Re: ER Diagram
From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: 2 Dec 2002 03:46:02 -0800
Message-ID: <a20d28ee.0212020346.41750ca5_at_posting.google.com>
Date: 2 Dec 2002 03:46:02 -0800
Message-ID: <a20d28ee.0212020346.41750ca5_at_posting.google.com>
"aa" <aa_at_aa.com> wrote in message news:<asf36v$ikd30_at_imsp212.netvigator.com>...
> .....hello..................
>
> i want to ask about ER Diagram...........
>
> Question:
> 1. Each entity must have one foreign key or not?
Not necessarily. Dept in the scott schema doesn't have foreign keys, and it is only referred to. Each entity *must* have a *primary* key though, to enforce uniqueness.
Hth
Sybrand Bakker
Senior Oracle DBA
Received on Mon Dec 02 2002 - 12:46:02 CET