From: Alvaro Herrera <alvherre@commandprompt.com>
To: Ray Madigan <ray@madigans.org>
Cc: Pgsql-Sql <pgsql-sql@postgresql.org>
Subject: Re: Select in From clause
Date: Fri, 9 Nov 2007 15:35:59 -0300
Message-ID: <20071109183559.GA7161@alvh.no-ip.org> (raw)
In-Reply-To: <IIEPJABILGOCODDLDNJFGENDCEAA.ray@madigans.org>
References: <IIEPJABILGOCODDLDNJFGENDCEAA.ray@madigans.org>
Ray Madigan wrote:
> I have never seen this done before, but it seems like it is supposed to work
> from reading the manual.
>
> I want to be able to get a table name from another table and use it in the
> from clause of a select.
>
> Something like
>
> SELECT * FROM (SELECT name FROM bar WHERE conditions) AS b WHERE b.condition
> = xxx;
>
> which translates to something like
>
> SELECT * FROM Dealer AS b WHERE b.zipcode = 12345;
No, that's not how it works. The stuff returned by the inner select is
a set of rows which can be further operated upon by the outer select.
It is not expanded into a table name.
One way to construct queries is to build plpgsql functions and use
EXECUTE. However, the approach you are using looks like bad practice
(read: bad database design).
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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To: pgsql-sql@postgresql.org
Cc: alvherre@commandprompt.com, ray@madigans.org
Subject: Re: Select in From clause
In-Reply-To: <20071109183559.GA7161@alvh.no-ip.org>
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