Oracle 11g数据库安装的时候，跳过了密码设置那一项。在后来需要使用sys和system的时候，老是提示密码不对。这里提供一种能重新设置这些用户密码的方法。

使用sqlplus登陆数据库：

bash-3.00$ sqlplus / as sysdba

sql*Plus: Release 10.2.0.2.0 - Production on Fri Nov 30 16:29:59 2012

Copyright (c) 1982,2005,Oracle. All Rights Reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.2.0 - Production
With the Partitioning,OLAP and Data Mining options

sql> alter user sys identified by admin;

User altered.

sql> conn sys/admin as sysdba;
Connected.
sql> alter user system identified by admin;

User altered.

至此，你就可以使用自己设置的密码登陆数据库了。