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Date: Tue, 6 Apr 2010 19:47:14 +0100
From: Ben Morrow <ben@morrow.me.uk>
To: junaidmalik14@gmail.com, pgsql-sql@postgresql.org
Subject: Re: count function alternative in postgres
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Quoth junaidmalik14@gmail.com (junaidmalik14):
> 
> Is there any alternative of mysql function COUNT(DISTINCT expr,[expr...]) in
> postgres. We get error if we 
> 
> write count like this count(distinct profile.id, profile.name, profile.age)
> but it works well in mysql.

Pg does support COUNT(DISTINCT ), but only for a single column. The best
I can come up with for multiple columns is

    select count(distinct profile.tuple) from
        (select (id, name, age) as tuple from profile)
            as profile;

or alternatively

    select count(*) from
        (select distinct (id, name, age) as tuple from profile)
            as profile;

Ben