Subject: Re: ALL() question
From: Julien Cigar <jcigar@ulb.ac.be>
To: Richard Huxton <dev@archonet.com>
Cc: pgsql-sql@postgresql.org
In-Reply-To: <473AE27E.6050103@archonet.com>
References: <1195047542.3190.9.camel@frodon.be-bif.ulb.ac.be>
	<473AE27E.6050103@archonet.com>
Content-Type: text/plain
Date: Wed, 14 Nov 2007 15:50:00 +0100
Message-Id: <1195051800.3190.18.camel@frodon.be-bif.ulb.ac.be>
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On Wed, 2007-11-14 at 11:56 +0000, Richard Huxton wrote:
> Julien Cigar wrote:
> > 
> > What I would like is a query that returns all the specimen_id of 
> > this table which have _all_ the given test_bit_id. 
> [snip]
> > With the following I got a syntax error:
> > select specimen_id 
> > from specimen_test_bits 
> > where test_bit_id = all(1,2,3,4);
> 
> It's expecting an array here. You'd have to write
>   = all('{1,2,3,4}')
> But that would have the same problem as...
> 
> > The following works but no rows are returned :
> > select specimen_id 
> > from specimen_test_bits 
> > where test_bit_id = all(select id from test_bits where id in (1,2,3,4));
> 
> It's testing each row individually and of course one row can't match ALL 
> four values.
> 
> What you want to do is count the distinct values. Something like:
> 
> SELECT
>    specimen_id
> FROM foo
> GROUP BY
>    specimen_id
> HAVING
>    count(distinct test_bit_id) = 4
> ;
> 

I don't think it would work, for example if I have:
specimen_id | test_bit_id
------------+------------
   100	       1
   100         3
   101         1
   101         2

the test_bit_ids are parameters, so with the given test_bit_id 1,3 it
would return specimen_id 101 too, which I don't want ...
What I would like is the specimen_id which match _exactly_ the given
test_bit_ids, so it should return only 100 in this example ..

from the documentation ALL() can take a subquery too, not only an ARRAY
(http://www.postgresql.org/docs/8.2/static/functions-subquery.html)