If I am understanding you correctly, you are looking for a way to determine what systems do not have a particular file, and when you are doing your query, you are getting just about everything including the systems that have the file because there are tons of other files stored that are not the file you are looking at. Not being especially SQL savvy, I would just create a query that returns computers having the file. Then I create query that returns all computers not in the list of computers in the first query. This is most easily done (for me) by applying the first query to a collection, then basing another collection on computers that are not a member of the first collection. Hopefully I helped and did not just confuse you more.