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:

1. SQL> col fscn for 9999999999999999999
2. SQL> col nscn for 9999999999999999999
3. SQL> select name,FIRST_CHANGE# fscn,NEXT_CHANGE# nscn,FIRST_TIME from v$archived_log;
4. ...................
5. NAME                               FSCN       NSCN FIRST_TIME
6. ----------------------------     ---------   -------------------
7. /mwarch/oracle/1_52413.dbf     12929941968   12929942881 2005-06-22 14:38:28
8. /mwarch/oracle/1_52414.dbf     12929942881   12929943706 2005-06-22 14:38:32
9. /mwarch/oracle/1_52415.dbf     12929943706   12929944623 2005-06-22 14:38:35
10. /mwarch/oracle/1_52416.dbf     12929944623   12929945392 2005-06-22 14:38:38
11. /mwarch/oracle/1_52417.dbf     12929945392   12929945888 2005-06-22 14:38:41
12. /mwarch/oracle/1_52418.dbf     12929945888   12929945965 2005-06-22 14:38:44
13. /mwarch/oracle/1_52419.dbf     12929945965   12929948945 2005-06-22 14:38:45
14. /mwarch/oracle/1_52420.dbf     12929948945   12929949904 2005-06-22 14:46:05
15. /mwarch/oracle/1_52421.dbf     12929949904   12929950854 2005-06-22 14:46:08
16. /mwarch/oracle/1_52422.dbf     12929950854   12929951751 2005-06-22 14:46:11
17. /mwarch/oracle/1_52423.dbf     12929951751   12929952587 2005-06-22 14:46:14
18. ...................
19. /mwarch/oracle/1_52498.dbf     12930138975   12930139212 2005-06-22 15:55:57
20. /mwarch/oracle/1_52499.dbf     12930139212   12930139446 2005-06-22 15:55:59
21. /mwarch/oracle/1_52500.dbf     12930139446   12930139682 2005-06-22 15:56:00
22. NAME                             FSCN           NSCN FIRST_TIME
23. -------------------------  -------------       -----------
24. /mwarch/oracle/1_52501.dbf     12930139682    12930139915 2005-06-22 15:56:02
25. /mwarch/oracle/1_52502.dbf     12930139915    12930140149 2005-06-22 15:56:03
26. /mwarch/oracle/1_52503.dbf     12930140149    12930140379 2005-06-22 15:56:05
27. /mwarch/oracle/1_52504.dbf     12930140379    12930140610 2005-06-22 15:56:05
28. /mwarch/oracle/1_52505.dbf     12930140610    12930140845 2005-06-22 15:56:07
29. 14811 rows selected.

◆此时的SCN为：

1. SQL> select dbms_flashback.
2. get_system_change_number fscn from dual;
3. FSCN
4. --------------------
5. 12930142214

◆此时使用应用用户尝试闪回

1. SQL> connect username/password
2. Connected.

◆现有的数据

1. SQL> select count(*) from hs_passport;
2. COUNT(*)
3. ----------
4. 851998

◆创建恢复表

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

◆此处选择SCN向前恢复

1. 以下为引用的内容：
2. SQL> select count(*) from hs_passport as of scn 12929970422;
3. COUNT(*)
4. ----------
5. 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）

1. 以下为引用的内容：
2. SQL> select count(*) from hs_passport as of scn &scn;
3. Enter value for scn: 12929941968
4. old   1: select count(*) from hs_passport as of scn &scn
5. new   1: select count(*) from hs_passport as of scn 12929941968
6. COUNT(*)
7. ----------
8. 861684
9. SQL> /
10. Enter value for scn: 12927633776
11. old   1: select count(*) from hs_passport as of scn &scn
12. new   1: select count(*) from hs_passport as of scn 12927633776
13. select count(*) from hs_passport as of scn 12927633776
14. *
15. ERROR at line 1:
16. ORA-01466: unable to read data - table definition has changed
17. SQL> /
18. Enter value for scn: 12929928784
19. old   1: select count(*) from hs_passport as of scn &scn
20. new   1: select count(*) from hs_passport as of scn 12929928784
21. COUNT(*)
22. ----------
23. 825110
24. SQL> /
25. Enter value for scn: 12928000000
26. old   1: select count(*) from hs_passport as of scn &scn
27. new   1: select count(*) from hs_passport as of scn 12928000000
28. select count(*) from hs_passport as of scn 12928000000
29. *
30. ERROR at line 1:
31. 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

1. 以下为引用的内容：
2. SQL>
3. insert into hs_passport_recov
4. select * from hs_passport as of scn 12929941968;
5. 861684 rows created.
6. SQL> commit;
7. 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。