static function addCrlChave(CrlChave $ch)
 {
     TTransaction::open('my_config');
     if ($conn = TTransaction::get()) {
         $sql = "INSERT INTO ctrl_chaves\r\n                                 (professor_id,\r\n                                  laboratorio_id,\r\n                                  observacao_controle,\r\n                                  dt_inicial_controle) VALUES\r\n                                                               (?,?,?,?)";
         $sth = $conn->prepare($sql);
         $sth->execute(array($ch->getProfessorId(), $ch->getLaboratorioId(), $ch->getObservacaoControle(), $ch->getDtInicialControle()));
         $sql = "UPDATE laboratorios SET chave_laboratorio=1\r\n                       WHERE id_laboratorio = ?";
         $sth = $conn->prepare($sql);
         $sth->execute(array($ch->getLaboratorioId()));
         TTransaction::close();
     } else {
         echo 'Sem conexão com banco!';
     }
 }