SQL to LINQ, Hard Northwind Query

    private void TestLinqStuff()
        {
            using (var db = new NorthwindEntities())
            {
                var result = from customers in db.Customers
                             join orders in db.Orders on customers.CustomerID equals orders.CustomerID
                             join orderDetails in db.Order_Details on orders.OrderID equals orderDetails.OrderID
                             group new { Customers = customers, OrderDetails = orderDetails } by new
                             {
                                 customers.CompanyName,
                                 customers.Country
                             }
                                 into g
                                 orderby
                                     g.Key.Country
                                 select new
                                 {
                                     g.Key.CompanyName,
                                     g.Key.Country,
                                     Discount = g.Average(p => p.OrderDetails.Discount)
                                 };

                myDataGrid.DataSource = result.ToList();
            }
        }