$ sqlplus / as sysdba 

 SQL> select instance_name from v$instance; 

 SQL> show user 

 export NLS_DATE_FORMAT='YYYY-MM-DD HH24:MI:SS'

 SQL> alter user scott identified by oracle account unlock; 

 SQL> grant execute on dbms_flashback to scott; 

 sqlplus scott/oracle 

 SQL> select systimestamp from dual; 

 SQL> select dbms_flashback.get_system_change_number() from dual; 

 SQL> create table empty as select * from em;