Re: What is the use of a primary key?
From: Lauri Pietarinen <lauri.pietarinen_at_atbusiness.com>
Date: Thu, 21 Nov 2002 13:57:34 +0200
Message-ID: <3DDCCA2E.5030505_at_atbusiness.com>
Date: Thu, 21 Nov 2002 13:57:34 +0200
Message-ID: <3DDCCA2E.5030505_at_atbusiness.com>
That's a good question, and my unerstanding is that there is no "theoretical" reason for choosing one of the candidate keys as primary. The main reason is - I quess - that this is how it has been always done.
Maybe it is also clearer that all foreign key references are done to the same key.
regards,
Lauri Pietarinen
Juan Pardillos wrote:
>Hi,
>
>I've got the following doubt: why is necessary to define a primary
>key?. I mean, the candidate keys must be defined as not null and
>unique (just the same that with the primary key), so... what's the
>difference?. Why is it necessary to consider a primary key instead of
>simply defining a set of candidate keys?.
>
>Thanks
>
>
Received on Thu Nov 21 2002 - 12:57:34 CET