如何利用Flashback Query 恢复误删除的数据

网上有很多关于数据回复的文章，这里整理一篇供大家参考，希望能帮助的大家！

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好了，言归正传！如果你在工作中误删除了一部分重要的数据，并且已经提交，如果你需要回复这些数据，你可以登陆到数据库上仔细查看，是Oracle9iR2的话，你可以首先尝试使用flashback query闪回数据。

◆第一步：确认数据库的SCN变化:

SQL> col fscn for 9999999999999999999
SQL> col nscn for 9999999999999999999
SQL> select name,FIRST_CHANGE# fscn,NEXT_CHANGE# nscn,FIRST_TIME from v$archived_log;
...................
NAME FSCN NSCN FIRST_TIME
---------------------------- --------- -------------------
/mwarch/oracle/1_52413.dbf 12929941968 12929942881 2005-06-22 14:38:28
/mwarch/oracle/1_52414.dbf 12929942881 12929943706 2005-06-22 14:38:32
/mwarch/oracle/1_52415.dbf 12929943706 12929944623 2005-06-22 14:38:35
/mwarch/oracle/1_52416.dbf 12929944623 12929945392 2005-06-22 14:38:38
/mwarch/oracle/1_52417.dbf 12929945392 12929945888 2005-06-22 14:38:41
/mwarch/oracle/1_52418.dbf 12929945888 12929945965 2005-06-22 14:38:44
/mwarch/oracle/1_52419.dbf 12929945965 12929948945 2005-06-22 14:38:45
/mwarch/oracle/1_52420.dbf 12929948945 12929949904 2005-06-22 14:46:05
/mwarch/oracle/1_52421.dbf 12929949904 12929950854 2005-06-22 14:46:08
/mwarch/oracle/1_52422.dbf 12929950854 12929951751 2005-06-22 14:46:11
/mwarch/oracle/1_52423.dbf 12929951751 12929952587 2005-06-22 14:46:14
...................
/mwarch/oracle/1_52498.dbf 12930138975 12930139212 2005-06-22 15:55:57
/mwarch/oracle/1_52499.dbf 12930139212 12930139446 2005-06-22 15:55:59
/mwarch/oracle/1_52500.dbf 12930139446 12930139682 2005-06-22 15:56:00
NAME FSCN NSCN FIRST_TIME
------------------------- ------------- -----------
/mwarch/oracle/1_52501.dbf 12930139682 12930139915 2005-06-22 15:56:02
/mwarch/oracle/1_52502.dbf 12930139915 12930140149 2005-06-22 15:56:03
/mwarch/oracle/1_52503.dbf 12930140149 12930140379 2005-06-22 15:56:05
/mwarch/oracle/1_52504.dbf 12930140379 12930140610 2005-06-22 15:56:05
/mwarch/oracle/1_52505.dbf 12930140610 12930140845 2005-06-22 15:56:07
14811 rows selected.

◆此时的SCN为：

SQL> select dbms_flashback.
get_system_change_number fscn from dual;
FSCN
--------------------
12930142214

◆此时使用应用用户尝试闪回

SQL> connect username/password
Connected.

◆现有的数据

SQL> select count(*) from hs_passport;
COUNT(*)
----------
851998

◆创建恢复表

SQL> create table hs_passport_recov
as select * from hs_passport where 1=0;
Table created.

◆此处选择SCN向前恢复

以下为引用的内容：
SQL> select count(*) from hs_passport as of scn 12929970422;
COUNT(*)
----------
861686

◆尝试多个SCN，获取最佳值（注释：如果可以得知具体时间，那样则可以获得准确的数据闪回）

以下为引用的内容：
SQL> select count(*) from hs_passport as of scn &scn;
Enter value for scn: 12929941968
old 1: select count(*) from hs_passport as of scn &scn
new 1: select count(*) from hs_passport as of scn 12929941968
COUNT(*)
----------
861684
SQL> /
Enter value for scn: 12927633776
old 1: select count(*) from hs_passport as of scn &scn
new 1: select count(*) from hs_passport as of scn 12927633776
select count(*) from hs_passport as of scn 12927633776
*
ERROR at line 1:
ORA-01466: unable to read data - table definition has changed
SQL> /
Enter value for scn: 12929928784
old 1: select count(*) from hs_passport as of scn &scn
new 1: select count(*) from hs_passport as of scn 12929928784
COUNT(*)
----------
825110
SQL> /
Enter value for scn: 12928000000
old 1: select count(*) from hs_passport as of scn &scn
new 1: select count(*) from hs_passport as of scn 12928000000
select count(*) from hs_passport as of scn 12928000000
*
ERROR at line 1:
ORA-01466: unable to read data - table definition has changed

◆注意：最后选择恢复到SCN为12929941968的时间点

以下为引用的内容：
SQL>
insert into hs_passport_recov
select * from hs_passport as of scn 12929941968;
861684 rows created.
SQL> commit;
Commit complete.

注释：至此，则可以满足需要，找回误删除的部分数据，闪回恢复成功。