早上使用PL/SQL连接Oracle的时候，报错如下

解决办法：

找到文件listener.ora，新增以下红色区域，注意：路径需要根据自己的Oracle安装路径自行设置

# listener.ora Network Configuration File: D:\app\OLIVER\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 = D:\app\OLIVER\product\11.2.0\dbhome_1)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:D:\app\OLIVER\product\11.2.0\dbhome_1\bin\oraclr11.dll")
    )
    (SID_DESC =
    (GLOBAL_DBNAME = ORCL)
    (ORACLE_HOME = D:\app\OLIVER\product\11.2.0\dbhome_1)
    (SID_NAME = ORCL)
    )
  )

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

ADR_BASE_LISTENER = D:\app\OLIVER

设置完成后以管理员的方式打开cmd,使用命令重启监听服务即可