title: Difference between two mysql query
body: <p>I have two query like below.
  First one returning 757 data
  and second one returning 545 data</p>
  
  <p>Here I am not getting where is the difference between two query.
  I used first one for optimize query execution time</p>
  
  <pre><code> SELECT supul.user_point_log_used_id, supul.point
                  FROM user_point_used_logs supul
                      left join user_point_logs supl
                      on supul.user_point_log_id=supl.return_id
                      and supl.return_id is null
  </code></pre>
  
  <p>And Another one</p>
  
  <pre><code>SELECT user_point_used_logs.user_point_log_used_id, user_point_used_logs.point
              FROM user_point_used_logs
              WHERE user_point_log_id NOT IN (
                  SELECT DISTINCT return_id
                  FROM user_point_logs
                  WHERE return_id IS NOT NULL
              )
  </code></pre>
  
  <p><strong><a href="https://www.db-fiddle.com/f/pSYWaJdyjKJxWSywvExLfy/4" rel="nofollow noreferrer">FIDDLE LINK</a></strong></p>