以上连接方式使用sys用户或者其他通过密码文件验证的用户都不需要数据库处于可用状态，操作系统认证也不需要数据库可用，普通用户因为是数据库认证，所以数据库必需处于open状态。

然后就是

#-------------

平时排错可能会用到的

1.lsnrctl status查看服务器端listener进程的状态

LSNRCTL> help

The following operations are available

An asterisk (*) denotes a modifier or extended command:

start stop status

services version reload

save_config trace change_password

quit exit set*

show*

LSNRCTL> status

2.tnsping 查看客户端sqlnet.ora和tnsname.ora文件的配置正确与否，及对应的服务器的listener进程的状态。

C:>tnsping orcl

TNS Ping Utility for 32-bit Windows: Version 10.1.0.2.0 - Production on 16-8月 -

2005 09:36:08

Copyright (c) 1997, 2003, Oracle. All rights reserved.

Used parameter files:

E:oracleproduct10.1.0Db_2 etworkadminsqlnet.ora

Used TNSNAMES adapter to resolve the alias

Attempting to contact (DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)

(HOST = 127.0.0.1)(PORT = 1521))) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_

NAME = orcl)))

OK (20 msec)