Employee 表包含所有员工信息，每个员工有其对应的 Id, salary 和 department Id。
+----+-------+--------+--------------+ | Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+ | 1 | Joe | 70000 | 1 | | 2 | Jim | 90000 | 1 | | 3 | Henry | 80000 | 2 | | 4 | Sam | 60000 | 2 | | 5 | Max | 90000 | 1 | +----+-------+--------+--------------+ Department 表包含公司所有部门的信息。
+----+----------+ | Id | Name | +----+----------+ | 1 | IT | | 2 | Sales | +----+----------+ 编写一个 SQL 查询，找出每个部门工资最高的员工。对于上述表，您的 SQL 查询应返回以下行（行的顺序无关紧要）。
+------------+----------+--------+ | Department | Employee | Salary | +------------+----------+--------+ | IT | Max | 90000 | | IT | Jim | 90000 | | Sales | Henry | 80000 | +------------+----------+--------+ 解释：
Max 和 Jim 在 IT 部门的工资都是最高的，Henry 在销售部的工资最高。
select b.Name as `Department`,a.Name as `Employee`,a.Salary from Employee a left join Department b on b.Id = a.DepartmentId where a.Salary in ( select max(Salary) from Employee where DepartmentId = b.Id ) or select b.name as `Department`,a.Name as `Employee`,a.Salary from Employee a, Department b where b.Id = a.DepartmentId and a.Salary in ( select max(Salary) from Employee where DepartmentId = b.Id )
