Re: Newbie question

On Mon, 20 Jun 2005 10:04:03 +0200, Jon Heggland <heggland_at_idi.ntnu.no> wrote:

>Off the top of my head, the main
>advantages of surrogate keys vs. natural keys are that they are stable
>(I.e. they don't change),

Why is this an advantage?

But most natural keys don't change.

> and they are never unknown.

Most natural keys are never unknown.

>(But that does not mean that you shouldn't record any natural key(s) as
>well, and designate them as keys, too. The distinction between
>"primary" and "alternate" keys really *is* bogus.)

It is out of the scope of the Relational Model.

>Anyway, many "real-world" keys are really surrogates---SSNs, account
>numbers, registration numbers, student numbers and so on.

And that is a reason for not creating new surrogates.

Regards Received on Mon Jun 20 2005 - 17:21:49 CEST