title: one-to-many or one-to-one, what to use here?
body: <p>actually I am a bit confused now, after reading when to use 1:1, 1:n and n:m</p>
  
  <p>First a basic question: if I have two tables:</p>
  
  <pre><code>users      roles
  -----      -----
  user_id    role_id
  role_id    ....
  ....
  </code></pre>
  
  <p>and have a FK <code>fk_users_roles1</code>, is this n:1 (many users can have one role)?</p>
  
  <hr>
  
  <p>and a second question to that: </p>
  
  <pre><code>users    companies    companymembers
  -----    ---------    --------------
  user_id  company_id   company_id
                        user_id
  </code></pre>
  
  <p>with two FKs in <code>companymembers</code>: <code>fk_companymembers_companies1</code> and <code>fk_companymembers_users1</code>, what is the correct relation here? 1:1 or 1:n? </p>