From: Volkan YAZICI <yazicivo@ttnet.net.tr>
To: george young <gry@ll.mit.edu>
Cc: pgsql-sql@postgresql.org
Subject: Re: Expressing a result set as an array (and vice versa)?
Date: Sun, 26 Mar 2006 08:56:25 +0300
Message-ID: <20060326055625.GA185@alamut> (raw)
In-Reply-To: <20060325221102.31de88d7.gry@ll.mit.edu>
References: <F3E0C44C-6118-41C6-AC71-2B19258F4F07@genome.stanford.edu>
<20060325221102.31de88d7.gry@ll.mit.edu>
On Mar 25 10:11, george young wrote:
> On Mar 23 11:44, Don Maier <dMaier@genome.stanford.edu> wrote:
> > Conversely, is it possible to construct a (single column) result set
> > from a select expression on a one-dimensional array with an unknown
> > number of elements?
>
> Not so easy without a custom function.
But not that hard:
test=> SELECT id, val FROM t_arr;
id | val
----+---------------
1 | {1,2,3}
2 | {4,5,6}
3 | {7,8,9}
4 | {10,11,12,13}
(4 rows)
--
-- First Way
--
test=> SELECT id, val[s.i]
test-> FROM t_arr
test-> LEFT OUTER JOIN
test-> (SELECT g.s
test(> FROM generate_series(1, (SELECT max(array_upper(val, 1)) FROM t_arr)) AS g(s)
test(> ) AS s(i)
test-> ON (s.i <= array_upper(val, 1));
id | val
----+-----
1 | 1
1 | 2
1 | 3
2 | 4
2 | 5
2 | 6
3 | 7
3 | 8
3 | 9
4 | 10
4 | 11
4 | 12
4 | 13
(13 rows)
--
-- Second Way (by using contrib/intagg)
--
SELECT id, int_array_enum(val) FROM t_arr;
Regards.
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To: pgsql-sql@postgresql.org
Cc: yazicivo@ttnet.net.tr, gry@ll.mit.edu
Subject: Re: Expressing a result set as an array (and vice versa)?
In-Reply-To: <20060326055625.GA185@alamut>
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