The NULLIF function tests to see if the first expression is equal to the second expression, and returns the first expression if they are not equal and NULL if they are equal.

This function returns the same datatype as the first expression, or NULL if the two expressions are equal.

NULLIF( expression_1, expression_2 )

Required. An expression using SQL language that produces a value. A scalar expression is generally equivalent to a select item in the SQL SELECT statement, and can be a character expression, numeric expression or date expression.

> select NULLIF(name, individual) identifier from individuals;

IDENTIFIER
--------------------------------------------------
MS. MARY LEWIS
MRS. ALICE R TOLLIVER
MR. SIDNEY K TOLLIVER
MRS. JENNIFER J HOPKINS
MR. CHARLIE HOPKINS
MS. KIMBERLY BLUE
KATHLEEN TUCKER

See also: