leetcode 185. Department Top Three Salaries

The 

Employee

 table holds all employees. Every employee has an Id, 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            |
| 5  | Janet | 69000  | 1            |
| 6  | Randy | 85000  | 1            |
+----+-------+--------+--------------+

The 

Department

 table holds all departments of the company.

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

Write a SQL query to find employees who earn the top three salaries in each of the department. For the above tables, your SQL query should return the following rows.

+------------+----------+--------+
| Department | Employee | Salary |
+------------+----------+--------+
| IT         | Max      | 90000  |
| IT         | Randy    | 85000  |
| IT         | Joe      | 70000  |
| Sales      | Henry    | 80000  |
| Sales      | Sam      | 60000  |
+------------+----------+--------+

CREATE TABLE [Employees](
[Id] [int] NOT NULL Primary Key,
[Name] [nvarchar](20)
4000
NOT NULL,
[Salary] decimal NOT NULL,
[DepartmentId] [int] NOT NULL
)

insert into [Employees] values
(1,'Joe',70000,1),
(2,'Henry',80000,2),
(3,'Sam',60000,2),
(4,'Max',90000,1),
(5,'Janet',69000,1),
(6,'Randy',85000,1);

CREATE TABLE [Department](
[Id] [int] NOT NULL Primary Key,
[Name] [nvarchar](20) NOT NULL
)

insert into [Department] values
(1,'IT'),
(2,'Sales');

with temp as
(
select e.Id,e.Name Employee,e.Salary,e.DepartmentId,D.Name Department,RN=ROW_NUMBER() over(PARTITION BY d.Id order by e.salary desc)
from [Employees] e inner join [Department] d on e.DepartmentId=d.Id
)
select temp.Department,temp.Employee,temp.Salary from temp where RN<4
order by temp.DepartmentId,temp.RN