C# code in using combo box to display value in Text Box

 SqlConnection conn;
 SqlCommand cmd;
public Form1()
        {
            InitializeComponent();
           conn=new SqlConnection(@"Data Source=DTPC-123P\SQLEXPRESS;Initial Catalog=PrabuDB;Integrated Security=True");
           cmd = new SqlCommand();
           ds = new DataSet();
        }

private void Form1_Load(object sender, EventArgs e)
        {
            conn.Open();
cmd = conn.CreateCommand();
           cmd.CommandText = "Select * from employee";
           dr = cmd.ExecuteReader();

           while (dr.Read())
           {
               Program.frm.comboBox1.Items.Add(dr["empname"].ToString());
           }
           cmd.Dispose();
if(conn.State == ConnectionState.Open)
           conn.Close();

        }

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
           conn.Open();
cmd = conn.CreateCommand();
           cmd.CommandText = "Select * from employee";
           dr = cmd.ExecuteReader();

           while (dr.Read())
           {
               if (Program.frm.comboBox1.Text == dr["empname"].ToString())
               {
                   Program.frm.textBox1.Text = dr["empno"].ToString();
                   Program.frm.textBox2.Text = dr["empname"].ToString();
                   Program.frm.textBox3.Text = dr["salary"].ToString();
                   Program.frm.textBox4.Text = dr["company"].ToString();
               }
           }
           cmd.Dispose();
if(conn.State == ConnectionState.Open)
           conn.Close();
        }