SQL Server - "IS NULL" - Testing NULL Values in SQL Server

From previous tutorials, you learned that comparing expressions with NULL will always result NULL. So you can not use comparison operators to test if an expression represents a NULL value or not.

To test expressions for NULL values, you should use one of the following special operators:

expression IS NULL 
-- Returns TRUE if the expression is a NULL value

expression IS NOT NULL
-- Returns TRUE if the expression is not a NULL value

The tutorial script below shows you how to use IS NULL and IS NOT NULL:

IF 0 IS NULL PRINT 'TRUE'
ELSE PRINT 'FALSE';
GO
FALSE

IF NULL IS NULL PRINT 'TRUE'
ELSE PRINT 'FALSE';
GO
TRUE

IF 1+NULL IS NULL PRINT 'TRUE'
ELSE PRINT 'FALSE';
GO
TRUE

IF 'NULL' IS NOT NULL PRINT 'TRUE'
ELSE PRINT 'FALSE';
GO
TRUE

⇒Working with NULL Values in SQL Server Transact-SQL

⇒⇒SQL Server Transact-SQL Tutorials

2017-02-03, 277👍, 0💬