[LeetCode] 184. Department Highest Salary

😎풀이

1. Employee 테이블과 Department 테이블 JOIN
2. 조인 결과 중 departmentId별 최고 급여를 할당
3. 부서, 이름, 급여를 반환

SELECT 
    d.name AS Department,
    e.name AS Employee,
    e.salary AS Salary
FROM 
    Employee e
JOIN 
    Department d ON e.departmentId = d.id
JOIN (
    SELECT 
        departmentId, 
        MAX(salary) AS max_salary
    FROM 
        Employee
    GROUP BY 
        departmentId
) AS max_salaries
ON 
    e.departmentId = max_salaries.departmentId 
    AND e.salary = max_salaries.max_salary;