Listing 3: NULLIF and ISNULL compared with CASE
DECLARE @expression1 INT;
DECLARE @expression2 INT;
SET @expression1 = 1;
SET @expression2 = 0;
 
--Example of NULLIF
SELECT NULLIF(@expression1,@expression2) Result;
SELECT CASE WHEN @expression1 = @expression2 THEN NULL ELSE @expression1 END Result;
 
--Example of ISNULL
SELECT ISNULL(@expression1,@expression2) Result;
SELECT CASE WHEN @expression1 IS NULL THEN @expression2 ELSE @expression1 END Result;