Oracle databases, tablespaces, and tables

I. Databases

A database is a collection of data, while Oracle is a software system that manages these data sets. It is an object-relational database management system.

Ii. tablespace

The tablespace is the logical ing of Oracle to the data in the physical database. A database is logically divided into several tablespaces, each of which contains a set of logically associated structures. Each database has at least one tablespace (called the system tablespace ).

Each tablespace consists of one or more files on the same disk. These files are called data files ). A data file can belong to only one tablespace.

Iii. Instances

Each running database corresponds to an oracle instance. When the Oracle database on the server is started, Oracle first allocates an area in the memory-called system global area (SGA), and then starts one or more Oracle processes.

Together with these processes, SGA is called an oracle instance. The memory and Process Manager in the instance are used to efficiently access database data and provide services for one or more users.

A database can be opened by multiple instances, but only one database can be opened by one instance at any time. Multiple instances can run on the same machine at the same time, and they access each other's independent physical databases.

[Code = & quot; Java & quot;] -- create a temporary tablespace

Create temporary tablespace test_temp

Tempfile 'e: \ oracle \ product \ 10.2.0 \ oradata \ testserver \ test_temp01.dbf'

Size 32 m

Autoextend on

Next 32 m maxsize 2048 m

Extent management local;

-- Create a data table space

Create tablespace test_data

Logging

Datafile 'e: \ oracle \ product \ 10.2.0 \ oradata \ testserver \ test_data01.dbf'

Size 32 m

Autoextend on

Next 32 m maxsize 2048 m

Extent management local;

-- Create a user and specify a tablespace

Create User Username identified by password

Default tablespace test_data

Temporary tablespace test_temp;

The simplest way to create a database is to use dbca and use the command & quot; dbca & quot; in DOS.