Re: Database-valued attributes?

From: Paul Vernon <paul.vernon_at_ukk.ibmm.comm>
Date: Wed, 12 Nov 2003 10:46:19 -0000
Message-ID: <bot382$ops$1@gazette.almaden.ibm.com>

"Jonathan Leffler" <jleffler_at_earthlink.net> wrote in message news:cijsb.8002$nz.6409_at_newsread2.news.pas.earthlink.net...
> Paul Vernon wrote:
> > Q. Do D&D explicitly define what a possiable representaion is. I.e. is a
> > poss rep with more than 1 component a tuple of those components, or a
list,
> > a set, an array or just 'a thing with components'?
> >
> > E.g. would
> >
> > POSSREP XY_POINT { X NUMERIC, Y NUMERIC }
> >
> > be the same poss rep as
> >
> > POSSREP XY_POINT { Y NUMERIC, X NUMERIC }
> >
> > in thier book?
>
> Those would be the same, I'm sure. The attributes are identified by
> name, not position. See the Database Foundation Papers #3, IIRC, at
> dbdebunk.com.

OK. So possible representations are really rather like tuple types. Personally, I can't see why we can't define them as such. I guess Bob will tell me why not. ;-)

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Wed Nov 12 2003 - 04:46:19 CST