1. 连接到Oralce
At the operating system prompt, enter the following command to start the SQL
Command Line and connect to the database:
CONN / AS SYSDBA
The slash (/) indicates that the database should authenticate you with operating
system authentication.
也可以用 conn username/passwd as sysdba
system/manager
2. 启动Oracle和关闭Oracle
At the SQL Command Line prompt, enter the following command:
SQL> STARTUP
SQL> SHUTDOWN IMMEDIATE // 如果shutdown失败，可以输入这个命令：SHUTDOWN ABORT. 之后可以重新启动和关闭oracle。
3. 数据库连接
connect username/password@[//]host[:port][/service_name]
4. Oracle体系结构
DATABASE：
The Oracle Database XE instance (which consists of the Oracle Database XE
background processes and allocated memory) works with a single database only.
Rather than enabling you to create multiple databases to accommodate different
applications, Oracle Database XE uses a single database, and accommodates multiple
applications by enabling you to separate data into different schemas.
TABLESPACE：
There are various tablespaces, including the following:
1. Permanent tablespace 2. Temporary tablespace 3. Undo tablespace
undo tablespace的目的：1） to undo any uncommitted changes. 2) to provide read consistency. 3) to support the flashback query feature.
tablespaces: SYSTEM SYSAUX TEMP UNDO USERS
5. 用户和权限。
默认用户：
sys 密码是 change_on_install // must connect to the database "AS SYSDBA."
system 密码是 manager