Re: One-To-One Relationships

From: JOG <jog_at_cs.nott.ac.uk>
Date: Fri, 30 Nov 2007 11:06:16 -0800 (PST)
Message-ID: <35ace054-f42c-4f82-ae4e-ad033159fcc3_at_o6g2000hsd.googlegroups.com>


On Nov 30, 6:46 pm, paul c <toledobythe..._at_ooyah.ac> wrote:
> Tegiri Nenashi wrote:
> > On Nov 30, 8:19 am, Jan Hidders <hidd..._at_gmail.com> wrote:
> > The distinction between entities /
> >> relationships, domain objects / predicates is pretty well-established
> >> in linguistics, philosophy and logic.
>
> > That certainly means you can define them formally in database terms,
> > right?
> > Here is one such attempt:
> >http://arxiv.org/PS_cache/arxiv/pdf/0710/0710.2083v1.pdf
> > It defines an entity as a relation (aka table:-) with a single
> > noncomposite key, and relationship as a table with composite key. Does
> > this definition pretty much exhausts the entity-relationship theory?
>
> > (But then BB remark was that order line is a weak entity).
>
> If you are accurate that an entity depends on a relation, then I'd agree
> ER theory gets exhausted pretty quickly indeed.
>
> Not to encourage the literalists here but an ordinary dictionary
> definition of entity, eg.,
>
> "The existence of something considered apart from its properties."
>
> suggests even more directly how superfluous ER modeling is.

<check dictionary> entity = thing</check> er... ok...
<check dictionary_again> thing = entity</check> er....no.. hold on... Received on Fri Nov 30 2007 - 20:06:16 CET

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