nullif

Description

Syntax:

nullif(expr1, expr2)

If the two parameters are equal, the function will return null. Otherwise, it will return the value of the first parameter. This function has the same effect as case when:

CASE
     WHEN expr1 = expr2 THEN NULL
     ELSE expr1
END

Example

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

mysql> select nullif(1,0);
+--------------+
| nullif(1, 0) |
+--------------+
|            1 |
+--------------+

Keywords

NULLIF

ifnull nvl