understanding different types and use of integrity constraint

Author: techysanoj

integrity_constraint.sql

@@ -0,0 +1,22 @@
+use temp_db;
+
+show tables;
+
+/* different types of integrity constraint
+1. NOT NULL
+ 2. UNIQUE
+ 3. PRIMARY KEY
+ 4. FOREIGN KEY
+ 5. CHECK
+ 6. DEFAULT
+
+ these are applied on table column 
+ at the time of creating the table and altering the table
+*/
+
+-- example using NOT NULL means we can not be having any NULL values in the table
+create table emp_new(s_no int NOT NULL, s_name varchar(15)); -- here s_no can not be null
+
+insert into emp_new values(1, 'SANOJ'); -- successfully inserted
+insert into emp_new values (NULL, 'Kumar'); -- it will return error that s_no cannot be null
+insert into emp_new(s_name) values ('Kumar'); -- it will also return error same error