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: <1195051800.3190.18.camel@frodon.be-bif.ulb.ac.be>
References: <1195047542.3190.9.camel@frodon.be-bif.ulb.ac.be>
	<473AE27E.6050103@archonet.com>
	<1195051800.3190.18.camel@frodon.be-bif.ulb.ac.be>
Content-Type: text/plain
Date: Wed, 14 Nov 2007 15:57:50 +0100
Message-Id: <1195052270.3190.21.camel@frodon.be-bif.ulb.ac.be>
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I finally found a solution:

SELECT specimen_id 
FROM specimen_test_bits 
GROUP BY specimen_id 
HAVING array_accum(test_bit_id) =  '{2,3,4}';

.. but I don't think it's very "clean" ..

what do you think ?

Thanks

On Wed, 2007-11-14 at 15:50 +0100, Julien Cigar wrote:
> 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)
> 
>