题解 | #分组排序练习题#

select university,
avg(question_cnt) as avg_question_cnt
from user_profile
group by university
order by avg_question_cnt;
使用的是order by

由于SQL语句执行顺序如下：
FROM - ON - JOIN - WHERE - GROUP BY - WITH - HAVING - SELECT - DISTINCT - ORDER BY - LIMIT
因此ORDER BY后应添加avg_qusetion_cnt，而不是聚合函数AVG(question_cnt)