Re: Lucid statement of the MV vs RM position?
From: paul c <toledobythesea_at_oohay.ac>
Date: Fri, 05 May 2006 12:28:16 GMT
Message-ID: <AxH6g.126405$7a.65839_at_pd7tw1no>
>
>
> I can't parse the above, but as I read the GROUP definition, R GROUP ()
> AS RVA is equivalent to EXTEND R ADD TABLE_DEE AS RVA.
> ...
Date: Fri, 05 May 2006 12:28:16 GMT
Message-ID: <AxH6g.126405$7a.65839_at_pd7tw1no>
Jon Heggland wrote:
> paul c wrote:
>
>>Jon Heggland wrote: >> >>>Uh... If you group all the attributes in a relation, you get a relation >>>with a single attribute (the type of which is the same as of the >>>original relation) and a single tuple (containing the original >>>relation)? ... >> >>That's what I guessed. Also guess that when you group on none of them, >>the empty set is the identity attribute set for group.
>
>
> I can't parse the above, but as I read the GROUP definition, R GROUP ()
> AS RVA is equivalent to EXTEND R ADD TABLE_DEE AS RVA.
> ...
Oh, maybe this is a question for the authors. I thought it was equivalent to R JOIN TABLE_DEE and now that I think about it maybe I was wrong to say that group always implies a new FD.
p Received on Fri May 05 2006 - 14:28:16 CEST