SQL查找从不订购的客户

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

例如给定上述表格，你的查询应返回：

Customers
Henry
Max

思路一、使用not exists

select c.Name as Customers from Customers c 

where not exists 

(select distinct o.CustomerId Id from Orders o where c.Id = o.CustomerId);

思路二、使用 not in

select c.Name as Customers from Customers c 

where c.Id not in 

(select distinct o.CustomerId Id from Orders o);

思路三、使用左连接

select c.Name as Customers from Customers c 

left join Orders o on c.Id = o.CustomerId

where o.CustomerId  is null;