[Oracle - Database] Find Last active DDL and DLL on Table

/* Formatted on 1/16/2016 11:17:22 AM (QP5 v5.149.1003.31008) */
SELECT (SELECT last_ddl_time
          FROM dba_objects
         WHERE object_name = 'TAB$' AND owner = 'SYS')
          "DDL Time",
       DECODE (maxscn, 0, 'N/A', SCN_TO_TIMESTAMP (maxscn)) "DML Time"
  FROM (SELECT NVL (MAX (ORA_ROWSCN), 0) maxscn FROM SYS.TAB$);