public void JoinWithArithmeticExpressionOrderByCalulatedColumn()
        {
            CustomerCollection collection = new CustomerCollection();
            collection.es.Connection.ConnectionString =
                UnitTestBase.GetFktString(collection.es.Connection);

            string orderAlias = "";
            switch (collection.es.Connection.ProviderSignature.DataProviderName)
            {
                case "EntitySpaces.MSAccessProvider":
                    orderAlias = "<'TotalSales'>";
                    break;
                default:
                    orderAlias = "TotalSales";
                    break;
            }

            // Notice I create a calulated columns based on the TotalSales,
            // then Order by it descending
            CustomerQuery cust = new CustomerQuery("c");
            OrderQuery order = new OrderQuery("o");
            OrderItemQuery item = new OrderItemQuery("oi");

            cust.Select(cust.CustomerName,
                (item.Quantity * item.UnitPrice).Sum().As("TotalSales"));
            cust.InnerJoin(order).On(order.CustID == cust.CustomerID);
            cust.InnerJoin(item).On(item.OrderID == order.OrderID);
            cust.GroupBy(cust.CustomerName);
            cust.OrderBy(orderAlias, esOrderByDirection.Descending);

            Assert.IsTrue(collection.Load(cust));
            Assert.AreEqual(6, collection.Count);
        }