Re: What kind of JOIN, if any?

From: Sam Mason <sam(at)samason(dot)me(dot)uk>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: What kind of JOIN, if any?
Date: 2009-09-17 15:20:57
Message-ID: 20090917152057.GO5407@samason.me.uk
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On Thu, Sep 17, 2009 at 10:29:11AM -0400, Paul M Foster wrote:
> I want all the records of the
> url table, one row for each record, plus the userid field that goes with
> it, for a specified user (paulf), with NULLs as needed

Maybe something like this?

SELECT a.userid, u.url
FROM urls u
LEFT JOIN access a ON u.id = a.url_id AND a.userid = 'paulf';

> I can do *part* of this with various JOINs, but the moment I specify
> userid = 'paulf', I don't get the rows with NULLs.

I guess you were putting "userid = 'paulf'" into the WHERE clause,
that's the wrong place. It needs to be up in the ON clause.

--
Sam http://samason.me.uk/

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