Re: noobie join question - Mailing list pgsql-general

On Mon, 2015-05-11 at 06:46 -0400, Steve Clark wrote:
> Hi List,
> I am having trouble trying to figure out
> how to get the result listed at the bottom.
>
> I have 3 tables units, types of units which has a description of the units,
> and a table that list associations of the units. I can't figure out
> how to do the proper joins. Any pointers would be appreciated.

SELECT  us.udevice, ts.descr, ud.udevice, td.descr
  FROM  assoc AS a
        LEFT JOIN units AS us
           ON a.src_id = us.uid
        LEFT JOIN types AS ts
           ON us.utype = ts.id
        LEFT JOIN units AS ud
           ON a.dest_id = ud.uid
        LEFT JOIN types AS td
           ON ud.utype = td.id;