SELECT gender, university, //表头的性别和学校
COUNT(university) AS user_num, //用户数
ROUND(AVG(active_days_within_30),1) AS avg_active_day, //平均活跃数，保留一位小数
ROUND(avg(question_cnt),1)AS avg_question_cnt //平均发帖数，保留一位小数
FROM user_profile 
group by gender, university//按照性别和学校分组