Solved -> 185. Department Top Three Salaries

Author: NandiSoham

06_Subqueries/185. Department Top Three Salaries.sql

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+/* 
+
+Problem Link -> https://leetcode.com/problems/department-top-three-salaries/description/?envType=study-plan-v2&envId=top-sql-50
+
+------------------------------------------------------------- QUESTION -----------------------------------------------------------
+
+Table: Employee
+
++--------------+---------+
+| Column Name  | Type    |
++--------------+---------+
+| id           | int     |
+| name         | varchar |
+| salary       | int     |
+| departmentId | int     |
++--------------+---------+
+id is the primary key (column with unique values) for this table.
+departmentId is a foreign key (reference column) of the ID from the Department table.
+Each row of this table indicates the ID, name, and salary of an employee. It also contains the ID of their department.
+ 
+
+Table: Department
+
++-------------+---------+
+| Column Name | Type    |
++-------------+---------+
+| id          | int     |
+| name        | varchar |
++-------------+---------+
+id is the primary key (column with unique values) for this table.
+Each row of this table indicates the ID of a department and its name.
+ 
+
+A company's executives are interested in seeing who earns the most money in each of the company's departments. A high earner in a department is an employee who has a salary in the top three unique salaries for that department.
+Write a solution to find the employees who are high earners in each of the departments.
+Return the result table in any order.
+The result format is in the following example.
+ 
+
+Example 1:
+
+Input: 
+Employee table:
++----+-------+--------+--------------+
+| id | name  | salary | departmentId |
++----+-------+--------+--------------+
+| 1  | Joe   | 85000  | 1            |
+| 2  | Henry | 80000  | 2            |
+| 3  | Sam   | 60000  | 2            |
+| 4  | Max   | 90000  | 1            |
+| 5  | Janet | 69000  | 1            |
+| 6  | Randy | 85000  | 1            |
+| 7  | Will  | 70000  | 1            |
++----+-------+--------+--------------+
+
+Department table:
++----+-------+
+| id | name  |
++----+-------+
+| 1  | IT    |
+| 2  | Sales |
++----+-------+
+
+Output: 
++------------+----------+--------+
+| Department | Employee | Salary |
++------------+----------+--------+
+| IT         | Max      | 90000  |
+| IT         | Joe      | 85000  |
+| IT         | Randy    | 85000  |
+| IT         | Will     | 70000  |
+| Sales      | Henry    | 80000  |
+| Sales      | Sam      | 60000  |
++------------+----------+--------+
+
+Explanation: 
+In the IT department:
+- Max earns the highest unique salary
+- Both Randy and Joe earn the second-highest unique salary
+- Will earns the third-highest unique salary
+
+In the Sales department:
+- Henry earns the highest salary
+- Sam earns the second-highest salary
+- There is no third-highest salary as there are only two employees
+
+*/
+
+-- ----------------------------------------------------------- SOLUTION -----------------------------------------------------------
+
+SELECT
+    D.name AS Department,
+    E.name AS Employee,
+    E.salary AS Salary
+FROM Employee E INNER JOIN Department D
+ON E.departmentId = D.id
+WHERE 3 > (
+    SELECT COUNT(DISTINCT(emp.salary))
+    FROM Employee emp
+    WHERE emp.salary > E.salary
+    AND E.departmentId = emp.departmentId
+)
+