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On Mon, 26 Nov 2007 10:11:37 -0800
Steve Crawford <scrawford@xxxxxxxxxxxxxxxxxxxx> wrote:
> Although I haven't seen it much, recently, semi-trucks used to
> regularly have with numerous plates - one for each state in which
> they operated. And some states such as Texas allow you to have the
> same amateur-radio plate number on multiple vehicles.
>
> I won't argue that there are no reasonable natural keys. But I have
> sure seen plenty of cases where what appeared to be a natural key was
> discovered, generally at a very inopportune time in the development
> process, to be not-so-natural after all.
In "theory" the item that would be a natural key in this instance is
the VIN. You would of course have to make some kind of allowance for
cars that don't have a VIN (nothing in the last what... 50 years?).
Joshua D. Drake
>
> Cheers,
> Steve
>
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