c# asp.net 生成唯一订单号

string OrderNo = DateTime.Now.Year.ToString().Substring(2, 2) + DateTime.Now.Month.ToString().PadLeft(2, ‘0‘) + DateTime.Now.Day.ToString().PadLeft(2, ‘0‘) + DateTime.Now.Hour.ToString().PadLeft(2, ‘0‘) + DateTime.Now.Minute.ToString().PadLeft(2, ‘0‘) + DateTime.Now.Second.ToString().PadLeft(2, ‘0‘) + DateTime.Now.ToString("fff");