Oracle Drop 表数据恢复

利用Oracle 数据回闪机制进行恢复，当一个表被drop掉，表会被放入recyclebin回收站，可通过回收站做表的闪回。表上的索引、约束等同样会被恢复
不支持sys/system用户表空间对象，可通过alter system set recyclebin=off;关闭回收站功能。

Retrieving a Dropped Table: Example If you accidentally drop the pm.print_media table and want to retrieve it, then issue the following statement:

1	`FLASHBACK TABLE print_media TO BEFORE DROP;`

If another print_media table has been created in the pm schema, then use the RENAME TO clause to rename the retrieved table:

1	`FLASHBACK TABLE print_media TO BEFORE DROP RENAME TO print_media_old;`

If you know that the employees table has been dropped multiple times, and you want to retrieve the oldest version, then query the USER_RECYLEBIN table to determine the system-generated name, and then use that name in the FLASHBACK TABLE statement. (System-generated names in your database will differ from those shown here.)

SELECT object_name, droptime FROM user_recyclebin 
   WHERE original_name = 'PRINT_MEDIA';
 
OBJECT_NAME                    DROPTIME
------------------------------ -------------------
RB$$45703$TABLE$0              2003-06-03:15:26:39
RB$$45704$TABLE$0              2003-06-12:12:27:27
RB$$45705$TABLE$0              2003-07-08:09:28:01　

其他回闪语句：

1.闪回数据库
　　FLASHBACK DATABASE TO TIMESTAMP to_timestamp('2019-10-14 14:28:33','yyyy-mm-dd HH24:MI:SS');;
　　flashback database to scn 16813234;
2.闪回表
　　flashback table table_name to scn scn_number;
　　flashback table table_name to timestamp to_timestamp('2019-10-14 14:28:33','yyyy-mm-dd hh24:mi:ss');
3.闪回查询
　　select * from table_name as of timestamp to_timestamp('2019-10-14 14:28:33','yyyy-mm-dd hh24:mi:ss');
　　select * from scott.dept as of scn 16801523;
4.闪回快照
   create restore point before_201910151111 guarantee flashback database;
   flashback database to restore point before_201910151111;