title: Re-writing query to avoid WHERE IN with a subquery
body: <p>I have the following query which returns the correct results but I am aware of the overheads associated with subqueries in a WHERE IN clause.</p>
  
  <pre><code>SELECT event_start_date 
    FROM events
         JOIN joins 
              ON event_id = join_event_id
         JOIN groups 
              ON join_type_id IN (SELECT group_id 
                                    FROM view_groups 
                                   WHERE user_id = 3)
   WHERE user_id = 3
         AND event_start_date &gt;= now()
  GROUP BY 
         event_start_date;
  </code></pre>
  
  <p>Can anyone help out with rewriting this query to avoid the subquery and/or the WHERE IN clause.</p>