Створити поле
catalog\model\checkout\order.php
public function addOrder($data) {
$this->db->query("INSERT INTO " . DB_PREFIX . "order_product SET order_id = '" . (int)$order_id . "', product_id = '" . (int)$product['product_id'] . "', name = '" . $this->db->escape($product['name']) . "', model = '" . $this->db->escape($product['model']) . "', quantity = '" . (int)$product['quantity'] . "', price = '" . (float)$product['price'] . "', total = '" . (float)$product['total'] . "', tax = '" . (float)$product['tax'] . "', reward = '" . (int)$product['reward'] . "'");
Ось це потрібно
$order_product_id = $this->db->getLastId();
$this->db->query("UPDATE " . DB_PREFIX . "order_product op
SET sku = SELECT sku FROM " . DB_PREFIX . "product WHERE product_id = '" . (int)$product['product_id'] . "'
WHERE order_product_id = " . (int) $order_product_id . " AND order_id = '" . (int)$order_id . "'
Как-то так