Can I make an identity field span multiple tables in SQL Server?

Posted by johnnycakes on Stack Overflow See other posts from Stack Overflow or by johnnycakes
Published on 2010-03-11T20:04:16Z Indexed on 2010/03/11 20:09 UTC
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identity-column

Can I have an "identity" (unique, non-repeating) column span multiple tables? For example, let's say I have two tables: Books and Authors.

Authors
  AuthorID
  AuthorName
Books
  BookID
  BookTitle

The BookID column and the AuthorID column are identity columns. I want the identity part to span both columns. So, if there is an AuthorID with a value of 123, then there cannot be a BookID with a value of 123. And vice versa.

I hope that makes sense.

Is this possible?

Thanks.

Why do I want to do this? I am writing an APS.NET MVC app. I am creating a comment section. Authors can have comments. Books can have comments. I want to be able to pass an entity ID (a book ID or an author ID) to an action and have the action pull up all the corresponding comments. The action won't care if it's a book or an author or whatever. Sound reasonable?

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