Tom Lane wrote:
> UPDATE totals SET
> xmax = ss.xmax, xmin = ss.xmin, ...
> FROM
> (SELECT groupid, max(x) AS xmax, ... FROM details GROUP BY groupid) ss
> WHERE groupid = ss.groupid;
As long as any individual item that you can express in the
parenthesized (Informix) syntax can also be expressed as an element in
a SELECT, then the above is equivalent in every way to the Informix
syntax. And since SELECT allows subselects, it seems to me that the
PG syntax is complete.
My question is whether or not there's likely to be an approved
standard way of accomplishing what either syntax does. Is there
anything in the current draft that addresses this?
--
Kevin Brown kevin(at)sysexperts(dot)com