题解 | #获取每个部门中当前员工薪水最高的相关信息#

 莫忘deptno排序：
select  d.dept_no,
    de.dept_name, count(*) sum from dept_emp d left join departments de on d.dept_no = de.dept_no left join salaries s on d.emp_no = s.emp_no group by d.dept_no,de.dept_name order by d.dept_no