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Re: Primary and Foreign Key?

From: "Wayne Unruh" <waynepunruh(at)hotmail(dot)com>
To: abanks(at)insightbb(dot)com, pgsql-novice(at)postgresql(dot)org
Subject: Re: Primary and Foreign Key?
Date: 2005-09-24 06:45:45
Message-ID: BAY106-F12E52354080C494806E050AF890@phx.gbl (view raw or flat)
Thread:
Lists: pgsql-novice
In relational databases  A table can have at most one primary key.  However, 
you are not required to have a primary key, so I would just have the two 
foreign keys in the table PEOPLEGROUPS.

For more information on Constraints see
http://www.postgresql.org/docs/8.0/interactive/ddl-constraints.html

Wayne Unruh

From : 	A. Banks <abanks(at)insightbb(dot)com>
Sent : 	Wednesday, September 21, 2005 8:46 PM
To : 	<pgsql-novice(at)postgresql(dot)org>
Subject : 	[NOVICE] Primary and Foreign Key?



I have the following related tables:

PEOPLE
--------------
peopleid pkey,
name,
etc


GROUPS
-------------
groupid pkey,
description,
etc


PEOPLEGROUPS
-------------------
peopleid pkey/fkey,
groupid pkey/fkey


What is the CORRECT way (in Postgres) to define the PEOPLEGROUPS table so
that it has both the double primary key AND still acts as a foreign key for
people.peopleid and groups.groupid? Can i specify both or is this not
necessary? Any suggestions would be appreciated.

Thanks!



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