title: Message board database design
body: <p>I'm building a message board but I have a question about the database design.
  once a new message added, if it is a new message, a subject will be created. The question is, should I keep the create date and the creator of the subject in the subject table, or should I get it from the message table with sql?</p>
  
  <p><strong>option a - database:</strong></p>
  
  <ul>
  <li>user: id, username</li>
  <li>subject: id, subject, create_date, creator_id(user)</li>
  <li>message: id, subject_id, create_date, creator_id(user)</li>
  </ul>
  
  <p><strong>option b - database:</strong></p>
  
  <ul>
  <li>user: id, username</li>
  <li>subject: id, subject</li>
  <li>message: id, subject_id, create_date, creator_id(user)</li>
  </ul>
  
  <p>Second seems better in design, no more repeated data.
  But in first option, there will be lighter sql queries..</p>
  
  <p>Which one is better?</p>