181. Employees Earning More Than Their Managers【leetcode】,sql，inner join ，where

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      |
+----------+
方法一：使用inner，效率更高

select a.Name AS  Employee  FROM Employee a inner join Employee  b ON
(a.ManagerId =b.Id and a.Salary >b.Salary )

方法二：使用where

SELECT E.Name Employee
    FROM Employee E ,Employee M
    WHERE E.ManagerId=M.Id AND E.Salary>M.Salary;