Parameter definition in report

I will use the last_update_date parameter in the report I prepare. But I want to use the last_update_date column in more than one table in a single parameter.

For Ex: per_all_people_f , per_all_assignments_m, per_people_legislative_f.. I want to select last_update_date in these tables and use it as a parameter.

(CASE

      WHEN (SUBSTR (TO_CHAR (ppnf.LAST_UPDATE_DATE, 'DD.MM.YYYY'),

             1,

             16)) >

         (SUBSTR (TO_CHAR (PAAM.LAST_UPDATE_DATE, 'DD.MM.YYYY'),

             1,

             16))

      THEN

        (SUBSTR (TO_CHAR (PPNF.LAST_UPDATE_DATE, 'DD.MM.YYYY'),

             1,

             16))

      ELSE

        (SUBSTR (TO_CHAR (PAAM.LAST_UPDATE_DATE, 'DD.MM.YYYY'),