Re: return a text agreggate from a subselect

On Wed, 2001-12-19 at 11:11, Louis-David Mitterrand wrote:

> The subselect: (SELECT company_name FROM table)
>
> The output I'd like: 'Company1|Company2|Company3|etc.'
>
> Should I write a function or a new agreggate for this or is there is
> simpler way?

I'm afraid the cleanest way to do this is with an aggregate.

CREATE FUNCTION barjoin(text, text) RETURNS text AS '
SELECT CASE WHEN length($1) > 0 THEN $1 || ''|'' || $2
ELSE $2 END;' LANGUAGE 'sql';

CREATE AGGREGATE barconcat(basetype=text, sfunc=barjoin,
stype=text, initcond='');

SELECT barconcat(company_name) FROM table;

If you're in the mood to pointlessly performance tune the snot out of
it, you could implement barjoin to simply do $1|$2, and then write a
final function for the aggregate that trimmed off the beginning |...

--
Andrew G. Hammond mailto:drew(at)xyzzy(dot)dhs(dot)org
http://xyzzy.dhs.org/~drew/
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