using min|max in where

Hi, I have some sql like so:

SELECT min(date) INTO d FROM interest_rate WHERE m_code = NEW.code;
UPDATE interest_rate SET date = NEW.start_date, rate = NEW.initial_rate
WHERE m_code = NEW.code AND date = d;

Actually this is pgsql but I don't think that matters.

I am wondering if I can make this more compact by somehow including the
'min' function in the WHERE clause, but WITHOUT simply moving the select in
there. So not this..

UPDATE interest_rate SET date = NEW.start_date, rate = NEW.initial_rate
WHERE m_code = NEW.code AND date = (SELECT min(date) FROM interest_rate
WHERE m_code = NEW.code);

This is just an example but I seem to find this pattern a lot in my
functions.

B