SQL> select log_mode,open_mode,flashback_on from v$database;LOG_MODE     OPEN_MODE    FLASHBACK_ON
------------ -------------------- ------------------
ARCHIVELOG   READ WRITE    NO

SQL> alter system set db_recovery_file_dest_size=1G;System altered.SQL> alter system set db_recovery_file_dest = '/data/flash_dir';System altered.SQL> show parameter db_recovery;NAME         TYPE  VALUE
------------------------------------ ----------- ----------------
db_recovery_file_dest       string  /data/flash_dir
db_recovery_file_dest_size      big integer 1G

SQL> show parameter db_flashback;NAME         TYPE  VALUE
------------------------------------ ----------- ---------------------
db_flashback_retention_target      integer  1440

SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.Total System Global Area  780824576 bytes
Fixed Size      2257312 bytes
Variable Size    511708768 bytes
Database Buffers   264241152 bytes
Redo Buffers      2617344 bytes
Database mounted.
SQL> alter database flashback on;Database altered.SQL> alter database open;Database altered.

-- 基于时间点；常用该方式
flashback database to timestamp to_timestamp('2010-10-24 13:04:30','yyyy-mm-dd hh24:mi:ss');
-- 基于scn
flashback database to scn 918987;
-- 基于恢复点
flashback database ro restore point b1_load;

SQL> conn lottu/li0924
Connected.
-- 创建实验对象表tbl_flash_01
SQL> create table tbl_flash_01 (id number,name varchar2(20));
Table created.SQL> insert into tbl_flash_01 values (1001,'lottu');
1 row created.
SQL> commit;
Commit complete.--记录误操作时间之前的时刻。
SQL> select to_char(sysdate,'yyyymmddhh24miss') from dual;
TO_CHAR(SYSDAT
--------------
20180814224948-- truncate表tbl_flash_01
SQL> truncate table tbl_flash_01;
Table truncated.--误操作之后的日志
SQL> insert into tbl_flash_01 values (1002,'rax');
1 row created.
SQL> commit;
Commit complete.-- 执行闪回操作
--1. 关闭数据库
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.--2. 启动数据到mount状态
SQL> startup mount;
ORACLE instance started.Total System Global Area  780824576 bytes
Fixed Size      2257312 bytes
Variable Size    511708768 bytes
Database Buffers   264241152 bytes
Redo Buffers      2617344 bytes
Database mounted.--3. 执行闪回操作
SQL> flashback database to timestamp to_timestamp('20180814224948','yyyymmddhh24miss');Flashback complete.SQL> alter database open resetlogs;Database altered.SQL> conn lottu/li0924
Connected.
SQL> select * from tbl_flash_01;ID NAME
---------- --------------------1001 lottu

-- 1. 演示drop table后；闪回恢复表
SQL> conn lottu/li0924
Connected.
SQL> drop table tbl_flash_01;Table dropped.SQL> show recyclebin;
ORIGINAL NAME  RECYCLEBIN NAME  OBJECT TYPE  DROP TIME
---------------- --------------------------- ------------ ---------
TBL_FLASH_01  BIN$c2hFCisICOXgU+oBqMCsVQ==$0 TABLE 2018-08-14:23:57:40SQL> flashback table tbl_flash_01 to before drop;Flashback complete.SQL> select * from tbl_flash_01;ID NAME
---------- --------------------1001 lottu
-- 2. 演示purge之后；是不能进行闪回。
SQL> drop table tbl_flash_01 purge;Table dropped.SQL> flashback table tbl_flash_01 to before drop;
flashback table tbl_flash_01 to before drop
*
ERROR at line 1:
ORA-38305: object not in RECYCLE BIN-- 3. 演示闪回对象名已经存在；又该如何恢复
SQL> drop table tbl_flash_01;Table dropped.SQL> create table tbl_flash_01 (id number,name varchar2(20));Table created.SQL> flashback table tbl_flash_01 to before drop;
flashback table tbl_flash_01 to before drop
*
ERROR at line 1:
ORA-38312: original name is used by an existing objectSQL> flashback table tbl_flash_01 to before drop rename to tbl_flash_02;Flashback complete.-- 4. 若回收站中存在两个相同的原表名，则闪回时总是闪回最近的版本，如果闪回特定的表，需要指定该表在回收站中的名称
SQL> create table tbl_flash_01 (id number,name varchar2(20));Table created.SQL> drop table tbl_flash_01;Table dropped.SQL> create table tbl_flash_01 (id number,name varchar2(20),reg_time date);Table created.SQL> drop table tbl_flash_01;Table dropped.SQL> show recyclebin;
ORIGINAL NAME  RECYCLEBIN NAME  OBJECT TYPE  DROP TIME
---------------- ------------------------------ ------------ ---------
TBL_FLASH_01  BIN$c2hFCisLCOXgU+oBqMCsVQ==$0 TABLE 2018-08-15:00:47:38
TBL_FLASH_01  BIN$c2hFCisKCOXgU+oBqMCsVQ==$0 TABLE 2018-08-15:00:24:22-- 选择恢复最先删除的。
SQL> flashback table "BIN$c2hFCisKCOXgU+oBqMCsVQ==$0" to before drop;Flashback complete.SQL> desc tbl_flash_01 ;Name        Null?    Type-------------- -------- ------------------ID          NUMBERNAME          VARCHAR2(20)

-- 查询表tab_flash_02 5分钟之前的数据
select * from tab_flash_02 as of timestamp sysdate - 5/1440;
-- 查询表tab_flash_02 某个时间点的记录
select * from tab_flash_02 as of timestamp to_timestamp('2018-08-13 17:26:08','yyyy-mm-dd hh24:mi:ss');