Nice work Jacob.

Here's a 3rd way, this time using XML PATH...

SELECT

OrderHeader.Name AS 'OrderHeader/Name',

OrderHeader.Address AS 'OrderHeader/Address',

OrderHeader.Code AS 'OrderHeader/Code',

OrderDetails.OrderNumber AS 'OrderDetails/OrderNumber',

OrderDetails.ItemNumber AS 'OrderDetails/ItemNumber',

OrderDetails.Qty AS 'OrderDetails/Qty'

FROM

OrderDetails LEFT OUTER JOIN

(SELECT 'Jacob' AS 'Name', '401, TIME SQUARE' AS 'Address', '007' AS 'Code') OrderHeader

ON OrderDetails.ItemNumber = 'A001'

FOR XML PATH (''), ROOT ('OrderInfo')