[LeetCode] 서브쿼리 : 184. Department Highest Salary

1. 문제

 

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  | Jim   | 90000  | 1            |
| 3  | Henry | 80000  | 2            |
| 4  | Sam   | 60000  | 2            |
| 5  | 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, your SQL query should return the following rows (order of rows does not matter).

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

Explanation:

Max and Jim both have the highest salary in the IT department and Henry has the highest salary in the Sales department.

---

2. 답

SELECT d.name AS Department
    , e.name AS Employee
    , e.salary AS Salary
FROM employee e
    INNER JOIN (
        SELECT departmentid, MAX(salary) AS max_salary
        FROM employee
        GROUP BY departmentid
    )e2 ON e.departmentid = e2.departmentid AND e.salary = e2.max_salary
    INNER JOIN department d ON e.departmentid = d.id

---

3. KEY POINT

 

• 부서별 최고 임금의 테이블을 employee 테이블과 INNER JOIN 시켜 부서별 최고 임금과 최고 임금자를 추출

---

 

leetcode.com/problems/department-highest-salary/

Department Highest Salary - LeetCode