I'm a self taught beginner and, with a lot of luck, I've managed to build a db to schedule classes, rooms, and students. But I'm stuck on ensuring students aren't double booked. I assigned a code to all my available time slots, so I can't double book the room, and I have a sub form on my Classes form so that I can see the Instructors schedule. I also have it that a student can't be scheduled for the same class twice. But my mushy brain can't figure out how to get an error message if the student is already scheduled for a session at 8 on Monday. I have to go to the form with the student's schedule. Help - I'm melting!