C# .NET ถามเรื่องการดึงข้อมูลจากฐานข้อมูล Database ขึ้นมาแสดงบน Listbox ค่ะ

private void button1_Click(object sender, System.EventArgs e)
{
   // Create an instance of the ListBox.
   ListBox listBox1 = new ListBox();
   // Set the size and location of the ListBox.
   listBox1.Size = new System.Drawing.Size(200, 100);
   listBox1.Location = new System.Drawing.Point(10,10);
   // Add the ListBox to the form.
   this.Controls.Add(listBox1);
   // Set the ListBox to display items in multiple columns.
   listBox1.MultiColumn = true;
   // Set the selection mode to multiple and extended.
   listBox1.SelectionMode = SelectionMode.MultiExtended;

   // Shutdown the painting of the ListBox as items are added.
   listBox1.BeginUpdate();
   // Loop through and add 50 items to the ListBox.
   for (int x = 1; x <= 50; x++)
   {
      listBox1.Items.Add("Item " + x.ToString());
   }
   // Allow the ListBox to repaint and display the new items.
   listBox1.EndUpdate();

   // Select three items from the ListBox.
   listBox1.SetSelected(1, true);
   listBox1.SetSelected(3, true);
   listBox1.SetSelected(5, true);

   // Display the second selected item in the ListBox to the console.
   System.Diagnostics.Debug.WriteLine(listBox1.SelectedItems[1].ToString());
   // Display the index of the first selected item in the ListBox.
   System.Diagnostics.Debug.WriteLine(listBox1.SelectedIndices[0].ToString());             
}

		System.Data.SqlClient.SqlConnection objConn = new System.Data.SqlClient.SqlConnection();
		System.Data.SqlClient.SqlDataAdapter dtAdapter = new System.Data.SqlClient.SqlDataAdapter();
		DataTable dt = new DataTable();
       
       
		String strConnString;
		strConnString = "Server=localhost;UID=sa;PASSWORD=;database=mydatabase;Max Pool Size=400;Connect Timeout=600;";;
		objConn = new System.Data.SqlClient.SqlConnection(strConnString);
		objConn.Open();

		String strSQL;
		strSQL = "SELECT * FROM customer";
		
		dtAdapter = new System.Data.SqlClient.SqlDataAdapter(strSQL, objConn);
		dtAdapter.Fill(dt);

		dtAdapter = null;

		objConn.Close();
		objConn = null;

		this.listBox1.DataSource = dt; 
		this.listBox1.DisplayMember = "Name";
		this.listBox1.ValueMember = "CustomerID";

Dim objConn As New System.Data.SqlClient.SqlConnection()
Dim dtAdapter As New System.Data.SqlClient.SqlDataAdapter()
Dim dt As New DataTable()


Dim strConnString As [String]
strConnString = "Server=localhost;UID=sa;PASSWORD=;database=mydatabase;Max Pool Size=400;Connect Timeout=600;"


objConn = New System.Data.SqlClient.SqlConnection(strConnString)
objConn.Open()

Dim strSQL As [String]
strSQL = "SELECT * FROM customer"

dtAdapter = New System.Data.SqlClient.SqlDataAdapter(strSQL, objConn)
dtAdapter.Fill(dt)

dtAdapter = Nothing

objConn.Close()
objConn = Nothing

Me.listBox1.DataSource = dt
Me.listBox1.DisplayMember = "Name"
Me.listBox1.ValueMember = "CustomerID"

SqlConnection conn = new SqlConnection(connStr);
            conn.Open();

            for (int i = 0; i <= lstb_setplant.Items.Count - 1; i++)
            {
                string lstbplnt = lstb_setplant.Items[i].ToString();
                string idplnt = lstbplnt.Substring(0, 5); //สมมติว่ามีข้อมูล 5 ตัว

                string sqlComm = "INSERT INTO Test(Plnt_id) VALUES (@plntid)";

                SqlCommand add = new SqlCommand(sqlComm, conn);
                //add.Parameters.AddWithValue("seid", lstb_plnt.Items);
                add.Parameters.AddWithValue("plntid", idplnt.Items);

                int result = add.ExecuteNonQuery();
                add.Dispose();

                if (result < 1)
                {
                    MessageBox.Show("บันทึกข้อมูลผิดพลาด!!");
                }

                else
                {
                    MessageBox.Show("บันทึกเรียบร้อยแล้ว");

                }
                conn.Close();
            }