title: What's the difference between having a required foreign key to a primary key?
body: <p>I'm working on a database for a racing game. In this diagram, a race must happen on a track (so TrackID must be referenced on table Race), and I may have a track where many to no races ocurred:</p>
  
  <p><a href="https://i.stack.imgur.com/Co9Yh.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Co9Yh.png" alt="enter image description here"></a></p>
  
  <p>So minimum cardinality from Race to Track should be 1, setting the relationship as <strong>Identifying</strong>. But that would also make TrackID on table Race become a PK. And I don't see why I would need that. So I thought I'd rather have it as a 'required' FK; what would change besides just not having it as a PK? With TrackID as a FK on Race, Microsoft Visio automatically sets that minimum cardinality as 0, which is making me scratch me head...</p>
  
  <p>I am new to modeling databases, and this question might make it evident, but please help me understand this.</p>