1.查询v$database获得

因为DBID在控制文件和数据文件里都存在记录,所以假设可以mount数据库就行查询v$database视图获得. 

SQL> alter database mount;

Database altered.

SQL> select dbid from v$database;

      DBID

----------

1363251591

2.在nomount状态时

假设数据库配置了自己主动控制文件备份(Oracle9i),而且名称是缺省的,那么我们能够从自己主动备份文件获得DBID. 

[oracle@jumper dbs]$ cd $ORACLE_HOME/dbs

[oracle@jumper dbs]$ ll c-*

-rw-r----- 1 oracle dba 3375104 Dec 21 11:13 c-1363251591-20051221-00

-rw-r----- 1 oracle dba 3358720 Jan 21 14:03 c-1363251591-20060121-00

-rw-r----- 1 oracle dba 3358720 Jan 21 14:08 c-1363251591-20060121-01

这里的1363251591就是DBID。在10g中，使用Flash Recovery Area。则没有这个命名规则。

3.从自己主动备份中恢复

须要或缺DBID进行恢复一般是由于丢失了全部的控制文件.在恢复时会遇到错误.

[oracle@jumper dbs]$ rman target  /

Recovery Manager: Release 9.2.0.4.0 - Production

Copyright (c) 1995, 2002, Oracle Corporation.  All rights reserved.

connected to target database: conner (not mounted)

RMAN> restore controlfile from autobackup;

Starting restore at 05-FEB-06

using target database controlfile instead of recovery catalog

allocated channel: ORA_DISK_1

channel ORA_DISK_1: sid=11 devtype=DISK

RMAN-00571: ===========================================================

RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

RMAN-00571: ===========================================================

RMAN-03002: failure of restore command at 02/05/2006 20:47:25

RMAN-06495: must explicitly specify DBID with SET DBID command 

假设存在自己主动备份,我们通常能够直接恢复控制文件,mount数据库之后就好办了: 

RMAN> restore controlfile from '/opt/oracle/product/9.2.0/dbs/c-1363251591-20051221-00';

Starting restore at 05-FEB-06

using channel ORA_DISK_1

channel ORA_DISK_1: restoring controlfile

channel ORA_DISK_1: restore complete

replicating controlfile

input filename=/opt/oracle/oradata/conner/control01.ctl

output filename=/opt/oracle/oradata/conner/control02.ctl

output filename=/opt/oracle/oradata/conner/control03.ctl

Finished restore at 05-FEB-06

 

4.直接从幸存的文件里读取

因为DBID存在于数据文件及控制文件里,所以我们能够通过PL/SQL程序直接从文件里读取: 

SQL> select eygle.get_dbid('/opt/oracle/oradata/conner','user02.dbf') from dual;

EYGLE.GET_DBID('/OPT/ORACLE/OR

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

1363251591

SQL> select dbid from v$database;

DBID

----------

1363251591

 事实上更简单的，用BBED就好了。

这样的方法仅为測试兴趣所致,不被推荐.

--此处为eygle自己定义的函数  （抽时间我会补上）

5、通过dump数据文件获取dbid：

SYS@orcl> alter system dump datafile 'D:\APP\ADMINISTRATOR\ORADATA\ORCL\USERS01.DBF' block 1000;

系统已更改。

SYS@orcl> select tracefile from v$process where addr in (select paddr from v$session where sid in (select sid from v$mystat));

--查看trace文件：Db ID=1363251591

TRACEFILE

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

d:\app\administrator\diag\rdbms\orcl\orcl\trace\orcl_ora_6740.trc

Start dump data block from file D:\APP\ADMINISTRATOR\ORADATA\ORCL\USERS01.DBF minblk 0 maxblk -1

 V10 STYLE FILE HEADER:

Compatibility Vsn = 186646528=0xb200000

Db ID=1363251591=0x51419187, Db Name='ORCL'

Activation ID=0=0x0

Control Seq=10579=0x2953, File size=1600=0x640

File Number=4, Blksiz=8192, File Type=3 DATA

Dump all the blocks in range:

...

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

Dylan    Presents.