Re: a union is always a join!

From: rpost <>
Date: Mon, 23 Mar 2009 18:09:04 +0000 (UTC)
Message-ID: <gq8j80$23q5$>

>> Yes, but what I meant to say is that in general, the tuples
>> don't really express facts regarding those domain values,
>> they just help express information about other domain values.
>Tuples do not express facts about domain values. They contain domain


True, I didn't express myself clearly enough.

But I don't need your lecturing. My point is that in a relational database, the tuples of a relation often correspond not just to the propositions of an associated predicate, but to observations; explicitly asserted, rather than derived information. To propositional logic, it's all the same, of course.

Received on Mon Mar 23 2009 - 19:09:04 CET

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