Date: 11/29/07 (MySQL Communtiy)    Keywords: no keywords

SELECT
    COUNT( * )
FROM
    customers
    LEFT JOIN orders ON customers.id = orders.id
WHERE
    YEAR( orders.order_date ) =2007 AND
     orders.total <= 1500
GROUP BY
   orders.id

SELECT COUNT(*) FROM (query above) AS grand_total;

Source: http://community.livejournal.com/mysql/121631.html