急！！！！关于mysql统计百分比问题

比如统计出
sex major title answer baifenbi
男 机电 1 a 50%
男 机电 2 b 20%

像这样的数据该如何去写sql语句

SELECT
a.sex, a.major, a.title, a.answer,a.answercnt/b.titlecnt
FROM (SELECT sex, major, title, answer,SUM(1) AS answercnt FROM Table GROUP BY sex, major, title, answer) a
JOIN (SELECT sex, major, title,SUM(1) AS titlecnt FROM Table GROUP BY sex, major, title) b
ON a.sex = b.sex
AND a.major = b.major
AND a.title = b.title

说得不太清楚，不好写，可以用case when 加group by 来做。可以说详细点？

参考MySQL求百分率
先通过一个语句获取每个分组的总计数