MVC3＂不允许启动新事务，因为有其他线程正在该会话中运行＂错误解决方法

 public void UPdateStockForAudit(string ordercode)
        {
            var ditems=_db.Orderdetails.Where(o=>o.OrderCode==ordercode);
            foreach (var item in ditems)
            {
                decimal inventory= item.PCS * item.Stock.TonPerPCS;
                UpdateStock(item.StockId, item.PCS,inventory);
            }
        }
        private void UpdateStock(int stockid,int selledpcs,decimal inventory)
        {
            var item=_db.Stocks.SingleOrDefault(s=>s.StockId==stockid);
            item.Selled=selledpcs;
            item.Inventory=inventory;  
            _db.SaveChanges();          
        }

 public void UPdateStockForAudit(string ordercode)
        {
            var ditems=_db.Orderdetails.Where(o=>o.OrderCode==ordercode);
            foreach (var item in ditems)
            {
                decimal inventory= item.PCS * item.Stock.TonPerPCS;
                UpdateStock(item.StockId, item.PCS,inventory);
            }
            _db.SaveChanges();
        }
        private void UpdateStock(int stockid,int selledpcs,decimal inventory)
        {
            var item=_db.Stocks.SingleOrDefault(s=>s.StockId==stockid);
            item.Selled=selledpcs;
            item.Inventory=inventory;            
        }