Date: Thu, 22 Feb 2007 14:25:36 +0100
From: "A. Kretschmer" <andreas.kretschmer@schollglas.com>
To: pgsql-sql@postgresql.org
Subject: Re: how to generate a list of distinct scalar values from a column
	which type is array
Message-ID: <20070222132536.GE15488@a-kretschmer.de>
References: <2cfc7c940702211021u1ba47031l25112a69cfb18338@mail.gmail.com>
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am  Wed, dem 21.02.2007, um 19:21:09 +0100 mailte Sergio Andreozzi folgendes:
> Dear all,
> 
> given a column which type is for instance varchar(20)[], is there any SQL
> command that let me generate the list of distinct scalar values?
> 
> 
> e.g.:
>              col1
> row 1: (aaa, bb, c)
> row 2: (dddd, eeee)
> row 3: (aaa, eeee)
> 
> the query should return:
> 
> aaa
> bb
> c
> dddd
> eeee

Okay, next solution:

test=*# select * from a;
      c
-------------
 {aaa,bb,c}
 {dddd,eeee}
 {aaa,eeee}
(3 rows)


test=*# select distinct c[s] from a,  generate_series(1,3)s where c[s] is not null;
  c
------
 aaa
 bb
 c
 dddd
 eeee
(5 rows)


You need to know the greatest upper dimension of the array, in this case
3, for the generate_series - function.


Andreas
-- 
Andreas Kretschmer
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