Date: Fri, 19 Jan 2007 19:45:24 -0600
From: Bruno Wolff III <bruno@wolff.to>
To: mawrya <mawrya@furthernorth.net>
Cc: pgsql-sql@postgresql.org
Subject: Re: select based on multi-column primary keys
Message-ID: <20070120014524.GC30390@wolff.to>
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	mawrya <mawrya@furthernorth.net>, pgsql-sql@postgresql.org
References: <45B16602.2080508@furthernorth.net>
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On Fri, Jan 19, 2007 at 16:44:50 -0800,
  mawrya <mawrya@furthernorth.net> wrote:
> I have set up a table with a multi-column primary key constraint:
> 
> If I had a row in the table where systemid=123, enclosureid=ab, 
> pointid=56, I would have a Primary Key ("ID") of 123ab56 for that row.
> 
> I now want to run a select based on the Primary Key, something like:
> 
> SELECT * FROM iopoints WHERE ID = 123ab56
> 
> Is something like this even possible?  Or am I forced to do:
> 
> SELECT * FROM iopoints WHERE systemid=123 AND enclosureid=ab AND pointid=56

SELECT * FROM iopoints WHERE systemid=123 AND enclosureid='ab' AND pointid=56

While in theory you could concatenate the columns and test that against a
particular value, you probably don't want to do that. (If you do, use a
functional index.)