Date: Wed, 12 May 2004 12:13:24 +0200 (CEST)
From: Christian Kratzer <ck@cksoft.de>
To: Jie Liang <jie@stbernard.com>
Cc: pgsql-admin@postgresql.org, pgsql-sql@postgresql.org
Subject: Re: [SQL] \set
In-Reply-To: <E7E213858379814A9AE48CA6754F5ECB36336D@mail01.stbernard.com>
Message-ID: <20040512120015.E61036@vesihiisi.cksoft.de>
References: <E7E213858379814A9AE48CA6754F5ECB36336D@mail01.stbernard.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed

Hi,

On Tue, 11 May 2004, Jie Liang wrote:

> Hi,
> How to use an internal variable?
> Original question was how to set a variable in postgresql?
> If I want to set a variable like start_date='2004-05-10';
> How could I use it in my SQL statement?
> E.g.
>
> Db> set start_date '2004-05-10'
> Db> select start_date as 'start date';
>
> It's not executable!

from doc/postgresql/html/sql-set.html

--snipp--
 	Synopsis

 	SET [ SESSION | LOCAL ] name { TO | = } { value | 'value' | DEFAULT }
 	SET [ SESSION | LOCAL ] TIME ZONE { timezone | LOCAL | DEFAULT }

 	...
 	...
 	...

 	name

 	    Name of a settable run-time parameter.
 	    Available parameters are documented in Section 16.4 and below. 
--snipp--

that is you can only use SET to change specific predefined parameters.
It does not say you could use SET to store other data local to the database
session.

As far as I know there are no session local variables in postgresql.
I could use something like this myself. The only workaround I know of 
to have data local to a session is to create a temporary table for the data.

There are local variables in plpgsql if you are just looking for local
variables.

Greetings
Christian

-- 
Christian Kratzer                       ck@cksoft.de
CK Software GmbH                        http://www.cksoft.de/
Phone: +49 7452 889 135                 Fax: +49 7452 889 136