leetcode181 超過經理收入的員工 Employees Earning More Than Their Managers

Employee表包含全部員工，包括他們的經理。每一個員工都有一個 Id，此外還有一列對應的經理Id。

建立表和數據：

drop table Employee
Create table If Not Exists Employee (Id int, Name varchar(255), Salary int, ManagerId int);
Truncate table Employee;
insert into Employee (Id, Name, Salary,ManagerId) values ('1', 'Joe', '70000', '3');
insert into Employee (Id, Name, Salary,ManagerId) values ('2', 'Henry', '80000', '4');
insert into Employee (Id, Name, Salary,ManagerId) values ('3', 'Sam', '60000', Null);
insert into Employee (Id, Name, Salary,ManagerId) values ('4', 'Max', '90000', Null);

解法：

1.經過表的自鏈接，找出每一個員工的經理，篩選出薪水比經理薪水高的員工。

select E1.Name as Employee
from Employee as E1 join Employee as E2 on (E1.ManagerId  = E2.Id and E1.salary > E2.salary)