To add to Cindy's response, the reason you need to do this with 2 queries instead of one, is that a UNION is a combination of 2 queries in one statement, each of which can have its own GROUP BY clause. So, you can't take the results and get a single value for each combination of Custno, Column2 and Column3 unless you join the results of both queries first, and then group them in a second query.