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，当你需要恢复数据的时候，你可以登陆到数据库上仔细查看，如果是Oracle9iR2，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

 

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）

 

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

 

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。