Bob Badour wrote:
> Jon Heggland wrote:
>> "Every attribute" would also be a superkey (speaking loosely). The empty
>> set is a subset of every set.
>
> I respectfully suggest the confusion caused by your use of key without
> the 'candidate' qualification demonstrates exactly why we have the term.
> I suppose irreducible key would do just as well, but for historical
> reasons, candidate key already means an irreducible key.
I don't think the confusion is on my part. "Key" (as opposed to
"superkey") already implies irreducibility; that's the point of the
superkey/key distinction. A "candidate key" is certainly irreducible
(due to being a key), but "irreducible key" is redundant.
--
Jon
Received on Sat Jul 01 2006 - 12:24:43 CDT
