nullif

Description

Returns NULL if expr1 is equal to expr2. Otherwise, returns expr1.

Syntax

nullif(expr1,expr2);

Parameters

expr1 and expr2 must be compatible in data type.

Return value

The return value has the same type as expr1.

Examples

mysql> select nullif(1,2);
+--------------+
| nullif(1, 2) |
+--------------+
|            1 |
+--------------+

mysql> select nullif(1,1);
+--------------+
| nullif(1, 1) |
+--------------+
|         NULL |
+--------------+