Handles even selling

StockDal.Interface/IStockRepository.cs

@@ -13,6 +13,7 @@ namespace StockDAL.Interface
         IEnumerable<StockMember> GetAllStocks();
         void InsertMany(List<StockMember> stockMembers);
         void SaveStockMember(StockMember stockMember);
+        void UpdateActualForSell(int id, int sellAmount, decimal sellPrice, DateTime sellDate);
         void UpdateActualPrice(int id, decimal price);
     }
 }