Will this help you, sire?

WITH CTE AS

(

SELECT Cust.ID ,Cust.CustomerName , Cust.OrderDate , Items.ProductName , Items.Quantity

FROM TestCustomerOrders Cust

JOIN TestCustomerOrderItems Items

ON Cust.ID = Items.TestCustomerOrdersID

)

SELECT p1.id ,CustomerName , OrderDate,

STUFF ( ( SELECT ','+ ProductName

FROM CTE p2

WHERE p2.id = p1.id

ORDER BY ID

FOR XML PATH(''),TYPE

).value('.','VARCHAR(MAX)') , 1,1,SPACE(0)) AS Concat_Values

FROM CTE p1

GROUP BY p1.id ,CustomerName , OrderDate ;