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:
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：
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
SQL> connect username/passWord Connected.
◆現有的數據:
SQL> select count(*) from hs_passport; COUNT(*) ---------- 851998
◆創建恢復表
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
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）
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
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。
