Oracle/PLSQL: NULLIF Function

In Oracle/PLSQL, the NULLIF function compares expr1 and expr2. If expr1 and expr2 are equal, the NULLIF function returns NULL. Otherwise, it returns expr1.

The syntax for the NULLIF function is:

NULLIF( expr1, expr2 )

expr1 and expr2 must be either numeric values or values that are of the same datatype.

Note:

expr1 can be an expression that evaluates to NULL, but it can not be the literal NULL.

Applies To:

Oracle 9i, Oracle 10g, Oracle 11g

For example:

NULLIF(12, 12) would return NULL

NULLIF(12, 13) would return 12

NULLIF('apples', 'apples') would return NULL

NULLIF('apples', 'oranges') would return 'apples'

NULLIF(NULL, 12) would return an ORA-00932 error because expr1 can not be the literal NULL