[LeetCode] Department Highest Salary

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

Department Highest Salary - LeetCode

부서별 봉급이 가장 높은 사람의 아이디, 봉급, 부서이름을 출력

 

나의 풀이

SELECT 
    D.name AS Department,
    Employee,
    salary 
FROM
    (
        SELECT 
            name AS Employee,
            salary,
            E.departmentId 
        FROM Employee E,
        (
        SELECT
            MAX(salary) AS m,
            departmentId 
        FROM Employee
        GROUP BY departmentId
        )AS top
        WHERE (top.m, top.departmentId) = (E.salary, E.departmentId)
    ) AS MAX_E
JOIN Department D
ON MAX_E.departmentId = D.id
;

 

풀면서 뭔가 더 단축할 수 있을 것 같았다.

 

LeetCode 솔루션

SELECT
    Department.name AS 'Department',
    Employee.name AS 'Employee',
    Salary
FROM
    Employee
        JOIN
    Department ON Employee.DepartmentId = Department.Id
WHERE
    (Employee.DepartmentId , Salary) IN
    (   SELECT
            DepartmentId, MAX(Salary)
        FROM
            Employee
        GROUP BY DepartmentId
    )
;

이렇게 푸는게 훨씬 가독성이 좋아보인다.

근데 속도는 내가 더 빨랐다.. 왜지?