title: Problem with addSelect() doctrine repository. Many to Many relation
body: <p>I have symfony 5, doctrine 2and  php 7.3</p>
  
  <p>Four entities : </p>
  
  <ol>
  <li>OrderworkMeeting who contain one Meeting</li>
  <li>Meeting who contain multiple MeetingUsers, </li>
  <li>MeetingUser who contain one User and one Meeeting(for many to many relationship between Meeting and User) </li>
  <li>User</li>
  </ol>
  
  <p>When i do a request in OrderworkMeeting repository to get all OrederworkMeeting with one specific user, doctrine return only one user, impossible to view others users in same meeting ???.</p>
  
  <p>I think it's bug because if i duplicate the request before this but without specific user, it's work !</p>
  
  <p>here is the code :</p>
  
  <pre><code>    $list = $repo_om-&gt;getByUser([15]);
      foreach ($list as $oo) {
          var_dump(count($oo-&gt;getMeeting()-&gt;getUsers()));
      }
  </code></pre>
  
  <p>Return 1</p>
  
  <pre><code>    $listForNothing = $repo_om-&gt;getByUser();
  
      $list = $repo_om-&gt;getByUser([15]);
      foreach ($list as $oo) {
          var_dump(count($oo-&gt;getMeeting()-&gt;getUsers()));
      }
  </code></pre>
  
  <p>Return 2</p>
  
  <p>And in my OrderworkMeetingrepository :</p>
  
  <pre><code>public function getByUser($userId=0){
      $qb = $this-&gt;createQueryBuilder('om');
      $qb -&gt;leftJoin('om.meeting', 'm')
          -&gt;addSelect('m')
          -&gt;leftJoin('m.users', 'mu')
          -&gt;addSelect('mu')
          -&gt;leftJoin('mu.user', 'u')
          -&gt;addSelect('u');
  
      $this-&gt;setQbListLink($qb);
      $this-&gt;addQbOtherListLink($qb);
  
      if($userId){
         $or = $qb-&gt;expr()-&gt;orX();
         $or-&gt;add('u.id IN (:id)');
         $qb-&gt;setParameter('id', $userId);
         $qb-&gt;andWhere($or);
      }
  
      -&gt;orderBy('m.date', 'DESC');
      return $qb-&gt;getQuery()-&gt;getResult();
  }
  </code></pre>
  
  <p>What's append i don't understand ?
  Your help is welcome, i think i'm fools :)</p>
  
  <p>Thanks in advance</p>
  
  <p><strong>Edit:</strong></p>
  
  <p>After other test in my project, i saw that my doctrine queries have explosed : </p>
  
  <p>with addSelect() : 16 queries, 
  without : 84 queries. </p>
  
  <p>So i really need addSelect to reduce queries !</p>
  
  <p>I don't understand why this resolve my problem when i remove addSelect ? I read that addSelect "merge" fields of query but How and why this change my result ? 
  Is that came from fields name ?</p>
  
  <p>Thanks a lot for your help</p>