oracle删除表和表数据后如何闪回

10G开始默认drop表后改名移动到回收站;
闪回（flashback）语句：
1、能在一个语句中把表恢复到指定的时间点；
2、恢复表数据连同索引与约束信息；
3、能返回表及其内容到指定时间点或系统变更号（SCN）；
4、修复表的误操作

--闪回简单示例：
SQL> drop table emp2;
Table dropped
SQL> select original_name,operation,droptime from recyclebin;
ORIGINAL_NAME                    OPERATION DROPTIME
-------------------------------- --------- -------------------
EMP2                             DROP      2012-11-16:10:49:13

SQL> flashback table emp2 to before drop;
Done
SQL> select count(*) from emp2;
  COUNT(*)
----------
       107

--恢复误删表数据示例：
SQL>  select sysdate 时间, timestamp_to_scn(sysdate) SCN from dual;
时间               SCN
----------- ----------
2012/11/16     1230043

SQL> delete from emp2;
107 rows deleted

SQL> commit;
Commit complete

SQL> select count(*) from emp2;
  COUNT(*)
----------
         0

SQL> flashback table emp2 to scn 1230043;
flashback table emp2 to scn 1230043
ORA-08189: cannot flashback the table because row movement is not enabled

SQL> alter table emp2 enable row movement;
Table altered

SQL> flashback table emp2 to scn 1230043;
Done

SQL> select count(*) from emp2;

  COUNT(*)
----------
       107