题解 | #统计每个学校的答过题的用户的平均答题数#
统计每个学校的答过题的用户的平均答题数
http://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
select university ,
round(count(question_id )/count(distinct device_id ),4) as avg_answer_cnt
from user_profile
join question_practice_detail
using (device_id )
group by university
round(count(question_id )/count(distinct device_id ),4) as avg_answer_cnt
from user_profile
join question_practice_detail
using (device_id )
group by university