Added Department Highest Salary

Author: ignacio-chiazzo

LeetcodeProblems/Databases/Department_Highest_Salary.sql

@@ -0,0 +1,43 @@
+/*
+Department Highest Salary
+https://leetcode.com/problems/department-highest-salary/
+
+The Employee table holds all employees. Every employee has an Id, a salary, and there is also a column for the department Id.
+
++----+-------+--------+--------------+
+| Id | Name  | Salary | DepartmentId |
++----+-------+--------+--------------+
+| 1  | Joe   | 70000  | 1            |
+| 2  | Jim   | 90000  | 1            |
+| 3  | Henry | 80000  | 2            |
+| 4  | Sam   | 60000  | 2            |
+| 5  | Max   | 90000  | 1            |
++----+-------+--------+--------------+
+The Department table holds all departments of the company.
+
++----+----------+
+| Id | Name     |
++----+----------+
+| 1  | IT       |
+| 2  | Sales    |
++----+----------+
+Write a SQL query to find employees who have the highest salary in each of the departments. For the above tables, your SQL query should return the following rows (order of rows does not matter).
+
++------------+----------+--------+
+| Department | Employee | Salary |
++------------+----------+--------+
+| IT         | Max      | 90000  |
+| IT         | Jim      | 90000  |
+| Sales      | Henry    | 80000  |
++------------+----------+--------+
+Explanation:
+
+Max and Jim both have the highest salary in the IT department and Henry has the highest salary in the Sales department.
+*/
+
+SELECT DepartmentName AS Department, Employee.Name as Employee,  Employee.Salary
+FROM Employee JOIN (
+    SELECT Department.Name AS DepartmentName, Department.Id AS DepartmentId, Max(Salary) as  Salary
+    FROM Employee JOIN Department ON Employee.DepartmentId = Department.Id
+    GROUP BY Employee.DepartmentId
+) AS t ON Employee.Salary = t.Salary AND Employee.DepartmentId = t.DepartmentId

README.md

@@ -85,6 +85,8 @@ To run a specific problem in your console, go to the file test, add the call to
 | [Second Highest Salary](/LeetcodeProblems/Databases/Second_highest_salary.sql)| Easy   | https://leetcode.com/problems/second-highest-salary |
 | [Nth Highest Salary](/LeetcodeProblems/Databases/nth_Highest_Salary.sql) | Medium | https://leetcode.com/problems/nth-highest-salary |
 | [Customers Who Never Order](/LeetcodeProblems/Databases/Customers_Who_Never_Order.sql)| Easy |  https://leetcode.com/problems/customers-who-never-order |
+| [Department Highest Salary](/LeetcodeProblems/Databases/Department_Highest_Salary.sql) | Medium | https://leetcode.com/problems/department-highest-salary/ |
+
 
 ### UtilsClasses