安装数据库时的用户名和密码忘了
安装oracle时建立的那个id和password，忘了。

------解决方案--------------------
用SYS用户去登陆

CONN /AS SYSDBA


然后修改密码

------解决方案--------------------
C:\Documents and Settings\Administrator> sqlplus /nolog

SQL*Plus: Release 9.2.0.1.0 - Production on Thu May 10 12:57:48 2007

Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.

SQL> conn /as sysdba
Connected.
SQL> alter user sys identified by oracle;

User altered.

SQL>