title: No Duplicate Primary Key
body: <p>I am working on a school activity. This is my sample form:</p>
  
  <p><a href="http://i53.tinypic.com/14xlrl.png" rel="nofollow noreferrer">sample form http://i53.tinypic.com/14xlrl.png</a></p>
  
  <p>What I'm trying to do is that when a user adds a record that has the same CourseID (Primary Key) with one of the records listed, there should be some Message box that will appear that says "Cannot insert same CourseID or cannot duplicate CourseID (Because PRIMARY KEY cannot be DUPLICATED)."</p>