Re: Artificial Primary keys
Date: Wed, 23 Jan 2002 23:51:47 +0100
"--CELKO--" <71062.1056_at_compuserve.com> skrev i en meddelelse
> ... How do you know that number 123 is
> really "John Smith" and pay salaries and taxes to him? Did you put
> him in the database twice? Did someone else get his number? Who
> knows? With SSN, which you have to have anyway, you can verify it
> with other documents and the tax boys.
In the same way as he knows that "John Smith" is "John Smith", and has this
SNN, that Address etc.
He has one or more (near) candidate keys (eg SSN) with unique indices if possible and useful.
A surrogate (artificial) key doesn't rule out the use of natural candidate keys in the communication etc. with the users. I guaranties that he can handle even a person with none or unknown SSN.
A key should be imutable, and should therefore be without information in it
Skip the start-date as part of the key. Received on Wed Jan 23 2002 - 23:51:47 CET