ora-12514

之前连接数据库好好的，不知道为什么突然报这个错，解决办法如下：

到oracle的安装目录下D:\app\admin\product\11.2.0\dbhome_1\NETWORK\ADMIN
打开listener.ora文件，进行以下编辑

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = CLRExtProc)
      (ORACLE_HOME = D:\app\admin\product\11.2.0\dbhome_1)
      (PROGRAM = extproc)
      (ENVS = "EXTPROC_DLLS=ONLY:D:\app\admin\product\11.2.0\dbhome_1\bin\oraclr11.dll")
    )
   (SID_DESC =
      (GLOBAL_DBANAME = orcl)
      (ORACLE_HOME = D:\app\admin\product\11.2.0\dbhome_1)
      (SID_NAME = orcl)
    )  )

LISTENER =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1521))
      (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.0.123)(PORT =1521))
    )
  )

ADR_BASE_LISTENER = D:\app\admin

红色部分为新添加的，将你创建的数据库的SID描述告知给监听器，重启服务，好了。