Re: looking for old Datamation poster on Normalizing
From: Jon Heggland <jon.heggland_at_idi.ntnu.no>
Date: Mon, 28 Aug 2006 08:00:48 +0200
Message-ID: <ecu0qe$ds6$1_at_orkan.itea.ntnu.no>
Date: Mon, 28 Aug 2006 08:00:48 +0200
Message-ID: <ecu0qe$ds6$1_at_orkan.itea.ntnu.no>
[Quoted] David Cressey wrote:
> PMFJI. I've allways been disturbed by the presentation of 4NF in the
> "puppies & tricks" poster. It seems to me that there's a misprint,
> somewhere, or that the key of one of the tables has undergone a shift
> between the 3NF example and the 4NF example. Am I the only one who sees a
> problem, or has this been discussed before?
The keys (assuming /italics/ indicate keys) are wrong. It would make more sense if the key for the initial allegedly non-4NF "Puppy Tricks" were { Puppy Number, Trick ID, Costume }, and the the key for "Puppy Costumes" were { Puppy Number, Costume }, but the explanation is still bad. As presented, it looks more like an example of 2NF than 4NF.
-- JonReceived on Mon Aug 28 2006 - 08:00:48 CEST