ORA-12505 oracle监听问题

修改listener.ora文件 

原listener.ora文件：

# listener.ora Network Configuration File: D:\oracle\product\10.1.0\Db_4\network\admin\listener.ora

# Generated by Oracle configuration tools.

SID_LIST_LISTENER =

  (SID_LIST =

    (SID_DESC =

      (SID_NAME = PLSExtProc)

      (ORACLE_HOME = D:\oracle\product\10.1.0\Db_4)

      (PROGRAM = extproc)

    )

  )

LISTENER =

  (DESCRIPTION_LIST =

    (DESCRIPTION =

      (ADDRESS_LIST =

        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))

      )

      (ADDRESS_LIST =

        (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))

      )

    )

  )

修改后的文件：

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

# listener.ora Network Configuration File: D:\oracle\product\10.1.0\Db_4\network\admin\listener.ora

# Generated by Oracle configuration tools.

SID_LIST_LISTENER =

  (SID_LIST =

    (SID_DESC =

      (SID_NAME = PLSExtProc)

      (ORACLE_HOME = D:\oracle\product\10.1.0\Db_4)

      (PROGRAM = extproc)

)

(SID_DESC =

       (GLOBAL_DBNAME = orcl)

       (ORACLE_HOME =  D:\oracle\product\10.1.0\Db_4)  

       (SID_NAME = orcl)

      )

   )

LISTENER =

  (DESCRIPTION_LIST =

    (DESCRIPTION =

      (ADDRESS_LIST =

        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))

      )

      (ADDRESS_LIST =

        (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))

      )

    )

  )

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

如果错误还存在，也可以那试一下:
set oracle_sid=<sid_name>
sqlplus /nolog
connect sys/pwd as sysdba
start