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 |
解法
SELECT Name AS Employee from (
SELECT a.Name, a.Salary, b.Salary AS ManagerSalary FROM Employee a INNER JOIN Employee b ON a.ManagerId = b.Id
) c WHERE c.Salary > c.ManagerSalary参考答案：
SELECT a.Name AS Employee FROM
Employee a
INNER JOIN Employee b ON a.ManagerId = b.Id AND a.Salary > b.Salary显然自己的方法多余了。。。