题解 | #分组计算练习题#

select gender, 
university, 
count(device_id) as user_num,
round(avg(active_days_within_30), 1) as avg_active_day,
round(avg(question_cnt), 1) as avg_question_cnt
from user_profile
group by university, gender;
最后一行 group by 表示是按照 后面属性的组合建立新表查询