Didn't we already have this discussion? Is this not a repetition of this earlier thread?

I am under the impression that either you are describing something incorrectly or your design is flawed. I pointed that out in the previous post and you never answered. This whole thing sounds like a variation on a lease. A person "leases" a locker for a term, and has a lock which has a combination. If the locks can be removed and have serial numbers, assigning locks to lockers is child's play.

What's the problem? Why would you need to update all 3 tables? sounds like improper normalization - a piece of information belongs in exactly ONE table. How is this scenario different?