181_Employees Earning More Than Their Managers

TheEmployeetable holds all employees including their managers. Every employee has an Id, and there is also a column for the manager Id.

+----+-------+--------+-----------+
| Id | Name  | Salary | ManagerId |
+----+-------+--------+-----------+
| 1  | Joe   | 70000  | 3         |
| 2  | Henry | 80000  | 4         |
| 3  | Sam   | 60000  | NULL      |
| 4  | Max   | 90000  | NULL      |
+----+-------+--------+-----------+

Given theEmployeetable, write a SQL query that finds out employees who earn more than their managers. For the above table, Joe is the only employee who earns more than his manager.

+----------+
| Employee |
+----------+
| Joe      |
+----------+

Solution 1: self join

# self join
SELECT E1.Name AS Employee
FROM Employee AS E1 INNER JOIN Employee AS E2
ON E1.ManagerId = E2.Id
WHERE E1.Salary > E2.Salary;

Solution 2: equijoin

# equijoin
SELECT E1.Name AS Employee
FROM 
    Employee AS E1,
    Employee AS E2
WHERE 
    E1.ManagerId = E2.Id
    AND E1.Salary > E2.Salary;