Checking an input param if not Null and using it in where in SQL Server

sql-server sql-server-2008 null where-clause coalesce

You can use IsNull

 where some_column = IsNull(@yourvariable, 'valueifnull')

EDIT:

What you described in the comment can be done like:

where (@code is null or code = @code)

sql-server sql-server-2008 null where-clause coalesce

How about

WHERE (Column1 = @Var1 OR @Var1 IS NULL)AND (Column2 = @Var2 OR @Var2 IS NULL)

sql-server sql-server-2008 null where-clause coalesce

Here's another approach

SELECT * FROM Thingies WHERE ( @thingId IS NULL OR ThingID = @thingId )

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