改变DBID(数据库内部的惟一标识符,RMAN中区分不同数据库):
A.关闭数据库
     conn sys/orcl@orcl as sysdba
     shutdown immediate
     startup mount

B.改变DBID
    host nid target=sys/oracle@orcl
    或
    nid target=sys/oracle@orcl (在DOS下)

C.装载并打开数据库
    conn sys/orcl@orcl as sysdba
    startup mount
    alter database open resetlogs

ITPub博客

dbnewid使用