Re: Artificial Primary keys
Date: Fri, 25 Jan 2002 17:25:13 +0100
"Bernard Peek" <bap_at_shrdlu.com> skrev i en meddelelse
> In message <3c505454$0$89112$edfadb0f_at_dspool01.news.tele.dk>, Jan Emil
> Larsen <jel_at_g-it.dk> writes
> >"Bernard Peek" <bap_at_shrdlu.com> skrev i en meddelelse
> >> In message <3c4f3e5e$0$13976$edfadb0f_at_dspool01.news.tele.dk>, Jan Emil
> >> Larsen <jel_at_g-it.dk> writes
> >> >A key should be imutable, and should therefore be without information
> >> >self.
> >> The first is true but the second doesn't follow from it.
> >That is right. It goes the other way round: If it has information in it
> >it may change.
> >No-information in the key is a measure to secure immutability.
> No, that's still not right. Immutability is important but artificial
> keys are not the only way to get it. If you have a natural key that
> truly identifies one and only one thing then it is immutable. If it
> changes then either it wasn't a real key or someone recorded the wrong
Or could you give an example - that is: of a natural key that holds information, but is immutable? Received on Fri Jan 25 2002 - 17:25:13 CET