Re: Artificial Primary keys

In message <3c5bc52a$0$211$edfadb0f_at_dspool01.news.tele.dk>, Jan Emil Larsen <jel_at_g-it.dk> writes
>
>"John Doherty" <jdoherty_at_null.com> skrev i en meddelelse
>news:jdoherty-0102021610350001_at_192.168.2.9...
>> In article <3c5186c2$0$14015$edfadb0f_at_dspool01.news.tele.dk>, "Jan Emil
>> Larsen" <jel-nospam_at_g-it.dk> wrote:
>>
>> > Or could you give an example - that is: of a natural key that holds
>> > information, but is immutable?
>>
>> An ISBN.
>
>Is that a natural key?

No, it's artificial. There's an arbitrary coding scheme that links the numeric values in the ISBN to real-world data. There's no inherent connection between the number 56592 and the publisher it identifies.

-- 
Bernard Peek
bap_at_shrdlu.com

In search of cognoscenti