Employee表包含所有員工，他們的經理也屬於員工。每個員工都有一個 Id，此外還有一列對應員工的經理的 Id。

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

給定Employee表，編寫一個 SQL 查詢，該查詢可以獲取收入超過他們經理的員工的姓名。在上面的表格中，Joe 是唯一一個收入超過他的經理的員工。

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

解法一：

# Write your MySQL query statement below
select Name as Employee from Employee as a where Salary > (select Salary from Employee where Id = a.ManagerId)

解法二：將兩個表做連線，比解法一效率高

# Write your MySQL query statement below
select a.Name 
 
as Employee from Employee as a join Employee as b on a.ManagerId = b.Id and a.Salary > b.Salary