I need the code below to say - if myReader reads a null entry a new method is called. At the moment it will not display data from tables that contain a null value

        conDataBase.Open();
        myReader = cmdDataBase.ExecuteReader();

            while (myReader.Read())
            {
                if (myReader["Code_CodeID"] != DBNull.Value)
                {
                string sFirst = myReader["First"].ToString();
                string sLast = myReader["Last"].ToString();
                string sAdd1 = myReader["Address1"].ToString();
                string sCode = myReader["Code"].ToString();


                txtFirst.Text = sFirst;
                txtSecond.Text = sLast;
                txtadd1.Text = sAdd1;                   
                txtDeviceIMEI.Text = sCode;
                }

            }
        }
        else
        {
            //go to a new method
        }
    }