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 |
+----------+
思路:
自连接
# Write your MySQL query statement below
select A.Name as 'Employee'
from Employee as A,Employee as B
where A.ManagerId=B.Id and A.Salary>B.Salary;
子查询包含主查询内容的效率比较慢,所以不推荐使用。
select a.name as Employee
from Employee as a
where a.salary > (select b.salary from Employee as b where b.id = a.managerid);