"D. Jay Newman" <jay(at)sprucegrove(dot)com> writes:
> I would like to create a standard deviation function using the basic
> SQL statements "CREATE AGGREGATE" and "CREATE FUNCTION" using Postgres 7.0.2.
> I can't find a way to return a modified array.
It's possible to do this in pltcl but I don't think there is any syntax
for constructing array values on-the-fly in SQL or plpgsql functions.
(A definite shortcoming, that; should have a TODO item for it.)
BTW, stddev/variance are in current sources for 7.1.
regards, tom lane