Mysql My SQL Workbench在SQL中添加外键时出现错误1064

我想向名为“address”的表中添加一个外键

此请求由MySQLWorkbench自动生成。 但是你会得到这个错误

ERROR 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ')
REFERENCES `students1`.`country` ()
ON DELETE NO ACTION
ON UPDATE NO ACT' at line 3

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如何解决此问题？

我不知道您的两个表是否具有相同的列

id\u country

但这种情况下的语法是：

ALTER TABLE `students1`.`address` 
    ADD CONSTRAINT 
    FOREIGN KEY (`id_country`)
    REFERENCES `students1`.`country`(`id_country`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION;

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这只是无效的SQL。你到底想做什么？我想给另一个已经存在的表添加一个外键。

ALTER TABLE `students1`.`address` 
    ADD CONSTRAINT 
    FOREIGN KEY (`id_country`)
    REFERENCES `students1`.`country`(`id_country`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION;