String SQL =

                "select o.customerID, c.CompanyName, p.productName, sum(od.quantity) as Qty " +

                " from orders o " +

                " inner join [order details] od on o.orderID = od.orderID " +

                " inner join Products p on od.ProductID = p.ProductID " +

                " inner join Customers c  on o.CustomerID = c.CustomerID " +

                " group by o.customerID, c.CompanyName, p.ProductName " +

                " order by o.customerID";

            conn = new SqlConnection( "Server=(local);Database=Northwind;uid=xx;pwd=xx");

            conn.Open();

            com = new SqlCommand(SQL, conn);

            try

            {

                dg.DataSource = Pivot(com.ExecuteReader(),"CustomerID","ProductName","Qty");

            }

            catch (SqlException ex)

            {

                MessageBox.Show(ex.Message);

            }

        }