Doctrine\DBAL\Connection::beginTransaction PHP Method

    public function beginTransaction()
    {
        $this->connect();
        ++$this->_transactionNestingLevel;
        $logger = $this->_config->getSQLLogger();
        if ($this->_transactionNestingLevel == 1) {
            if ($logger) {
                $logger->startQuery('"START TRANSACTION"');
            }
            $this->_conn->beginTransaction();
            if ($logger) {
                $logger->stopQuery();
            }
        } elseif ($this->_nestTransactionsWithSavepoints) {
            if ($logger) {
                $logger->startQuery('"SAVEPOINT"');
            }
            $this->createSavepoint($this->_getNestedTransactionSavePointName());
            if ($logger) {
                $logger->stopQuery();
            }
        }
    }

 /**
  * Starts a new transactional block, if none is open, or silently completes, if the transaction
  * is already opened.
  */
 public function requestTransaction()
 {
     if (!$this->inTransaction) {
         $this->conn->beginTransaction();
         $this->inTransaction = true;
     }
 }