Re: Constraints and Functional Dependencies
Date: Sat, 24 Feb 2007 21:17:58 GMT
> "Marshall" <marshall.spight_at_gmail.com> wrote in message
> Nitpicking response: the above not only expresses the foreign key concept,
> but also referential integrity.
That may be right but I'm not sure. The reason is that when I search the web, I find Codd's Twelve Rules over and over again, but since the various quotes of the rules are different, I can't be sure what his original 1985 articles said. I looks to me as if people are mis-quoting Codd. I've always presumed he invented the term even though I don't see it in his first three famous papers.
I found one version
(http://www.nao.org.uk/intosai/edp/intoit_articles/18p60top62.pdf) that in rule 10 b, specifically says that referential integrity requires a "matching primary key". If this version quotes Codd accurately, then I would have to nitpick Walt's nitpick.
p Received on Sat Feb 24 2007 - 22:17:58 CET