title: QPSQL Not always possible to accept an answer
body: <p>The answer comes when using this form of request:</p>
  
  <pre><code>SELECT id FROM link WHERE uid_fl = '%1';
  </code></pre>
  
  <p>Otherwise it does not come:</p>
  
  <pre><code>auto db = QSqlDatabase::addDatabase("QPSQL");
  </code></pre>
  
  <p>...</p>
  
  <pre><code>QSqlQuery query(db);
  QString request = QString(
      "SELECT id FROM link WHERE uid_fl = '%1' AND end_fl IS NULL;"
              )
      .arg(is_uid);
  query.exec(request);
  
  while (query.next())
  {
      qDebug() &lt;&lt; "id" &lt;&lt; query.record().value(0).toString();
  }
  </code></pre>