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 | +----------+
这道题给我们了一个Employee表,里面有员工的薪水信息和其经理的信息,经理也属于员工,其经理Id为空,让我们找出薪水比其经理高的员工,那么就是一个很简单的比较问题了,我们可以生成两个实例对象进行内交通过ManagerId和Id,然后限制条件是一个Salary大于另一个即可:
解法一:
SELECT e1.Name FROM Employee e1 JOIN Employee e2 ON e1.ManagerId = e2.Id WHERE e1.Salary > e2.Salary;
我们也可以不用Join,直接把条件都写到where里也行:
解法二:
SELECT e1.Name FROM Employee e1, Employee e2 WHERE e1.ManagerId = e2.Id AND e1.Salary > e2.Salary;
本文转自博客园Grandyang的博客,原文链接:员工挣得比经理多[LeetCode] Employees Earning More Than Their Managers ,如需转载请自行联系原博主。