lahm66

分类

/ 注册

全部文章（共116篇）

题解 | 统计每个学校各难度的用户平均刷题数

select university,difficult_level,round(count(qpd.question_id)/count(distinct qpd.device_id),4) avg_answer_cn from user_profile up join question_pract...

2025-10-18

1 14

题解 | 统计每个学校的答过题的用户的平均答题数

select university,round(count(question_id)/count(distinct qpd.device_id),4)avg_answer_cnt from user_profile up join question_practice_detail qpd on u...

2025-10-16

1 10

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 in ( select device_id from user_profile where university...

2025-10-16

1 14

题解 | 分组排序练习题

select university,round(avg(question_cnt),4) avg_question_cnt from user_profile group by university order by avg_question_cnt;

2025-10-15

1 13

题解 | 分组过滤练习题

select university,round(avg(question_cnt),3) avg_question_cnt,round(avg(answer_cnt),3) avg_answer_cnt from user_profile group by university having avg...

2025-10-15

1 12

题解 | 分组计算练习题

select gender,university,count(*) user_num,round(avg(active_days_within_30),1) avg_active_day,round(avg(question_cnt),1) avg_question_cnt from user_pr...

2025-10-15

1 10

题解 | 电话号码格式校验

select id,name,phone_number from contacts where phone_number regexp '^[1-9][0-9]{9}$' or phone_number regexp '^[1-9][0-9]{2}-[0-9]{3}-[0-9]{4}$';

2025-10-15

0 13

题解 | 计算男生人数以及平均GPA

select count(*) male_num,avg(gpa) avg_gpa from user_profile where gender='male';

2025-10-14

0 11

题解 | 查找GPA最高值

select gpa from user_profile where university='复旦大学' order by gpa desc limit 0,1; # 第二种 select max(gpa) gpa from user_profile where university='复旦大学'

2025-10-14

1 11

题解 | 查看学校名称中含北京的用户

_：匹配任意一个字符%：匹配0个或多个字符 select device_id,age,university from user_profile where university like '%北京%';

2025-10-13

1 12