一、查看实例名、表等
[oracle@912616.cn ~]$ sqlplus scott/tiger@orcl
SQL> show user;
USER is "SCOTT"
SQL> select * from tab;
TNAME TABTYPE CLUSTERID
------------------------------ ------- ----------
BONUS TABLE
DEPT TABLE
EMP TABLE
SALGRADE TABLE
SQL> conn sys/oracle@orcl as sysdba
Connected to Oracle Database 11g Enterprise Edition Release 11.2.0.3.0
Connected as sys@orcl AS SYSDBA
SQL> select name from v$database;
NAME
---------
ORCL
SQL> select status from v$instance;
STATUS
------------
OPEN
二、启动几个阶段状态实验
1. nomount
SQL> startup nomount
ORACLE instance started.
Total System Global Area 1286066176 bytes
Fixed Size 2228024 bytes
Variable Size 352321736 bytes
Database Buffers 922746880 bytes
Redo Buffers 8769536 bytes
SQL> select status from v$instance;
STATUS
------------
STARTED
SQL> select open_mode from v$database;
select open_mode from v$database
*
ERROR at line 1:
ORA-01507: database not mounted
2. mount
SQL> alter database mount;
Database altered.
SQL> select status from v$instance;
STATUS
------------
MOUNTED
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
MOUNTED
3.open
SQL> alter database open ;
Database altered.
SQL> select status from v$instance;
STATUS
------------
OPEN
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
READ WRITE
4. close
SQL> alter database close;
Database altered.
SQL> select status from v$instance;
STATUS
------------
MOUNTED
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
MOUNTED
# 数据库open_mode的read only和read write，改变了需要重新启动数据库。