Re: Artificial Primary keys

From: Jan Emil Larsen <>
Date: Thu, 24 Jan 2002 19:37:46 +0100
Message-ID: <3c505454$0$89112$>

"Bernard Peek" <> skrev i en meddelelse news:1RWc$oFw4BU8Ew$$
> In message <3c4f3e5e$0$13976$>, Jan Emil
> Larsen <> writes
> >A key should be imutable, and should therefore be without information in
> >self.
> The first is true but the second doesn't follow from it.

That is right. I goes the other way round: If it has information in it self, it may change.
No-information in the key is a measure to secure immutability.

>You should
> definitely try as hard as you can to have an immutable primary key but
> where possible it should be immutable because the data in it really does
> identify one and only one thing.

Agreed. A key should identify one and only one thing (an entity; or the table at BCNF)

>It's only when you don't have such a
> key that you need an artificial one.

Yes, but that happens quite often. Received on Thu Jan 24 2002 - 19:37:46 CET

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