Re: erd to db
Date: Wed, 27 Mar 2002 21:37:10 -0800
Message-ID: <jIxo8.151$pV.127451_at_news.uswest.net>
"Jan Hidders" <hidders_at_uia.ua.ac.be> wrote in message
news:3c9f223a$1_at_news.uia.ac.be...
> "Daniel Guntermann" <guntermann_at_uswest.net> wrote in message
> news:Fa_m8.6$JN1.10619_at_news.uswest.net...
> >
> > "Jan Hidders" <hidders_at_uia.ua.ac.be> wrote in message
> > news:3c9af4b6$1_at_news.uia.ac.be...
Jan,
Having had a chance to reread your reply (below), I would have to entirely agree with you in your assertion that a line should be drawn between 'data modeling', and relational databases/ the relational model. It's clear, at least in my opinion, that a data model should be flexible enough to be *manifested* or *implemented* in a wide range of systems, whether it be relational, inverted list, hierarchical, network, or anything else out there (not to leave OO out).
Sorry for misunderstanding the first time.
In regards to shivers down your spine when others reference a primay key in association with an entity, I defer to section 2.3.1, entitled Primary Keys, in Peter Chen's, "The Entity-Relationship Model -- Toward a Unified Model of Data."
> I beg to differ. It is not true that a relationship *is* or *can be* a
> relation. What is true is that it *can be implemented* or *modeled* as a
> table. The most important reason that we are in this terminology-mess is
> that many people mix the terms of ER modelling and the relational model.
The
> two should be kept apart. Every time I hear people talk about the primary
> key of an entity type, it sends shivers down my spine. These people don't
> seem to understand why Codd introduced the notion of primary key (as
opposed
> to candidate key) in the first place.
>
> Kind regards,
>
> -- Jan Hidders
> > >Received on Thu Mar 28 2002 - 06:37:10 CET