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@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 - 07:28:16 CDT