题解 | #分组过滤练习题#

select university,
       avg(question_cnt) as avg_question_cnt,//平均
       avg(answer_cnt) as avg_answer_cnt//平均
from user_profile
group by university//每个学校
having avg_question_cnt < 5 //having　＋　分组后删选的条件
            or
       avg_answer_cnt < 20;