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Date: Tue, 4 Oct 2005 17:34:50 -0500
From: "Jim C. Nasby" <jnasby@pervasive.com>
To: Matt Emmerton <matt@gsicomp.on.ca>
Cc: Russell Simpkins <russellsimpkins@hotmail.com>,
	pgsql-sql@postgresql.org
Subject: Re: Help with multistage query
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On Wed, Sep 07, 2005 at 05:37:47PM -0400, Matt Emmerton wrote:
> 
>   ----- Original Message ----- 
>   From: Russell Simpkins 
>   To: pgsql-sql@postgresql.org 
>   Sent: Wednesday, September 07, 2005 4:05 PM
>   Subject: Re: [SQL] Help with multistage query
> 
>     I have a perl script that issues a series of SQL statements to perform some queries.  The script works, but I believe there must be a more elegant way to do this.
> 
> 
> 
>     The simplified queries look like this:
> 
> 
> 
>     SELECT id FROM t1 WHERE condition1;   ;returns about 2k records which are stored in @idarray
> 
> 
> 
>     foreach $id (@idarray) {
> 
>        SELECT x FROM t2 WHERE id=$id;   ; each select returns about 100 records which are saved in a perl variable
> 
>     }
> 
>   how about 
>   select t1.id from t1, t2 where t1.id = t2.id and t2.id = x
> 
> or more correctly, based on the OP's example:
> 
> select t2.x from t1, t2 where t1.id = t2.id and t1.id = <condition>

Actually, I think you want AND t2.x <condition>, not t1.id.

BTW, I recommend not using id as a bareword field name. Very easy to get
confused when you start joining a bunch of stuff together.
-- 
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461