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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.
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◆此时的scn为：
sql> select dbms_flashback.
get_system_change_number fscn from dual;
fscn
--------------------
12930142214
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◆此时使用应用用户尝试闪回
sql> connect username/password
connected.
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◆现有的数据:
sql> select count(*) from hs_passport;
count(*)
----------
851998
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◆创建恢复表
sql> create table hs_passport_recov
as select * from hs_passport where 1=0;
table created.
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1
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下一页>>
◆此处选择scn向前恢复
sql> select count(*) from hs_passport as of scn 12929970422;
count(*)
----------
861686
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◆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
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◆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.
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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。
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