title: MYSQL Union All with aliases
body: <p>I am trying to find all the applications that exist in the app table that do not yet have a review in the review table.</p>
  
  <pre><code>SELECT * 
      FROM (
          SELECT app_id FROM apps
          UNION ALL 
          SELECT app_id FROM reviews
            )  
      GROUP BY app_id 
      HAVING COUNT(*) = 1
  </code></pre>
  
  <p>After finding which applications do not have a review, I would like to have all the values from the app table in order to list out the applications that still need a review. The app_id corresponds at the key for the application information in the apps table and when an application is reviewed, the app_id is then entered into the reviews table under app_id along with comments and the rankings in their respected fields.</p>
  
  <p>I am getting this error and can't seem to figure out how to correctly add the aliases.</p>
  
  <blockquote>
    <p>Every derived table must have its own alias</p>
  </blockquote>