Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: What is the use of a primary key?

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@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 - 05:57:34 CST

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US