Oracle tutorial database introduction, oracle tutorial Database

Oracle tutorial database introduction, oracle tutorial Database

I. Database Classification

1. Small databases: access and foxbase

2. Medium-sized databases: informix, SQL server, and mysql

3. Large Databases: sybase, db2, and oracle

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2. How to use the database properly in the project can be started from the following three aspects:

Project scale:

A. What is the load, that is, the number of users?

B. Cost

C. Security

Eg:

Small Databases

1. The load is small, and the number of users is about 100

For example: Message Board and Information Management System

2. The cost is within a thousand RMB

3. Low Security Requirements

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Medium-sized Databases

For example, the daily access volume is 5000 ~ 10000

The cost is within RMB

For example, a business website

Bytes ---------------------------------------------------------------------------------------------

Large Databases

Massive load, can process massive data (sybase

High Security, relatively expensive

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Iii. sys and system users

Oracle Installation will automatically generate sys and system users

(1) The sys user is a Super User and has the highest permission. It has the sysdba role and the create database permission. The default password of this user is change_on_install.

(2) system users are management operators with great permissions. Has the sysoper role and does not have the create database permission. The default password is manager.

(3) generally, you can use the system user to log on to the database for database maintenance.

Note: The biggest difference between sys and system is whether you have the create database permission.

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Iv. Introduction to SQL * plus

SQL * plus is a tool software provided by oracle. It is mainly used to execute SQL statements and pl \ SQL blocks.

The procedure is as follows:

(1) sqlplusw.exe in the Directory D: \ app \ Administrator \ virtual \ product \ 12.2.0 \ dbhome_1 \ bin \

(D: \ app \ Administrator \ virtual \ product \ 12.2.0 \ dbhome_1 \ is the oracle Installation Directory)

(2) Enter "sqlplusw" in the running column.

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V. Introduction to sqlplus dostool

(1). Overview: sqlplus is a tool for operating oracle in dos. Its functions are similar to SQL * plus.

(2) perform the following operations: Enter "sqlplus" in the running column.

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6. The PLSQL Developer tool needs to be installed by yourself. We recommend that you use it.