题意分析：要查询出的字段有gender, university,用户数量，30天的平均天数，发帖数量的平均数。对性别，学校分组group by gender,university分组后，对性别进行计数。为用户数量count(gender) user_num平均天数、发贴平均数avg(active_days_within_30), avg(question_cnt) as avg_question_cnt性别、学校升序排列order by gender, university select gender, university, count(gender) as user_num, #count...
