Re: quastions about primary key

I try use uique instead of primary key. And it works, it allows null values.
Is there any other difference between primary key and unique?

Jack
----- Original Message -----
From: "Stephan Szabo" <sszabo@megazone23.bigpanda.com>
To: "jack" <datactrl@tpg.com.au>
Cc: <pgsql-sql@postgresql.org>
Sent: Saturday, January 25, 2003 1:14 AM
Subject: Re: [SQL] quastions about primary key


> On Fri, 24 Jan 2003, jack wrote:
>
> > Is that possible to have a two columns primary key on a table with null
> > value on second column?
>
> No, because primary key implies not null on all columns involved
> (technically I think it's that a non-deferrable primary key implies
> not null on all columns involved, but we don't support deferrable ones)
>
>