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:
Orders
表:
例如给定上述表格,你的查询应返回:
左外连接
SELECT Name AS Customers FROM Customers a left JOIN Orders b ON a.Id = b.CustomerId WHERE b.Id IS NULL;
嵌套子查询
SELECT Name AS Customers FROM Customers WHERE Id NOT IN(SELECT Customerid FROM Orders);
知识点:无
总结:无