Greg,
GS> There's no efficient way to write this in standard SQL.
GS> However Postgres has an extension DISTINCT ON that would
GS> do it:
Works as advertised - many thanks! I'd missed the DISTINCT
ON extension...
This really is a great list - you've saved me a couple of
hours of agony, I suspect.
------------------
Geoff Caplan
Vario Software Ltd
(+44) 121-515 1154