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NULLIF() Function in SQL Server
  • Last Updated : 21 Jan, 2021

NULLIF() :

This function in SQL Server is used to check if the two specified expressions are equal or not.

Features :

  • This function is used to check if the two given expressions are equal or not.
  • This function returns NULL if the given two expressions are equal.
  • This function returns the first expression if the two given expressions are not equal.
  • This function comes under Advanced Functions.
  • This function accepts two parameters i.e, the first expression, and the second expression.

Syntax :

NULLIF(expr1, expr2)

Parameter :



This method accepts two parameters.

  • expr1, expr2 – Specified expressions that are to be compared.

Returns :

It returns NULL if the given two expressions are equal else it returns the first expression if the two given expressions are not equal.

Example-1 :

Using the NULLIF() function and getting the output.

SELECT NULLIF(11, 11);

Output :

NULL

Here, NULL is returned as both the expressions are equal.

Example-2 :



Using the NULLIF() function and getting the output.

SELECT NULLIF('ab', 'abc');

Output :

ab

Here, ‘ab’ is returned as output as the stated expressions are not equal.

Example-3 :

Using NULLIF() function and getting the output using variables.

DECLARE @exp1 VARCHAR(50);
DECLARE @exp2 VARCHAR(50);
SET @exp1 = '2021/01/08';
SET @exp2 = '2021/01/08';
SELECT NULLIF(@exp1, @exp2);

Output :

NULL

Example-4 :

Using NULLIF() function and getting the output using CAST() function.

SELECT NULLIF(11, CAST(11.65 AS int));

Output :

NULL

Application :

This function is used to test if the two stated expressions are equal or not.

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