Oracle SQL / PLSQL used the NULLIF function to compare 2 expressions.
If the expressions are equal then the SQL NULLIF function returns NULL, else SQL NULLIF function will return the first expression.
Oracle SQL / PLSQL Syntax for the NULLIF function is:
SELECT NULLIF (expression_1, expression_2)
FROM table_name;
Here, expression_1 and expression_2 are the expressions to be compared.
Example: Using Oracle SQL /PLSQL NULLIF Function in SQL SELECT Statement
1 | SELECT NULLIF(1,1) |
2 | FROM dual; |
Will return NULL
1 | SELECT NULLIF(1,2) |
2 | FROM dual; |
Will return 2
1 | SELECT NULLIF('Tech Honey','Tech Honey') |
2 | FROM dual; |
Will return NULL
1 | SELECT NULLIF('Tech','Honey') |
2 | FROM dual; |
Will return ‘Tech’
1 | SELECT NULLIF(NULL,'Honey') |
2 | FROM dual; |
Will return an ORA-00932 error because expression_1 cannot be literal NULL.
The example above shows use of Oracle SQL / PLSQL NULLIF Function.