From: msi77 <msi77@yandex.ru>
To: Neil Stlyz <neilstylz@yahoo.com>,pgsql-sql@postgresql.org
In-Reply-To: <995516.81823.qm@web113717.mail.gq1.yahoo.com>
References: <995516.81823.qm@web113717.mail.gq1.yahoo.com>
Subject: Re: combine SQL SELECT statements into one
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Message-Id: <37481265019051@webmail107.yandex.ru>
Date: Mon, 01 Feb 2010 13:10:51 +0300
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Hi,

SELECT
(SELECT COUNT(distinct model) FROM inventory WHERE modified >= '2010-02-01') as count1,
(SELECT COUNT(distinct model) FROM inventory WHERE modified >= '2010-01-20') as count2,
(SELECT COUNT(distinct model) FROM inventory WHERE modified >= '2010-01-01') as count3

Serge

> Good Evening, Good Morning Wherever you are whenever you may be reading this. 
> I am new to this email group and have some good experience with SQL and PostgreSQL database. 
> I am currently working on a PHP / PostgreSQL project and I came upon something I could not figure out in SQL. I was wondering if anyone here could take a look and perhaps offer some guidance or assistance in helping me write this SQL query. 
> Please Consider the following information: 
> ------------------------------------------- 
> I have a postgresql table called 'inventory' that includes two fields: 'model' which is a character varying field and 'modified' which is a timestamp field. 
> So the table inventory looks something like this: 
> model                          modified
> -------------                ----------
> I778288176                2010-02-01 08:27:00 
> I778288176                 2010-01-31 11:23:00
> I778288176                 2010-01-29 10:46:00
> JKLM112345              2010-02-01 08:25:00
> JKLM112345              2010-01-31 09:52:00
> JKLM112345              2010-01-28 09:44:00
> X22TUNM765            2010-01-17 10:13:00
> V8893456T6               2010-01-01 09:17:00 
> Now with the table, fields and data in mind look at the following three queries: 
> SELECT COUNT(distinct model) FROM inventory WHERE modified >= '2010-02-01';
> SELECT COUNT(distinct model) FROM inventory WHERE modified >= '2010-01-20';
> SELECT COUNT(distinct model) FROM inventory WHERE modified >= '2010-01-01'; 
> All three of the above queries work and provide results. However, I want to combine the three into one SQL Statement that hits the database one time. How can I do this in one SQL Statement? Is it possible with sub select? 
> Here is what result I am looking for from one SELECT statement using the data example from above: 
> count1 |  count2  | count3
> -------------------------------
> 2              2              4 
> Can this be done with ONE SQL STATEMENT? touching the database only ONE time? 
> Please let me know. 
> Thanx> :)
> NEiL 
> 

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