dataifle误删除的模拟recover

Oracle 恢复试习一：
　1. 热备份tablespace users.
  2. a) scott login,
     b) create table tt( seq number);
     c) declare
          i number;
        begin
          for i in 1..20
          loop
             insert into tt values(i);
          end loop;
          commit;
        end;
      d) alter system switch logfile;
      e) insert into tt values(21);
         alter system switch logfile;
         ...
         直到所有online redo file都做了archived(测试archived log的应用)
      f) commit;
   3. shutdown immediate;
   4. rm datafile users;

恢复如下：
SQL> startup
ORACLE instance started.

Total System Global Area  285212672 bytes
Fixed Size     1218992 bytes
Variable Size   121636432 bytes
Database Buffers   159383552 bytes
Redo Buffers     2973696 bytes
Database mounted.
ORA-01157: cannot identify/lock data file 4 - see DBWR trace file
ORA-01110: data file 4: '/oracle/oracle/product/10.2.0/oradata/orcl/users01.dbf'


SQL> host cp /oracle/backup/users01.dbf /oracle/oracle/product/10.2.0/oradata/orcl/

SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01113: file 4 needs media recovery
ORA-01110: data file 4: '/oracle/oracle/product/10.2.0/oradata/orcl/users01.dbf'

SQL> recover tablespace users;
ORA-00279: change 546700 generated at 05/14/2013 20:51:07 needed for thread 1
ORA-00289: suggestion : /oracle/oracle/product/10.2.0/db_1/flash_recovery_area/ORCL/archivelog/2013_05_14/o1_mf_1_6_%u_.arc
ORA-00280: change 546700 for thread 1 is in sequence #6

--- ORA-00289　：寻archived log file恢复...因为

Specify log: {<RET>=suggested | filename | AUTO | CANCEL}

Log applied.
Media recovery complete.
SQL> alter database open;

Database altered.


注：
scn的查看：
1.select file#,checkpoint_change# from v$datafile_header;
2.select file#,checkpoint_change# from v$datafile;
  v$datafile_header的信息来自各数据文件的文件头.
  v$datafile的信息则来自control file
3.select sequence#,first_change#,next_change# from v$archived_log;
4.select dbms_flashback.get_system_change_number from dual;-- system scn