SQL> select current_scn,to_char(sysdate,'yyyy/mm/dd hh24:mi:ss') from v$database;
CURRENT_SCN TO_CHAR(SYSDATE,'YY
----------- -------------------
12529246 2012/06/18 13:14:19
SQL> select scn_to_timestamp(12529246) from dual;
SCN_TO_TIMESTAMP(12529246)
---------------------------------------------------------------------------
18-JUN-12 01.14.18.000000000 PM
SQL> select systimestamp from dual;
SYSTIMESTAMP
---------------------------------------------------------------------------
18-JUN-12 01.16.01.146523 PM +08:00
SQL> select timestamp_to_scn(to_timestamp('18-JUN-12 01.16.01.146523 PM')) from dual;
TIMESTAMP_TO_SCN(TO_TIMESTAMP('18-JUN-1201.16.01.146523PM'))
------------------------------------------------------------
12529314