Re: Newbie question about db normalization theory: redundant keys OK?

From: Brian Selzer <>
Date: Fri, 21 Dec 2007 14:58:55 GMT
Message-ID: <PwQaj.297$>

"Anith Sen" <> wrote in message news:fkc110$b5k$
>>> I can't imagine saying to database users "Use updates if you mean that
>>> this particular individual already existed. Use other operators if you
>>> mean something else." I for one wouldn't want to have anything to do
>>> with such a DBMS!
> I am quite sure Brian had been told about the distinctions between
> external and internal predicates and how the distinction matters
> significantly while mapping a business representation to a logical model.
> For whatever reasons, he chooses not to heed. Fabian has an article
> somewhere in his site namely, "The desirable and the possible" that
> clarifies the distinction pretty well.

Under the domain closure, unique name and closed world assumptions, each term represents one and only one individual, and there are no other individuals. So existence can be determined independent of an interpretation. Identity can also be determined independent of an interpretation, as long as it is understood that each comparand will be assigned meaning under the same interpretation. It was also always intended that key values map to individuals, so in what way does advocating the use of delete to convey information that one or more individuals no longer exist, of update to convey information that the appearance of one or more individuals has changed or of insert to convey information that one or more individuals came into existence indicate that I don't understand the distinction between internal and external predicates?

> --
> Anith
Received on Fri Dec 21 2007 - 15:58:55 CET

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