题解 | #统计每个学校各难度的用户平均刷题数#
统计每个学校各难度的用户平均刷题数
https://www.nowcoder.com/practice/5400df085a034f88b2e17941ab338ee8
SELECT
a. university, c. difficult_level, count(b. question_id)/count(distinct a. device_id) avg_answer_cnt
from
user_profile a
JOIN
question_practice_detail b on a. device_id = b. device_id
JOIN
question_detail c on b. question_id = c. question_id
GROUP BY a. university, c. difficult_level
a. university, c. difficult_level, count(b. question_id)/count(distinct a. device_id) avg_answer_cnt
from
user_profile a
JOIN
question_practice_detail b on a. device_id = b. device_id
JOIN
question_detail c on b. question_id = c. question_id
GROUP BY a. university, c. difficult_level
