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题解 | 统计每个用户的平均刷题数

select up.university, qd.difficult_level, round(count(qpd.id) / count(distinct qpd.device_id), 4) as avg_answer_cnt from user_profile ...

2025-12-20

0 9

题解 | 计算每日累计利润

select profit_id, profit_date, profit, sum(profit) over ( order by profit_date rows between unbounded preceding and cu...

2025-12-20

0 9

题解 | 浙大不同难度题目的正确率

select qd.difficult_level, round( sum( case when qpd.result = 'right' then 1 else 0 ...

2025-12-20

0 7

题解 | 统计复旦用户8月练题情况

select up.device_id, up.university, count(qpd.question_id) as question_cnt, sum( case when result = 'right' then 1...

2025-12-20

0 10

题解 | 找出每个学校GPA最低的同学

select up.device_id, up.university, up.gpa from user_profile up join ( select university, min(gpa) as min_gpa ...

2025-12-20

0 11

题解 | 截取出年龄

select substring_index(substring_index(profile, ',', 3), ',', -1) as age, count(device_id) as number from user_submit group by age su...

2025-12-20

0 10

题解 | 提取博客URL中的用户名

select device_id, substring_index(blog_url, '/', -1) as user_name from user_submit select device_id, replace(blog_url,'http:/url/','...

2025-12-17

0 12

题解 | 统计每种性别的人数

select case when profile like '%female' then 'female' else 'male' end as 'gender', count(*) as number from user_submit...

2025-12-17

0 12

题解 | 计算用户的平均次日留存率

SELECT round( sum( CASE WHEN p2.device_id IS NOT NULL THEN 1 ELSE 0 END ) ...

2025-12-17

0 11

题解 | 计算用户8月每天的练题数量

select day(date) as day, count(question_id) as question_cnt from question_practice_detail where year(date) = 2021 and month(date) ...

2025-12-17

0 8