public void SaveBill(string cusId, string staffId, int sum, List <BillProduct> proList) { string now = DateTime.Now.ToString("yyyy-MM-dd hh:mm:ss"); string lastBillId = dal.GetLastBillId().Rows.Count == 0?"":dal.GetLastBillId().Rows[0][0].ToString(); dal.AddBill(AddBillBLL.NextId("HD", lastBillId, 2), now, cusId, staffId, sum, proList); }