题解 | #分组过滤练习题#

select
    university,
    avg(question_cnt) avg_question_cnt,
    avg(answer_cnt) avg_answer_cnt
from
    user_profile
group by
    university
having
    avg_question_cnt <5
    or avg_answer_cnt < 20;
	-- 细节,当我们分组了之后,是不能用where 控制语句的 只能用having