MySQL NULLIF() Function

Compare two expressions:

SELECT NULLIF(25, 25);

Definition and Usage

The NULLIF() function compares two expressions and returns NULL if they are equal. Otherwise, the first expression is returned.

NULLIF( expr1, expr2)

Parameter	Description
expr1, expr2	Required. The two expressions to be compared

Works in:	From MySQL 4.0

Compare two expressions:

SELECT NULLIF(25, "Hello");

Compare two expressions:

SELECT NULLIF("Hello", "world");

Compare two expressions:

SELECT NULLIF("2017-08-25", "2017-08-25");