牛客SQL题解 - 获取所有部门中当前员工薪水最高的相关信息

题目描述

获取所有部门中当前员工薪水最高的相关信息，给出dept_no, emp_no以及其对应的salary
CREATE TABLE `dept_emp` (
`emp_no` int(11) NOT NULL,
`dept_no` char(4) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`dept_no`));
CREATE TABLE `salaries` (
`emp_no` int(11) NOT NULL,
`salary` int(11) NOT NULL,
`from_date` date NOT NULL,
`to_date` date NOT NULL,
PRIMARY KEY (`emp_no`,`from_date`));

输出描述

dept_no	emp_no	salary
d001	10001	88958
d002	10006	43311
d003	10005	94692
d004	10004	74057
d005	10007	88070
d006	10009	95409

试题详解

先建立子查询筛选出当前最高薪水的员工，之后再从原始雇员表中取出相应雇员信息。代码如下：

SELECT de.dept_no,de.emp_no,s.salary
FROM dept_emp AS de INNER JOIN salaries AS s
ON de.emp_no = s.emp_no
AND de.to_date = '9999-01-01'
AND s.to_date = '9999-01-01'
where s.salary = (select max(s2.salary)
              from dept_emp AS de2 inner join salaries AS s2
              on de2.emp_no = s2.emp_no
              and de2.to_date = '9999-01-01'
              and s2.to_date = '9999-01-01'
              where de2.dept_no = de.dept_no
              group by de2.dept_no)
order by de.dept_no;