Oracle忘记用户名密码怎么办？

对于oracle10g来说：

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:

 Oracle Database  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：Oracle 10g 默认安装带来的用户名/密码

Username	Password	Description	See Also
CTXSYS		The Oracle Text account	Oracle Text Reference
DBSNMP		The account used by the Management Agent component of Oracle Enterprise Manager to monitor and manage the database	Oracle Enterprise Manager Grid Control Installation and Basic Configuration
LBACSYS		The Oracle Label Security administrator account	Oracle Label Security Administrator's Guide
MDDATA		The schema used by Oracle Spatial for storing Geocoder and router data	Oracle Spatial User's Guide and Reference
MDSYS		The Oracle Spatial and Oracle interMedia Locator administrator account
DMSYS		The Oracle Data Mining account.	Oracle Data Mining Administrator's Guide Oracle Data Mining Concepts
OLAPSYS	MANAGER	The account used to create OLAP metadata structures. It owns the OLAP Catalog (CWMLite).	Oracle OLAP Application Developer's Guide
ORDPLUGINS		The Oracle interMedia user. Plug-ins supplied by Oracle and third party format plug-ins are installed in this schema.	Oracle interMedia User's Guide
ORDSYS		The Oracle interMedia administrator account
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.	Oracle Database Performance Tuning Guide
SI_INFORMTN_SCHEMA		The account that stores the information views for the SQL/MM Still Image Standard
SYS	CHANGE_ON_INSTALL	The account used to perform database administration tasks	Oracle Database Administrator's Guide
SYSMAN		The account used to perform Oracle Enterprise Manager database administration tasks. Note that SYS and SYSTEM can also perform these tasks.
SYSTEM		Another account used to perform database administration tasks.