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题解 | #牛客每个人最近的登录日期(四)#

select login.date,ifnull(n1.new_num,0)from login left join(select a.t_date,count(user_id) as new_numfrom(select min(date) as t_date,user_id from login...

2021-08-03

0 362

题解 | #牛客每个人最近的登录日期(三)#

SELECTround(count(distinct user_id)*1.0/(select count(distinct user_id)from login),3)from loginwhere (user_id,date)in(select user_id,date_add(min(date...

2021-08-03

0 425

题解 | #异常的邮件概率#

select a.date,round(sum(case a.type when'completed' then 0 else 1 end )*1.0/count(a.type),3)as pfrom (select e.send_id,e.receive_id,e.type,e.date,u1.i...

2021-08-02

0 375

题解 | #出现三次以上相同积分的情况#

select numberfrom gradegroup by numberhaving count(*)>=3 having 和 where 的区别https://www.huaweicloud.com/articles/00d8b9053add55b50c807934f79ee0d2.ht...

2021-08-02

0 411

题解 | #对于employees表中，给出奇数行的first_name#

SELECT e.first_nameFROM employees e JOIN( SELECT first_name , ROW_NUMBER() OVER(ORDER BY first_name ASC) AS r_num FROM employe...

2021-08-02

0 353

题解 | #统计salary的累计和running_total#

select emp_no, salary,sum(salary) over(order by emp_no) as running_totalfrom salarieswhere to_date='9999-01-01' https://zhuanlan.zhihu.com/p/120269203...

2021-08-02

0 355

题解 | #获取有奖金的员工相关信息。#

select employees.emp_no,employees.first_name,employees.last_name,b.btype,s.salary,(case b.btypewhen 1 then salary0.1when 2 then salary0.2else salary*0...

2021-07-29

0 352

题解 | #使用含有关键字exists查找未分配具体部门的员工的所有信息。#

select * from employeeswhere not EXISTS (select emp_no from dept_emp where employees.emp_no=dept_emp.emp_no) exists的详细解释在：https://zhuanlan.zhihu.com/p...

2021-07-29

0 372

题解 | #分页查询employees表，每5行一页，返回第2页的数据#

select *from employeesLIMIT 5,5这道题主要是limit 具体的教程在：https://www.w3cschool.cn/mysql/5nab1ptx.html注意用order by 和 limit 可以输出前几名这种

2021-07-29

0 375

题解 | #查找排除当前最大、最小salary之后的员工的平均工资avg_salary#

select avg(salary) as avg_salaryfrom salaries awhere to_date='9999-01-01'and a.salary not in (select max(salary) from salaries where to_date='9999-01-...

2021-07-29

0 460