getting maximum entry from a sum()

Hi,

I have a table, which essentially is:

transactions (
id serial,
amount numeric(8,2),
dt date
)

I use this to keep track of my expenses. I want to take out the
maximum expense for a date/week/month/year. But let's just focus on a
date. I start out with this query:

economy=> select dt,sum(amount) as asum from transactions group by dt
order by asum;

As expected, this will yield a list of all dates I have wasted my
money, and how much I wasted for those dates. Now let's day I only
wanted the maximum amount I spent and what date that was.

Obviously I could "order by asum" and "limit 1", but this would only
get a single date. What if I want *all* dates which have the same
maximum asum?

Essentially, I want:

select dt,sum(amount) as asum where asum=(select max(asum) ...) group by dt

But I can't seem to understand how to formulate such a query.. I've
been trying off and on for a few days now, and I'm only getting more and
more frustrated by it.

Any hints?

--
Kind Regards,
Jan Danielsson
Te audire non possum. Musa sapientum fixa est in aure.