Michael Blakeley <mike@blakeley.com> writes:
> I'm trying to find the average age of the records. I've gotten as far as:
> SELECT DISTINCT ON(id) age(stamp) FROM EVENTS;
> Now, I need the DISTINCT ON(id), but that means I can't simply avg() the age:
> ERROR: Attribute events.id must be GROUPed or used in an
> aggregate function
You don't say *why* you need DISTINCT ON, or exactly what output you
are hoping to get (presumably not a straight average over all the table
entries) ... but perhaps something like
SELECT id, avg(age(stamp)) FROM events GROUP BY id;
is what you need?
regards, tom lane