185. Department Top Three Salaries : leetcode

-- 각 부서별로 월급 높은 3명 출력
SELECT  Department, Employee, Salary

FROM (
    SELECT  d.name as Department, 
            e.name as Employee ,
            e.salary as Salary, 
            DENSE_RANK() OVER(PARTITION BY e.departmentId ORDER BY e.salary DESC) as rnk
    FROM    Employee e INNER JOIN Department d
            ON  e.departmentId = d.id
)   as department_salary_rnk
WHERE   rnk < 4