"IS NULL" - Testing NULL Values in SQL Server
Q
How To Test NULL Values Properly in SQL Server Transact-SQL?
✍: FYIcenter.com
A
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
⇒ ISNULL() - Replacing NULL Values in Expressions in SQL Server
⇐ NULL Values Involved in Boolean Operations in SQL Server
2017-02-03, 3250🔥, 0💬
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