Re: referential intergrity

From: James Petts <jpetts_at_celltech.co.uk>
Date: 1998/03/05
Message-ID: <34feb980.283815019@firewall.celltech>#1/1

On Thu, 5 Mar 1998 05:16:48 -0500, Tong Zhai <tzhai_at_expert.cc.purdue.edu> wrote:

>Hi, all:
> we are setting up a db, one of the table is works_on, and the primary key
>for that table are composite of project_number and Employee_ssn, so by
>definition they can't be null, but if I do want to insert a record with
>null project_number, how can I do that ?

You can't. Components of a primary key must ALL be non-null. As long as the primary key constraint is enabled, you will not be able to put a null in any column which forms part of the primary key. James "I'd rather fall off Ilustrada than ride any other horse!" Petts Received on Thu Mar 05 1998 - 00:00:00 CST