Re: Base Normal Form
From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Tue, 12 Jul 2005 21:28:30 GMT
Message-ID: <2CWAe.143408$aP1.7605303_at_phobos.telenet-ops.be>
> ABanything->C (as in ABD->C),
Date: Tue, 12 Jul 2005 21:28:30 GMT
Message-ID: <2CWAe.143408$aP1.7605303_at_phobos.telenet-ops.be>
Gene Wirchenko wrote:
> On Fri, 08 Jul 2005 22:42:27 GMT, Jan Hidders
> <jan.hidders_at_REMOVETHIS.pandora.be> wrote:
>
> [snip]
>
>
>>Note by the way that the link between functional dependencies and >>interpreting relations as functions is very close. If the relation >>R(A,B,C,D,E) has the dependencies AB->C and BD->E and ABD->C the I >>wouldn't say it represents a function, I would say it represents three >>functions.> there is an error or something questionable. If AB->C then
>
> I struggle to follow these arguments. In the above, I think that
> ABanything->C (as in ABD->C),
Yes, well observed, the FD ABC->C is redundant.
A relation can sometimes represent several functions, not just one.
- Jan Hidders