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题解 | #计算25岁以上和以下的用户数量#

select case when age<25 or age is null then "25岁以下" when age>=25 then "25岁及以上" end as age_cut, count(*)&...

Mysql

2022-09-14

0 224

题解 | #查找山东大学或者性别为男生的信息#

select device_id,gender,age,gpa from user_profile where university='山东大学' union all select device_id,gender,age,gpa from user_profile where gend...

Mysql

2022-09-14

0 202

题解 | #统计每个用户的平均刷题数#

select university ,difficult_level,count(qpd.question_id)/count(DISTINCT qpd.device_id) as avg_answer_cnt from user_profile as u inner join question_p...

Mysql

2022-09-14

0 158

题解 | #计算用户的平均次日留存率#

SELECT COUNT(distinct q2.device_id,q2.date)/COUNT(distinct q1.device_id,q1.date) as avg_ret FROM question_practice_detail q1 LEFT JOIN question_...

Mysql

2022-09-14

0 268

题解 | #统计每种性别的人数#

SELECT substring_index(profile, ',', -1) as gender,COUNT(*) AS number FROM user_submit group by gender;

Mysql

2022-09-14

0 203

题解 | #统计每个学校各难度的用户平均刷题数#

SELECT a. university, c. difficult_level, count(b. question_id)/count(distinct a. device_id) avg_answer_cnt from user_prof...

Mysql

2022-09-14

0 203

题解 | #统计每个学校的答过题的用户的平均答题数#

select u.university, count(u.university)/count(DISTINCT u.device_id)as answer from user_profile as u inner join question_practice_detail as q on u.dev...

Mysql

2022-09-14

0 233

题解 | #浙江大学用户题目回答情况#

SELECT user_profile.device_id, question_practice_detail.question_id, question_practice_detail.result from user_profile inner join...

Mysql

2022-09-14

0 210

题解 | #分组排序练习题#

select university,avg(question_cnt) as avg_question_cnt from user_profile group by university order by avg(question_cnt);

Mysql

2022-09-13

0 217

题解 | #分组过滤练习题#

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_...

Mysql

2022-09-13

0 192