What are the characteristics of database management systems?

Characteristics of the database management system: 1. Data structure; 2. High sharing, low redundancy, easy to expand; 3. High data independence; 4. Data is unified by the database management system (DBMS) Management and control.

The operating environment of this tutorial: Windows 7 system, DELL G3 computer.

Database Management System (Database Management System) is a large-scale software that manipulates and manages databases. It is used to establish, use and maintain databases, referred to as DBMS.

It provides unified management and control of the database to ensure the security and integrity of the database. Users access data in the database through DBMS, and database administrators also perform database maintenance through DBMS.

It can support multiple applications and users to use different methods to create, modify and query the database at the same time or at different times.

Most DBMS provide data definition language DDL (Data Definition Language) and data manipulation language DML (Data Manipulation Language) for users to define the schema structure and permission constraints of the database and implement operations such as appending and deleting data. .

Main features of database management system

1. Data structuring

Database management system Achieving the overall structuring of data is one of the main features of the database, and it is also the essential difference between the database management system and the file system.

• The first one means: the data is not only internally structured, but the data and the direct connections between the data are unified and managed to make it structured.

  
  

• The second point is: the data in the database is not only for a certain application, but for all applications of the entire organization. For example, a school's information system must not only consider the student performance management of the Academic Affairs Office, but also the student status registration management, student rewards and punishment management, student family member management, and the Finance Office's student payment management; it must also consider Postgraduate management of the Graduate School, scientific research management of the Scientific Research Office, faculty personnel management and salary management of the Personnel Office, etc. Therefore, the student data in the school information system must be oriented to the application of various functional management departments and departments throughout the school, not just a student performance management application of the Academic Affairs Office.

2. High sharing, low redundancy, easy to expand

• • Database management system from Describe and organize data from a holistic perspective. The data is no longer oriented to a certain application, but to the entire system.
  • Data can be shared and used by multiple users and Togo applications

  • Data sharing It can greatly reduce data redundancy and avoid inconsistencies between data

3. High data independence

Data independence refers to the separation of the use of data (i.e., the application) and the description of the data (i.e., the organization structure and storage method of the data)

• In this way, the application only needs to consider how to use the data , without caring about how the data in the database is structured and stored.

• Therefore, changes made by all parties (within a certain range) do not affect each other

Data independence is used to describe the degree of dependence between the application and the data structure. Including the physical independence of data and the logical independence of data. The lower the degree of dependence, the higher the independence.

• Physical independence means that the user's application and the physical structure of the data in the database are independent of each other. The DBMS is responsible for how the data is organized and stored on the disk. The application only cares about the logical structure of the data; when the physical storage structure of the data changes, the application does not need to modify it

• Logical independence is It means that the user's application program and the logical structure of the data in the database are independent of each other. The DBMS is responsible for the (global) logical structure of the data. The application only cares about the local logical structure of the data (i.e. the application view). If the (global) logical structure of the data changes, the application does not need to modify it

4. Data is managed and controlled uniformly by the database management system (DBMS)

• Data security protection: protect data to prevent illegal use Causing data leakage and damage

• Data integrity check: control the data within a valid range, or ensure that data satisfy certain relationships

• Concurrency control: Control and coordinate concurrent operations of multiple users or applications accessing the same data at the same time to ensure that correct modification results are obtained or the integrity of the database is not destroyed

• Database recovery: When a hardware or software failure occurs in the computer system, the database needs to be restored from an error state to a correct state

[Related recommendations: mysql video Tutorial】

The above is the detailed content of What are the characteristics of database management systems?. For more information, please follow other related articles on the PHP Chinese website!