You have a request that you do not want to be placed in the lock queue if it cannot be serviced immediately. In this case, use the NOWAIT option. For example:
LOCKING employee FOR READ NOWAIT SELECT employee_number, last_name FROM employee WHERE department_number=401; *** Failure 7423 Object already locked and NOWAIT. Transaction Aborted. Statement# 1, Info =0
Another request had employee locked, so you must resubmit the request.
LOCKING employee FOR READ NOWAIT SELECT employee_number, last_name FROM employee WHERE department_number=401; *** Query completed. 7 rows found. 2 columns returned. *** Total elapsed time was 1 second. employee_number last_name --------------- -------------------- 1003 Trader 1004 Johnson 1013 Phillips 1002 Brown 1010 Rogers 1022 Machado 1001 Hoover
This time, no locks were being held on employee, so the request completed successfully.