Re: Why spurious tuples with fifth normal form?
From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Fri, 17 Jun 2005 19:22:58 GMT
Message-ID: <mqFse.123639$uh6.6996063_at_phobos.telenet-ops.be>
Date: Fri, 17 Jun 2005 19:22:58 GMT
Message-ID: <mqFse.123639$uh6.6996063_at_phobos.telenet-ops.be>
Ahem. *cough* Just checking if you guys were paying attention. :-)
Jan Hidders wrote:
>
> step 1. H = { ABC, ABD, CE }
> step 2. (#1) H = { ABCD, CE } (because ABC and ABC share the c.k. AB)
^^^
Should be "ABD"
> step 2. (#2) H = { ABCDE } (because ABCDE and CE share the c.k. C)
^^^^^
Should be "ABCD"
> step 3. no more two distinct components with common cand. key
> step 4. The JD is implied by the cand. keys because ABCDE is in H
>
> So even though this join dependency holds, you do not have to split.
That's still correct. :-)
- Jan Hidders