How to get number of years, months, days between two dates

SELECT    TRUNC (MONTHS_BETWEEN (:end_date, :start_date) / 12)

       || ' YEARS '

       || MOD (TRUNC (MONTHS_BETWEEN (:end_date, :start_date)), 12)

       || ' MONTHS '

       || (  TO_DATE (:end_date)

           - ADD_MONTHS (:start_date,

                         TRUNC (MONTHS_BETWEEN (:end_date, :start_date))

                        )

          )

       || ' DAYS'

  FROM DUAL;