RE: FKs, UKs and PKs

From: Powell, Mark D <mark.powell_at_eds.com>
Date: Wed, 15 Nov 2006 09:35:35 -0500
Message-ID: <D1DC33E67722D54A93F05F702C99E2A9252AC5@usahm208.amer.corp.eds.com>

When the UK is built on a business value that needs to be carried in the child table and the PK of the parent is an artificial key is one situation where this may happen.

Mark D Powell -- Phone (313) 592-5148

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Charlotte Hammond Sent: Wednesday, November 15, 2006 6:57 AM To: oracle-l_at_freelists.org
Subject: FKs, UKs and PKs

Hi All,

I've got a quick Data modelling concepts question: Under what circumstances would you create a FK that points to a UK instead of the PK?

I can see how you can sometimes save a table join if the UK data is "meaningful" but the PK is a sequential id. But is this purely a denormalization technique or can such a FK->UK relationship exist in a normalized schema?

Thanks for any comments,
Charlotte