SQL 183. 从不订购的客户

题目：

某网站包含两个表，Customers 表和 Orders 表。编写一个 SQL 查询，找出所有从不订购任何东西的客户。

Customers 表：

±—±------+
| Id | Name |
±—±------+
| 1 | Joe |
| 2 | Henry |
| 3 | Sam |
| 4 | Max |
±—±------+
Orders 表：

±—±-----------+
| Id | CustomerId |
±—±-----------+
| 1 | 3 |
| 2 | 1 |
±—±-----------+

Create table If Not Exists Customers (Idint, Name varchar(255));
Create table If Not Exists Orders (Id int,CustomerId int);
Truncate table Customers;
insert into Customers (Id, Name) values('1', 'Joe');
insert into Customers (Id, Name) values('2', 'Henry');
insert into Customers (Id, Name) values('3', 'Sam');
insert into Customers (Id, Name) values('4', 'Max');
Truncate table Orders;
insert into Orders (Id, CustomerId) values('1', '3');
insert into Orders (Id, CustomerId) values('2', '1');

答案

select Name Customers
from Customers
left join Orders on Customers.Id=Orders.CustomerId
where Orders.CustomerId is null;