title: Average of a Count in Select Statement
body: <p>I can't seem to solve this riddle. I have the following statement:</p>
  
  <pre><code>SELECT schedule_test.ID, LEFT(schedule_test.Course,2) AS 'Type', COUNT(*) AS  
  'Count'
  FROM schedule_test
  GROUP BY ID, Type
  </code></pre>
  
  <p>It echos the following:</p>
  
  <p><a href="https://i.stack.imgur.com/y6ZYg.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/y6ZYg.png" alt="enter image description here"></a></p>
  
  <p>What can I add to the Select statement to add a 4th column with the average of the count for each Type? In other words, what was the average count of Type "HS" across all employees? Tried adding <code>AVG(COUNT(*))</code> but I get an error, <code>Invalid use of group function</code>.</p>