ORACLE 11G failed to connect to the database instance troubleshooting

This article describes in detail the Oracle 11G failure to connect to the database instance troubleshooting

ORACLE 11G If the report--enterprise Manager is unable to connect to the database instance, you can troubleshoot the problem by following these methods:

1, using SQL PLUS.

Run SQL PLUS in DOS mode.

Sql> Conn

Please enter user name: SYS as SYSDBA

Enter Password:

Connection Successful

Sql>desc dba_users

Note: If you are prompted to find that the view is invalid. The new building of User_astatus_map, dba_users with D:\ORACLE\PRODUCT\10.2.0\DB_1\RDBMS\ADMINSQL.BSQ. Otherwise, the following information is displayed:

is the name empty? Type

----------------------------------------- -------- ----

USERNAME not NULL VARCHAR2 (30)

USER_ID not NULL number

PASSWORD VARCHAR2 (30)

Account_status not NULL VARCHAR2 (32)

Lock_date DATE

Expiry_date DATE

Default_tablespace not NULL VARCHAR2 (30)

Temporary_tablespace not NULL VARCHAR2 (30)

CREATED not NULL DATE

Profile not NULL VARCHAR2 (30)

Initial_rsrc_consumer_group VARCHAR2 (30)

External_name VARCHAR2 (4000)

Sql> Select Username,account_status from dba_users where username= ' Sysman ';

USERNAME Account_status

------------------------------ ---------------------

Sysman LOCKED

Sql>alter user Sysman account unlock;

The user has changed.

The system can now connect to the database.