Disappearing Dynamic ComboBox

Question

Created the following code to workout some bugs in a bigger program. That said, when I click the button to add a row, the next row is added, but the previously created ComboBox (cmboPhoneType) disappears with each new click. What am I missing how to correct? Does this maybe have something to do with the name of the control?

using System;
using System.Data;
using System.Drawing;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace AddNewRowTest
{
    public partial class Form1 : Form
    {
      
        int leftControl = 1;
        ComboBox cmboPhoneType = new ComboBox();
       


        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            addLabels();
            btn_AddRow.PerformClick();
        }

        private void btn_AddRow_Click(object sender, EventArgs e)
        {
            

            //Connection Information redacted
            reConn.Open();

            MySqlCommand phoneTypeCommand = new MySqlCommand("Select * from lutable_phonetype order by Type;", reConn);
            MySqlDataAdapter phoneTypeAdapter = new MySqlDataAdapter();
            DataTable phoneTypeTable = new DataTable();
            phoneTypeAdapter.SelectCommand = phoneTypeCommand;
            phoneTypeAdapter.Fill(phoneTypeTable);
            
            this.Controls.Add(cmboPhoneType);
            cmboPhoneType.Top = leftControl * 36;
            cmboPhoneType.Left = 12;
            cmboPhoneType.Size = new Size(100, 20);
            cmboPhoneType.DataSource = phoneTypeTable;
            cmboPhoneType.DisplayMember = "Type";
            cmboPhoneType.ValueMember = "TypeID";
            cmboPhoneType.DataBindings.Add("SelectedValue", phoneTypeTable, "TypeID");
            cmboPhoneType.SelectedIndexChanged += new System.EventHandler(cmboPhoneType_SelectedIndexChanged);

            MaskedTextBox msktxtPhone = new MaskedTextBox();
            this.Controls.Add(msktxtPhone);
            msktxtPhone.Top = leftControl * 36;
            msktxtPhone.Left = 116;
            msktxtPhone.Size = new Size(100, 20);
            msktxtPhone.Mask = "(999) 000-0000";

            reConn.Close();
            leftControl++;
           
        }

        private void addLabels()
        {
            Label lblPhoneType = new Label();
            this.Controls.Add(lblPhoneType);
            lblPhoneType.Top = leftControl * 12;
            lblPhoneType.Left = 12;
            lblPhoneType.Text = "Phone Type";

            Label lblPhoneNumber = new Label();
            this.Controls.Add(lblPhoneNumber);
            lblPhoneNumber.Top = leftControl * 12;
            lblPhoneNumber.Left = 116;
            lblPhoneNumber.Text = "Phone Number";
        }

     
        private void cmboPhoneType_SelectedIndexChanged(object sender, EventArgs e)
        {
            cmboPhoneType.DataBindings.Clear();
        }
       
       
    }
}

Answer 1

Your Adding a "New" Masked Text Box in your Click Event but no "New" Combo Box. Then after you Declare a new cmbophonetype you will need to move, this.Controls.Add(cmboPhoneType); down, to just before you add the SelectedIndexChanged event handler. That will keep the Combobox visible but you may have some more problems separating all of the events.