NULLIF

Description

Returns NULL if the two input values are equal; otherwise, returns the first input value. This function is equivalent to the following CASE WHEN expression:

CASE
    WHEN <expr1> = <expr2> THEN NULL
    ELSE <expr1>
END

Syntax

NULLIF(<expr1>, <expr2>)

Parameters

Parameter	Description
<expr1>	The first input value to compare.
<expr2>	The second input value to compare against the first.

Return Value

• Returns NULL if <expr1> is equal to <expr2>.
• Otherwise, returns the value of <expr1>.

Examples

SELECT NULLIF(1, 1);

+--------------+
| NULLIF(1, 1) |
+--------------+
|         NULL |
+--------------+

SELECT NULLIF(1, 0);

+--------------+
| NULLIF(1, 0) |
+--------------+
|            1 |
+--------------+