How to view selected item from combox into textbox?

string constr = @"Data Source=192.168.*.*; Database=wsditsupport; User ID=**; Password=**";
       public Form7()
       {
           InitializeComponent();

           MySqlConnection cn = new MySqlConnection(constr);
           string value = "SELECT passover_info FROM probing_production";
           MySqlDataAdapter adp = new MySqlDataAdapter(value, cn);
           DataTable dt = new DataTable();
           adp.Fill(dt);
           comboBox1.DataSource = dt;
           comboBox1.DisplayMember = "passover_info";
           cn.Close();
       }

       private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
       {
           if (comboBox1.SelectedIndex == -1)
           {
               textBox1.Text = string.Empty;
           }
           else
           {
               textBox1.Text = comboBox1.SelectedItem.ToString();
           }
       }
   }