PL/SQL ORA-12514 TNS 监听程序当前无法识别连接描述符中请求服务

方法1：

通过Net Configuration Assistant  重新进行“监听程序配置”。

方法2：

在Network/admin目录下找到listener.ora 

增加红色字体部分内容，重启服务器。
SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = D:\app\product\11.2.0\dbhome_1)
      (PROGRAM = extproc)
    )
   (SID_DESC =
    (GLOBAL_DBNAME = ORCL)
    (ORACLE_HOME = D:\app\product\11.2.0\dbhome_1)
    (SID_NAME = ORCL)
    )
 )
LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
      (ADDRESS = (PROTOCOL = TCP)(HOST = onest)(PORT = 1521))
    )
  )