ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务

前几天我建立了数据库,名为Demo,并且配置了监听,端口为1521,一切正常运行.今天我又建立了个数据库,名为ORCL,和Demo共用一个监听.
现在遇到一个问题,我每一次用sqlplus sys/orcl@orcl as sysdba  登录没有问题,但是我执行SHUTDOWN IMMEDIATE后,再用sqlplus sys/orcl@orcl as sysdba 登录,就不行了,

C:\>sqlplus sys/orcl@orcl as sysdba

SQL*Plus: Release 10.2.0.1.0 - Production on 星期二 12月 30 13:02:30 2008

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

ERROR:
ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务


但是用 sqlplus sys/orcl as sysdba 登录就可以,不知道这是什么,另一个库DEMO 一切正常.
为什么用sqlplus sys/orcl@orcl as sysdba 不行,用sqlplus sys/orcl as sysdba 就可以登录呢？listener.ora和tnsnames.ora如下

listener.ora
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = demo)
      (ORACLE_HOME = D:\oracle\product\10.2.0\db_1)
    )
  )

LISTENER =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = Colin)(PORT = 1521))
  )

tnsnames.ora

DEMO =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = Colin)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = demo)
    )
  )

ORCL =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = TCP)(HOST = Colin)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = orcl)
    )
  )

EXTPROC_CONNECTION_DATA =
  (DESCRIPTION =
    (ADDRESS_LIST =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
    )
    (CONNECT_DATA =
      (SID = PLSExtProc)
      (PRESENTATION = RO)
    )
  )

解决办法是把listener.ora改为如下：

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = demo)
      (ORACLE_HOME = D:\oracle\product\10.2.0\db_1)
      (SID_NAME = demo)
    )
    (SID_DESC =
      (GLOBAL_DBNAME = ORCL)
      (ORACLE_HOME = D:\oracle\product\10.2.0\db_1)
      (SID_NAME = ORCL)
    )
  )

LISTENER =
  (DESCRIPTION =
    (ADDRESS = (PROTOCOL = TCP)(HOST = Colin)(PORT = 1521))
  )

重启下监听

还有类似的一个问题解决办法：
昨天配置了oracle数据库,出现TNS问题

问题描述:
    当配置完listener和tnsname后,在确认listener服务有正常启动的前提下,在sqlplus下尝试连接数据库,返回以下错误:
ORA-12514: TNS:监听程序当前无法识别连接描述符中请求的服务
ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
解决方法:
在listener.ora文件中添加以下内容:
(SID_DESC =
(GLOBAL_DBNAME = orcl)
(ORACLE_HOME = D:\oracle\product\10.2.0\db_1)
(SID_NAME = orcl)
)
注意:orcl为数据库名,D:\oracle\product\10.2.0\db_1为$ORACLE_HOME的路径,修改后的listener.ora文件内容如下:
# listener.ora Network Configuration File: e:\oracle\product\10.1.0\Db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = e:\oracle\product\10.1.0\Db_1)
      (PROGRAM = extproc)
    )
  (SID_DESC =
    (GLOBAL_DBNAME = orcl)
      (ORACLE_HOME = D:\oracle\product\10.2.0\db_1)
      (SID_NAME = orcl)
    )
  )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = TCP)(HOST = linewell-d29e66.mshome.net)(PORT = 1521))
      )
      (ADDRESS_LIST =
        (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC))
      )
    )
  )

相关说明:

Cause:
The listener received a request to establish a connection to a database or other service. The connect descriptor received by the listener specified a service name for a service (usually a database service) that either has not yet dynamically registered with the listener or has not been statically configured for the listener. This may be a temporary condition such as after the listener has started, but before the database instance has registered with the listener.
Action:
- Wait a moment and try to connect a second time.
- Check which services are currently known by the listener by executing: lsnrctl services
- Check that the SERVICE_NAME parameter in the connect descriptor of the net service name used specifies a service known by the listener.
- If an easy connect naming connect identifier was used, check that the service name specified is a service known by the listener.
- Check for an event in the listener.log file.