Ok, I can manage to get the firstname, lastname, and email by writing:
into the corresponding VALUES.
But I have no idea how to get the: $current_product_id, $transaction_id, $clientdate and $sale_price.
I tried pasting:
$cart_item_data_num = $current_cart_item;
$current_product_id = $cart_item_data_num;
But that didn’t help