题解 | #分组过滤练习题#
分组过滤练习题
http://www.nowcoder.com/practice/ddbcedcd9600403296038ee44a172f2d
#依据学校得出的平均发帖数
select avg(question_cnt) from user_profile group by university
#依据学校的出的平均回贴数
select avg(answer_cnt) from user_profile group by university
得出结果: select university,avg(question_cnt),avg(answer_cnt) from user_profile group by university having avg(question_cnt)<5 or avg(answer_cnt)<20 having对分组值进行过滤