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题解 | #21年8月份练题总数#

SELECT COUNT(DISTINCT device_id), COUNT(question_id) FROM question_practice_detail WHERE date LIKE '2021-08%'

Mysql

2022-09-15

0 210

题解 | #查找后降序排列#

SELECT device_id,gpa,age FROM user_profile ORDER BY gpa DESC,age DESC

Mysql

2022-09-15

1 195

题解 | #查找后多列排序#

select device_id,gpa,age from user_profile order by gpa,age;

Mysql

2022-09-15

0 182

题解 | #查找后排序#

SELECT device_id,age FROM user_profile ORDER BY age

Mysql

2022-09-15

0 283

题解 | #浙大不同难度题目的正确率#

SELECT qd.difficult_level,( SUM(CASE WHEN qpd.result='right' THEN 1 ELSE 0 END )/COUNT(qpd.result) ) c...

Mysql

2022-09-15

0 228

题解 | #统计复旦用户8月练题情况#

select t1.device_id, t1.university, sum(case when t2.result is not null then 1 else 0 end), sum(case when t2.result = 'right' then 1 else 0 end) FROM ...

Mysql

2022-09-15

0 224

题解 | #找出每个学校GPA最低的同学#

SELECT device_id,university,gpa FROM ( SELECT *,ROW_NUMBER() over (PARTITION BY university ORDER BY gpa) AS rn FROM user_p...

Mysql

2022-09-15

0 177

题解 | #截取出年龄#

SELECT age,COUNT(*) number FROM (SELECT SUBSTR(PROFILE,12,2) age FROM user_submit) ages GROUP BY age

Mysql

2022-09-15

0 174

题解 | #计算用户8月每天的练题数量#

select day(date) as day,count(id) as question_cnt from question_practice_detail where month(date)=08 group by day

Mysql

2022-09-14

0 181

题解 | #查看不同年龄段的用户明细#

select device_id,gender, case when age<20 then '20岁以下' when age <=24 and age>=20 then '20-24岁' when age>=25 then '25岁及以上' else '其他' ...

Mysql

2022-09-14

0 221