From: | Joel Burton <jburton(at)scw(dot)org> |
---|---|
To: | Christian Marschalek <cm(at)chello(dot)at> |
Cc: | "'Bruce Richardson'" <pgsql(at)itsbruce(dot)uklinux(dot)net>, "[GENERAL] PostgreSQL" <pgsql-general(at)postgresql(dot)org> |
Subject: | RE: Unique or Primary Key? |
Date: | 2001-05-03 20:49:46 |
Message-ID: | Pine.LNX.4.21.0105031648200.8245-100000@olympus.scw.org |
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Thread: | |
Lists: | pgsql-general |
> > Besides, I couldn't see much use in creating it as a primary
> > key. How
> > would I ever reference it from another table?
If you're questioning how to use a multi-field primary key, it's easy...
create table p (id1 int not null, id2 int not null, primary key(id1,
id2));
create table c (id1 int, id2 int, foreign key (id1, id2) references p);
insert into p values (1,2);
insert into c values (1,1);
insert into c values (1,0);
ERROR: <unnamed> referential integrity violation - key referenced from c
not found in p
--
Joel Burton <jburton(at)scw(dot)org>
Director of Information Systems, Support Center of Washington
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