MySQL: Abfrage der ersten Bestellung eines Kunden in einem bestimmten Zeitraum

SELECT *
FROM oxuser as a
JOIN
(
SELECT MIN(oxorderdate) AS oxorderdate, oxuserid AS oxuserid
FROM oxorder AS b WHERE oxorderdate >= "2000-01-01 00:00:00" AND oxorderdate <= "2014-10-22 14:04:19"
GROUP BY oxuserid
) b ON a.oxid = b.oxuserid