MERGE INTO main_menu mm
    USING
    ( SELECT c001 menu_id
      FROM   APEX_COLLECTIONS
      WHERE  collection_name = 'COLLECTION_MENUTREE'
    ) col
    ON (mm.menu_id = to_number(col.menu_id))
    WHEN MATCHED THEN
      UPDATE
      SET mm.flag = 1;

apex.access.page_to_emp (p_page_id, p_flag
 );

    MERGE INTO main_menu mm
    USING
    ( SELECT c001 menu_id
      FROM   APEX_COLLECTIONS
      WHERE  collection_name = 'COLLECTION_MENUTREE'
    ) col
    ON (mm.menu_id = to_number(col.menu_id))
    WHEN MATCHED THEN
      UPDATE
      SET mm.flag = 1;