第一次写这么长的sql语句

SELECT t1.Department AS depId, t2.Name AS Department, t3.Name AS Unit, 
COUNT(t1.Department) AS depSum, ROUND(AVG(t1.Percent), 2) AS percentAvg, 
COUNT(IF(t1.Percent>=100,true,null)) AS finishCount 
FROM task AS t1, department AS t2, unit AS t3 
WHERE t1.Department = t2.Id AND t2.Unit = t3.Id AND t1.Department NOT IN (3,4,5,6) 
GROUP BY t1.Department 
ORDER BY percentAvg DESC 
LIMIT 10