I've got a table of exchange rates:
EXCH_RATE
----------------------------------
id | name | amount | rate | date_set
1 c1 1 100 2004-01-01
2 c2 100 86 2004-01-01
3 c3 1 25 2004-01-01
1 c1 1 101 2004-01-10
2 c2 100 87 2004-01-10
1 c1 1 110 2004-02-01
2 c2 100 90 2004-02-01
3 c3 1 26 2004-02-01

for a particular date there is an appropriate exchange rate. If rate is not changed for a given date it comes from the last changed date. Now I'd like to do a query to find out what is the current exchange rate for all currencies. I can do it for one currency, say with id 2 like this
SELECT * FROM EXCH_RATE
WHERE id = 2 AND
date_set = (SELECT max(date_set) FROM EXCH_RATE WHERE id = 2)

result:
id | name | amount | rate | date_set
2 c2 100 90 2004-02-01

The question is how to retirieve the last exchange rates for all currencies?
Thank you in advance

SELECT * FROM EXCH_RATE a
WHERE
a.date_set = (SELECT max(b.date_set) FROM EXCH_RATE b WHERE b.id = a.id)

Thank you, it was a real quick reply.