ORA-12505错误

在使用oracle时遇到了一个问题：
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor
The Connection descriptor used by the client was:
localhost:1521:orcl

查阅了很多网上的内容，知道了是oracle 的sid注册有问题。

按照网上的步骤解决如下：
1.在oracle目录下查找listener.ora文件,修改成如下格式的：
# listener.ora Network Configuration File: D:\oracle10g\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
(SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = D:\oracle10g)
      (PROGRAM = extproc)
    )
    (SID_DESC =
      (GLOBAL_DBNAME = ORCL)
      (ORACLE_HOME = D:\oracle10g)
      (SID_NAME = ORCL)
    )
)

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