Re: Return LEFT JOINed tables when one has no matching column

From: Harald Fuchs <hari(dot)fuchs(at)gmail(dot)com>
To: pgsql-general(at)postgresql(dot)org
Subject: Re: Return LEFT JOINed tables when one has no matching column
Date: 2009-06-24 17:46:03
Message-ID: pueit91q5g.fsf@srv.protecting.net
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In article <4A425379(dot)90907(at)alteeve(dot)com>,
Madison Kelly <linux(at)alteeve(dot)com> writes:

> SELECT
> a.tbl1_name,
> b.tbl2_date,
> c.tbl3_value AS some_value
> FROM
> table_1 a
> LEFT JOIN
> table_2 b ON (a.tbl1_id=b.tbl2_tbl1_id)
> LEFT JOIN
> table_3 c ON (a.tbl1_id=c.tbl3_tbl1_id)
> WHERE
> c.tbl3_variable='some_variable'
> AND
> a.tbl1_id=123;

> I want the data from table_1 and table_2 to return and table_3 to
> return NULL when there is no matching
> c.tbl3_variable='some_variable'. Is this possible?

Move "c.tbl3_variable='some_variable'" from WHERE to c's ON clause.

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