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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
我使用带有 MYSQL 的“虚拟数据库”进行查询测试。
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