private void Product_IndexChanged(object sender, EventArgs e) { int PreviousPrice = 0; productID = cboProduct.SelectedValue.ToInt(); if (releaseService.IsUpperData(productGroupID, productID, ref PreviousPrice, ref PreviousTime) == true) { txtPreviousPrice.Text = PreviousPrice.ToString("#,0"); dtpStartDate.Value = PreviousTime.Value.AddDays(1); } else { txtPreviousPrice.Text = "-"; } }