我们能否在单个表中创建外键 [英] Can we able to create foreign key in a single table

问题描述

亲爱的朋友，

我们可以在一个表中创建外键吗?


我有一张学生桌.它包含列，如sid，sfirstname，slastname，saddress和sno.在此表中，sid是主键.我想将sno作为引用sid的外键.




在此先感谢

Dear friends,

Can we able to create foreign key in one table


I have a student table. It contains columns as sid,sfirstname,slastname,saddress and sno. In this table sid is the primary key. I want to make sno as foreign key which references to sid.




Thanks in advance

推荐答案

外键是在其他表上定义的，而不是在同一表上定义的，除非您想建立自引用链接，例如Employee.ManagedBy-> Employee.pid

Foreign keys are defined on other tables, not on the same table unless you want to make self referencing links e.g. Employee.ManagedBy --> Employee.pid

有可能！在此处阅读: http://en.wikipedia.org/wiki/Foreign_key [

It is possible! Read here: http://en.wikipedia.org/wiki/Foreign_key[^]. What you are trying to do is known as a self-referencing or recursive foreign key.

Best Regards,

—MRB

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