Date: Wed, 2 Sep 2009 13:26:10 +0200
From: "A. Kretschmer" <andreas.kretschmer@schollglas.com>
To: pgsql-sql@postgresql.org
Subject: Re: Min and max element of an array column
Message-ID: <20090902112610.GD31088@a-kretschmer.de>
References: <4A9E4FC0.1010908@gmail.com>
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In response to Gianvito Pio :
> Hello,
> is it possible to obtain the minimum and the maximum single element of 
> an array column?
> 
> Example:
> [1, 2 ,5]
> [3, -1, 6]
> [9, 18,-4 ]
> 
> I'd just like to make a query that gives me the min (-4) and the max(18) 
> of the column. Is that possible without a function? Thanks

test=*# select * from pio;
     i
-----------
 {1,2,5}
 {3,-1,6}
 {9,18,-4}
(3 rows)

test=*# select min(unnest), max(unnest) from (select unnest(i) from pio)
foo;
 min | max
-----+-----
  -4 |  18
(1 row)


It is 8.4, if you have a version < 8.4, you need the unnest-function:

CREATE OR REPLACE FUNCTION unnest(ANYARRAY) RETURNS SETOF ANYELEMENT
LANGUAGE SQL AS $$SELECT $1[i] FROM
generate_series(array_lower($1,1),array_upper($1,1)) i;$$;

(with Thx to David Fetter)


Andreas
-- 
Andreas Kretschmer
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