WW在搜寻
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题解 | #找出每个学校GPA最低的同学#
SELECT device_id,temp.u,temp.m FROM user_profile up, (SELECT university u,MIN(gpa) m FROM user_profile GROUP BY university ORDER BY university) temp W...
Mysql
2022-01-15
0
168
题解 | #统计每种性别的人数#
SELECT (CASE WHEN CHAR_LENGTH(profile)=18 THEN 'male' ELSE 'female' END) AS gender,COUNT(*) number FROM user_submit GROUP BY gender;#这个方法不是很保险,前提前面字符...
Mysql
2022-01-14
0
197
题解 | #计算用户8月每天的练题数量#
SELECT DISTINCT DAY(qpd.date) AS day ,COUNT(DAY(qpd.date)) AS question_cnt FROM question_practice_detail qpd WHERE MONTH(date)=8 GROUP BY day; #主要得分组
Mysql
2022-01-14
0
177
题解 | #查看不同年龄段的用户明细#
SELECT device_id,gender,(CASE WHEN age>=25 THEN '25岁及以上' WHEN age>=20 THEN '20-24岁' WHEN age>0 THEN '20岁以下' ELSE '其他' END) AS age_cut FROM...
Mysql
2022-01-14
0
147
题解 | #计算25岁以上和以下的用户数量#
SELECT (CASE WHEN age>=25 THEN '25岁及以上' ELSE '25岁以下' END) AS age_cut,COUNT(device_id) as number FROM user_profile GROUP BY age_cut;
Mysql
2022-01-14
0
247
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='ma...
Mysql
2022-01-14
0
209
题解 | #统计每个用户的平均刷题数#
SELECT u.university,d.difficult_level,COUNT(qpd.question_id) / COUNT(DISTINCT u.device_id) FROM user_profile u JOIN question_practice_detail qpd ON u...
Mysql
2022-01-14
0
175
题解 | #统计每个学校各难度的用户平均刷题数#
SELECT u.university,qe.difficult_level ,COUNT(qe.question_id) / COUNT(DISTINCT q.device_id) AS avg_answer_cnt FROM user_profile u JOIN question_pract...
Mysql
2022-01-14
0
224
题解 | #浙江大学用户题目回答情况#
SELECT device_id,question_id,result FROM question_practice_detail WHERE device_id=( SELECT device_id FROM user_profile WHERE university='浙江大学' );
Mysql
2022-01-13
0
176
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_questi...
Mysql
2022-01-13
0
176
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