【leetcode SQL】Customers Who Never Order

Table: Orders.

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

+-----------+ | Customers | +-----------+ | Henry | | Max | +-----------+

解决方案如下：

 

select name as Customers
from Customers a left join Orders b on a.Id=b.CustomerId
where CustomerId is null