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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 ...

Mysql

2021-12-04

0 251

题解 | #统计每个用户的平均刷题数#

select university,difficult_level,count(qpd.question_id) / count(distinct qpd.device_id) as avg_answer_cnt from user_profile as up inner join question...

Mysql

2021-12-04

0 284

题解 | #统计每个学校各难度的用户平均刷题数#

select university,difficult_level,COUNT(qpd.question_id) / count(distinct qpd.device_id) as avg_answer_cnt from user_profile up inner join question_p...

Mysql

2021-12-04

1 299

题解 | #统计每个学校的答过题的用户的平均答题数#

SELECT university,COUNT(question_id)/COUNT(DISTINCT u.device_id) AS avg_answer_cnt FROM user_profile u INNER JOIN question_practice_detail qpd ON u.de...

Mysql

2021-12-04

1 259

题解 | #浙江大学用户题目回答情况#

select q.device_id,question_id,result from question_practice_detail as q inner join user_profile as u on q.device_id = u.device_id where university = ...

Mysql

2021-12-04

0 267

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_question...

Mysql

2021-12-04

1 358

题解 | #分组计算练习题#

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

Mysql

2021-12-04

1 297

题解 | #使用join查询方式找出没有分类的电影id以及名称#

CREATE table actor_name ( first_name varchar(45) not null comment '名字', last_name varchar(45) not null comment '...

Mysql

2021-11-24

2 269

题解 | #使用join查询方式找出没有分类的电影id以及名称#

select f.title,f.description from film_category fc inner join film f on fc.film_id=f.film_id inner join category c on fc.category_id =c.category_id w...

Mysql

2021-11-21

2 280

题解 | #汇总各个部门当前员工的title类型的分配数目#

select d.dept_no,d.dept_name,t.title,count(*) as count from dept_emp de inner join departments d on de.dept_no = d.dept_no inner join titles t on de.e...

Mysql

2021-11-21

2 404