Database System Overview

What is a database

A database is a repository of data that is organized, stored, and managed according to a structure, and is a collection of related data that is stored together.

What is a database management system

The database Management system, DBMS, is a large-scale software for operating and managing data that is used to establish/use and maintain databases. He has unified management and control of data crying, To ensure the security and integrity of the database. The user accesses the data in the database through the database management system, the database administrator also carries on the database maintenance through the database management system,

The definition of the data.

DBMS provides a data definition language, with user-defined constraints such as database object/integrity constraints and confidentiality restrictions

Data manipulation

The DBMS provides data manipulation languages that enable users to manipulate data, such as inserting, modifying, deleting, and querying,

Data organization, storage and management

DBMS to classify organization, storage and management of various data, including data dictionary, user data, access path, etc., need to determine what file structure and storage in the spring and the organization of the data, how to achieve the link between the data. The basic goal of data organization and storage is to provide your storage space utilization, Choose the right access method to provide Oh you access efficiency and ensure that the data is correct and effective

Security management of the database

The data in the database is the strategic resource of the information society, and the security management of all data is critical. The DBMS protects the database mainly through the database reply/concurrency control/Integrity Control/security control and so on.

Establishment and maintenance of database

The establishment and maintenance of database includes the loading of database initial data, storage/recovery/re-organization of database, system performance monitoring, analysis and other functions.

Database system

Database System,dbs is a software system that can store/maintain and provide data for an IB system. The diamond ring, the collective of the management system that handles the object

Data model

Data is a symbolic record that describes things. The model is the abstraction of the real world, the data model is the abstraction of the data characteristic, and is the framework of the teaching form of the database management. The database system is used to provide the form architecture of information representation and manipulation. The data model includes the structure part of the database data, the operation part and the constraint condition.

The data model is divided into three types according to different Dingdong levels: conceptual model, data model and physical model

Conceptual model

The first model, which is abstracted from the world, is mainly used to describe the concept of the world, the analysis of the data and the connection between the data, and the data management system, and the conceptual model must be replaced by the data model to be implemented in the DBMS.

The longest-used conceptual model is the E-R model, which is represented as a e-r graph. E-r is also known as entity-contact graph, which provides you with a method of strength type, properties and linkage. He's an effective way of describing the world's conceptual structure.

Data model

The data model is Oh, uh, Hu. The model that is seen from the database is the data model supported by the DBMS, which is both user-oriented and system-oriented, and is mainly used for DBMS implementation.

hierarchical model, network model, and relational model are used in the field of database.

Physical model

The physical model is the organization data which is oriented to the computer physical representation, describes the organization structure of the data on the storage ring, it is not only related to the specific DBMS, but also the U operating system and hardware. Each logical data model has a physical data model that is relevant to the reality. DBMS in order to guarantee the tolerance of rationality and portability, The implementation of most physical data models is done automatically by the system, and designers design and index, aggregation and other special structures

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Database System Overview