刚刚从上一个问题得到了这个答案，就可以了！

SELECT username, (SUM(rating)/COUNT(*)) as TheAverage, Count(*) as TheCount 
FROM ratings WHERE month='Aug' GROUP BY username HAVING TheCount > 4
ORDER BY TheAverage DESC, TheCount DESC

但是当我在其中添加额外的位时会出现以下错误：

文档＃1267-操作’=’的排序规则（latin1_swedish_ci，IMPLICIT）和（latin1_general_ci，IMPLICIT）的非法混合

SELECT username, (SUM(rating)/COUNT(*)) as TheAverage, Count(*) as TheCount FROM 
ratings WHERE month='Aug' 
**AND username IN (SELECT username FROM users WHERE gender =1)**
GROUP BY username HAVING TheCount > 4 ORDER BY TheAverage DESC, TheCount DESC

该表是：

id, username, rating, month