超过经理的工资的员工

地址:https://leetcode-cn.com/problems/employees-earning-more-than-their-managers/

## 编写一个 SQL查询，交换所有的 f 和 m 值（例如，将所有 f 值更改为 m，反之亦然
     示例：
     Employee 表包含所有员工，他们的经理也属于员工。每个员工都有一个 Id，此外还有一列对应员工的经理的 Id。
     
     +----+-------+--------+-----------+
     | Id | Name  | Salary | ManagerId |
     +----+-------+--------+-----------+
     | 1  | Joe   | 70000  | 3         |
     | 2  | Henry | 80000  | 4         |
     | 3  | Sam   | 60000  | NULL      |
     | 4  | Max   | 90000  | NULL      |
     +----+-------+--------+-----------+
     给定 Employee 表，编写一个 SQL 查询，该查询可以获取收入超过他们经理的员工的姓名。在上面的表格中，Joe 是唯一一个收入超过他的经理的员工。
     
     +----------+
     | Employee |
     +----------+
     | Joe      |
     +----------+
    
     
 
`解题思路`

1 使用where

    `select a.Name as Employee from 
     Employee as a,
     Employee as b
     where a.ManagerId =b.id and a.Salary>b.Salary;
`
     
2 使用join

        `select b.Name as Employee from Employee as a join 
         Employee as b
         on
         a.id =b.ManagerId and a.Salary<b.Salary`