Display message if SqlDataReader has no rows (data) using C# in ASP.Net

If No Data is retrieve then display message

i am retrieving data from database, if no data is retrieve then display message, Currently my page getting crashed.

        private void loadbarcodeno()
        {
            SqlCommand cmde = new SqlCommand("Sp_Ret_ContainerDetail_Code", con);
            cmde.CommandType = CommandType.StoredProcedure;
            cmde.Parameters.AddWithValue("@CID", txtid.Text);
            cmde.Connection = con;
            try
            {
                con.Open();
                SqlDataReader sdr = cmde.ExecuteReader();
                while (sdr.Read())
                {
                    txtTweght.Text = sdr["weight"].ToString();
                    txttotalbales.Text = sdr["qty"].ToString();
                    DDLContno.SelectedValue = sdr["no"].ToString();
                    txtctweight.Text = sdr["conwt"].ToString();
                    txtissuebales.Text = sdr["conqty"].ToString();
                    lbisuid.Text = sdr["I_ID"].ToString();
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {

            }
        }