Re: What kind of JOIN, if any?

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От Sam Mason
Тема Re: What kind of JOIN, if any?
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Msg-id 20090917152057.GO5407@samason.me.uk
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Ответ на What kind of JOIN, if any?  (Paul M Foster <paulf@quillandmouse.com>)
Ответы Re: What kind of JOIN, if any?  (Paul M Foster <paulf@quillandmouse.com>)
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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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