Re: enforcing uniqueness across tables

[paul denny]

Many thanks for the helpful replies.

Am I correct in thinking that Peter's reply would not prevent the database from inserting stock simultaneously into repair and customer and furthermore that this is the usual approach to this sort of situation? Hence, per Rick, I'd need to enforce this in the applications that do the CRUD work?

I can do that, but thought that it was best practice to enforce business logic in the database itself. Is that not possible in this instance?

Thank you for your patience with this beginner - Paul