获取所有部门中当前员工薪水最高的相关信息

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` ));

select dept_no,s.emp_no,max(salary) salary from dept_emp de left join salaries s on de.emp_no = s.emp_no where de.to_date = '9999-01-01' and s.to_date = '9999-01-01' group by dept_no having s.salary = max(salary)