Leetcode 181. Employees Earning More Than Their Managers (Database)
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 | +----------+
思路:考虑同一个table Employee的两个copy e1 和 e2。Where 里面可以用AND。在一个table中根据一些条件选出一部分内容,如果这个条件牵扯到table里的其他row,那么往往使用select from table的多个copy。
# Write your MySQL query statement below select e1.Name as Employee from Employee as e1, Employee as e2 where e1.Salary > e2.Salary and e1.ManagerId=e2.Id)