public void AutoGenerateSalesId() { decimal AlreadyExistData = _SalesRepository.AlreadyExistData(); int code = 1; if (AlreadyExistData >= 1) { var GetLastCode = _SalesRepository.GetLastPurchaseId(); if (GetLastCode != null) { code = Convert.ToInt32(GetLastCode.SalesId); code++; } txtSalesId.Text = code.ToString("0000"); } else { txtSalesId.Text = "0001"; } }