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Date: Sat, 25 Jan 2003 22:23:39 -0600
From: Bruno Wolff III <bruno@wolff.to>
To: jack <datactrl@tpg.com.au>
Cc: pgsql-sql@postgresql.org
Subject: Re: quastions about primary key
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On Sun, Jan 26, 2003 at 12:29:12 +1000,
  jack <datactrl@tpg.com.au> wrote:
> 
> 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?

I believe that the primary key is the default key for foreign key references
into a table.