Re: object algebra
From: Eric Kaun <ekaun_at_yahoo.com>
Date: Thu, 26 Feb 2004 18:23:05 GMT
Message-ID: <dQq%b.50105$pV2.7103_at_newssvr33.news.prodigy.com>
Date: Thu, 26 Feb 2004 18:23:05 GMT
Message-ID: <dQq%b.50105$pV2.7103_at_newssvr33.news.prodigy.com>
"Neo" <neo55592_at_hotmail.com> wrote in message
news:4b45d3ad.0402251354.17d9d72f_at_posting.google.com...
> > I never heard any statement to the effect that Codd said NULLs
> > were *required.*
>
> C. J. Date's "An Introduction to Database Systems" 6th Edition.
> ISBN 0-201-54329-X
> Chapter 5, Section 5.6 - Nulls (A Digresssion), pg 123
>
> "Codd now regards nulls as an integral part of the relational model"
Yes, and it's obvious from context how critical Date is of that notion!
So we have some disagreement in the relational community, at least with Codd. However, Date is right, for the reasons in his book. Received on Thu Feb 26 2004 - 19:23:05 CET