title: Why do you need a junction table to implement a many-to-many relationship?
body: <p>This has been bugging me, maybe someone can help clarify.</p>
  
  <p>Say I have books, and authors: one book can be written by many authors, and an author can write many books.</p>
  
  <p>Why couldn't I capture this with the following schema? Why do I need a junction table?</p>
  
  <pre>
  Books
  --------
  BookID (PK)
  AuthorID (PK)
  BookName
  </pre>
  
  <pre>
  Authors
  --------
  AuthorID (PK)
  AuthorName
  </pre>