How To Assign NULL Values to Variables or Columns in SQL Server Transact-SQL?

The rule for assigning NULL values to variables or table columns is simple: Use keyword "NULL" directly as normal values.

• "NULL" can be used in SET statements to assign NULL values to variables.
• "NULL" can be used in SET clauses in UPDATE statements.
• "NULL" can be used in value lists in INSERT statements.
• "NULL" can be used in parameter lists when calling stored procedures or functions.

The tutorial script below gives you some good examples:

USE FyiCenterData;
GO

-- assign NULL values to variables
DECLARE @birth_date DATETIME;
SET @birth_date = NULL;
SELECT @birth_date;
GO
-----------------------
NULL

-- assign NULL values to columns
UPDATE fyi_links SET notes = NULL;
GO
(8 row(s) affected)

-- assign NULL values to parameters
EXEC sp_help NULL;
GO
Name            
----------------
fyi_links_dump  
fyi_links_top   
fyi_links_view  
...

⇒Working with NULL Values in SQL Server Transact-SQL

⇒⇒SQL Server Transact-SQL Tutorials