Employees Earning More Than Their 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.

+----+-------+--------+-----------+
| 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 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      |
+----------+ 

Naive Way: 这回一次就过了。

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

Improved Way:还有用left join 的，来自kkamkou

 SELECT e1.`Name`  
  FROM `Employee` e1  
   LEFT JOIN `Employee` e2 ON(e2.`Id` = e1.`ManagerId`)  
   WHERE e1.`ManagerId` IS NOT NULL AND e1.`Salary` > e2.`Salary`