title: How to determine where to place the foreign key in this scenario?
body: <p>If I have two tables - Logins and Users, as follows:</p>
  
  <pre><code>Logins
   LoginIdNo
   UserIdNo
   HashedPassword 
  
  Users
   UserIdNo
   LoginIdNo
   Username
  </code></pre>
  
  <p>Each login "has a user" and each user "has a login" but which "belongs to" which?</p>
  
  <p>Is it simply a judgment call or is there a clearcut formula for determining where the foreign key should reside?</p>