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Re: count (DISTINCT expression [ , ... ] ) anddocumentation

From: David Fetter <david(at)fetter(dot)org>
To: Ivan Sergio Borgonovo <mail(at)webthatworks(dot)it>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: count (DISTINCT expression [ , ... ] ) anddocumentation
Date: 2008-12-26 18:43:25
Message-ID: 20081226184325.GC4185@fetter.org (view raw or flat)
Thread:
Lists: pgsql-general
On Fri, Dec 26, 2008 at 03:34:33PM +0100, Ivan Sergio Borgonovo wrote:
> I noticed that starting from 8.2 the documentation at
> http://www.postgresql.org/docs/8.2/interactive/sql-expressions.html
> say that multiple distinct expressions are supported
> 
> aggregate_name (DISTINCT expression [, expression] )

In 8.4, you'll be able to do:

WITH d AS (
    SELECT DISTINCT c1, c2 FROM table1
)
SELECT count(*) FROM d;

and very likely an OLAP version. :)

Cheers,
David.
> 
> While previous docs just listed one:
> 
> aggregate_name (DISTINCT expression)
> 
> Still I'm using 8.3 and
> 
> select count(distinct c1, c2) from table1;
> 
> report:
> 
> No function matches the given name and argument types. You might
> need to add explicit type casts.
> 
> What should I write in spite of?
> 
> select count(distinct c1, c2) from table1;
> 
> -- 
> Ivan Sergio Borgonovo
> http://www.webthatworks.it
> 
> 
> -- 
> Sent via pgsql-general mailing list (pgsql-general(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-general

-- 
David Fetter <david(at)fetter(dot)org> http://fetter.org/
Phone: +1 415 235 3778  AIM: dfetter666  Yahoo!: dfetter
Skype: davidfetter      XMPP: david(dot)fetter(at)gmail(dot)com

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Next:From: Pavel StehuleDate: 2008-12-26 18:47:06
Subject: Re: count (DISTINCT expression [ , ... ] ) and documentation
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