pending.
primary key.
PTF See program temporary fix.
principal
QSAM
An entity that can communicate securely
See queued sequential access method.
with another entity. In Kerberos,
principals are represented as entries in the query A component of certain SQL statements
Kerberos registry database and include that specifies a result table.
users, servers, computers, and others.
query block
principal name The part of a query that is represented by
The name by which a principal is known one of the FROM clauses. Each FROM
to the DCE security services. clause can have multiple query blocks,
depending on DB2 processing of the
privilege
query.
The capability of performing a specific
function, sometimes on a specific object. query CP parallelism
See also explicit privilege. Parallel execution of a single query, which
is accomplished by using multiple tasks.
privilege set
See also Sysplex query parallelism.
| v For the installation SYSADM ID, the set
| of all possible privileges. query I/O parallelism
Parallel access of data, which is
| v For any other authorization ID,
accomplished by triggering multiple I/O
| including the PUBLIC authorization ID,
requests within a single query.
| the set of all privileges that are
| recorded for that ID in the DB2 catalog. queued sequential access method (QSAM)
An extended version of the basic
process
sequential access method (BSAM). When
In DB2, the unit to which DB2 allocates
this method is used, a queue of data
resources and locks. Sometimes called an
blocks is formed. Input data blocks await
application process, a process involves the
processing, and output data blocks await
execution of one or more programs. The
transfer to auxiliary storage or to an
execution of an SQL statement is always
output device.
associated with some process. The means
of initiating and terminating a process are quiesce point
dependent on the environment. A point at which data is consistent as a
result of running the DB2 QUIESCE
program
utility.
A single, compilable collection of
executable statements in a programming RACF Resource Access Control Facility. A
language. component of the z/OS Security Server.
program temporary fix (PTF) | range-partitioned table space
A solution or bypass of a problem that is | A type of universal table space that is
diagnosed as a result of a defect in a | based on partitioning ranges and that
current unaltered release of a licensed | contains a single table. Contrast with
program. An authorized program analysis | partition-by-growth table space. See also
report (APAR) fix is corrective service for | universal table space.
an existing problem. A PTF is preventive
RBA See relative byte address.
service for problems that might be
encountered by other users of the RCT See resource control table.
product. A PTF is temporary, because a
| RDO See resource definition online.
permanent fix is usually not incorporated
into the product until its next release. read stability (RS)
An isolation level that is similar to
protected conversation
repeatable read but does not completely
A VTAM conversation that supports
isolate an application process from all
two-phase commit flows.
other concurrently executing application

1136 Application Programming and SQL Guide

processes. See also cursor recovery log
stabilityrepeatable read, and uncommitted A collection of records that describes the
read. events that occur during DB2 execution
and indicates their sequence. The
rebind
recorded information is used for recovery
The creation of a new application plan for
in the event of a failure during DB2
an application program that has been
execution.
bound previously. If, for example, you
have added an index for a table that your recovery manager
application accesses, you must rebind the A subcomponent that supplies
application in order to take advantage of coordination services that control the
that index. interaction of DB2 resource managers
during commit, abort, checkpoint, and
rebuild
restart processes. The recovery manager
The process of reallocating a coupling
also supports the recovery mechanisms of
facility structure. For the shared
other subsystems (for example, IMS) by
communications area (SCA) and lock
acting as a participant in the other
structure, the structure is repopulated; for
subsystem’s process for protecting data
the group buffer pool, changed pages are
that has reached a point of consistency.
usually cast out to disk, and the new
structure is populated only with changed A coordinator or a participant (or both),
pages that were not successfully cast out. in the execution of a two-phase commit,
that can access a recovery log that
record The storage representation of a row or
maintains the state of the logical unit of
other data.
work and names the immediate upstream
record identifier (RID) coordinator and downstream participants.
A unique identifier that DB2 uses to
recovery pending (RECP)
identify a row of data in a table. Compare
A condition that prevents SQL access to a
with row identifier.
table space that needs to be recovered.
record identifier (RID) pool
recovery token
An area of main storage that is used for
An identifier for an element that is used
sorting record identifiers during
in recovery (for example, NID or URID).
list-prefetch processing.
RECP See recovery pending.
record length
The sum of the length of all the columns redo A state of a unit of recovery that indicates
in a table, which is the length of the data that changes are to be reapplied to the
as it is physically stored in the database. disk media to ensure data integrity.
Records can be fixed length or varying
reentrant code
length, depending on how the columns
Executable code that can reside in storage
are defined. If all columns are
as one shared copy for all threads.
fixed-length columns, the record is a
Reentrant code is not self-modifying and
fixed-length record. If one or more
provides separate storage areas for each
columns are varying-length columns, the
thread. See also threadsafe.
record is a varying-length record.
referential constraint
Recoverable Resource Manager Services
The requirement that nonnull values of a
attachment facility (RRSAF)
designated foreign key are valid only if
A DB2 subcomponent that uses Resource
they equal values of the primary key of a
Recovery Services to coordinate resource
designated table.
commitment between DB2 and all other
resource managers that also use RRS in a | referential cycle
z/OS system. | A set of referential constraints such that
| each base table in the set is a descendent
recovery
| of itself. The tables that are involved in a
The process of rebuilding databases after
| referential cycle are ordered so that each
a system failure.

DB2 glossary 1137

| table is a descendent of the one before it, remigration
| and the first table is a descendent of the The process of returning to a current
| last table. release of DB2 following a fallback to a
previous release. This procedure
referential integrity
constitutes another migration process.
The state of a database in which all
values of all foreign keys are valid. remote
Maintaining referential integrity requires Any object that is maintained by a remote
the enforcement of referential constraints DB2 subsystem (that is, by a DB2
on all operations that change the data in a subsystem other than the local one). A
table on which the referential constraints remote view, for example, is a view that is
are defined. maintained by a remote DB2 subsystem.
Contrast with local.
referential structure
A set of tables and relationships that remote subsystem
includes at least one table and, for every Any relational DBMS, except the local
table in the set, all the relationships in subsystem, with which the user or
which that table participates and all the application can communicate. The
tables to which it is related. subsystem need not be remote in any
physical sense, and might even operate
refresh age
on the same processor under the same
The time duration between the current
z/OS system.
time and the time during which a
materialized query table was last reoptimization
refreshed. The DB2 process of reconsidering the
access path of an SQL statement at run
registry
time; during reoptimization, DB2 uses the
See registry database.
values of host variables, parameter
registry database markers, or special registers.
A database of security information about
| reordered row format
principals, groups, organizations,
| A row format that facilitates improved
accounts, and security policies.
| performance in retrieval of rows that have
relational database | varying-length columns. DB2 rearranges
A database that can be perceived as a set | the column order, as defined in the
of tables and manipulated in accordance | CREATE TABLE statement, so that the
with the relational model of data. | fixed-length columns are stored at the
| beginning of the row and the
relational database management system
| varying-length columns are stored at the
(RDBMS)
| end of the row. Contrast with basic row
A collection of hardware and software
| format.
that organizes and provides access to a
relational database. REORG pending (REORP)
A condition that restricts SQL access and
| relational schema
most utility access to an object that must
| See SQL schema.
be reorganized.
relationship
REORP
A defined connection between the rows of
See REORG pending.
a table or the rows of two tables. A
relationship is the internal representation repeatable read (RR)
of a referential constraint. The isolation level that provides
maximum protection from other executing
relative byte address (RBA)
application programs. When an
The offset of a data record or control
application program executes with
interval from the beginning of the storage
repeatable read protection, rows that the
space that is allocated to the data set or
program references cannot be changed by
file to which it belongs.
other programs until the program reaches

1138 Application Programming and SQL Guide

a commit point. See also cursor stability, | definition data set. In earlier releases of
read stability, and uncommitted read. | CICS, resources were defined by using the
| resource control table (RCT), which is no
repeating group
| longer supported.
A situation in which an entity includes
multiple attributes that are inherently the resource limit facility (RLF)
same. The presence of a repeating group A portion of DB2 code that prevents
violates the requirement of first normal dynamic manipulative SQL statements
form. In an entity that satisfies the from exceeding specified time limits. The
requirement of first normal form, each resource limit facility is sometimes called
attribute is independent and unique in its the governor.
meaning and its name. See also
resource limit specification table (RLST)
normalization.
A site-defined table that specifies the
replay detection mechanism limits to be enforced by the resource limit
A method that allows a principal to detect facility.
whether a request is a valid request from
resource manager
a source that can be trusted or whether an
untrustworthy entity has captured v A function that is responsible for
information from a previous exchange managing a particular resource and that
and is replaying the information exchange guarantees the consistency of all
to gain access to the principal. updates made to recoverable resources
within a logical unit of work. The
request commit resource that is being managed can be
The vote that is submitted to the prepare physical (for example, disk or main
phase if the participant has modified data storage) or logical (for example, a
and is prepared to commit or roll back. particular type of system service).
requester v A participant, in the execution of a
The source of a request to access data at a two-phase commit, that has recoverable
remote server. In the DB2 environment, resources that could have been
the requester function is provided by the modified. The resource manager has
distributed data facility. access to a recovery log so that it can
commit or roll back the effects of the
resource
logical unit of work to the recoverable
The object of a lock or claim, which could
resources.
be a table space, an index space, a data
partition, an index partition, or a logical restart pending (RESTP)
partition. A restrictive state of a page set or
partition that indicates that restart
resource allocation
(backout) work needs to be performed on
The part of plan allocation that deals
the object.
specifically with the database resources.
RESTP
resource control table
See restart pending.
| A construct of previous versions of the
| CICS attachment facility that defines result set
| authorization and access attributes for The set of rows that a stored procedure
| transactions or transaction groups. returns to a client application.
| Beginning in CICS Transaction Server
result set locator
| Version 1.3, resources are defined by
A 4-byte value that DB2 uses to uniquely
| using resource definition online instead of
identify a query result set that a stored
| the resource control table. See also
procedure returns.
| resource definition online.
result table
resource definition online (RDO)
The set of rows that are specified by a
| The recommended method of defining
SELECT statement.
| resources to CICS by creating resource
| definitions interactively, or by using a retained lock
| utility, and then storing them in the CICS A MODIFY lock that a DB2 subsystem

DB2 glossary 1139

was holding at the time of a subsystem | of the cursor as part of a FETCH
failure. The lock is retained in the | statement, with respect to a single row
coupling facility lock structure across a | (for example, NEXT, LAST, or ABSOLUTE
DB2 for z/OS failure. | n). Contrast with rowset-positioned fetch
| orientation.
RID See record identifier.
rowset
RID pool
A set of rows for which a cursor position
See record identifier pool.
is established.
right outer join
rowset cursor
The result of a join operation that
A cursor that is defined so that one or
includes the matched rows of both tables
more rows can be returned as a rowset
that are being joined and preserves the
for a single FETCH statement, and the
unmatched rows of the second join
cursor is positioned on the set of rows
operand. See also join, equijoin, full outer
that is fetched.
join, inner join, left outer join, and outer
join. rowset-positioned fetch orientation
| The specification of the desired placement
RLF See resource limit facility.
| of the cursor as part of a FETCH
RLST See resource limit specification table. | statement, with respect to a rowset (for
| example, NEXT ROWSET, LAST
| role A database entity that groups together
| ROWSET, or ROWSET STARTING AT
| one or more privileges and that can be
| ABSOLUTE n). Contrast with
| assigned to a primary authorization ID or
| row-positioned fetch orientation.
| to PUBLIC. The role is available only in a
| trusted context. row trigger
A trigger that is defined with the trigger
rollback
granularity FOR EACH ROW.
The process of restoring data that was
changed by SQL statements to the state at RRSAF
its last commit point. All locks are freed. See Recoverable Resource Manager
Contrast with commit. Services attachment facility.
root page RS See read stability.
The index page that is at the highest level
savepoint
(or the beginning point) in an index.
A named entity that represents the state
routine of data and schemas at a particular point
| A database object that encapsulates in time within a unit of work.
| procedural logic and SQL statements, is
SBCS See single-byte character set.
| stored on the database server, and can be
| invoked from an SQL statement or by SCA See shared communications area.
| using the CALL statement. The main
scalar function
| classes of routines are procedures and
An SQL operation that produces a single
| functions.
value from another value and is
row The horizontal component of a table. A expressed as a function name, followed
row consists of a sequence of values, one by a list of arguments that are enclosed in
for each column of the table. parentheses.
row identifier (ROWID) scale In SQL, the number of digits to the right
A value that uniquely identifies a row. of the decimal point (called the precision
This value is stored with the row and in the C language). The DB2 information
never changes. uses the SQL definition.
row lock schema
A lock on a single row of data. The organization or structure of a
database.
row-positioned fetch orientation
| The specification of the desired placement

1140 Application Programming and SQL Guide

A collection of, and a way of qualifying, statements such as COMMIT,
database objects such as tables, views, ROLLBACK, and some SET statements do
routines, indexes or triggers that define a not use a section.
database. A database schema provides a
| security label
logical classification of database objects.
| A classification of users’ access to objects
scrollability | or data rows in a multilevel security
The ability to use a cursor to fetch in | environment.″
either a forward or backward direction.
segment
The FETCH statement supports multiple
A group of pages that holds rows of a
fetch orientations to indicate the new
single table. See also segmented table
position of the cursor. See also fetch
space.
orientation.
segmented table space
scrollable cursor
A table space that is divided into
A cursor that can be moved in both a
equal-sized groups of pages called
forward and a backward direction.
segments. Segments are assigned to tables
search condition so that rows of different tables are never
A criterion for selecting rows from a table. stored in the same segment. Contrast with
A search condition consists of one or partitioned table space and universal table
more predicates. space.
secondary authorization ID self-referencing constraint
An authorization ID that has been A referential constraint that defines a
associated with a primary authorization relationship in which a table is a
ID by an authorization exit routine. dependent of itself.
secondary group buffer pool self-referencing table
For a duplexed group buffer pool, the A table with a self-referencing constraint.
structure that is used to back up changed
sensitive cursor
pages that are written to the primary
A cursor that is sensitive to changes that
group buffer pool. No page registration or
are made to the database after the result
cross-invalidation occurs using the
table has been materialized.
secondary group buffer pool. The z/OS
equivalent is new structure. sequence
A user-defined object that generates a
secondary index
sequence of numeric values according to
A nonpartitioning index that is useful for
user specifications.
enforcing a uniqueness constraint, for
clustering data, or for providing access sequential data set
paths to data for queries. A secondary A non-DB2 data set whose records are
index can be partitioned or organized on the basis of their successive
nonpartitioned. See also data-partitioned physical positions, such as on magnetic
secondary index (DPSI) and tape. Several of the DB2 database utilities
nonpartitioned secondary index (NPSI). require sequential data sets.
section sequential prefetch
The segment of a plan or package that A mechanism that triggers consecutive
contains the executable structures for a asynchronous I/O operations. Pages are
single SQL statement. For most SQL fetched before they are required, and
statements, one section in the plan exists several pages are read with a single I/O
for each SQL statement in the source operation.
program. However, for cursor-related
serialized profile
statements, the DECLARE, OPEN,
A Java object that contains SQL
FETCH, and CLOSE statements reference
statements and descriptions of host
the same section because they each refer
variables. The SQLJ translator produces a
to the SELECT statement that is named in
serialized profile for each connection
the DECLARE CURSOR statement. SQL
context.

DB2 glossary 1141

server The target of a request from a remote process by an attachment facility to
requester. In the DB2 environment, the enable DB2 to verify that it is authorized
server function is provided by the to use DB2 resources.
distributed data facility, which is used to
simple page set
access DB2 data from remote applications.
A nonpartitioned page set. A simple page
service class set initially consists of a single data set
An eight-character identifier that is used (page set piece). If and when that data set
by the z/OS Workload Manager to is extended to 2 GB, another data set is
associate user performance goals with a created, and so on, up to a total of 32
particular DDF thread or stored data sets. DB2 considers the data sets to
procedure. A service class is also used to be a single contiguous linear address
classify work on parallelism assistants. space containing a maximum of 64 GB.
Data is stored in the next available
service request block
location within this address space without
| A unit of work that is scheduled to
regard to any partitioning scheme.
| execute.
simple table space
session
A table space that is neither partitioned
A link between two nodes in a VTAM
nor segmented. Creation of simple table
network.
spaces is not supported in DB2 Version
session protocols 9.1 for z/OS. Contrast with partitioned
The available set of SNA communication table space, segmented table space, and
requests and responses. universal table space.
| set operator single-byte character set (SBCS)
| The SQL operators UNION, EXCEPT, and A set of characters in which each
| INTERSECT corresponding to the character is represented by a single byte.
| relational operators union, difference, and Contrast with double-byte character set or
| intersection. A set operator derives a multibyte character set.
| result table by combining two other result
single-precision floating point number
| tables.
A 32-bit approximate representation of a
shared communications area (SCA) real number.
A coupling facility list structure that a
SMP/E
DB2 data sharing group uses for
See System Modification
inter-DB2 communication.
Program/Extended.
share lock
SNA See Systems Network Architecture.
A lock that prevents concurrently
executing application processes from SNA network
changing data, but not from reading data. The part of a network that conforms to
Contrast with exclusive lock. the formats and protocols of Systems
Network Architecture (SNA).
shift-in character
A special control character (X’0F’) that is socket A callable TCP/IP programming interface
used in EBCDIC systems to denote that that TCP/IP network applications use to
the subsequent bytes represent SBCS communicate with remote TCP/IP
characters. See also shift-out character. partners.
shift-out character sourced function
A special control character (X’0E’) that is | A function that is implemented by
used in EBCDIC systems to denote that | another built-in or user-defined function
the subsequent bytes, up to the next | that is already known to the database
shift-in control character, represent DBCS | manager. This function can be a scalar
characters. See also shift-in character. | function or an aggregate function; it
| returns a single value from a set of values
sign-on
A request that is made on behalf of an
individual CICS or IMS application

1142 Application Programming and SQL Guide

| (for example, MAX or AVG). Contrast SQLDA
| with built-in function, external function, See SQL descriptor area.
| and SQL function.
SQL descriptor area (SQLDA)
source program A structure that describes input variables,
A set of host language statements and output variables, or the columns of a
SQL statements that is processed by an result table.
SQL precompiler.
SQL escape character
source table The symbol that is used to enclose an
A table that can be a base table, a view, a SQL delimited identifier. This symbol is
table expression, or a user-defined table the double quotation mark (″). See also
function. escape character.
source type SQL function
An existing type that DB2 uses to | A user-defined function in which the
represent a distinct type. | CREATE FUNCTION statement contains
| the source code. The source code is a
space A sequence of one or more blank
| single SQL expression that evaluates to a
characters.
| single value. The SQL user-defined
special register | function can return the result of an
| A storage area that DB2 defines for an | expression. See also built-in function,
| application process to use for storing | external function, and sourced function.
| information that can be referenced in SQL
SQL ID
| statements. Examples of special registers
See SQL authorization ID.
| are SESSION_USER and CURRENT
| DATE. SQLJ Structured Query Language (SQL) that is
embedded in the Java programming
specific function name
language.
A particular user-defined function that is
known to the database manager by its SQL path
specific name. Many specific user-defined An ordered list of schema names that are
functions can have the same function used in the resolution of unqualified
name. When a user-defined function is references to user-defined functions,
defined to the database, every function is distinct types, and stored procedures. In
assigned a specific name that is unique dynamic SQL, the SQL path is found in
within its schema. Either the user can the CURRENT PATH special register. In
provide this name, or a default name is static SQL, it is defined in the PATH bind
used. option.
SPUFI See SQL Processor Using File Input. SQL procedure
| A user-written program that can be
SQL See Structured Query Language.
| invoked with the SQL CALL statement.
SQL authorization ID (SQL ID) | An SQL procedure is written in the SQL
The authorization ID that is used for | procedural language. Two types of SQL
checking dynamic SQL statements in | procedures are supported: external SQL
some situations. | procedures and native SQL procedures.
| See also external procedure and native
SQLCA
| SQL procedure.
See SQL communication area.
SQL processing conversation
SQL communication area (SQLCA)
Any conversation that requires access of
A structure that is used to provide an
DB2 data, either through an application or
application program with information
by dynamic query requests.
about the execution of its SQL statements.
SQL Processor Using File Input (SPUFI)
SQL connection
A facility of the TSO attachment
An association between an application
subcomponent that enables the DB2I user
process and a local or remote application
server or database server.

DB2 glossary 1143

to execute SQL statements without information. Each statement handle is
embedding them in an application associated with the connection handle.
program.
statement string
SQL return code For a dynamic SQL statement, the
Either SQLCODE or SQLSTATE. character string form of the statement.
SQL routine statement trigger
A user-defined function or stored A trigger that is defined with the trigger
procedure that is based on code that is granularity FOR EACH STATEMENT.
written in SQL.
static cursor
| SQL schema A named control structure that does not
| A collection of database objects such as change the size of the result table or the
| tables, views, indexes, functions, distinct order of its rows after an application
| types, schemas, or triggers that defines a opens the cursor. Contrast with dynamic
| database. An SQL schema provides a cursor.
| logical classification of database objects.
static SQL
SQL statement coprocessor | SQL statements, embedded within a
An alternative to the DB2 precompiler | program, that are prepared during the
that lets the user process SQL statements | program preparation process (before the
at compile time. The user invokes an SQL | program is executed). After being
statement coprocessor by specifying a | prepared, the SQL statement does not
compiler option. | change (although values of variables that
| are specified by the statement might
SQL string delimiter
| change).
A symbol that is used to enclose an SQL
string constant. The SQL string delimiter storage group
is the apostrophe (’), except in COBOL | A set of storage objects on which DB2 for
applications, where the user assigns the | z/OS data can be stored. A storage object
symbol, which is either an apostrophe or | can have an SMS data class, a
a double quotation mark (″). | management class, a storage class, and a
| list of volume serial numbers.
SRB See service request block.
stored procedure
stand-alone
A user-written application program that
An attribute of a program that means that
can be invoked through the use of the
it is capable of executing separately from
SQL CALL statement. Stored procedures
DB2, without using DB2 services.
are sometimes called procedures.
star join
string See binary string, character string, or
A method of joining a dimension column
graphic string.
of a fact table to the key column of the
corresponding dimension table. See also strong typing
join, dimension, and star schema. A process that guarantees that only
user-defined functions and operations that
star schema
are defined on a distinct type can be
The combination of a fact table (which
applied to that type. For example, you
contains most of the data) and a number
cannot directly compare two currency
of dimension tables. See also star join,
types, such as Canadian dollars and U.S.
dimension, and dimension table.
dollars. But you can provide a
statement handle user-defined function to convert one
In DB2 ODBC, the data object that currency to the other and then do the
contains information about an SQL comparison.
statement that is managed by DB2 ODBC.
structure
This includes information such as
dynamic arguments, bindings for
dynamic arguments and columns, cursor
information, result values, and status

1144 Application Programming and SQL Guide

v A name that refers collectively to two 16-bit code units, in which the first
different types of DB2 objects, such as value of the pair is a high-surrogate code
tables, databases, views, indexes, and unit in the range U+D800 through
table spaces. U+DBFF, and the second value is a
v A construct that uses z/OS to map and low-surrogate code unit in the range
manage storage on a coupling facility. U+DC00 through U+DFFF. Surrogate
See also cache structure, list structure, pairs provide an extension mechanism for
or lock structure. encoding 917 476 characters without
requiring the use of 32-bit characters.
Structured Query Language (SQL)
A standardized language for defining and SVC dump
manipulating data in a relational A dump that is issued when a z/OS or a
database. DB2 functional recovery routine detects
an error.
structure owner
In relation to group buffer pools, the DB2 sync point
member that is responsible for the See commit point.
following activities: syncpoint tree
v Coordinating rebuild, checkpoint, and The tree of recovery managers and
damage assessment processing resource managers that are involved in a
v Monitoring the group buffer pool logical unit of work, starting with the
threshold and notifying castout owners recovery manager, that make the final
when the threshold has been reached commit decision.

subcomponent synonym
A group of closely related DB2 modules | In SQL, an alternative name for a table or
that work together to provide a general | view. Synonyms can be used to refer only
function. | to objects at the subsystem in which the
| synonym is defined. A synonym cannot
subject table | be qualified and can therefore not be used
The table for which a trigger is created. | by other users. Contrast with alias.
When the defined triggering event occurs
on this table, the trigger is activated. Sysplex
See Parallel Sysplex.
subquery
A SELECT statement within the WHERE Sysplex query parallelism
or HAVING clause of another SQL Parallel execution of a single query that is
statement; a nested SQL statement. accomplished by using multiple tasks on
more than one DB2 subsystem. See also
subselect query CP parallelism.
| That form of a query that includes only a
| SELECT clause, FROM clause, and system administrator
| optionally a WHERE clause, GROUP BY The person at a computer installation
| clause, HAVING clause, ORDER BY who designs, controls, and manages the
| clause, or FETCH FIRST clause. use of the computer system.

substitution character system agent

A unique character that is substituted A work request that DB2 creates such as
during character conversion for any prefetch processing, deferred writes, and
characters in the source program that do service tasks. See also allied agent.
not have a match in the target coding | system authorization ID
representation. | The primary DB2 authorization ID that is
subsystem | used to establish a trusted connection. A
A distinct instance of a relational database | system authorization ID is derived from
management system (RDBMS). | the system user ID that is provided by an
| external entity, such as a middleware
surrogate pair | server.
A coded representation for a single
character that consists of a sequence of

DB2 glossary 1145

system conversation v The set contains a base table and
The conversation that two DB2 associated auxiliary tables.
subsystems must establish to process
A table space set can contain both types
system messages before any distributed
of relationships.
processing can begin.
task control block (TCB)
System Modification Program/Extended (SMP/E)
A z/OS control block that is used to
A z/OS tool for making software changes
communicate information about tasks
in programming systems (such as DB2)
within an address space that is connected
and for controlling those changes.
to a subsystem. See also address space
Systems Network Architecture (SNA) connection.
The description of the logical structure,
TB Terabyte. A value of 1 099 511 627 776
formats, protocols, and operational
bytes.
sequences for transmitting information
through and controlling the configuration TCB See task control block.
and operation of networks.
TCP/IP
table A named data object consisting of a A network communication protocol that
specific number of columns and some computer systems use to exchange
number of unordered rows. See also base information across telecommunication
table or temporary table. Contrast with links.
auxiliary table, clone table, materialized
TCP/IP port
query table, result table, and transition
A 2-byte value that identifies an end user
table.
or a TCP/IP network application within a
table-controlled partitioning TCP/IP host.
A type of partitioning in which partition
template
boundaries for a partitioned table are
A DB2 utilities output data set descriptor
controlled by values that are defined in
that is used for dynamic allocation. A
the CREATE TABLE statement.
template is defined by the TEMPLATE
table function utility control statement.
A function that receives a set of
temporary table
arguments and returns a table to the SQL
A table that holds temporary data.
statement that references the function. A
Temporary tables are useful for holding
table function can be referenced only in
or sorting intermediate results from
the FROM clause of a subselect.
queries that contain a large number of
table locator rows. The two types of temporary table,
| A mechanism that allows access to trigger which are created by different SQL
| tables in SQL or from within user-defined statements, are the created temporary
| functions. A table locator is a fullword table and the declared temporary table.
| integer value that represents a transition Contrast with result table. See also created
| table. temporary table and declared temporary
table.
table space
A page set that is used to store the thread See DB2 thread.
records in one or more tables. See also
threadsafe
partitioned table space, segmented table
A characteristic of code that allows
space, and universal table space.
multithreading both by providing private
table space set storage areas for each thread, and by
A set of table spaces and partitions that properly serializing shared (global)
should be recovered together for one of storage areas.
the following reasons:
three-part name
v Each of them contains a table that is a The full name of a table, view, or alias. It
parent or descendent of a table in one
of the others.

1146 Application Programming and SQL Guide

consists of a location name, a schema new state. Contrast with auxiliary table,
name, and an object name, separated by a base table, clone table, and materialized
period. query table.
time A three-part value that designates a time transition variable
of day in hours, minutes, and seconds. A variable that contains a column value
of the affected row of the subject table in
timeout
its state before or after the triggering
Abnormal termination of either the DB2
event occurs. Triggered SQL statements in
subsystem or of an application because of
the trigger definition can reference the set
the unavailability of resources. Installation
of old values or the set of new values.
specifications are set to determine both
the amount of time DB2 is to wait for tree structure
IRLM services after starting, and the A data structure that represents entities in
amount of time IRLM is to wait if a nodes, with a most one parent node for
resource that an application requests is each node, and with only one root node.
unavailable. If either of these time
trigger
specifications is exceeded, a timeout is
| A database object that is associated with a
declared.
| single base table or view and that defines
Time-Sharing Option (TSO) | a rule. The rule consists of a set of SQL
An option in z/OS that provides | statements that run when an insert,
interactive time sharing from remote | update, or delete database operation
terminals. | occurs on the associated base table or
| view.
timestamp
A seven-part value that consists of a date trigger activation
and time. The timestamp is expressed in The process that occurs when the trigger
years, months, days, hours, minutes, event that is defined in a trigger
seconds, and microseconds. definition is executed. Trigger activation
consists of the evaluation of the triggered
trace A DB2 facility that provides the ability to
action condition and conditional
monitor and collect DB2 monitoring,
execution of the triggered SQL statements.
auditing, performance, accounting,
statistics, and serviceability (global) data. trigger activation time
An indication in the trigger definition of
| transaction
whether the trigger should be activated
| An atomic series of SQL statements that
before or after the triggered event.
| make up a logical unit of work. All of the
| data modifications made during a trigger body
| transaction are either committed together The set of SQL statements that is executed
| as a unit or rolled back as a unit. when a trigger is activated and its
triggered action condition evaluates to
transaction lock
true. A trigger body is also called
A lock that is used to control concurrent
triggered SQL statements.
execution of SQL statements.
trigger cascading
transaction program name
The process that occurs when the
In SNA LU 6.2 conversations, the name of
triggered action of a trigger causes the
the program at the remote logical unit
activation of another trigger.
that is to be the other half of the
conversation. triggered action
The SQL logic that is performed when a
transition table
trigger is activated. The triggered action
A temporary table that contains all the
consists of an optional triggered action
affected rows of the subject table in their
condition and a set of triggered SQL
state before or after the triggering event
statements that are executed only if the
occurs. Triggered SQL statements in the
condition evaluates to true.
trigger definition can reference the table
of changed rows in the old state or the

DB2 glossary 1147

triggered action condition | trusted context
An optional part of the triggered action. | A database security object that enables the
This Boolean condition appears as a | establishment of a trusted relationship
WHEN clause and specifies a condition | between a DB2 database management
that DB2 evaluates to determine if the | system and an external entity.
triggered SQL statements should be
| trusted context default role
executed.
| A role associated with a trusted context.
triggered SQL statements | The privileges granted to the trusted
The set of SQL statements that is executed | context default role can be acquired only
when a trigger is activated and its | when a trusted connection based on the
triggered action condition evaluates to | trusted context is established or reused.
true. Triggered SQL statements are also
| trusted context user
called the trigger body.
| A user ID to which switching the current
trigger granularity | user ID on a trusted connection is
In SQL, a characteristic of a trigger, which | permitted.
determines whether the trigger is
| trusted context user-specific role
activated:
| A role that is associated with a specific
v Only once for the triggering SQL | trusted context user. It overrides the
statement | trusted context default role if the current
v Once for each row that the SQL | user ID on the trusted connection matches
statement modifies | the ID of the specific trusted context user.
triggering event | trusted relationship
| The specified operation in a trigger | A privileged relationship between two
| definition that causes the activation of | entities such as a middleware server and
| that trigger. The triggering event is | a database server. This relationship allows
| comprised of a triggering operation | for a unique set of interactions between
| (insert, update, or delete) and a subject | the two entities that would be impossible
| table or view on which the operation is | otherwise.
| performed.
TSO See Time-Sharing Option.
triggering SQL operation
TSO attachment facility
| The SQL operation that causes a trigger to
A DB2 facility consisting of the DSN
| be activated when performed on the
command processor and DB2I.
| subject table or view.
Applications that are not written for the
trigger package CICS or IMS environments can run under
A package that is created when a the TSO attachment facility.
CREATE TRIGGER statement is executed.
typed parameter marker
The package is executed when the trigger
A parameter marker that is specified
is activated.
along with its target data type. It has the
| trust attribute general form:
| An attribute on which to establish trust. A CAST(? AS data-type)
| trusted relationship is established based
| on one or more trust attributes. type 2 indexes
Indexes that are created on a release of
| trusted connection DB2 after Version 7 or that are specified
| A database connection whose attributes as type 2 indexes in Version 4 or later.
| match the attributes of a unique trusted
| context defined at the DB2 database UCS-2 Universal Character Set, coded in 2 octets,
| server. which means that characters are
represented in 16-bits per character.
| trusted connection reuse
| The ability to switch the current user ID UDF See user-defined function.
| on a trusted connection to a different user UDT User-defined data type. In DB2 for z/OS,
| ID.

1148 Application Programming and SQL Guide

the term distinct type is used instead of | universal table space
user-defined data type. See distinct type. | A table space that is both segmented and
| partitioned. Contrast with partitioned
uncommitted read (UR)
| table space, segmented table space,
The isolation level that allows an
| partition-by-growth table space, and
application to read uncommitted data. See
| range-partitioned table space.
also cursor stability, read stability, and
repeatable read. unlock
The act of releasing an object or system
underlying view
resource that was previously locked and
The view on which another view is
returning it to general availability within
directly or indirectly defined.
DB2.
undo A state of a unit of recovery that indicates
untyped parameter marker
that the changes that the unit of recovery
A parameter marker that is specified
made to recoverable DB2 resources must
without its target data type. It has the
be backed out.
form of a single question mark (?).
Unicode
updatability
A standard that parallels the ISO-10646
The ability of a cursor to perform
standard. Several implementations of the
positioned updates and deletes. The
Unicode standard exist, all of which have
updatability of a cursor can be influenced
the ability to represent a large percentage
by the SELECT statement and the cursor
of the characters that are contained in the
sensitivity option that is specified on the
many scripts that are used throughout the
DECLARE CURSOR statement.
world.
update hole
| union An SQL operation that involves the
The location on which a cursor is
| UNION set operator, which combines the
positioned when a row in a result table is
| results of two SELECT statements. Unions
fetched again and the new values no
| are often used to merge lists of values
longer satisfy the search condition. See
| that are obtained from two tables.
also delete hole.
unique constraint
update trigger
An SQL rule that no two values in a
A trigger that is defined with the
primary key, or in the key of a unique
triggering SQL operation update.
index, can be the same.
UR See uncommitted read.
unique index
An index that ensures that no identical user-defined data type (UDT)
key values are stored in a column or a set See distinct type.
of columns in a table.
user-defined function (UDF)
unit of recovery (UOR) A function that is defined to DB2 by
A recoverable sequence of operations using the CREATE FUNCTION statement
within a single resource manager, such as and that can be referenced thereafter in
an instance of DB2. Contrast with unit of SQL statements. A user-defined function
work. can be an external function, a sourced
function, or an SQL function. Contrast
unit of work (UOW)
with built-in function.
A recoverable sequence of operations
within an application process. At any user view
time, an application process is a single In logical data modeling, a model or
unit of work, but the life of an application representation of critical information that
process can involve many units of work the business requires.
as a result of commit or rollback
UTF-8 Unicode Transformation Format, 8-bit
operations. In a multisite update
encoding form, which is designed for ease
operation, a single unit of work can
of use with existing ASCII-based systems.
include several units of recovery. Contrast
The CCSID value for data in UTF-8
with unit of recovery.

DB2 glossary 1149

format is 1208. DB2 for z/OS supports | v A version of a record is a copy of the
UTF-8 in mixed data fields. | record at a point in time.
UTF-16 | view A logical table that consists of data that is
Unicode Transformation Format, 16-bit | generated by a query. A view can be
encoding form, which is designed to | based on one or more underlying base
provide code values for over a million | tables or views, and the data in a view is
characters and a superset of UCS-2. The | determined by a SELECT statement that is
CCSID value for data in UTF-16 format is | run on the underlying base tables or
1200. DB2 for z/OS supports UTF-16 in | views.
graphic data fields.
Virtual Storage Access Method (VSAM)
value The smallest unit of data that is | An access method for direct or sequential
manipulated in SQL. | processing of fixed- and varying-length
| records on disk devices.
variable
A data element that specifies a value that Virtual Telecommunications Access Method
can be changed. A COBOL elementary (VTAM)
data item is an example of a host An IBM licensed program that controls
variable. Contrast with constant. communication and the flow of data in an
SNA network (in z/OS).
variant function
See nondeterministic function. volatile table
A table for which SQL operations choose
varying-length string
index access whenever possible.
| A character, graphic, or binary string
| whose length varies within set limits. VSAM
| Contrast with fixed-length string. See Virtual Storage Access Method.
version VTAM
| A member of a set of similar programs, See Virtual Telecommunications Access
| DBRMs, packages, or LOBs. Method.
| v A version of a program is the source warm start
| code that is produced by precompiling The normal DB2 restart process, which
| the program. The program version is involves reading and processing log
| identified by the program name and a records so that data that is under the
| timestamp (consistency token). control of DB2 is consistent. Contrast with
| v A version of an SQL procedural cold start.
| language routine is produced by
WLM application environment
| issuing the CREATE or ALTER
A z/OS Workload Manager attribute that
| PROCEDURE statement for a native
is associated with one or more stored
| SQL procedure.
procedures. The WLM application
| v A version of a DBRM is the DBRM environment determines the address
| that is produced by precompiling a space in which a given DB2 stored
| program. The DBRM version is procedure runs.
| identified by the same program name
| and timestamp as a corresponding | WLM enclave
| program version. | A construct that can span multiple
| dispatchable units (service request blocks
| v A version of an application package is
| and tasks) in multiple address spaces,
| the result of binding a DBRM within a
| allowing them to be reported on and
| particular database system. The
| managed by WLM as part of a single
| application package version is
| work request.
| identified by the same program name
| and consistency token as the DBRM. write to operator (WTO)
| v A version of a LOB is a copy of a LOB An optional user-coded service that
| value at a point in time. The version allows a message to be written to the
| number for a LOB is stored in the system console operator informing the
| auxiliary index entry for the LOB.

1150 Application Programming and SQL Guide

operator of errors and unusual system | kind tests, that describe a path within an
conditions that might need to be corrected | XML document in an XML column. The
(in z/OS). | pattern is a restrictive form of path
| expressions, and it selects nodes that
WTO See write to operator.
| match the specifications. XML patterns are
WTOR | specified to create indexes on XML
Write to operator (WTO) with reply. | columns in a database.
XCF See cross-system coupling facility. XML publishing function
| A function that returns an XML value
XES See cross-system extended services.
| from SQL values. An XML publishing
XML See Extensible Markup Language. | function is also known as an XML
| constructor.
XML attribute
A name-value pair within a tagged XML | XML schema
element that modifies certain features of | In XML, a mechanism for describing and
the element. | constraining the content of XML files by
| indicating which elements are allowed
| XML column
| and in which combinations. XML schemas
| A column of a table that stores XML
| are an alternative to document type
| values and is defined using the data type
| definitions (DTDs) and can be used to
| XML. The XML values that are stored in
| extend functionality in the areas of data
| XML columns are internal representations
| typing, inheritance, and presentation.
| of well-formed XML documents.
| XML schema repository (XSR)
| XML data type
| A repository that allows the DB2 database
| A data type for XML values.
| system to store XML schemas. When
XML element | registered with the XSR, these objects
A logical structure in an XML document | have a unique identifier and can be used
that is delimited by a start and an end | to validate XML instance documents.
tag. Anything between the start tag and
| XML serialization function
the end tag is the content of the element.
| A function that returns a serialized XML
| XML index | string from an XML value.
| An index on an XML column that
| XML table
| provides efficient access to nodes within
| An auxiliary table that is implicitly
| an XML document by providing index
| created when an XML column is added to
| keys that are based on XML patterns.
| a base table. This table stores the XML
| XML lock | data, and the column in the base table
| A column-level lock for XML data. The | points to it.
| operation of XML locks is similar to the
| XML table space
| operation of LOB locks.
A table space that is implicitly created
XML node when an XML column is added to a base
The smallest unit of valid, complete table. The table space stores the XML
structure in a document. For example, a table. If the base table is partitioned, one
node can represent an element, an partitioned table space exists for each
attribute, or a text string. XML column of data.
| XML node ID index X/Open
| An implicitly created index, on an XML An independent, worldwide open systems
| table that provides efficient access to XML organization that is supported by most of
| documents and navigation among the world’s largest information systems
| multiple XML data rows in the same suppliers, user organizations, and
| document. software companies. X/Open’s goal is to
increase the portability of applications by
| XML pattern
combining existing and emerging
| A slash-separated list of element names,
standards.
| an optional attribute name (at the end), or

DB2 glossary 1151

XRF See Extended Recovery Facility.
| XSR See XML schema repository.
| zIIP See IBM System z9 Integrated Processor.
z/OS An operating system for the System z
product line that supports 64-bit real and
virtual storage.
z/OS Distributed Computing Environment (z/OS
DCE) A set of technologies that are provided by
the Open Software Foundation to
implement distributed computing.

1152 Application Programming and SQL Guide

Index
Special characters application program (continued)
design considerations
_ (underscore) checkpoint 720
assembler host variable 241 IMS calls 720
’ (apostrophe) programming for DL/I batch 720
string delimiter precompiler option 904 SQL statements 720
stored procedures 521
structure 999
Numerics synchronization call abends 720
31-bit addressing 984 using ISPF (interactive system productivity
facility) 887
XRST call 720
A duplicate CALL statements 763
external stored procedures 531
abend including queries 127
effect on cursor position 674 object extensions 476
for synchronization calls 720 preparation
IMS assembling 915
U0102 1003 binding 916
system compiling 915
X″04E″ 720 DB2 precompiler option defaults 912
abend recovery routine defining to CICS 915
in CAF 51 DRDA access 928
access path example 957
direct row access 702 link-editing 915
accessibility precompiler option defaults 890
keyboard xiv preparing for running 887
shortcut keys xiv program preparation panel 887
accessing data using DB2I (DB2 Interactive) 887
from an application program 627 preparation overview 947
activity sample table 1049 running
adding CICS 1008
data 605 IMS 1008
ALL quantified predicate 661 program synchronization in DL/I batch 720
ALLOCATE CURSOR statement 600 TSO 995
ALTER PROCEDURE statement TSO CLIST 1008
external stored procedure 597 table and view declarations 129
AMODE link-edit option 915, 984 test environment 995
ANY quantified predicate 661 testing 995
APOST precompiler option 904 application program design
application planning for changes 16
rebinding 936 application programming
application 936 DCLGEN example 138
Application Messaging Interface (AMI) DCLGEN variable declarations 135
policies 846 application programs
services 845 compatible data types 148
WebSphere MQ 845 host structures 144
application plan host variable arrays 144
binding 922 host variables 143
creating 916 performance 720
dynamic plan selection for CICS applications 935 applications
invalidated 944 designing 1
listing packages 922 migrating 1
rebinding 938 planning 1
application program arithmetic expressions in UPDATE statement 620
bill of materials 453 array pointer host variable
checking success of SQL statements 141 declaring 273
coding SQL statements 127 referencing in SQL statements 272
coding conventions 227 AS clause
data entry 605 naming columns for view 633
dynamic SQL 162, 166 naming columns in union 633
selecting rows using a cursor 670

© Copyright IBM Corp. 1983, 2009 1153

AS clause (continued) bind options
naming derived columns 633 planning for 18
naming result columns 633 recommendations for distributed applications 34
ORDER BY name 631 BIND PACKAGE subcommand of DSN
ASCII data, retrieving 169 options
assembler application program CURRENTDATA 929
assembling 915 DBPROTOCOL 929
data type compatibility 236 ENCODING 929
declaring tables 241 KEEPDYNAMIC 199
declaring views 241 location-name 929
defining the SQLDA 141, 230 OPTIONS 929
host variable SQLERROR 929
naming convention 241 options associated with DRDA access 928, 930
host variable, declaring 230 remote 917
INCLUDE statement 241 BIND PLAN subcommand of DSN
including SQLCA 229 options
indicator variable declaration 235 CACHESIZE 934
reentrant 241 CURRENTDATA 928
SQLCODE host variable 229 DBPROTOCOL 928
SQLSTATE host variable 229 DISCONNECT 928
variable declaration 231 ENCODING 929
assignment, compatibility rules 426 KEEPDYNAMIC 199
ASSOCIATE LOCATORS statement 600 SQLRULES 928, 946
ATTACH precompiler option 905 options associated with DRDA access 928
attachment facility remote 917
options in z/OS environment 45 binding
AUTH SIGNON (connection function of RRSAF) application plans 916
language examples 99 changes that require 16
syntax 99 checking BIND PACKAGE options 930
authority DBRMs precompiled elsewhere 892
authorization ID 1007 options associated with DRDA access 928
creating test tables 1011 packages
SYSIBM.SYSTABAUTH table 627 remote 917
AUTOCOMMIT field of SPUFI panel 1018 planning for 14
automatic query rewrite 438 plans 922
automatic rebind remote package requirements 917
conditions for 944 specify SQL rules 946
invalid plan or package 944 binding method
SQLCA not available 944 deciding 14
block fetch
preventing 671
B with cursor stability 671
BMP (batch message processing) program
batch processing
checkpoints 26
access to DB2 and DL/I together
bounded character pointer host variable
binding a plan 930
declaring 273
checkpoint calls 720
description 273
commits 720
referencing in SQL statements 272
precompiling 892
BTS (batch terminal simulator) 1043
batch DB2 application
running 1007
starting with a CLIST 1008
bill of materials applications 453 C
binary host variable C application program
assembler 231 declaring tables 280
C/C++ 251 sample application 1071
COBOL 298 C/C++
PL/I 377 creating stored procedure 577
binary host variable array C/C++ application program
C/C++ 262 data type compatibility 275
PL/I 382 DCLGEN support 135
binary large object (BLOB) 430 declaring views 280
BIND defining the SQLDA 141, 250
command line processor command 920 host structure 268
BIND COPY INCLUDE statement 280
for native SQL procedures 554 including SQLCA 249
BIND COPY REPLACE indicator variable array declaration 271
for native SQL procedures 555 indicator variable declaration 271

1154 Application Programming and SQL Guide

C/C++ application program (continued) CCSID (coded character set identifier)
naming convention 280 controlling in COBOL programs 320
precompiler option defaults 912 precompiler option 905
SQLCODE host variable 249 setting for host variables 146
SQLSTATE host variable 249 SQLDA 169
variable array declaration 262 CD-ROM, books on 1097
variable declaration 251 CEEDUMP
with classes, preparing 892 using to debug stored procedures 1030
C/C++ application programs character host variable
pointer host variables 273 assembler 231
cache (dynamic SQL) C/C++ 251
statements 195 COBOL 298
CACHESIZE Fortran 365
option of BIND PLAN subcommand 934 PL/I 377
REBIND subcommand 934 character host variable array
CAF (call attachment facility) C/C++ 262
description 49 COBOL 307
CAF functions PL/I 382
summary of behavior 57 character input data
calculated values REXX procedure 410
groups with conditions 643 character large object (CLOB) 430
summarizing group values 642 character string
call attachment facility (CAF) literals 227
application program mixed data 426
examples 71 width of column in results 1023, 1026
preparation 53 check constraint
attention exit routines 51 check integrity 435
authorization IDs 50 considerations 434
behavior summary 57 CURRENT RULES special register effect 435
connection functions 58 defining 434
connection name 50 description 434
connection properties 50 determining violations 1047
connection type 50 enforcement 434
DB2 abends 50 programming considerations 1047
description 49 CHECK-pending status 435
error messages 69 checkpoint
implicit connections to 54 calls 24, 26
invoking 46 specifying frequency 26
parameters for CALL DSNALI 55 CHKP call, IMS 24
program requirements 53 CICS
recovery routines 51 DSNTIAC subroutine
register changes 54 assembler 241
return codes C 280
example of checking 71 COBOL 326
return codes and reason codes 69 PL/I 393
sample scenarios 70 environment planning 1008
scope 50 facilities
terminated task 50 command language translator 901
trace 69 control areas 995
call attachment language interface EDF (execution diagnostic facility) 1043
loading 52 language interface module (DSNCLI)
making available 52 use in link-editing an application 915
CALL DSNALI operating
parameter list 55 running a program 995
required parameters 55 preparing with JCL procedures 953
CALL DSNRLI programming
parameter list 86 DFHEIENT macro 241
required parameters 86 sample applications 1073, 1077
CALL statement SYNCPOINT command 20
command line processor 1006 storage handling
examples 735 assembler 241
multiple 763 C 280
syntax for invoking DSNTPSMP 566 COBOL 326
catalog table PL/I 393
SYSIBM.LOCATIONS 838 sync point 20
SYSIBM.SYSCOLUMNS 627 unit of work 20
SYSIBM.SYSTABAUTH 627

Index 1155
CICS applications column (continued)
thread reuse 125 labels, usage 169
CICS attachment facility name, with UPDATE statement 620
controlling from applications 124 retrieving, with SELECT 628
detecting whether it is operational 124 specified in CREATE TABLE 425
starting 124 width of results 1023, 1026
stopping 124 COMMA precompiler option 905
client 32 command line processor
CLOSE binding 919
statement CALL statement 1006
description 679 stored procedures 1006
recommendation 685 commit point
WHENEVER NOT FOUND clause 167, 169 description 20
CLOSE (connection function of CAF) IMS unit of work 24
description 58 COMMIT statement
language examples 65 description 1018
program example 71 in a stored procedure 598
syntax 65 when to issue 20
COALESCE function 652 with RRSAF 80
COBOL common table expressions
creating stored procedure 577 description 452
COBOL application program examples 453
compiling 915 in a CREATE VIEW statement 451
controlling CCSID 320 in a SELECT statement 451
data type compatibility 322 in an INSERT statement 451
DB2 precompiler option defaults 912 infinite loops 657
DCLGEN support 135 recursion 453
declaring tables 326 comparison
declaring views 326 compatibility rules 426
defining the SQLDA 141, 296 HAVING clause
dynamic SQL 166 subquery 661
host structure 314 operator, subquery 661
host variable WHERE clause
use of hyphens 326 subquery 661
host variable array, declaring 297 compatibility
host variable, declaring 297 data types 426
INCLUDE statement 326 rules 426
including SQLCA 295 composite key 440
indicator variable array declaration 319 compound statement
indicator variable declaration 319 example
naming convention 326 dynamic SQL 531
object-oriented extensions 333 nested IF and WHILE statements 529
options 326 EXIT handler 540
preparation 915 labels 529
resetting SQL-INIT-FLAG 326 compound statements
sample program 333 nested 537
SQLCODE host variable 295 within the declaration of a condition handler 541
SQLSTATE host variable 295 concurrency 18
variable array declaration 307 condition handlers
variable declaration 298 empty 549
WHENEVER statement 326 conditions
with classes, preparing 892 ignoring 549
coding SQL statements CONNECT
dynamic 162 statement
collection, package SPUFI 1018
identifying 925 CONNECT (connection function of CAF)
SET CURRENT PACKAGESET statement 925 description 58
colon language examples 59
preceding a host variable 151 program example 71
preceding a host variable array 159 syntax 59
column CONNECT LOCATION field of SPUFI panel 1018
data types 426 CONNECT precompiler option 906
default value CONNECT processing option
system-defined 425 enforcing restricted system rules 34
user-defined 426 CONNECT statement, with DRDA access 837
displaying, list of 627 connecting
heading created by SPUFI 1027 DB2 45

1156 Application Programming and SQL Guide

connection CREATE TRIGGER (continued)
DB2 description 457
connecting from tasks 999 example 457
function of CAF timestamp 469
CLOSE 65 trigger naming 457
CONNECT 59 CREATE TYPE statement
DISCONNECT 66 example 476
OPEN 63 CREATE VIEW statement 449
TRANSLATE 68 created temporary table
function of RRSAF instances 444
AUTH SIGNON 99 use of NOT NULL 444
CONTEXT SIGNON 103 working with 445
CREATE THREAD 111 creating objects
FIND_DB2_SYSTEMS 118 in an application program 425
IDENTIFY 89 creating stored procedures
SET_CLIENT_ID 109 external SQL procedures 561
SET_ID 107 CURRENT PACKAGESET special register
SIGNON 95 dynamic plan switching 935
SWITCH TO 93 identify package collection 925
TERMINATE IDENTIFY 115 CURRENT RULES special register
TERMINATE THREAD 114 effect on check constraints 435
TRANSLATE 116 usage 946
connection properties current server 32
call attachment facility (CAF) 50 CURRENT SERVER special register
Resource Recovery Services attachment facility description 924
(RRSAF) 81 saving value in application program 840
connection to DB2 CURRENT SQLID special register
environment requirements 45 use in test 1009
constants, syntax value in INSERT statement 426
C/C++ 251 cursor
Fortran 365 attributes
CONTEXT SIGNON (connection function of RRSAF) using GET DIAGNOSTICS 694
language examples 103 using SQLCA 693
syntax 103 closing 679
CONTINUE clause of WHENEVER statement 208 CLOSE statement 685
CONTINUE handler (SQL procedure) deleting a current row 681
description 540 description 670
example 541 duplicate 763
coordinating updates dynamic scrollable 671
distributed data 33 effect of abend on position 674
correlated reference example
correlation name 664 retrieving backward with scrollable cursor 698
SQL rules 644 updating specific row with rowset-positioned
usage 644 cursor 700
using in subquery 664 updating with non-scrollable cursor 697
correlation name 664 updating with rowset-positioned cursor 699
create insensitive scrollable 672
external SQL procedure by using DSNTPSMP 565 maintaining position 674
external SQL procedure by using JCL 573 non-scrollable 671
external stored procedure 577 open state 674
CREATE GLOBAL TEMPORARY TABLE statement 443 OPEN statement 677
CREATE PROCEDURE statement result table 670
external stored procedure 577 row-positioned
for external SQL procedures 573 declaring 675
CREATE TABLE statement deleting a current row 678
DEFAULT clause 425 description 670
NOT NULL clause 425 end-of-data condition 677
PRIMARY KEY clause 438 retrieving a row of data 678
relationship names 441 steps in using 675
UNIQUE clause 425, 439 updating a current row 678
usage 425 rowset-positioned
CREATE THREAD (connection function of RRSAF) declaring 680
language examples 111 description 670
program example 121 end-of-data condition 680
syntax 111 number of rows 681
CREATE TRIGGER number of rows in rowset 684
activation order 469 opening 680

Index 1157
cursor (continued) DB2 MQ tables
rowset-positioned (continued) descriptions 853
retrieving a rowset of data 681 DB2 private protocol access
steps in using 680 coding an application 835
updating a current rowset 681 compared to DRDA access 32
scrollable DB2-established address spaces
description 671 stored procedures 534
dynamic 671 DB2-supplied stored procedures 766
fetch orientation 685 DB2I
INSENSITIVE 672 default panels 889
retrieving rows 685 invoking DCLGEN 130
SENSITIVE DYNAMIC 673 DB2I (DB2 Interactive)
SENSITIVE STATIC 672 background processing
sensitivity 672 run-time libraries 961
static 671 EDITJCL processing
updatable 671 run-time libraries 961
static scrollable 671 interrupting 1013
types 671 menu 1013
WITH HOLD panels
description 674 BIND PACKAGE 967
BIND PLAN 970
Compile, Link, and Run 982
D Current SPUFI Defaults 1019
DB2I Primary Option Menu 955, 1013
data
Defaults for BIND PACKAGE 973
accessing from an application program 627
Defaults for BIND PLAN 976
adding 605
Precompile 964
adding to the end of a table 619
Program Preparation 957
associated with WHERE clause 630
System Connection Types 980
currency 671
preparing programs 887
distributed 32
program preparation example 957
modifying 605
selecting
not in a table 719
SPUFI 1013
retrieval using SELECT * 658
SPUFI 1013
retrieving a rowset 681
DB2I defaults
retrieving a set of rows 678
setting 889
retrieving large volumes 718
DBCS (double-byte character set)
scrolling backward through 694
translation in CICS 901
security and integrity 19
DBINFO
updating during retrieval 657
passing to external stored procedure 577
updating previously retrieved data 696
user-defined function 500
data encryption 442
DBRM (database request module)
data integrity
binding to a package 917
tables 433
binding to a plan 922
data type
deciding how to bind 14
built-in 426
description 897
comparisons 151
DBRMs in HFS files
compatibility
binding 919
assembler application program 236
DCLGEN
C application program 275
COBOL example 138
COBOL and SQL 322
data types 135
Fortran and SQL 369
declaring indicator variable arrays 130
PL/I application program 389
generating table and view declarations 129
REXX and SQL 404
generating table and view declarations from DB2I 130
result set locator 600
INCLUDE statement 137
data types
including declarations in a program 137
compatibility 148
invoking 129
used by DCLGEN 135
using from DB2I 130
DATE precompiler option 906
variable declarations 135
datetime data type 426
DCLGEN (declarations generator)
DB2
description 129
connection from a program 45
DDITV02 input data set 949
DB2 abend
DDOTV02 output data set 949
DL/I batch 720
debugging
DB2 books online 1097
recording messages for stored procedures 1036
DB2 coprocessor 898
stored procedures 1030
processing SQL statements 890
debugging application programs 1037
DB2 Information Center for z/OS solutions 1097

1158 Application Programming and SQL Guide

DEC15 DESCRIBE INPUT statement 194
precompiler option 906 DESCRIBE PROCEDURE statement 600
rules 658 DESCRIBE statement
DEC31 column labels 169
avoiding overflow 658 INTO clauses 169
precompiler option 906 designing
rules 658 applications 1
decimal designing applications
15 digit precision 658 distributed data 31
31 digit precision 658 designing your application for 18
arithmetic 658 DFHEIENT macro 241
DECIMAL data type DFSLI000 (IMS language interface module) 915
C/C++ 251 diagnostics area
declarations generator (DCLGEN) RESIGNAL affect on 552
description 129 SIGNAL affect on 552
DECLARE (SQL procedure) 527 direct row access 702
DECLARE CURSOR statement disability xiv
description, row-positioned 675 DISCONNECT (connection function of CAF)
description, rowset-positioned 680 description 58
FOR UPDATE clause 676 language examples 66
multilevel security 676 program example 71
prepared statement 167, 169 syntax 66
scrollable cursor 671 displaying
WITH HOLD clause 674 table columns 627
WITH RETURN option 584 table privileges 627
WITH ROWSET POSITIONING clause 680 DISTINCT
DECLARE GLOBAL TEMPORARY TABLE statement 445 clause of SELECT statement 632
DECLARE TABLE statement unique values 632
assembler 241 distinct type
C 280 assigning values 609
COBOL 326 comparing types 668
Fortran 371 description 477
in application programs 128 example
PL/I 393 argument of user-defined function (UDF) 478
declared temporary table arguments of infix operator 733
including column defaults 445 casting constants 733
including identity columns 446 casting function arguments 732
instances 445 casting host variables 733
ON COMMIT clause 447 LOB data type 478
qualifier for 445 function arguments 732
remote access using a three-part name 835 strong typing 477
requirements 446 UNION with INTERSECT 667
working with 445 with EXCEPT 667
declaring tables and views with UNION 667
advantages 128 distinct types
DELETE statement creating 476
correlated subquery 664 distributed applications
description 611, 622 OPTIMIZE FOR n ROWS 41
positioned distributed data 32
FOR ROW n OF ROWSET clause 681 choosing an access method 32
restrictions 678 coordinating updates 33
WHERE CURRENT clause 678, 681 copying a remote table 835
deleting DBPROTOCOL bind option 835, 926
current rows 678 designing applications for 31
data 622 encoding scheme of retrieved data 841
every row from a table 622 example
with TRUNCATE 623 accessing remote temporary table 837
rows from a table 622 calling stored procedure at remote location 926
delimiter, SQL 151 connecting to remote server 837, 926
DENSE_RANK specification 636 specifying location in table name 926
example 636 using alias for multiple sites 838
department sample table using RELEASE statement 839
creating 442 using three-part table names 835
description 1050 executing long SQL statements 841
DEPLOY bind option identifying server at run time 840
for native SQL procedures 558 maintaining data currency 671
DESCRIBE CURSOR statement 600 performance 34

Index 1159
distributed data (continued) DSNALI (continued)
planning making available 52
DB2 private protocol access 926 DSNALI (CAF language interface module)
DRDA access 926 example of deleting 71
program preparation 930 example of loading 71
programming DSNCLI (CICS language interface module) 915
coding with DB2 private protocol access 835 DSNH command of TSO 1038
coding with DRDA access 835 DSNHASM procedure 952
retrieving from ASCII or Unicode tables 841 DSNHC procedure 952
savepoints 32 DSNHCOB procedure 952
scrollable cursors 32 DSNHCOB2 procedure 952
three-part table names 835 DSNHCPP procedure 952
transmitting mixed data 839 DSNHCPP2 procedure 952
two-phase commit 33 DSNHFOR procedure 952
using alias for location 838 DSNHICB2 procedure 952
distributed queries DSNHICOB procedure 952
fast implicit close 44 DSNHLI entry point to DSNALI
DL/I batch program example 71
application programming 720 DSNHLI2 entry point to DSNALI
checkpoint ID 1005 program example 71
DB2 requirements 720 DSNHPLI procedure 952
DDITV02 input data set 949 DSNMTV01 module 1002
DSNMTV01 module 1002 DSNRLI
features 720 loading 83
SSM= parameter 1002 making available 83
submitting an application 1002 DSNTEDIT CLIST 939
double-byte character large object (DBCLOB) 430 DSNTEP2 and DSNTEP4 sample program
DRDA access specifying SQL terminator 1077, 1085
accessing remote temporary table 837 DSNTEP2 sample program
bind options 928 how to run 1069
coding an application 835 parameters 1069
compared to DB2 private protocol access 32 program preparation 1069
connecting to remote server 837 DSNTEP4 sample program
planning 926 how to run 1069
precompiler options 912 parameters 1069
preparing programs 928 program preparation 1069
programming hints 840 DSNTIAC subroutine
releasing connections 839 assembler 241
sample program 344 C 280
SQL limitations at different servers 840 COBOL 326
DRDA access with CONNECT statements PL/I 393
sample program 344 DSNTIAD sample program
DRDA with three-part names how to run 1069
sample program 351 parameters 1069
DROP TABLE statement 449 program preparation 1069
DSN applications, running with CAF 46 specifying SQL terminator 1083
DSN command of TSO DSNTIAR subroutine
return code processing 995 assembler 216
RUN subcommands 995 C 280
DSN_FUNCTION_TABLE COBOL 326
column descriptions 729 description 204
DSN_FUNCTION_TABLE table 729 Fortran 371
DSN_STATEMENT_CACHE_TABLE 198 PL/I 393
DSN8BC3 sample program 326 return codes 206
DSN8BD3 sample program 280 using 204
DSN8BE3 sample program 280 DSNTIAUL sample program
DSN8BF3 sample program 371 how to run 1069
DSN8BP3 sample program 393 parameters 1069
DSNACICS stored procedure 778 program preparation 1069
DSNAEXP stored procedure DSNTIJSD sample program
description 791 using to set up the Unified Debugger 1033
example call 793 DSNTIR subroutine 371
option descriptions 792 DSNTPSMP
output 793 creating external SQL procedures 565
syntax diagram 791 required authorizations 565
DSNALI syntax for invoking 566
loading 52 DSNTRACE data set 69

1160 Application Programming and SQL Guide

DSNXDBRM 897 DXXMQSHREDALLCLOB stored procedure (continued)
DSNXNBRM 897 output 810
duplicate CALL statements 763 parameter descriptions 809
DXXMQGEN stored procedure DXXMQSHREDCLOB stored procedure
description 813 description 801
invocation example 815 invocation example 802
invocation syntax 813 invocation syntax 801
output 816 output 803
parameter descriptions 814 parameter descriptions 802
DXXMQGENCLOB stored procedure DYNAM option of COBOL 326
description 820 dynamic buffer allocation
invocation example 822 FETCH WITH CONTINUE 691
invocation syntax 821 dynamic plan selection
output 823 restrictions with CURRENT PACKAGESET special
parameter descriptions 821 register 935
DXXMQINSERT stored procedure using packages with 935
description 794 dynamic SQL
invocation example 795 advantages and disadvantages 163
invocation syntax 794 assembler program 169
output 796 C program 169
parameter descriptions 794 caching prepared statements 195
DXXMQINSERTALL stored procedure COBOL application program 326
description 803 COBOL program 166
invocation example 805 description 162
invocation syntax 804 effect of bind option REOPT(ALWAYS) 169
output 805 effect of WITH HOLD cursor 189
parameter descriptions 804 EXECUTE IMMEDIATE statement 187
DXXMQINSERTALLCLOB stored procedure fixed-list SELECT statements 167
description 810 Fortran program 371
invocation example 812 host languages 166
invocation syntax 811 including in your program 162
output 813 non-SELECT statements 166, 189
parameter descriptions 811 PL/I 169
DXXMQINSERTCLOB stored procedure PREPARE and EXECUTE 189
description 798 programming 162
invocation example 800 requirements 163
invocation syntax 799 restrictions 163
output 801 sample C program 285
parameter descriptions 799 statement caching 195
DXXMQRETRIEVE stored procedure varying-list SELECT statements 169
description 816 DYNAMICRULES bind option 932
invocation example 819
invocation syntax 817
output 820
parameter descriptions 817
E
ECB (event control block)
DXXMQRETRIEVECLOB stored procedure
CONNECT function of CAF 59
description 824
IDENTIFY function of RRSAF 89
invocation example 826
EDIT panel, SPUFI
invocation syntax 824
SQL statements 1013
output 827
embedded semicolon
parameter descriptions 824
embedded 1083
DXXMQSHRED stored procedure
embedded SQL applications
description 796
XML data 217
invocation example 797
employee photo and resume sample table 1055
invocation syntax 796
employee sample table 1051
output 798
employee-to-project-activity sample table 1058
parameter descriptions 797
ENCRYPT_TDES function 442
DXXMQSHREDALL stored procedure
END-EXEC delimiter 151
description 806
end-of-data condition 677, 680
invocation example 807
environment
invocation syntax 806
setting up for stored procedures 533
output 808
error
parameter descriptions 806
arithmetic expression 216
DXXMQSHREDALLCLOB stored procedure
division by zero 216
description 808
handling 208
invocation example 809
messages generated by precompiler 1038
invocation syntax 808
overflow 216

Index 1161
error (continued) FETCH WITH CONTINUE 690
return codes 203 file reference variable 715
run 1037 DB2-generated construct 715
errors when retrieving data into a host variable FIND_DB2_SYSTEMS (connection function of RRSAF)
determining cause 147 language examples 118
EXCEPT syntax 118
eliminating duplicate rows 639 fixed buffer allocation
keeping duplicate rows with ALL 640 FETCH WITH CONTINUE 692
EXCEPT clause FLAG precompiler option 906
columns of result table 637 FLOAT precompiler option 906
exception condition handling 208 FOLD
EXEC SQL delimiter 151 value for C and CPP 907
EXECUTE IMMEDIATE statement 187 value of precompiler option HOST 907
EXECUTE statement FOR UPDATE clause 676
dynamic execution 189 FOREIGN KEY clause
parameter types 169 description 440
USING DESCRIPTOR clause 169 usage 440
EXISTS predicate, subquery 661 format
EXIT handler (SQL procedure) 540 SELECT statement results 1026
exit routine SQL in input data set 1013
abend recovery with CAF 51 formatting
attention processing with CAF 51 result tables 632
EXPLAIN Fortran application program
automatic rebind 944 @PROCESS statement 371
EXPLAIN STATEMENT CACHE ALL 198 byte data type 371
EXPLAIN tables 729 constant syntax 365
external SQL procedure data type compatibility 369
creating 561 declaring tables 371
external SQL procedures declaring views 371
creating by using DSNTPSMP 565 defining the SQLDA 141, 364
creating by using JCL 573 host variable, declaring 365
debugging with the Unified Debugger 1033 INCLUDE statement 371
migrating to native SQL procedures 559 including SQLCA 363
setting up the environment 533 indicator variable declaration 368
external stored procedure naming convention 371
creating 577 parallel option 371
modifying the definition 597 precompiler option defaults 912
package 582 SQLCODE host variable 363
package authorizations 582 SQLSTATE host variable 363
plan 582 statement labels 371
preparing 577 variable declaration 365
running as authorized program 577 WHENEVER statement 371
external stored procedures FROM clause
setting up the environment 533 joining tables 644
SELECT statement 628
FRR (functional recovery routine)
F in CAF 51
FULL OUTER JOIN clause 651
fast implicit close 44
function resolution 726
FETCH CURRENT CONTINUE 690
functional recovery routine (FRR)
FETCH FIRST n ROWS ONLY clause
in CAF 51
effect on distributed performance 34
FETCH statement
description, multiple rows 681
description, single row 678 G
fetch orientation 685 general-use programming information, described 1107
host variables 167 generating table and view declarations
multiple-row by using DCLGEN 129
assembler 241 with DCLGEN from DB2I 130
description 681 generating XML documents for MQ message queue 852
FOR n ROWS clause 684 GET DIAGNOSTICS statement
number of rows in rowset 684 condition items 209
using with descriptor 681 connection items 209
using with host variable arrays 681 data types for items 209, 212
row and rowset positioning 696 description 209
scrolling through data 694 multiple-row INSERT 209
USING DESCRIPTOR clause 169 RETURN_STATUS item 549
using row-positioned cursor 678 ROW_COUNT item 681

1162 Application Programming and SQL Guide

GET DIAGNOSTICS statement (continued) host variable array
statement items 209 C/C++ 262
using in handler 548 COBOL 297, 307
GO TO clause of WHENEVER statement 208 description 144, 159
governor (resource limit facility) 200 indicator variable array 145
GRANT statement 1011 inserting multiple rows 161
graphic host variable PL/I 376, 382
assembler 231 retrieving multiple rows 160
C/C++ 251 host variable processing
COBOL 298 errors 147
PL/I 377 host variables 142
graphic host variable array compatible data types 148
C/C++ 262
COBOL 307
PL/I 382
GRAPHIC precompiler option 906
I
IBM Data Studio Developer
GROUP BY clause
creating external SQL procedures 561
use with aggregate functions 642
creating native SQL procedures 535
GUPI symbols 1107
IDENTIFY (connection function of RRSAF)
language examples 89
program example 121
H syntax 89
handler, using in SQL procedure 540 identity column
HAVING clause defining 431, 609
selecting groups subject to conditions 643 IDENTITY_VAL_LOCAL function 433
HOST inserting in table 448
FOLD value for C and CPP 907 inserting values into 609
precompiler option 907 trigger 457
host language using as parent key 431
dynamic SQL 166 IKJEFT01 terminal monitor program in TSO 1007
host language data types implicit CAF connection 54
compatibility with SQL data types 148 implicit RRSAF connections 86
host structure IMS
C/C++ 268 checkpoint calls 24
COBOL 314 checkpoints 26
description 144 CHKP call 24
indicator structure 145 commit point 24
PL/I 386 environment planning 1008
retrieving row of data 161 language interface module (DFSLI000) 915
using SELECT INTO 161 link-editing 915
host variable recovery 21
assembler 230, 231 ROLB call 21, 24
C/C++ 251 ROLL call 21, 24
COBOL 297, 298 SYNC call 24
description 143 unit of work 24
FETCH statement 167 IMS programs
Fortran 365 recovery 28
indicator variable 145 IN predicate, subquery 661
inserting values into tables 158 index
LOB types
assembler 706 foreign key 440
C 706 primary 448
COBOL 707 unique 448
Fortran 709 unique on primary key 439
PL/I 709 indicator structure
PL/I 376, 377 description 145
PREPARE statement 167 indicator variable
retrieving a single row 152 description 145
setting the CCSID 146 inserting null values 158
static SQL flexibility 163 indicator variable array
updating values in tables 157 description 145
using 151 inserting null values 158
XML indicator variable arrays
assembler 218 declaring with DCLGEN 130
C 219 indicator variable arraysC/C++ syntax 271
COBOL 220 indicator variable arraysCOBOL syntax 319
PL/I 221 indicator variable arraysPL/I syntax 388

Index 1163
indicator variables join operation (continued)
using to pass large output parameters 756 joining a table to itself 650
indicator variablesassembler syntax 235 joining tables 644
indicator variablesC/C++ syntax 271 LEFT OUTER JOIN 652
indicator variablesCOBOL syntax 319 more than one join 647
indicator variablesFortran syntax 368 more than one join type 648
indicator variablesPL/I syntax 388 operand
infinite loop 657 nested table expression 644
informational referential constraint user-defined table function 644
automatic query rewrite 438 RIGHT OUTER JOIN 653
description 438 SQL rules 654
INNER JOIN clause 649
input data set DDITV02 949
input parameters
stored procedures 740
K
KEEPDYNAMIC option
INSERT statement
BIND PACKAGE subcommand 199
description 605
BIND PLAN subcommand 199
multiple rows 607
key
single row 606
composite 440
VALUES clause 605
foreign 440
with identity column 609
parent 440
with ROWID column 608
primary
inserting
choosing 439
values from host variable arrays 161
defining 439
inserting data
recommendations for defining 438
by using host variables 158
using timestamp 439
Interactive System Productivity Facility (ISPF) 1013
unique 448
internal resource lock manager (IRLM) 1002
INTERSECT
eliminating duplicate rows 639
keeping duplicate rows with ALL 640 L
INTERSECT clause label, column 169
columns of result table 637 language interface modules
invalid SQL terminator characters 1083 DSNCLI 915
invoking large object (LOB)
call attachment facility (CAF) 46 character conversion 712
Resource Recovery Services attachment facility declaring host variables 705
(RRSAF) 77 for precompiler 705
invoking stored procedures declaring LOB file reference variables 705
syntax for command line processor 1006 declaring LOB locators 705
isolation level defining and moving data into DB2 428
REXX 411 description 430
ISPF (Interactive System Productivity Facility) expression 713
browse 1018, 1026 file reference variable 715
DB2 uses dialog management 1013 indicator variable 712
DB2I Primary Option Menu 955 locator 711
Program Preparation panel 957 materialization 711
programming 999 sample applications 704
scroll command 1027 LEFT OUTER JOIN clause 652
ISPLINK SELECT services 998 LEVEL precompiler option 907
libraries
for table declarations and host-variable structures 138
J library 1097
LINECOUNT precompiler option 907
Java stored procedures
link-editing 915
debugging with the Unified Debugger 1033
AMODE option 984
JCL (job control language)
RMODE option 984
batch backout example 1003
LOAD z/OS macro used by CAF 53
DDNAME list format 896
LOAD z/OS macro used by RRSAF 85
page number format 897
LOB column, definition 428
precompilation procedures 952
LOB file reference variable
precompiler option list format 896
assembler 231
preparing a CICS program 953
C/C++ 251, 262
preparing a object-oriented program 892
COBOL 298, 307
starting a TSO batch application 1007
PL/I 377, 382
join operation
LOB host variable array
FULL OUTER JOIN 651
C/C++ 262
INNER JOIN 649

1164 Application Programming and SQL Guide

LOB host variable array (continued) MPP program
COBOL 307 checkpoints 26
PL/I 382 MQ message queue
LOB locator sending table data 852
assembler 231 shredding XML documents 852
C/C++ 251, 262 MQ XML composition stored procedures
COBOL 307 alternative method 852
Fortran 365 MQ XML decomposition stored procedures
PL/I 377, 382 alternative method 852
LOB values MQI DB2 MQ functions
fetching 690 converting applications to use 861
LOB variable MQSeries
assembler 231 DB2 functions
C/C++ 251 connecting applications 865
COBOL 298 MQPUBLISH 846
Fortran 365 MQPUBLISHXML 846
PL/I 377 MQREAD 846
location name 32 MQREADALL 846
lock MQREADALLCLOB 846
escalation MQREADALLXML 846
when retrieving large numbers of rows 718 MQREADCLOB 846
MQREADXML 846
MQRECEIVE 846
M MQRECEIVEALL 846
MQRECEIVEALLCLOB 846
mapping macro
MQRECEIVEALLXML 846
assembler applications 247
MQRECEIVECLOB 846
DSNXDBRM 897
MQRECEIVEXML 846
DSNXNBRM 897
MQSEND 846
MARGINS precompiler option 907
MQSENDXML 846
materialization
MQSENDXMLFILE 846
LOBs 711
MQSENDXMLFILECLOB 846
merging
MQSUBSCRIBE 846
data 611
MQUNSUBSCRIBE 846
message
programming considerations 846
analyzing 1038
retrieving messages 863
obtaining text
sending messages 863
assembler 216
DB2 scalar functions 846
C 280
DB2 stored procedures
COBOL 326
DXXMQINSERT 846
Fortran 371
DXXMQINSERTALL 846
PL/I 393
DXXMQINSERTALLCLOB 846
message data
DXXMQINSERTCLOB 846
WebSphere MQ 843
DXXMQRETRIEVE 846
message handling
DXXMQRETRIEVECLOB 846
WebSphere MQ 843
DXXMQSHRED 846
Message Queue Interface (MQI)
DXXMQSHREDALL 846
DB2 MQ tables 853
DXXMQSHREDALLCLOB 846
policies 844
DXXMQSHREDCLOB 846
services 844
DB2 table functions 846
WebSphere MQ 843
DB2 XML-specific functions 846
messages
MSGFILE runtime option
WebSphere MQ 842
using to debug stored procedures 1036
migrating
multilevel security (MLS) check
applications 1
referential constraints 437
mixed data
triggers 471
converting 839
multiple-row FETCH statement
description 426
checking DB2_LAST_ROW 212
transmitting to remote location 839
SQLCODE +100 203
MLS (multilevel security)
multiple-row INSERT statement
referential constraints 437
dynamic execution 191
triggers 471
NOT ATOMIC CONTINUE ON SQLEXCEPTION 209
modified source statements 897
using GET DIAGNOSTICS 209
modify
external stored procedure definition 597
modifying
data 605

Index 1165
N numeric host variable array (continued)
COBOL 307
naming convention PL/I 382
assembler 241 NUMTCB parameter 766
C 280
COBOL 326
Fortran 371
PL/I 393 O
REXX 405 object-oriented program, preparation 892
tables you create 442 objects
native SQL procedures creating in a application program 425
BIND COPY 554 ON clause, joining tables 644
BIND COPY REPLACE 555 ONEPASS precompiler option 909
creating 535 online 1097
debugging with the Unified Debugger 1033 online books 1097
deploying to another server 558 OPEN
deploying to production 558 statement
migrating from external SQL procedures 559 opening a cursor 677
packages for 554 opening a rowset cursor 680
replacing packages for 555 prepared SELECT 167
nested compound statements USING DESCRIPTOR clause 169
cursor declarations 539 without parameter markers 169
definition 537 OPEN (connection function of CAF)
for controlling scope of conditions 542 description 58
scope of variables 535 language examples 63
statement labels 537 program example 71
nested table expression syntax 63
correlated reference 645 syntax usage 63
correlation name 645 OPTIMIZE FOR n ROWS
join operation 644 effect on distributed applications 41
NEWFUN OPTIMIZE FOR n ROWS clause
precompiler option 908 effect on distributed performance 34
NODYNAM option of COBOL 326 OPTIONS precompiler option 909
NOFOR precompiler option 908 ORDER BY clause
NOGRAPHIC precompiler option 908 SELECT statement 634
nontabular data storage 620 with ORDER OF clause 619
NOOPTIONS precompiler option 908 ORDER OF clause 619
NOPADNTSTR precompiler option 908 organization application
NOSOURCE precompiler option 909 examples 1071
NOT FOUND clause of WHENEVER statement 208 outer join
not logged FULL OUTER JOIN 651
table spaces LEFT OUTER JOIN 652
recovering 30 RIGHT OUTER JOIN 653
NOXREF precompiler option 909 output host variable
NUL character in C 280 determining if null 154
null determining if truncated 154
determining value of output host variable 154 output host variable processing
NULL errors 147
pointer in C 280 output parameters
null value stored procedures 740, 756
column value of UPDATE statement 620
determining column value 156
inserting into columns 158 P
Null, in REXX 405 package
numeric advantages 14
data binding
width of column in results 1026 DBRM to a package 916
numeric data remote 917
description 426 to plans 922
width of column in results 1023 identifying at run time 924
numeric host variable invalid 16
assembler 231 invalidated 944
C/C++ 251 listing 922
COBOL 298 location 924
Fortran 365 rebinding examples 937
PL/I 377 rebinding with pattern-matching characters 936
numeric host variable array selecting 924, 925
C/C++ 262

1166 Application Programming and SQL Guide

package (continued) PL/I application program (continued)
trigger 468 naming convention 393
version, identifying 919 SQLCODE host variable 375
package authorization SQLSTATE host variable 375
for external stored procedures 582 statement labels 393
packages variable array declaration 382
collection ID for stored procedure packages 586 variable declaration 377
for external procedures 582 WHENEVER statement 393
for native SQL procedures 554 plan
for nested routines 586 invalid 16
packages bound on DB2 Version 3 and before 1 planning
PADNTSTR precompiler option 909 applications 1
panel bind options 18
Current SPUFI Defaults 1019, 1023 binding 14
DB2I Primary Option Menu 1013 planning application programs
DSNEPRI 1013 SQL processing options 13
DSNESP01 1013 planning applications
DSNESP02 1019 recovery 19
DSNESP07 1023 plans bound on DB2 Version 3 and before 1
EDIT (for SPUFI input data set) 1013 pointer host variables
SPUFI 1013 declaring 273
panels referencing in SQL statements 272
DB2I (DB2 Interactive) 138 policies
DB2I DEFAULTS 138 Application Messaging Interface (AMI) 846
DCLGEN 138 Message Queue Interface (MQI) 844
DSNEDP01 138 WebSphere MQ 843
DSNEOP01 138 precompiler
DSNEOP02 138 binding on another system 892
parameter list data sets used by 893
stored procedures 740 description 890
parameter marker diagnostics 897
casting in function invocation 733 functions 892
dynamic SQL 189 input 895
more than one 189 maximum size of input 895
values provided by OPEN 167 modified source statements 897
with arbitrary statements 169 option descriptions 904
parameter marker information options
obtaining by using an SQLDA 194 CONNECT 912
PARAMETER STYLE SQL option defaults 911
using to debug stored procedures 1030 DRDA access 912
parent key 440 SQL 912
PARMS option 998 output 897
performance precompiling programs 890
affected by running 892
application structure 998 starting
application programs 720 dynamically 896
distributed data 34 JCL for procedures 952
remote queries 34 submitting jobs
PERIOD precompiler option 909 ISPF panels 957
phone application, description 1071 submitting jobs with ISPF panels 887
PL/I predicate
creating stored procedure 577 general rules 630
PL/I application program predictive governing
coding considerations 393 in a distributed environment 201
data type compatibility 389 with DEFER(PREPARE) 201
DBCS constants 393 writing an application for 201
DCLGEN support 135 PRELINK utility 957
declaring tables 393 PREPARE statement
declaring views 393 dynamic execution 189
defining the SQLDA 141, 376 host variable 167
host structure 386 INTO clause 169
host variable array, declaring 376 prepared SQL statement
host variable, declaring 376 caching 199
INCLUDE statement 393 preparing programs
including SQLCA 375 overview 947
indicator variable array declaration 388 PRIMARY KEY clause
indicator variable declaration 388 ALTER TABLE statement 448

Index 1167
PRIMARY KEY clause (continued) recursive SQL (continued)
CREATE TABLE statement 438 single level explosion 453
problem determination, guidelines 1037 summarized explosion 453
procedures referential constraint
inheriting special registers 511 defining 436
WLM_SET_CLIENT_INFO 776 description 436
product-sensitive programming information, described 1107 determining violations 1047
production environment informational 438
deploying native SQL procedures 558 name 440
program preparation 887 on tables with data encryption 442
program problems checklist on tables with multilevel security 437
documenting error situations 1037 referential integrity
error messages 1042, 1043 effect on subqueries 666
programming interface information, described 1107 programming considerations 1047
project activity sample table 1057 register conventions
project application, description 1071 RRSAF 85
project sample table 1056 register XML schema
PSPI symbols 1107 XSR_REGISTER 827
registers
changed by CAF (call attachment facility) 54
Q release incompatibilities
applications and SQL 1
queries
RELEASE SAVEPOINT statement 28
in application programs 127
RELEASE statement, with DRDA access 839
tuning in application programs 720
remote queries
QUOTE precompiler option 909
performance 34
QUOTESQL precompiler option 909
REPLACE statement (COBOL) 326
requester 32
resetting control blocks
R CAF 66
RANK specification 636 RESIGNAL statement
example 636 raising a condition 549
reason code setting SQLSTATE value 551
CAF 69 resource limit facility (governor)
RRSAF 119 description 200
X″00D44057″ 720 writing an application for predictive governing 201
REBIND PACKAGE subcommand of DSN Resource Recovery Services attachment facility (RRSAF)
generating list of 939 application program
rebinding with wildcard characters 936 preparation 85
remote 917 authorization IDs 81
REBIND PLAN subcommand of DSN behavior summary 87
generating list of 939 connection functions 89
options connection name 81
NOPKLIST 938 connection properties 81
PKLIST 938 connection type 81
remote 917 DB2 abends 81
REBIND TRIGGER PACKAGE subcommand of DSN 468 description 80
rebinding implicit connections 86
automatically invoking 77
conditions for 944 loading 83
changes that require 16 making available 83
list of plans and packages 938 parameters for CALL DSNRLI 86
lists of plans or packages 938, 939 program examples 121
packages with pattern-matching characters 936 program requirements 85
planning for 944 register conventions 85
plans 938 return codes and reason codes 119
recovering sample JCL 121
table spaces that are not logged 30 sample scenarios 119
recovery scope 81
IMS programs 21, 28 terminated task 81
planning for in your application 19 restart, DL/I batch programs using JCL 1003
recursive SQL restricted system
controlling depth 453 definition 34
description 656 forcing rules 34
examples 453 update rules 34
infinite loops 657 restricted systems 31
rules 656

1168 Application Programming and SQL Guide

result column rollback
join operation 651 changes within a unit of work 28
naming with AS clause 633 ROLLBACK option
result set locator CICS SYNCPOINT command 20
assembler 231 ROLLBACK statement
C/C++ 251 description 1018
COBOL 298 error in IMS 720
example 600 in a stored procedure 598
Fortran 365 TO SAVEPOINT clause 28
how to use 600 when to issue 20
PL/I 377 with RRSAF 80
result table routines
description 632 inheriting special registers 511
example 632 row
of SELECT statement 632 selecting with WHERE clause 628
read-only 677 updating 620
result tables updating current 678
formatting 632 updating large volumes 622
retrieving ROW CHANGE TIMESTAMP 644
data in ASCII from DB2 for z/OS 169 row-level security 437
data in Unicode from DB2 for z/OS 169 ROWID
data using SELECT * 658 data type 426
data, changing the CCSID 169 inserting in table 448
large volumes of data 718 ROWID column
multiple rows into host variable arrays 160 defining 608, 704
retrieving a single row defining LOBs 428
into host variables 152 inserting values into 608
return code using for direct row access 702
CAF 69 ROWID host variable array
DSN command 995 C/C++ 262
RRSAF 119 COBOL 307
RETURN statement PL/I 382
returning SQL procedure status 553 ROWID variable
REXX assembler 231
creating stored procedure 577 C/C++ 251
REXX application program COBOL 298
including SQLCA 403 Fortran 365
SQLCODE host variable 403 PL/I 377
SQLSTATE host variable 403 rowset
REXX procedure deleting current 681
application programming interface updating current 681
CONNECT 409 rowset cursor
DISCONNECT 409 closing 685
EXECSQL 409 DB2 for z/OS down-level requester 842
character input data 410 declaring 680
data type conversion 404 end-of-data condition 680
DSNREXX 409 example 699
error handling 405 multiple-row FETCH 681
input data type 404 opening 680
isolation level 411 using 680
naming convention 405 RRSAF functions
naming cursors 413 summary of behavior 87
naming prepared statements 413 RUN subcommand of DSN
running 998 return code processing 995
SQLDA 141, 403 running a program in TSO foreground 995
statement label 405 run-time libraries, DB2I
RIB (release information block) background processing 961
CONNECT function of CAF 59 EDITJCL processing 961
IDENTIFY function of RRSAF 89 running application program
RID CICS 1008
for direct row access 702 errors 1037
RID function 702 IMS 1008
RIGHT OUTER JOIN clause 653
RMODE link-edit option 984
ROLB call, IMS 21, 24
ROLL call, IMS 21, 24
S
sample application
databases, for 1066

Index 1169
sample application (continued) scrollable cursor (continued)
DRDA access 344 static (continued)
DRDA access with CONNECT statements 344 static model 671
DRDA with three-part names 351 updatable 671
dynamic SQL 285 scrolling
environments 1073 backward through data 694
languages 1073 backward using identity columns 694
LOB 1071 backward using ROWIDs 694
organization 1071 in any direction 686
phone 1071 ISPF (Interactive System Productivity Facility) 1027
programs 1069 search condition
project 1071 comparison operators 630
static SQL 285 NOT keyword 630
stored procedure 1071 SELECT statement 659
structure of 1065 WHERE clause 630
use 1069 SELECT FROM DELETE statement
user-defined function 1071 description 624
sample applications 1049 retrieving
Sample applications multiple rows 624
TSO 1074 with INCLUDE clause 624
sample data 1049 SELECT FROM INSERT statement
sample program BEFORE trigger values 614
DSN8BC3 326 default values 613
DSN8BD3 280 description 613
DSN8BE3 280 inserting into view 615
DSN8BF3 371 multiple rows
DSN8BP3 393 cursor sensitivity 616
sample table effect of changes 617
DSN8910.ACT (activity) 1049 effect of SAVEPOINT and ROLLBACK 617
DSN8910.DEMO_UNICODE (Unicode sample ) 1059 effect of WITH HOLD 617
DSN8910.DEPT (department) 1050 processing errors 613
DSN8910.EMP (employee) 1051 result table of cursor 613
DSN8910.EMP_PHOTO_RESUME (employee photo and using cursor 615
resume) 1055 using FETCH FIRST 615
DSN8910.EMPPROJACT (employee-to-project using INPUT SEQUENCE 615
activity) 1058 result table 613
DSN8910.PROJ (project) 1056 retrieving
PROJACT (project activity) 1057 BEFORE trigger values 613
views on 1061 default values 613
sample tables 1049 generated values 613
samples multiple rows 613
provided by DB2 1049 special registers 613
savepoint using SELECT INTO 615
distributed environment 32 SELECT FROM MERGE statement
SAVEPOINT statement 28 description 612
savepoints 28 with INCLUDE clause 612
scalar pointer host variable SELECT FROM UPDATE statement
declaring 273 description 621
referencing in SQL statements 272 retrieving
scrollable cursor multiple rows 621
comparison of types 686 with INCLUDE clause 613, 621
DB2 for z/OS down-level requester 841 SELECT INTO
distributed environment 32 using with host variables 152
dynamic SELECT statement
dynamic model 671 AS clause
fetching current row 689 with ORDER BY clause 634
fetch orientation 685 changing result format 1026
retrieving rows 685 clauses
sensitive dynamic 673 DISTINCT 632
sensitive static 672 EXCEPT 637
sensitivity 686 FROM 628
static GROUP BY 642
creating delete hole 689 HAVING 643
creating update hole 689 INTERSECT 637
holes in result table 689 ORDER BY 634
number of rows 687 UNION 637
removing holes 688 WHERE 628

1170 Application Programming and SQL Guide

SELECT statement (continued) SOURCE precompiler option 909
derived column with AS clause 631 special register
filtering by time changed 644 behavior in stored procedures 599
fixed-list 167 behavior in user-defined functions and stored
named columns 628 procedures 511
ORDER BY clause CURRENT PACKAGE PATH 923
derived columns 634 CURRENT PACKAGESET 923
with AS clause 634 CURRENT RULES 946
parameter markers 169 SPUFI
search condition 659 browsing output 1026
selecting a set of rows 670 changed column widths 1026
subqueries 659 CONNECT LOCATION field 1018
unnamed columns 631 created column heading 1027
using with DB2 governor 1015
* (to select all columns) 628 default values 1019
column-name list 628 entering comments 1017
DECLARE CURSOR statement 675, 680 panels
varying-list 169 allocates RESULT data set 1017
selecting filling in 1013
all columns 628 format and display output 1026
named columns 628 previous values displayed on panel 1013
rows 628 selecting on DB2I menu 1013
some columns 628 processing SQL statements 1013
unnamed columns 631 retrieving Unicode data 1017
semicolon setting SQL terminator 1024
default SPUFI statement terminator 1019 specifying SQL statement terminator 1019
embedded 1083 SQLCODE returned 1026
sequence numbers SQL (Structured Query Language)
COBOL application program 326 checking execution 202
Fortran 371 coding
PL/I 393 dynamic 166
sequence object Fortran program 151
creating 474 object extensions 476
referencing 717 cursors 670
using across multiple tables 474 dynamic
server 32 coding 162
services sample C program 285
Application Messaging Interface (AMI) 845 return codes
Message Queue Interface (MQI) 844 checking 203
WebSphere MQ 843 handling 204
SET clause of UPDATE statement 620 statement terminator 1083
SET CURRENT PACKAGESET statement 925 string delimiter 962
SET ENCRYPTION PASSWORD statement 442 syntax checking 840
SET_CLIENT_ID (connection function of RRSAF) varying-list 169
language examples 109 SQL communication area (SQLCA)
syntax 109 description 203
SET_ID (connection function of RRSAF) using DSNTIAR to format 204
language examples 107 SQL data types
syntax 107 compatibility with host language data types 148
setting SQL terminator SQL precompiler option 910
DSNTIAD 1083 SQL procedure
SPUFI 1024 conditions, handling 540
shortcut keys preparation using DSNTPSMP procedure 562
keyboard xiv SQL variable 527
shredding XML documents from MQ messages 852 SQL procedure statement
SIGNAL statement CONTINUE handler 540
raising a condition 549 EXIT handler 540
setting condition message text 550 handler 540
SIGNON (connection function of RRSAF) handling errors 540
language examples 95 SQL procedures
program example 121 nested compound statements 537
syntax 95 SQL processing optionsplanning for 13
softcopy publications 1097 SQL statement nesting
SOME quantified predicate 661 restrictions 669
sort key stored procedures 669
ORDER BY clause 634 user-defined functions 669
ordering 634

Index 1171
SQL statement terminator SQL statements (continued)
modifying in DSNTEP2 and DSNTEP4 1077, 1085 PL/I program sections 393
modifying in DSNTIAD 1083 PREPARE 189
modifying in SPUFI 1019 RELEASE, with DRDA access 839
specifying in SPUFI 1019 REXX program sections 405
SQL statements SELECT
ALLOCATE CURSOR 600 description 628
ALTER FUNCTION 480 joining a table to itself 650
ASSOCIATE LOCATORS 600 joining tables 644
checking for successful execution 141 SELECT FROM DELETE 624
CLOSE 167, 679, 685 SELECT FROM INSERT 613
COBOL program sections 326 SELECT FROM MERGE 612
coding REXX 151 SELECT FROM UPDATE 621
comments set symbols 241
assembler 241 UPDATE
C 280 description 678, 681
COBOL 326 example 620
Fortran 371 WHENEVER 208
PL/I 393 SQL terminator, specifying in DSNTEP2 and DSNTEP4 1077,
REXX 405 1085
CONNECT, with DRDA access 837 SQL terminator, specifying in DSNTIAD 1083
continuation SQL variable 527
assembler 241 SQL-INIT-FLAG, resetting 326
C 280 SQLCA (SQL communication area)
COBOL 326 checking SQLCODE 207
Fortran 371 checking SQLERRD(3) 203
PL/I 393 checking SQLSTATE 207
REXX 405 checking SQLWARN0 203
CREATE FUNCTION 480 description 203
DECLARE CURSOR DSNTIAC subroutine
description 675, 680 assembler 241
example 167, 169 C 280
DELETE COBOL 326
description 678 PL/I 393
example 622 DSNTIAR subroutine
DESCRIBE 169 assembler 216
DESCRIBE CURSOR 600 C 280
DESCRIBE PROCEDURE 600 COBOL 326
embedded 895 Fortran 371
error return codes 204 PL/I 393
EXECUTE 189 sample C program 285
EXECUTE IMMEDIATE 187 SQLCA (SQL communications area)
FETCH assembler 229
description 678, 681 C/C++ 249
example 167 COBOL 295
Fortran program sections 371 deciding whether to include 141
in application programs 127 Fortran 363
INSERT 605 PL/I 375
labels REXX 403
assembler 241 SQLCODE
C 280 -923 949
COBOL 326 -925 720
Fortran 371 -926 720
PL/I 393 +100 208
REXX 405 +802 216
margins values 207
assembler 241 SQLCODE host variable
C 280 deciding whether to declare 141
COBOL 326 SQLDA
Fortran 371 setting an XML host variable 169
PL/I 393 XML column 169
REXX 405 SQLDA (SQL descriptor area)
MERGE allocating storage 169, 681
example 611 assembler 141, 230
OPEN assembler program 169
description 677, 680 C 169
example 167 C/C++ 141, 250

1172 Application Programming and SQL Guide

SQLDA (SQL descriptor area) (continued) stored procedure (continued)
COBOL 141, 296 DXXMQSHRED 796
declaring 681 DXXMQSHREDALL 806
dynamic SELECT example 169 DXXMQSHREDALLCLOB 808
for LOBs and distinct types 169 DXXMQSHREDCLOB 801
Fortran 141, 364 example 523
multiple-row FETCH statement 681 invoking from a trigger 465
no occurrences of SQLVAR 169 languages supported 531
OPEN statement 167 linkage conventions 741
parameter markers 169 returning non-relational data 585
PL/I 141, 169, 376 returning result set 584
requires storage addresses 169 running multiple instances 763
REXX 141, 403 use of special registers 599
setting output fields 681 using COMMIT in 598
storing parameter marker information 194 using host variables with 523
varying-list SELECT statement 169 using ROLLBACK in 598
SQLERROR clause of WHENEVER statement 208 using temporary tables in 585
SQLN field of SQLDA 169 WLM_REFRESH 774
SQLRULES, option of BIND PLAN subcommand 946 writing 531
SQLSTATE writing in REXX 594
″01519″ 216 stored procedures
″2D521″ 720 >DSNACCOX 766
″57015″ 949 ADMIN_COMMAND_DB2 766
values 207 ADMIN_COMMAND_DSN 766
SQLSTATE host variable ADMIN_COMMAND_UNIX 766
deciding whether to declare 141 ADMIN_DS_BROWSE 766
SQLSTATEs ADMIN_DS_DELETE 766
Web service consumer 883 ADMIN_DS_LIST 766
SQLVAR field of SQLDA 169 ADMIN_DS_RENAME 766
SQLWARNING clause of WHENEVER statement 208 ADMIN_DS_SEARCH 766
SSID (subsystem identifier), specifying 961 ADMIN_DS_WRITE 766
statement cache table 198 ADMIN_INFO_HOST 766
static SQL ADMIN_INFO_SSID 766
C/C++ application program ADMIN_JOB_CANCEL 766
examples 285 ADMIN_JOB_FETCH 766
description 162 ADMIN_JOB_QUERY 766
host variables 163 ADMIN_JOB_SUBMIT 766
sample C program 285 ADMIN_TASK_ADD 766
STDSQL precompiler option 910 ADMIN_TASK_REMOVE 766
storage ADMIN_UTL_SCHEDULE 766
acquiring ADMIN_UTL_SORT 766
retrieved row 169 calling other programs 586
SQLDA 169 creating native SQL procedures 535
addresses in SQLDA 169 DB2-supplied 766
storage group, for sample application data 1066 debugging 1030
stored procedure debugging with the Unified Debugger 1033
abend 735 DSNACCOR 766
accessing transition tables 513 DSNACICS 766
authorization to run 735 DSNAEXP 766
CALL statement 735 DSNAHVPM 766
calling from a REXX procedure 757 DSNAIMS 766
calling from an application 735 DSNAIMS2 766
compatible data types 757 DSNLEUSR 766
creating 521 DSNTBIND 766
creating external stored procedure 577 DSNTPSMP 766
Data types 589 DSNUTILS 766
defining parameter lists 741, 744, 745 DSNUTILU 766
DSNACICS 778 DSNWSPM 766
DSNAEXP 791 DSNWZP 766
DXXMQGEN 813 from command line processor 1006
DXXMQGENCLOB 820 GET_CONFIG 766
DXXMQINSERT 794 GET_MESSAGE 766
DXXMQINSERTALL 803 GET_SYSTEM_INFO 766
DXXMQINSERTALLCLOB 810 inheriting special registers 511
DXXMQINSERTCLOB 798 migrating external SQL to native SQL 559
DXXMQRETRIEVE 816 package collection ID 586
DXXMQRETRIEVECLOB 824 packages for nested routines 586

Index 1173
stored procedures (continued) SYSPRINT precompiler output (continued)
parameter list 740 used to analyze errors 1039
passing large output parameters 756 SYSTERM output to analyze errors 1038
recording debugging messages 1036
running concurrently 766
setting up the environment 533
SQLJ.ALTER_JAVA_PATH 766
T
table
SQLJ.DB2_INSTALL_JAR 766
altering
SQLJ.DB2_REMOVE_JAR 766
changing definitions 442
SQLJ.DB2_REPLACE_JAR 766
using CREATE and ALTER 216
SQLJ.DB2_UPDATEJARINFO 766
copying from remote locations 835
SQLJ.INSTALL_JAR 766
declaring in a program 128
SQLJ.REMOVE_JAR 766
deleting rows 622
SQLJ.REPLACE_JAR 766
dependent, cycle restrictions 436
syntax for invoking from command line processor 1006
displaying, list of 627
WLM_REFRESH 766
DROP statement 449
XDBDECOMPXML 766
filling with test data 1012
XSR_ADDSCHEMADOC 766
incomplete definition of 448
XSR_COMPLETE 766
inserting multiple rows 607
XSR_REGISTER 766
inserting single row 606
XSR_REMOVE 766
loading, in referential structure 435
stored proceduresmoving to a WLM-established
merging rows 611
environment 534
populating 1012
storm drain effect 124
referential structure 436
string
retrieving 670
data type 426
selecting values as you delete rows 624
structure array host variable
selecting values as you insert rows 613
declaring 273
selecting values as you merge rows 612
referencing in SQL statements 272
selecting values as you update rows 621
subquery
temporary 445
basic predicate 661
updating rows 620
conceptual overview 659
using three-part table names 835
correlated
table and view declarations
DELETE statement 664
including in an application program 137
description 663
table and view declarationsgenerating with DCLGEN 129
example 663
table declarations
UPDATE statement 664
adding to libraries 138
DELETE statement 664
table locator
description 659
assembler 231
EXISTS predicate 661
C/C++ 251
IN predicate 661
COBOL 298
quantified predicate 661
PL/I 377
referential constraints 666
table space
restrictions with DELETE 666
for sample application 1067
UPDATE statement 664
not logged
subsystem
recovering 30
identifier (SSID), specifying 961
tables
subsystem parameters 766
creating for data integrity 433
summarizing group values 642
TCB (task control block)
SWITCH TO (connection function of RRSAF)
capabilities with CAF 49
language examples 93
capabilities with RRSAF 80
syntax 93
temporary table
SYNC call, IMS 24
advantages of 445
synchronization call abends 720
working with 445
SYNCPOINT command of CICS 20
terminal monitor program (TMP) 995
syntax diagram
TERMINATE IDENTIFY (connection function of RRSAF)
how to read xv
language examples 115
SYSIBM.MQPOLICY_TABLE
program example 121
column descriptions 853
syntax 115
SYSIBM.MQSERVICE_TABLE
TERMINATE THREAD (connection function of RRSAF)
column descriptions 853
language examples 114
SYSLIB data sets 952
program example 121
SYSPRINT precompiler output
syntax 114
options section 1039
TEST command of TSO 1042
source statements section, example 1039
test environment, designing 995
summary section, example 1039
test tables 1009
symbol cross-reference section 1039
test views of existing tables 1009

1174 Application Programming and SQL Guide

TIME precompiler option 910 UNION clause (continued)
time that row was changed combining SELECT statements 637
determining 718 UNIQUE clause 439
TMP (terminal monitor program) unit of work
DSN command processor 995 CICS 20
running under TSO 1007 completion
transition table, trigger 457 open cursors 674
transition variable, trigger 457 description 19
TRANSLATE (connection function of CAF) IMS 24
description 58 TSO 20
language example 68 undoing changes within 28
program example 71 updatable cursor 676
syntax 68 UPDATE statement
TRANSLATE (connection function of RRSAF) correlated subqueries 664
language examples 116 description 620
syntax 116 positioned
translating requests into SQL 217 FOR ROW n OF ROWSET 681
trigger restrictions 678
activation order 469 WHERE CURRENT clause 678, 681
activation time 457 SET clause 620
cascading 468 updating
coding 457 during retrieval 657
data integrity 472 large volumes 622
delete 457 updating data
description 457 by using host variables 157
FOR EACH ROW 457 USER special register
FOR EACH STATEMENT 457 value in INSERT statement 426
granularity 457 value in UPDATE statement 620
insert 457 user-defined function (UDF)
interaction with constraints 470 abnormal termination 517
interaction with security label columns 471 accessing transition tables 513
naming 457 ALTER FUNCTION statement 480
parts example 457 authorization ID 724
parts of 457 call type 498
subject table 457 casting arguments 733
transition table 457 characteristics 485
transition variable 457 coding guidelines 487
triggering event 457 CREATE FUNCTION statement 480
update 457 data type promotion 726
using identity columns 457 DBINFO structure 500
with row-level security 471 definer 483
troubleshooting defining 485
errors for output host variables 147 description 483
TRUNCATE 623 diagnostic message 497
example 623 DSN_FUNCTION_TABLE 729
truncated example
determining value of output host variable 154 external scalar 481, 519
TSO external table 482
CLISTs function resolution 728
calling application programs 1008 overloading operator 481
running in foreground 1008 sourced 482
TEST command 1042 SQL 482
TWOPASS precompiler option 910 function resolution 726
host data types
assembler 490
U C 490
COBOL 490
Unicode
PL/I 490
data, retrieving from DB2 for z/OS 169
implementer 483
sample table 1059
implementing 484
Unified Debugger
indicators
debugging stored procedures 1033
input 497
setting up 1033
result 497
UNION
inheriting special registers 511
eliminating duplicate rows 639
invoker 483
keeping duplicate rows with ALL 640
invoking 723
UNION clause
invoking from a trigger 465
columns of result table 637

Index 1175
user-defined function (UDF) (continued) view (continued)
invoking from predicate 723 identity columns 450
main program 487 join of two or more tables 450
multiple programs 510 referencing special registers 449
naming 497 retrieving 670
nesting SQL statements 669 summary data 450
parallelism considerations 487 union of two or more tables 450
parameter conventions 490 using
assembler 503 deleting rows 622
C 504 inserting rows 605
COBOL 509 updating rows 620
PL/I 509
preparing 517
reentrant 510
restrictions 487
W
Web service consumer
samples 519
SQLSTATEs 883
scratchpad 498, 518
WebSphere MQ
scrollable cursor 723
APIs 842
setting result values 496
Application Messaging Interface (AMI) 845
simplifying function resolution 725
commit environment 851
specific name 497
description 842
steps in creating and using 483
interaction with DB2 842
subprogram 487
message handling 843
table locators
Message Queue Interface (MQI) 843
assembler 514
messages 842
C 515
WHENEVER statement
COBOL 515
assembler 241
PL/I 516
C 280
testing 1027
COBOL 326
types 483
CONTINUE clause 208
user-defined functions
Fortran 371
SOAPHTTPNC 883
GO TO clause 208
SOAPHTTPNV 883
NOT FOUND clause 208, 678
USING DESCRIPTOR clause
PL/I 393
EXECUTE statement 169
specifying 208
FETCH statement 169
SQL error codes 208
OPEN statement 169
SQLERROR clause 208
SQLWARNING clause 208
WHERE clause
V SELECT statement
VALUES clause, INSERT statement 605 description 628
varbinary host variable joining a table to itself 650
assembler 231 joining tables 644
C/C++ 251 WITH clause
COBOL 298 common table expressions 452
PL/I 377 WITH HOLD clause
varbinary host variable array and CICS 674
C/C++ 262 and IMS 674
PL/I 382 DECLARE CURSOR statement 674
variable restrictions 674
assembler 231 WITH HOLD cursor
C/C++ 251 effect on dynamic SQL 189
COBOL 298 WLM environment
declaring in SQL procedure 527 moving stored procedures 534
Fortran 365 WLM_REFRESH stored procedure
PL/I 377 description 774
variable array option descriptions 775
C/C++ 262 sample JCL 776
COBOL 307 syntax diagram 775
PL/I 382 WLM_SET_CLIENT_INFO procedure 776
version of a package 919 write-down privilege 471
VERSION precompiler option 911, 919
view
contents 450
declaring in a program 128
X
XDBDECOMPXML
description 449
authorization 833
dropping 451

1176 Application Programming and SQL Guide

XDBDECOMPXML (continued)
invocation syntax 833
parameter descriptions 833
stored procedure 833
XDBDECOMPXML stored procedure 833
XML data
embedded SQL applications 217
retrieving from tables in embedded SQL applications 224
selecting 631
updating tables in embedded SQL applications 222
XML decomposition
stored procedure 833
XML file reference variable
assembler 231
C/C++ 251, 262
COBOL 298, 307
PL/I 377, 382
XML host variable
SQLDA 169
XML host variable array
C/C++ 262
COBOL 307
PL/I 382
XML schema
stored procedure for completion of XML registration 830
stored procedure for removing 832
XML schema document
stored procedure to add 829
XML values
fetching 690
XML variable
assembler 231
C/C++ 251
COBOL 298
PL/I 377
XML_COMPLETE
stored procedure 830
XMLEXISTS 719
description 719
example 719
XMLQUERY 631
description 631
example 631
XPath 631
XPath contexts 631
XPath contexts
XMLEXISTS 719
XPath expressions 631
XREF precompiler option 911
XSR_ADDSCHEMADOC
stored procedure 829
XSR_ADDSCHEMADOC stored procedure 829
XSR_COMPLETE stored procedure 830
XSR_REGISTER
register XML schema 827
XSR_REMOVE
stored procedure 832
XSR_REMOVE stored procedure 832

Index 1177
1178 Application Programming and SQL Guide



Program Number: 5635-DB2

Printed in USA

SC18-9841-05
Spine information:

DB2 Version 9.1 for z/OS Application Programming and SQL Guide