public IOrderedEnumerable<PurchaseOrder> GetPurchaseOrdes()
        {
            PurchaseOrderCollection collection = new PurchaseOrderCollection();

            using (PurchaseOrderDataAdapter adapter = new PurchaseOrderDataAdapter())
            {
                IDataReader dr = adapter.GetPurchaseOrders();
                while (dr.Read())
                {
                    collection.Add(PopulateReader(dr));
                }
                dr.Dispose();
                adapter.Dispose();
            }
            return collection.OrderByDescending(P=>P.Id);
        }
 public void GetPurchaseOrders()
 {
     PurchaseOrderDataAdapter adapter = new PurchaseOrderDataAdapter();
     IDataReader reader = adapter.GetPurchaseOrders();
 }