public void CustomerReviewMainSurface(ComboBox comboBox1, ComboBox combobox2, ComboBox combobox3) { try { SqlDataReader rd; rd = dw.CustomerReviewMainSurface_2(); while (rd.Read()) { if ((!comboBox1.Items.Contains(rd["type"]) && (rd["type"] != ""))) { comboBox1.Items.Add(rd["type"]); } } } catch (Exception e) { MessageBox.Show(e.Message); } }