Kai Hessing wrote:
>
> The normal clause would look like:
>
> SELECT c.companyname, s.sectorname FROM company c, sector s,
> company_sector cs WHERE cs.cid = c.cid AND cs.sid = s.sid ORDER BY
> c.companyname;
> c.companyname | ??? (sectors)
> ---------------+------------------------
> company1 | sectora, sectorb
> company2 | sectora, sectorb, sectorc
> company3 | sectora
> company4 | sectorc
>
Search the mailing-list archives for "custom aggregate concat" and
you'll quickly find an example of how to write your own custom aggregate
(like SUM()).
Warning - I don't think you can guarantee the order of elements in the
aggregated sectors.
-- Richard Huxton Archonet Ltd
