题解 | #分组计算练习题#

select 
    gender, university,
    count(device_id) as user_num,
    avg(active_days_within_30) as avg_active_day,
    avg(question_cnt) as avg_question_cnt
from user_profile
group by gender, university
order by gender;

请注意，目前众多题解里面没有最后一句“order by gender”，因此会导致输出结果乱序。

根据题意需要在分组后，需在分组的基础上进行排序。故需加上 order by gender，才能运行出最终结果。