title: Show rows from table which another table doesn't contain
body: <p>Basically, I want to show all data from a certain table, which another table doesn't contain with a certain condition.</p>
  
  <p>I want to show all the people who haven't filled in their availability. This is what I do to see who have filled in their availability in SQL:</p>
  
  <pre><code>SELECT availability_id, availability_date, availability_start, availability_end, info_id, info_firstname, info_surname, job_name
  FROM Availability
  FULL JOIN Info
  ON Availability.availability_info_id = Info.info_id
  LEFT JOIN Job
  ON Job.job_id = Info.info_job_id
  WHERE Availability.availability_date = '2019-9-20'; //today
  </code></pre>
  
  <p>So this shows the people who are available today.</p>
  
  <p>Now I want to show the people who haven't filled in their availability. So I want to show everyone in table '<strong>Info</strong>', who are not in table '<strong>Availability</strong>' where <strong>date = 2019-09-20</strong>.</p>
  
  <p>How do I do this?</p>