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题解 | #统计复旦用户8月练题情况#

思路：在表的右边加一列，填入平均值，再对新表过滤出大于平均值和SQL的行，取得分最小值就行了 select min(y.score) as min_score_over_avg from exam_record as y lef...

Mysql

2022-02-11

2 1089

题解 | #统计复旦用户8月练题情况#

select up.device_id, up.university, count(qpd.result) as...

Mysql

2022-02-10

0 224

题解 | #统计每种性别的人数#

两种写法、 select if(right(profile,5)=',male','male','female') as gender, count(device_id) ...

Mysql

2022-02-09

0 252

题解 | #计算用户8月每天的练题数量#

select day(date) as day, count(result) as question_cnt from question_practice_...

Mysql

2022-02-09

0 286

题解 | #查看不同年龄段的用户明细#

两种写法都在这了 select device_id, gender, if(age<20,'20岁以下',if(...

Mysql

2022-02-09

0 361

题解 | #计算25岁以上和以下的用户数量#

#方法一：if SELECT IF(age<25&nbs***bsp;age IS NULL,'25岁以下','25岁及以上') as age_cut,COUNT(device_id) as Number FRO...

Mysql

2022-02-09

0 439

题解 | #高级操作符练习(2）#

三种写法： SELECT IF(age<25 OR age IS NULL,'25岁以下','25岁及以上') as age_cut,COUNT(device_id) as Number FROM user_profile GROUP BY age_cut #方法2：联合查询 SELECT...

Mysql Mysql

2022-02-09

0 372