题解 | 分组计算练习题
分组计算练习题
https://www.nowcoder.com/practice/009d8067d2df47fea429afe2e7b9de45
select gender, university, count(gender) 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 gender,university order by gender,university ASC
第一次的答案犯了典型错误，order by与group by的顺序错了，先分组，再聚合，最后排序，所以先group by，再order by
