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) 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<4order by temp.DepartmentId,temp.RN