Re: the two questions

From: David Cressey <cressey73_at_verizon.net>
Date: Sun, 25 Nov 2007 11:32:23 GMT
Message-ID: <b3d2j.8985$r81.5790_at_trndny05>


"Brian Selzer" <brian_at_selzer-software.com> wrote in message news:Dj92j.77429$Um6.17027_at_newssvr12.news.prodigy.net...
>
> "JOG" <jog_at_cs.nott.ac.uk> wrote in message
> news:8505d954-cdc3-4bf8-9107-b307563be0e8_at_r60g2000hsc.googlegroups.com...
> > On Nov 24, 12:38 am, vldm10 <vld..._at_yahoo.com> wrote:
> >> Not long time ago on this NG there were few posts which involved an
> >> entity with 200+ attributes.
> >> Let all these attributes satisfy the following two conditions:
> >> 1) All these attributes are mutually independent
> >
> > Then there are no functional dependencies so the entity can only be
> > identified by the collection of all its attributes - and hence you'd
> > end up with an equivalent superkey. If any of those attributes
> > "change" it would also therefore be a different entity altogether.
> >
>
> It cannot be determined whether two representations from two distinct
points
> in time refer to the same individual--even if all of the attribute values
> are identical--unless, of course, one of the attributes is a surrogate;

Do you mean "surrogate" or "synthetic" ? Received on Sun Nov 25 2007 - 12:32:23 CET

Original text of this message