title: SQL: Counting one to many relations
body: <p>Given following tables:</p>
  
  <ul>
  <li>User(u_id,c_id) </li>
  <li>Color(c_id, color_name)</li>
  </ul>
  
  <p>Assume that every user can only chose one color. How do you return (using SQL) a list of color names that have been chosen by more than 10 users?</p>