Oracle的閃回功能包括
1.閃回數據庫(前提 歸檔模式下 啟用閃回數據庫) mount 下 alter database archivelog; alter database flashback on ;
2.閃回回收站
3.閃回表
4.閃回查詢
4.1 閃回查詢表 SCN 時間 timestamp
4.2 閃回版本查詢 versions_xid
4.3 閃回事物查詢 flashback_transaction_query
（一）閃回表
flashback table
啟動行移動 功能，如果不啟動
SQL> flashback table scott.emp to scn 1101462;
flashback table scott.emp to scn 1101462
*
第 1 行出現錯誤:
ORA-08189: 因為未啟用行移動功能, 不能閃回表
alter table emp enable row movement;
flashback table hz_test_recycle to timestamp to_date('20110111123000','yyyymmddhh24miss')
存在限制：
不可以跨越ddl 操作
不可以閃回system表
（二）閃回回收站
啟用 回收站 recyclebin
SQL> show parameter recyclebin
NAME TYPE
------------------------------------ --------------------------------
VALUE
------------------------------
recyclebin string
on
測試
grant dba to scott;
create table wj(id number(5) primary key,name varchar2(20));
insert into wj (1,'dwj');
create materialized view log on wj with primary key; -
create materialized view mv_wj refresh fast on commit ；--創建物化視圖
as
select * from wj;
insert into wj values(2,'yj');
show recyclebin
drop table wj
flashback table wj to before drop;
insert into wj(3,'nr1');
select * from mv_wj;
commit; 報錯 --無法閃回視圖日志 需要重建
（三）閃回查詢
delete from emp where deptn=30;
select * from emp as of timestamp to_timestamp('2010-01-09 10:00:45','YYYY-MM-DD HH24:MI:SS')
where deptno=30 --利用回滾段里東西
（四）閃回版本查詢
select versions_xid,salary from employees versions between timestamp t1 and t2 where emplyee_id =200;
-- versions_xid 是偽列
update emp
set sal=2800
where ename='SMITH'
select sal from emp versions between scn minvalue and maxvalue where ename='SMITH'
哪些情況下不可以做：
--外部表
--臨時表
--FIXED表
--視圖
--不能跨越DDL
（五）閃回事務查詢
flashback_transaction_query --視圖
查詢語句在哪個事物當中 取得事物號
select empno,ename,sal,versions_operation,versions_xid,versions_starttime,versions_endtime,versions_operation from emp versions between timestamp minvalue and maxvalue;
select logon_user,table_name,table_owner,undo_sql from flashback_transaction_query where table_owner='SCOTT' and xid
='';