title: Differences between has and contains relationship in ERD?
body: <p><strong>ERD from Wikipedia:</strong></p>
  
  <p><img src="https://i.stack.imgur.com/24umg.png" alt="ERD from Wikipedia"></p>
  
  <p>I'm confused to distinguish "has" and "contains" relationship in ERD, what's the difference between them?</p>