简单的JOIN查询不起作用

Question

我正在学习SQL，有人可以告诉我查询有什么问题吗？

SELECT * FROM customers AS C
Inner Join customers AS CC
on CC.City=C.City
INNER JOIN customers AS CCC
ON
CCC.City=C.City

我使用“虚拟数据库”和MYSQL进行查询测试。

Answer 1

尝试这样做：

SELECT C.* FROM customers C 
Inner Join customers CC 
on CC.City=C.City 
INNER JOIN 
customers CCC ON CCC.City=C.City