[LeetCode#181]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      |
+----------+

本题是有一张表Employee，表中包含employee和他们的manager，分别有name列、Salary列和ManagerId列，需要找出employee比自己的manager领的薪水高的employee：

 解法一：

select e1.Name as employee  from employee e1,employee e2
where e1.ManagerId = e2.Id and e1.Salary > e2.Salary;

解法二：

select e1.Name as employee  from employee e1
join employee e2 on e1.ManagerId = e2.Id
where e1.Salary > e2.Salary;