查询当前的SCN:

SQL> select current_scn from v$database;

CURRENT_SCN

-----------

    1170420

清空表（truncate表后是不能进行闪回表的）

SQL> truncate table tom.t;

Table truncated.

SQL> select * from tom.t;

no rows selected

关闭实例启动到mount状态：

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount;      

ORACLE instance started.

Total System Global Area  417546240 bytes

Fixed Size                  2228944 bytes

Variable Size             318770480 bytes

Database Buffers           88080384 bytes

Redo Buffers                8466432 bytes

Database mounted.

闪回数据库到SNC 1170420:

SQL> flashback database to scn 1170420;

Flashback complete.

只读方式打开数据库，查询数据是否恢复:

SQL> alter database open read only;

Database altered.

SQL> select * from tom.t;

        ID NAME

---------- --------------------

         3 mark3

         1 mark1

         2 mark2

关闭数据库，以resetlogs方式打开数据库：

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount;

ORACLE instance started.

Total System Global Area  417546240 bytes

Fixed Size                  2228944 bytes

Variable Size             318770480 bytes

Database Buffers           88080384 bytes

Redo Buffers                8466432 bytes

Database mounted.

SQL> alter database open resetlogs;

Database altered.

SQL> select current_scn from v$database;

CURRENT_SCN

-----------

    1170730

SQL> archive log list;

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     1

Next log sequence to archive   1

Current log sequence           1

SQL>