RE: Unique or Primary Key?

> > 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