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 |
+-----------+
来源：力扣（LeetCode）
链接：https://leetcode-cn.com/problems/customers-who-never-order
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# 没有订单的用户 select name from Customers as c where c.Id not in (select CustomerId from Orders )
# 有订单的用户 select name from Customers as c , Orders as o where c.Id = o.CustomerId