undo_management   string   AUTO

undo_retention  integer 10800

undo_suppress_errors  boolean  FALSE

undo_tablespace   string   UNDOTBS1

ALTER SYSTEM SET undo_retention=10800 SCOPE=BOTH;

exec dbms_flashback.enable_at_time（to_date（'2007-07-23 10:21:00','yyyy-mm-dd hh24:mi:ss'））；

set serveroutput on

DECLARE r_temp hr.job_history%ROWTYPE;

CURSOR c_temp IS SELECT * FROM hr.job_history;

BEGIN

OPEN c_temp;

dbms_flashback.disable;

LOOP

FETCH c_temp INTO r_temp;

EXIT WHEN c_temp%NOTFOUND;

insert into hr.job_history（EMPLOYEE_ID,JOB_ID,START_DATE,END_DATE） values （r_temp.EMPLOYEE_ID,r_temp.JOB_ID,r_temp.START_DATE,r_temp.END_DATE）；

commit;

END LOOP;

CLOSE c_temp;

END;

select * from hr.job_history as of timestamp to_timestamp（'2007-07-23 10:20:00', 'yyyy-mm-dd hh24:mi:ss'）；

create table tableName_bak
as
select * from tableName as of TIMESTAMP to_timestamp（'20081126 103435','yyyymmdd hh24miss'）；