如何利用Flashback Query 恢復誤刪除的數據

網上有不少關於數據回覆的文章，這裏整理一篇供你們參考，但願能幫助的你們！

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好了，言歸正傳！若是你在工做中誤刪除了一部分重要的數據，而且已經提交，若是你須要回覆這些數據，你能夠登錄到數據庫上仔細查看，是Oracle9iR2的話，你能夠首先嚐試使用flashback query閃回數據。

 

◆第一步：確認數據庫的SCN變化:

 

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.

 

◆此時的SCN爲：

1. SQL> select dbms_flashback.
2. get_system_change_number fscn from dual;
4.                 FSCN
5. --------------------
6.          12930142214

◆此時使用應用用戶嘗試閃回

 

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

 

◆現有的數據

1. SQL> select count(*) from hs_passport;
   
2.  
3.   COUNT(*)
   
4. ----------
   
5.     851998

 

◆建立恢復表

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

 

◆此處選擇SCN向前恢復

1.  
2. 如下爲引用的內容：
   
3. SQL> select count(*) from hs_passport as of scn 12929970422;
   
4.   COUNT(*)
   
5. ----------
   
6.     861686

 

◆嘗試多個SCN，獲取最佳值（註釋：若是能夠得知具體時間，那樣則能夠得到準確的數據閃回）

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

 

 

◆注意：最後選擇恢復到SCN爲12929941968的時間點

1.  
2. 如下爲引用的內容：
   
3. SQL> 
   
4. insert into hs_passport_recov 
   
5. select * from hs_passport as of scn 12929941968;
   
6. 861684 rows created.
   
7. SQL> commit;
   
8. Commit complete.

 

註釋：至此，則能夠知足須要，找回誤刪除的部分數據，閃回恢復成功。