根据参数集从列表中选择不同的

I'm trying to get a distinct list of results, distinct based on user, where the selected result would be based on a set of parameters. To break it down, I have users, logs, and files. Each user can be on multiple logs and can have multiple files. Files CAN be associated with logs or not, and can also have a 'billing' flag set to true. What I'm trying to do when someone selects a log is bring up the list of files most closely associated with both the 'billing' flag and the log. I'm trying to get a distinct list of results, d