Re: Artificial Primary keys

"Bernard Peek" <bap_at_shrdlu.com> skrev i en meddelelse news:EfHws0Dzu+V8EwB8_at_shrdlu.com...
> In message <a35l0g$a5k$1_at_news.net.uni-c.dk>, Jan Emil Larsen
> <jel_at_g-it.dk> writes
>
>
>
> >> Correct. It stems from the definition of a key.
> >A (primary) key is a (combination of) attribute(s) that uniquely
identifies
> >an object (or a row in an RDB).
>
> The dependency works both ways. The value of the key is dependent on the
> object. If the object does not change then the key should also be
> unchanging. I am excluding the pathological condition where the data has
> been recorded incorrectly.

 Ok, but that "pathological condition" is quite common in real life, especially if the key is complicated ....

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>> Correct. It stems from the definition of a key.
 >Do you have an reference for your definition? Received on Fri Feb 01 2002 - 14:03:00 CET