Re: many to many relationship
Date: Fri, 7 Mar 2003 09:19:20 -0500
Message-ID: <b4a9p3$1tdad9$1_at_ID-114862.news.dfncis.de>
Don't confuse the conceptual model (ERD) with the physical model (realtional schema). An ERD models the business. It then gets translated into a physical model, which represents the implemented tables in a database.
If the business is modeled properly, and the proper mapping (translation) is done (and there _are_ rules to follow), then the resulting relational schema is almost always (99.9% of the time) in 3NF.
"Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message
news:b478s6$1h5m$2_at_sp15at20.hursley.ibm.com...
> All of which is an argument against the usefulness of the ER model's
> many-to-many relationships idea. In this case, was the ER model clearer
> without an explicit 'enrollement' entity?
>
> Regards
> Paul Vernon
> Business Intelligence, IBM Global Services
>
>
Received on Fri Mar 07 2003 - 15:19:20 CET