ORA-12514: TNS: 监听程序当前无法识别连接描述符中请求的服务

如下是解决思路：

根据出错信息判断出客户端未监听到实例服务名

1、通过重启服务的方式启动数据库，再次连接仍无法连接服务器。

2、既然第一种方法不能解决问题，那就第二种方法。考虑监听listener.ora

   监听配置文件listener.ora中可以不必指定监听的服务名（安装Oracle10g后也是没有指定的）。正常情况下一般只要数据库启动，客户端连接数据库也没有什么问题，但是有时重复启动关闭也会出现ORA-12514错误。

   既然listener.ora中没有指定监听，我们可以在listener.ora文件中指定监听的实例名，这样该问题应该可以连接。

修改监听程序参数文件的两种方案：

一、初次打开时，内容如下

# listener.ora Network Configuration File: C:\Program_Files\Oracle\DataBase_11G_R2\product\11.2.0\dbhome_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = C:\Program_Files\Oracle\DataBase_11G_R2\product\11.2.0\dbhome_1)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:C:\Program_Files\Oracle\DataBase_11G_R2\product\11.2.0\dbhome_1\bin\oraclr11.dll")
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST =localhost)(PORT = 1521))
    )
  )

ADR_BASE_LISTENER = C:\Program_Files\Oracle\DataBase_11G_R2

修改为：

# listener.ora Network Configuration File: C:\Program_Files\Oracle\DataBase_11G_R2\product\11.2.0\dbhome_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = orcl)
      (ORACLE_HOME = C:\Program_Files\Oracle\DataBase_11G_R2\product\11.2.0\dbhome_1)
      #(PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:C:\Program_Files\Oracle\DataBase_11G_R2\product\11.2.0\dbhome_1\bin\oraclr11.dll")
    )
  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = orcl))
      (ADDRESS = (PROTOCOL = TCP)(HOST =202.206.0.233)(PORT = 1521))
    )
  )

ADR_BASE_LISTENER = C:\Program_Files\Oracle\DataBase_11G_R2

SID_NAME，KEY 的值修改为要访问的oracle实例的名称，HOST 修为 oracle 服务器使用的地址

二、

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = E:\Oracle10g)
      (PROGRAM = extproc)
    )
   (SID_DESC =
    (GLOBAL_DBNAME = ORCL)
    (ORACLE_HOME = E:\Oracle10g)
    (SID_NAME = ORCL)
    )
 )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = onest)(PORT = 1521))
    )
  )

标红的为我添加的部分，ORCL为监听的实例名。