Provides an abbreviated CASE expression by comparing expressions.

Syntax

NULLIF( expression-1, expression-2 )

Parameters

Returns

Data type of the first argument.

Remarks

NULLIF compares the values of the two expressions.

If the first expression equals the second expression, NULLIF returns NULL.

If the first expression does not equal the second expression, or if the second expression is NULL, NULLIF returns the first expression.

The NULLIF function provides a short way to write some CASE expressions.

See also

• CASE expressions

Standards and compatibility

Example

The following statement returns the value a:

SELECT NULLIF( 'a', 'b' );

The following statement returns NULL.

SELECT NULLIF( 'a', 'a' );