From: Gregory Stark <stark@enterprisedb.com>
To: pgsql-sql@postgresql.org
Subject: Re: is there a 'table' data type in pg?
In-Reply-To: <20070724124246.GA22602@apartia.fr> (Louis-David Mitterrand's
	message of "Tue, 24 Jul 2007 14:42:46 +0200")
Organization: EnterpriseDB
References: <20070724124246.GA22602@apartia.fr>
Date: Tue, 24 Jul 2007 15:10:44 +0100
Message-ID: <87sl7d28pn.fsf@oxford.xeocode.com>
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"Louis-David Mitterrand" <vindex+lists-pgsql-sql@apartia.org> writes:

> Can I use a another column to store the type of the id_subject (ie: the 
> tabled it belongs to) ? Then I would be able to query that table for 
> additional info to print alongside the forum posts.

There are ways to identifier tables in Postgres but there's no way to run a
query against a table using them.

I would strongly recommend you define your own list of "object_types",
probably even have an object_type table with a primary key, a description
column, and a table_name column. Then you can in your application construct
the appropriate query depending on the object_type. 

One alternative you could do is have a set-returning plpgsql function which
has a big if statement and performs the right kind of query. I think the
records would have to all be the same -- they can't be different kinds of
records depending on the type of object.

-- 
  Gregory Stark
  EnterpriseDB          http://www.enterprisedb.com