/**
* @return void
*/
public function rollBack()
{
if ($this->transactions == 1) {
$this->pdo->rollBack();
} elseif ($this->transactions > 1 && $this->queryGrammar->supportsSavepoints()) {
$this->pdo->exec($this->queryGrammar->compileSavepointRollBack('trans' . $this->transactions));
}
$this->transactions = max(0, $this->transactions - 1);
$this->fireConnectionEvent('rollingBack');
}
