Employee 表包含所有员工，他们的经理也属于员工。每个员工都有一个 Id，此外还有一列对应员工的经理的 Id。
+----+-------+--------+-----------+ | Id | Name | Salary | ManagerId | +----+-------+--------+-----------+ | 1 | Joe | 70000 | 3 | | 2 | Henry | 80000 | 4 | | 3 | Sam | 60000 | NULL | | 4 | Max | 90000 | NULL | +----+-------+--------+-----------+
给定 Employee 表，编写一个 SQL 查询，该查询可以获取收入超过他们经理的员工的姓名。在上面的表格中，Joe 是唯一一个收入超过他的经理的员工。
+----------+ | Employee | +----------+ | Joe | +----------+
解法一：
# Write your MySQL query statement below select Name as Employee from Employee as a where Salary > (select Salary from Employee where Id = a.ManagerId)
解法二：将两个表做连接，比解法一效率高
# Write your MySQL query statement below select a.Name as Employee from Employee as a join Employee as b on a.ManagerId = b.Id and a.Salary > b.Salary
原文：https://www.cnblogs.com/huangzs/p/14174487.html