40+  

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 |
+-----------+

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

 

posted on 2021-05-12 17:51  大爱萝卜和青菜  阅读(4)  评论(0)    收藏  举报