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 |
+----------+
----------------------------
解析：
方法1：自身连接
select E1.Name as Employee
from Employee E1,Employee E2
where E1.ManagerId=E2.Id and E1.Salary > E2.Salary
方法2：谓词exists
select E1.Name as Employee
from Employee E1
where exists
( select *
from Employee E2
where E1.ManagerId=E2.Id and E1.Salary > E2.Salary )
方法3：内查询>
select E1.Name as Employee
from Employee E1
where salary >
( select salary
from Employee
where id=E1.ManagerId )
方法4：内查询in
select E1.Name as Employee
from Employee E1
where ManagerId in
( select id
from Employee
where E1.salary > salary )
https://leetcode-cn.com/problems/employees-earning-more-than-their-managers/
