Rich Shepard <rshep...@appl-ecosys.com> writes:
> What I need to do are three things:
> 1.) Find the date and site for the maximum value of a specified constituent
> on a named stream.
> 2.) Find the values of that same constituent at other sites on the named
> stream on that same date.
> 3.) Find the date of the maximum value of a constituent for all sites on
> the named stream.
You can do that type of thing using subqueries, eg
select ... from mytab
where col = (select max(col) from mytab where ...)
or if you don't mind a nonstandard construct, consider SELECT DISTINCT ON.
There's an example of how to use that in the SELECT reference page
(look for the weather-reports example). In any case you're going to
have to consider what you want to have happen when there are multiple
occurrences of the maximum value.
regards, tom lane
--
Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-general
