duplicate based between time(s)

[NPUser]

I designed simple resource scheduling database. All the aspects of scheduling work, except duplicates (overlap) management. How do i prevent duplicate entry based upon TimeOUT and TimeIN values. Here is my table structure:

Please advise this poor "STUCK" soul. Thanks in advance.


tbl_resch_schedule

scheduleID UserID ReschID date TimeOut TimeIN
1 23 10 11/20/04 10:00AM 11:00AM
2 23 10 11/20/04 11:30Am 12:20PM