BruceM wrote:
I really don't know what you mean by "porting to MSDE".

By MSDE I mean SQL Server, the free version. The support for
constraints is IMO slightly worse than Jet 4.0 but what MSDE does have
that Jet doesn't is triggers. If there isn't a suitable constraint,
then a trigger may be employed (a bit like your Before Update, I
assume, but at the database level).

You can strongly discourage using
the front end for such purposes, but have not provided a reason why.

Suggested reading:

Mop the Floor and Fix the Leak, Part 1, by Joe Celko
http://www.dbazine.com/ofinterest/oi-articles/celko25