Bernard Peek wrote in
:

The primary key is *always* made up
of attributes in the underlying entity and this does not include
the autonumber field.

You're just restating the old natural key vs. surrogate question as
though there is a right answer to the question. There isn't. You may
*prefer* natural keys, but that's only a preference.

No defender of natural keys has ever been able to answer the
question of how you define a natural key for a table storing data
about people without populating the fields with useless default
values (to avoid the Null problem, i.e., PKs can't have Nulls in any
of the fields).

--
David W. Fenton http://www.dfenton.com/
usenet at dfenton dot com http://www.dfenton.com/DFA/