启动数据库实例，分为两步：第一步，启动监听；第二步，启动数据库实例。

一、如何启动数据库实例
?? 1.进入到sqlplus启动实例
[oracle@redhat ~]$?su?- oracle???????????????????????????????? --“切换到oracle用户”
Password:
[oracle@redhat ~]$?lsnrctl start?????????????????????????????? --“打开监听”
LSNRCTL for Linux: Version 10.2.0.1.0 - Production on 14-OCT-2009 19:06:40
Copyright (c) 1991, 2005, Oracle.? All rights reserved.
Starting /home/oracle/product/10g/bin/tnslsnr: please wait...
TNSLSNR for Linux: Version 10.2.0.1.0 - Production
System parameter?file?is /home/oracle/product/10g/network/admin/listener.ora
Log messages written to /home/oracle/product/10g/network/log/listener.log
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC2)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=redhat)(PORT=1522)))
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=IPC)(KEY=EXTPROC2)))
STATUS of the LISTENER
------------------------
Alias???????????????????? LISTENER
Version?????????????????? TNSLSNR for Linux: Version 10.2.0.1.0 - Production
Start Date??????????????? 14-OCT-2009 19:06:40
Uptime??????????????????? 0 days 0 hr. 0 min. 0 sec
Trace Level?????????????? off
Security????????????????? ON: Local OS Authentication
SNMP????????????????????? OFF
Listener Parameter File?? /home/oracle/product/10g/network/admin/listener.ora
Listener Log File???????? /home/oracle/product/10g/network/log/listener.log
Listening Endpoints Summary...
? (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC2)))
? (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=redhat)(PORT=1522)))
Services Summary...
Service "PLSExtProc" has 1 instance(s).
? Instance "PLSExtProc",?status UNKNOWN, has 1 handler(s) for this service...
The command completed successfully
[oracle@redhat ~]$ sqlplus /nolog??????????????????????????????? --“进入到sqlplus”
SQL*Plus: Release 10.2.0.1.0 - Production on Wed Oct 14 19:06:45 2009
Copyright (c) 1982, 2005, Oracle.? All rights reserved.
SQL> conn /as sysdba????????????????????????????????????????????? --“连接到sysdba”
Connected to an?id