title: How to get opposite results of a specific sql query?
body: <p>I have 3 tables which are divided in users, user_courses and course.</p>
  
  <p>I wanted to create 2 queries:</p>
  
  <ol>
  <li>One query to return the subscribed courses of a specific user</li>
  <li>Another query to return the unsubscribes courses of a specific user</li>
  </ol>
  
  <p>I got the first query done but I can´t make the 2nd query work.</p>
  
  <p>I tried to negate the conditions and got the same rows multiple times.</p>
  
  <pre><code>SELECT 
      course.course_id,course_name,course_owner,course_date,course_time
  FROM
      course, users, user_courses
  WHERE 
      usershortcut = "mmuster" 
      AND user_courses.user_id = users.user_id 
      AND user_courses.course_id = course.course_id
  </code></pre>
  
  <p>This is the first query which gives out all the subscribed courses of a user and I have no clue how to reverse it so I get the unsub courses of that user.</p>