You need to return NULL only if the value of your data is a certain value. How do you do this? There are three different ways. NULLIFDECLARE @1 char(1)SELECT @1 ='D' SELECT NULLIF(@1,'D')REPLACEThis should not really be used, I just added it here to demonstrate that you can in fact use it.DECLARE @1 char(1)SELECT @1 ='D' SELECT ...