Re: Artificial Primary keys
Date: Fri, 25 Jan 2002 15:58:35 +0100
Message-ID: <3C51729B.6030803_at_racon-linz.at>
Bernard Peek wrote:
> In message <3c505454$0$89112$edfadb0f_at_dspool01.news.tele.dk>, Jan Emil
> Larsen <jel_at_g-it.dk> writes
>
[snip]
>> 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.
>
> 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
> value.
Would you e.g. use the currency code as a natural key? It surely identifies one and only one currency!
But beware, it may change without further notice when someone (probably a lot of someones!) at ISO decides so.
Regards,
Heinz
Received on Fri Jan 25 2002 - 15:58:35 CET