LeetCode: 184. Department Highest Salary

题目描述

The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id.

+----+-------+--------+--------------+
| Id | Name | Salary | DepartmentId | +----+-------+--------+--------------+
| 1  | Joe   | 70000  | 1            |
| 2  | Henry | 80000  | 2            |
| 3  | Sam   | 60000  | 2            |
| 4 | Max | 90000 | 1 | +----+-------+--------+--------------+

The Department table holds all departments of the company.

+----+----------+
| Id | Name | +----+----------+
| 1  | IT       |
| 2 | Sales | +----+----------+

Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, Max has the highest salary in the IT department and Henry has the highest salary in the Sales department.

+------------+----------+--------+
| Department | Employee | Salary | +------------+----------+--------+
| IT         | Max      | 90000  |
| Sales | Henry | 80000 | +------------+----------+--------+

解题思路

先找出每个部门最高的薪水，然后找出该薪水对应的人的信息。

AC 代码

SELECT D.Name AS Department, E.Name AS Employee, E.Salary AS Salary FROM Employee AS E, Department AS D, (SELECT DepartmentId, MAX(Salary) AS Salary FROM Employee GROUP BY DepartmentId) AS M WHERE E.DepartmentId = D.Id AND E.DepartmentId = M.DepartmentId AND E.Salary = M.Salary