Can the foreign key and primary key be the same?

  • Hi all,

    I have a main user table which stores basic information for which UserID is the primary key. I have another table, UserExtended which stores more detailed information about the user which i dont want to store in the user table. In this scenario, Can I have the UserID in the UserExtended as primary key and foreign key referencing the main User table or can i have a identity column as a primary key and have the UserID as a foreign key.

    I wanted to know can we have the same column as primary key and foreign key?

    Any suggestions is greatly appreciated.

    Thank you very much guys. This forum is awesome.

  • Yes, you absolutely can. It's a pretty common design method. The one place almost everyone will agree that something like this applies is in a many-to-many relationship. There are other places, such as what you outline, that will support it as well.

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  • Yeah, I do exactly that in what I call extended properties tables. PK and FK the same column.

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  • ThankYou Guys, I really appreciate that

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