Re: Primary key

From: Sybrand Bakker <postbus_at_sybrandb.demon.nl>
Date: Wed, 23 Aug 2000 15:17:34 +0200
Message-ID: <967069137.21340.1.pluto.d4ee154e@news.demon.nl>

Each table has one and only one primary key (as per relational database concepts). So you can't just have *another* primary key. You can of course extent the current primary key (by dropping and recreating it).

Regards,

Sybrand Bakker, Oracle DBA

"Lim Chin Yee" <ccelimcy_at_nus.edu.sg> wrote in message news:3447D7F0AFD4D011AE0400608C14CE561F3C638D_at_pfs01.ex.nus.edu.sg...
> Table A's primary key is made up of 2 fields( fieldx and fieldy)
> If i were to add in a new field(fieldz) and make it a primary key as
> well,
> what are the consequences?
>
> consequences that i've thought of.
> 1. since fieldz is of null value, existing data cannot be validated
> since the constraints cannot work.
>
>
>
> p.s: all 3 fields shld be NON-NULL
>
> TIA
>
Received on Wed Aug 23 2000 - 08:17:34 CDT