oracle忘记用户名密码怎样办？？？

一、忘记除SYS、SYSTEM用户之外的用户的登录密码。

　　用SYS (或SYSTEM)用户登录。

　　CONN SYS/PASS_WORD AS SYSDBA;

　　使用如下语句修改用户的密码。

　　ALTER USER user_name IDENTIFIED BY newpass;

　　注意：密码不能全是数字。并且不能是数字开头。否则会出现：ORA-00988: 口令缺失或无效

　　二、忘记SYS用户，或者是SYSTEM用户的密码。

　　如果是忘记SYSTEM用户的密码，可以用SYS用户登录。然后用ALTER USER 密令

　　修改密码。

　　CONN SYS//PASS_WORD AS SYSDBA;

　　ALTER USER SYSTEM IDENTIFIED BY newpass;

　　如果是忘记SYS用户的密码，可以用SYSTEM用户登录。然后用ALTER USER 密令

　　修改密码。

　　CONN SYSTEM//PASS_WORD ;

　　ALTER USER SYSTEM IDENTIFIED BY newpass;

　三、如果SYS,SYSTEM用户的密码都忘记或是丢失。

　　这一项尤其重要。

方法一、

　　可以使用ORAPWD.EXE 工具修改密码。

　　开始菜单->运行->输入‘CMD’,打开命令提示符窗口，输入如下命令：

　　orapwd file=D:\oracle\product\10.2.0\db_1\database\pwdctcsys.ora

　　password=newpass

　　这个命令重新生成了数据库的密码文件。密码文件的位置在ORACLE_HOME目录下

　　的\database目录下。　　这个密码是修改sys用户的密码。除sys和system其他用户的密码不会改变。

方法二、

1.如果不记得sys用户的密码了，采用如下方法可以修改密码：
(1)打开cmd，输入sqlplus /nolog，回车。
(2)输入“conn / as sysdba”;
(3)输入“alter user sys identified by 新密码;”（新密码必须以字母开头，另外每条SQL语句后得分号不能忘）
其他用户方式同理

2.(1)在cmd中启动sqlplus；

(2)用sqlplus/as sysdba登录，使其连接到:

OracleDatabase 10g Express Edition Release 10.2.0.1.0 - Production

(3)执行ALTER USER DBSNMP ACCOUNT UNLOCK；

(4) 从新用SQL/PLUS登录，设置用户名、密码；

附：Oracle10g 默认安装带来的用户名/密码

Username	Password	Description	See Also
CTXSYS	CTXSYS	The OracleText account	OracleText Reference
DBSNMP	DBSNMP	The account used by the Management Agent component of OracleEnterprise Manager to monitor and manage the database	OracleEnterprise Manager Grid Control Installation and Basic Configuration
LBACSYS	LBACSYS	The OracleLabel Security administrator account	OracleLabel Security Administrator's Guide
MDDATA	MDDATA	The schema used by OracleSpatial for storing Geocoder and router data	OracleSpatial User's Guide and Reference
MDSYS	MDSYS	The OracleSpatial and OracleinterMedia Locator administrator account	OracleSpatial User's Guide and Reference
DMSYS	DMSYS	The OracleData Mining account.	OracleData Mining Administrator's Guide OracleData Mining Concepts
OLAPSYS	MANAGER	The account used to create OLAP metadata structures. It owns the OLAP Catalog (CWMLite).	OracleOLAP Application Developer's Guide
ORDPLUGINS	ORDPLUGINS	The OracleinterMedia user. Plug-ins supplied by Oracleand third party format plug-ins are installed in this schema.	OracleinterMedia User's Guide
ORDSYS	ORDSYS	The OracleinterMedia administrator account	OracleinterMedia User's Guide
OUTLN	OUTLN	The account that supports plan stability. Plan stability enables you to maintain the same execution plans for the same SQL statements. OUTLN acts as a role to centrally manage metadata associated with stored outlines.	OracleDatabase Performance Tuning Guide
SI_INFORMTN_SCHEMA	SI_INFORMTN_SCHEMA	The account that stores the information views for the SQL/MM Still Image Standard	OracleinterMedia User's Guide
SYS	CHANGE_ON_INSTALL	The account used to perform database administration tasks	OracleDatabase Administrator's Guide
SYSMAN	CHANGE_ON_INSTALL	The account used to perform OracleEnterprise Manager database administration tasks. Note that SYS and SYSTEM can also perform these tasks.	OracleEnterprise Manager Grid Control Installation and Basic Configuration
SYSTEM	MANAGER	Another account used to perform database administration tasks.