一般这玩意没人修改，除非特殊情况，比如克隆数据库等等
步骤：
1.备份数据库
2.启动数据到mount状态
3.nid命令修改 （如果只是修改dbid，那么不需要dbname参数，需要更改dbname加上此参数即可，如果只修改dbname，那么需要setname参数为yes）
4.alter database open resetlogs打开数据库
nid语法以及参数含义：
| Parameter | Description |
|---|---|
TARGET |
Specifies the username and password used to connect to the database. The user must have the SYSDBA privilege. If you are using operating system authentication, then you can connect with the slash (/). If the $ORACLE_HOME and $ORACLE_SID variables are not set correctly in the environment, then you can specify a secure (IPC or BEQ) service to connect to the target database. A target database must be specified in all invocations of the DBNEWID utility. |
REVERT |
Specify YES to indicate that a failed change of DBID should be reverted (default is NO). The utility signals an error if no change DBID operation is in progress on the target database. A successfully completed change of DBID cannot be reverted. REVERT=YES is valid only when a DBID change failed. |
DBNAME=new_db_name |
Changes the database name of the database. You can change the DBID and the DBNAME of a database at the same time. To change only the DBNAME, also specify the SETNAME parameter. |
SETNAME |
Specify YES to indicate that DBNEWID should change the database name of the database but should not change the DBID (default is NO). When you specify SETNAME=YES, the utility writes only to the target database control files. |
LOGFILE=logfile |
Specifies that DBNEWID should write its messages to the specified file. By default the utility overwrites the previous log. If you specify a log file, then DBNEWID does not prompt for confirmation. |
APPEND |
Specify YES to append log output to the existing log file (default is NO). |
HELP |
Specify YES to print a list of the DBNEWID syntax options (default is NO). |
实例：
SQL> conn /as sysdba
Connected.
SQL> select dbid from v$database;
DBID
----------
148366931
SQL> startup mount;
ORACLE instance started.
Total System Global Area 5049942016 bytes
Fixed Size 2090880 bytes
Variable Size 1375733888 bytes
Database Buffers 3657433088 bytes
Redo Buffers 14684160 bytes
Database mounted.
SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
oracle@readerlogdb-> nid target=sys/sys@skyread
DBNEWID: Release 10.2.0.4.0 - Production on Mon Jul 1 11:16:09 2013
Copyright (c) 1982, 2007, Oracle. All rights reserved.
Connected to database SKYREAD (DBID=148366931)
Connected to server version 10.2.0
Control Files in database:
/database/oradata/skyread/control01.ctl
/database/oradata/skyread/control02.ctl
/database/oradata/skyread/control03.ctl
Change database ID of database SKYREAD? (Y/[N]) => y
Proceeding with operation
Changing database ID from 148366931 to 277140985
Control File /database/oradata/skyread/control01.ctl - modified
Control File /database/oradata/skyread/control02.ctl - modified
Control File /database/oradata/skyread/control03.ctl - modified
Datafile /database/oradata/skyread/system01.dbf - dbid changed
Datafile /database/oradata/skyread/tbs_test.dbf - dbid changed
Datafile /database/oradata/skyread/sysaux01.dbf - dbid changed
Datafile /database/oradata/skyread/users01.dbf - dbid changed
Datafile /database/oradata/skyread/system02.dbf - dbid changed
Datafile /database2/oradata/skyread/undotbs02.dbf - dbid changed
Datafile /database2/oradata/skyread/TBS_MRPMUSIC01.dbf - dbid changed
Datafile /database/oradata/skyread/sf01.dbf - dbid changed
Control File /database/oradata/skyread/control01.ctl - dbid changed
Control File /database/oradata/skyread/control02.ctl - dbid changed
Control File /database/oradata/skyread/control03.ctl - dbid changed
Instance shut down
Database ID for database SKYREAD changed to 277140985.
All previous backups and archived redo logs for this database are unusable.
Database is not aware of previous backups and archived logs in Recovery Area.
Database has been shutdown, open database with RESETLOGS option.
Succesfully changed database ID.
DBNEWID - Completed succesfully.
SQL> startup;
ORACLE instance started.
Total System Global Area 5049942016 bytes
Fixed Size 2090880 bytes
Variable Size 1375733888 bytes
Database Buffers 3657433088 bytes
Redo Buffers 14684160 bytes
Database mounted.
ORA-01589: must use RESETLOGS or NORESETLOGS option for database open
SQL> alter database open resetlogs;
Database altered.
SQL> select dbid from v$database;
DBID
----------
277140985
这里只是修改了dbid，其他的不再举例，有兴趣可以自己试验