Re: atomic
From: paul c <toledobythesea_at_ooyah.ac>
Date: Fri, 02 Nov 2007 16:07:46 GMT
Message-ID: <mXHWi.169333$th2.86331_at_pd7urf3no>
>
> With your predicate, I doubt one would, which is why one would declare a
> candidate key that would reject the relation.
Date: Fri, 02 Nov 2007 16:07:46 GMT
Message-ID: <mXHWi.169333$th2.86331_at_pd7urf3no>
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.
So for the examples so far, it seems that even if they aren't contradictory according to theory, I'd say they are at least a bit wacky as far as their predicates are concerned, unless a primary key is specified that doesn't include the "set" or RVA attributes. Received on Fri Nov 02 2007 - 17:07:46 CET