$transaction = new Varien_Object(); $transaction->setTransactionId('1234567890');
$order = Mage::getModel('sales/order')->load($orderId); $order->getPayment()->setTransactionId('9876543210'); $order->save();In this example, we load an order from Magento using its ID. We then set the transaction ID for the payment associated with the order to '9876543210' and save the changes. The Varien_Object class is part of the Magento PHP library.