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SQL刷题记录

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题解 | #计算25岁以上和以下的用户数量#

select if (age >= 25, "25岁及以上", "25岁以下") as age_cut, /* (case when age >= 25 then "25岁及以上" else "25岁以下&...

2024-09-25

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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 gender =...

2024-09-25

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题解 | #统计每个用户的平均刷题数#

select user_profile.university as university, question_detail.difficult_level as difficult_level, count(question_practice_detail.questio...

2024-09-25

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题解 | #统计每个学校各难度的用户平均刷题数#

select user_profile.university as university, question_detail.difficult_level as difficult_level, count(question_practice_detail.question...

2024-09-25

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题解 | #统计每个学校的答过题的用户的平均答题数#

select user_profile.university as university, count(question_practice_detail.question_id)/count(distinct question_practice_detail.device_id) as...

2024-09-25

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题解 | #浙江大学用户题目回答情况#

select user_profile.device_id,question_id,result from question_practice_detail join user_profile on question_practice_detail.device_id = user_pr...

2024-09-25

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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 ...

2024-09-25

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题解 | #分组计算练习题# group by 用法入门

select gender,university,count(id) as user_num, avg(active_days_within_30) as avg_active_day, avg(question_cnt) as avg_question_cnt from...

2024-09-25

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