Re: plpgsql setof help

From: Frank Bax <fbax(at)sympatico(dot)ca>
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: plpgsql setof help
Date: 2009-01-29 00:49:45
Message-ID: 4980FD29.7060502@sympatico.ca
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Tom Lane wrote:
> "Matthew T. O'Connor" <matthew(at)zeut(dot)net> writes:
>> I want the following:
>> select column_to_english_list( select towns from towns_table );
>
>> to return:
>> 'town1, town2 and town3'
>
> I wonder though if it wouldn't be better to recast the problem as an
> aggregate:
>
> select column_to_english_list(towns) from towns_table;
>
> probably using text[] as the transition state, and having the
> transition function just accumulate all the words into the array
> and then the final function decides where to plaster commas and
> "and"s.
>
> You can find examples of similar aggregates in the PG archives, IIRC.

Actually; an example is in docs:

http://www.postgresql.org/docs/8.3/static/xaggr.html

use array_accum(); then reformat final text (to remove {} and change
last comma to 'and').

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