Follow this up in the sql forums, but you want something like this:
SELECT b.BREWERY_CODE, b.BREWERY, COUNT(c.id) as num_coaster
FROM breweries b LEFT JOIN coasters c ON b.BREWERY_CODE =
c.BREWERY_CODE
Group by b.BREWERY_CODE
order by COUNT(c.id) DESC
UNTESTED!
This will get you what you want in one pass. (i think)