update: 1 solution

Author: hijiangtao

README.md

@@ -13,5 +13,6 @@ Progress: 9/
 |177|[Nth Highest Salary](https://leetcode.com/problems/nth-highest-salary/)| [SQL](./src/nth-highest-salary/res.txt)|Medium|
 |181|[Employees Earning More Than Their Managers](https://leetcode.com/problems/employees-earning-more-than-their-managers/) | [SQL](./src/employees-earning-more-than-their-managers/res.txt)|Easy|
 |182|[Duplicate Emails](https://leetcode.com/problems/duplicate-emails/) | [SQL](./src/duplicate-emails/res.txt)|Easy|
+|184|[Department Highest Salary](https://leetcode.com/problems/department-highest-salary/) | [SQL](./src/department-highest-salary/res.txt)|Medium|
 |197|[Rising Temperature](https://leetcode.com/problems/rising-temperature/) | [SQL](./src/rising-temperature/res.txt)|Easy|
 |434|[Number of Segments in a String](https://leetcode.com/problems/number-of-segments-in-a-string/) | [JavaScript](./src/number-of-segments-in-a-string/res.js)|Easy|

src/department-highest-salary/res.txt

@@ -0,0 +1,33 @@
+-- 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  | Henry | 80000  | 2            |
+-- | 3  | Sam   | 60000  | 2            |
+-- | 4  | 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, Max has the highest salary in the IT department and Henry has the highest salary in the Sales department.
+
+-- +------------+----------+--------+
+-- | Department | Employee | Salary |
+-- +------------+----------+--------+
+-- | IT         | Max      | 90000  |
+-- | Sales      | Henry    | 80000  |
+-- +------------+----------+--------+
+
+# Write your MySQL query statement below
+SELECT b.Name AS 'Department', a.Name AS 'Employee', a.Salary AS 'Salary' FROM Employee a 
+inner join (SELECT MAX(Salary) AS 'salary', DepartmentId as 'id' FROM Employee GROUP BY DepartmentId) c 
+ON a.Salary = c.salary AND a.DepartmentId=c.id
+inner join Department b 
+ON a.DepartmentId=b.Id