Re: atomic

From: paul c <>
Date: Fri, 02 Nov 2007 16:21:04 GMT
Message-ID: <Q7IWi.169342$th2.128561_at_pd7urf3no>

paul c wrote:
> Bob Badour wrote:

>> paul c wrote:

> ...
>>> I still wonder why one would want both tuples to apply to the same 
>>> pizza.
>> With your predicate, I doubt one would, which is why one would declare 
>> a candidate key that would reject the relation.

> I agree with that and with Roy H who I think has said the same thing.
> I ask myself how many ways could such a relation arise and the
> answer seems to be only one: because somebody defined it and populated
> it, eg., at least I don't think it could be produced with projection and
> group operators from some other relation(s). Not saying there isn't
> another way, just that I don't see one.
> ...

Oops again, I guess it's quite possible with UNION. (I had been deluding myself that relations of such a "form" were never a consequence of algebraic closure.) Received on Fri Nov 02 2007 - 17:21:04 CET

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