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Date: Sun, 2 Apr 2006 21:57:22 -0600
From: Michael Fuhr <mike@fuhr.org>
To: Paul M Foster <paulf@quillandmouse.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: References NULL field
Message-ID: <20060403035722.GA48847@winnie.fuhr.org>
References: <443099E6.3070101@quillandmouse.com>
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On Sun, Apr 02, 2006 at 11:43:34PM -0400, Paul M Foster wrote:
> I want to do a query (in PHP, FWIW) that returns all the fields in
> registrars, and the contents of any relevant notes records, or null for
> those fields if there is no corresponding record in the notes table. But
> when I do
> 
> SELECT * FROM registrars, notes WHERE regname = 'blah'
> 
> no matter that I put after the 'blah' (or nothing), I get no results. As
> soon as I add notes into the tables being queried, I get nothing.

The above query does a cross (cartesian) join of registrars and
notes.  Since notes is empty the join result is empty.  Try an
outer join:

SELECT *
FROM registrars LEFT OUTER JOIN notes USING (note_id)
WHERE regname = 'blah';

-- 
Michael Fuhr