如果你在工作中誤刪除了一部分重要的數據，並且已經提交，當你需要恢復數據的時候，你可以登陸到數據庫上仔細查看，如果是Oracle9iR2，你可以首先嘗試使用Flashback query閃回數據。
◆第一步：確認數據庫的SCN變化:
以下為引用的內容：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.
◆此時的SCN為：
以下為引用的內容：
SQL> select dbms_Flashback.
get_system_change_number fscn from dual;
FSCN
--------------------
12930142214
◆此時使用應用用戶嘗試閃回
以下為引用的內容：SQL> connect username/passWord
Connected.
◆現有的數據:
以下為引用的內容：
SQL> select count(*) from hs_passport;
COUNT(*)
----------
851998
◆創建恢復表
以下為引用的內容：SQL> create table hs_passport_recov
as select * from hs_passport where 1=0;
Table created.
◆此處選擇SCN向前恢復
以下為引用的內容：SQL> select count(*) from hs_passport as of scn 12929970422;
COUNT(*)
----------
861686
◆嘗試多個SCN，獲取最佳值（注釋：如果可以得知具體時間，那樣則可以獲得准確的數據閃回）
以下為引用的內容：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：最後選擇恢復到SCN為12929941968的時間點
以下為引用的內容：SQL>
insert into hs_passport_recov
select * from hs_passport as of scn 12929941968;
861684 rows created.
SQL> commit;
Commit complete.
注釋：至此，則可以滿足需要，找回誤刪除的部分數據，閃回恢復成功。
