select university,
       avg(question_cnt) as avg_question_cnt,
       avg(answer_cnt) as avg_answer_cnt
from user_profile
group by university
having avg_question_cnt < 5　／／ｈａｖｉｎｇ分组后过滤：聚合函数作为删选条件时不能用where
            or
       avg_answer_cnt < 20;