title: SQL Relational Division query
body: <p>I have three tables student(ID, name), takes(ID, course_id), course(course_id, dept_name).
  I would like to query student ID and name who take all courses from dept_name = 'Comp. Sci.'.
  I know I need to use Relation Division. But I'm not sure how to do.</p>
  
  <p>Can anyone explain how can I achieve this?</p>
  
  <p>PS. I just start learning SQL today. </p>