title: One-to many relationships in ER diagram
body: <p>I am trying to show the following in the ER diagram: </p>
  
  <pre><code>There are instructors and courses, a course is taught by only one instructor
  whereas an instructor can give many courses.
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/Z669P.jpg" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/pYK2a.jpg" alt="enter image description here"></p>
  
  <p>My question is, is there any difference between two diagrams, in other words, does it matter which line we turn into an arrow, or what only matters is only the direction of the arrow?</p>
  
  <p>Also, if we think about the mapping cardinalities; is it 1 to many or many to 1? If we think in terms of courses, then it is many to one but if we think in terms of instructors, then it is one to many. How do we decide this?
  Thank you.</p>