我的PLSQL不好用，提示ora-12514 错误时

我分两步干的：

1：用户名，密码，不写，提示错误后，cancel登陆

tools->preference左侧选->connection,右侧Oracle Home 里面选择OraDb10g_home1。

2：找到%oracle_home%NETWORK/ADMIN/LISTENER.ORA

修改如下：添加一段代码

# listener.ora Network Configuration File: D:/oracle/oracle10g/network/admin/listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (SID_NAME = PLSExtProc)
      (ORACLE_HOME = D:/oracle/oracle10g)
      (PROGRAM = extproc)
    )
     (SID_DESC =

(GLOBAL_DBNAME = ORCL)

(ORACLE_HOME = D:/oracle/oracle10g)

(SID_NAME = ORCL)

) 
  )

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