Re: Constraints and Functional Dependencies

From: paul c <toledobythesea_at_oohay.ac>
Date: Sun, 25 Feb 2007 18:31:54 GMT
Message-ID: <uCkEh.1135954$5R2.741171_at_pd7urf3no>


paul c wrote:
> Marshall wrote:
>

>> ...
>> Hmmm. Can we express keyness otherwise? I can't think how.
>> ...

> ... I sometimes wonder whether an alternative concept or two,
> such as a variation on D&D's GROUP/UNGROUP operators might allow
> definition of keys without rename or your prime operator. ...

eg., if you GROUP the non-key attributes of R, I think the result will equal R in the most literal way if the remaining attributes constitute a key (maybe somebody will correct me if that's wrong).

p Received on Sun Feb 25 2007 - 19:31:54 CET

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