Hello guys, are you looking for a simple example of how to use SELF JOIN in SQL? If yes, then you have come to the right place. This article will show you how to use Self join in solving interesting SQL problems from LeetCode. Along the way, you will also learn this useful SQL concept. So, what are you waiting for? Let's first check the problem, and then we'll write an SQL query using SELF Join to solve this problem.
Write an SQL Query to Find Employees Earning More Than Managers
The Employee table holds all employees, including their managers. Every employee has an Id, and there is also a column for the manager Id, as shown below:
+----+-------+--------+-----------+
| Id | Name | Salary | ManagerId |
+----+-------+--------+-----------+
| 1 | Joe | 70000 | 3 |
| 2 | Henry | 80000 | 4 |
| 3 | Sam | 60000 | NULL |
| 4 | Max | 90000 | NULL |
+----+-------+--------+-----------+
Given the Employee table, write a SQL query that finds employees who earn more than their managers. For the above table, Joe is the only employee who earns more than his manager because Henry's Manager is Max, who earns 90000, which is more than Henry's salary of 80000.
Write an SQL Query to Find Employees Earning More Than Managers
The Employee table holds all employees, including their managers. Every employee has an Id, and there is also a column for the manager Id, as shown below:
+----+-------+--------+-----------+
| Id | Name | Salary | ManagerId |
+----+-------+--------+-----------+
| 1 | Joe | 70000 | 3 |
| 2 | Henry | 80000 | 4 |
| 3 | Sam | 60000 | NULL |
| 4 | Max | 90000 | NULL |
+----+-------+--------+-----------+
Given the Employee table, write a SQL query that finds employees who earn more than their managers. For the above table, Joe is the only employee who earns more than his manager because Henry's Manager is Max, who earns 90000, which is more than Henry's salary of 80000.