Database management system is a large-scale software that manipulates and manages databases, referred to as DBMS, and is used to establish, use and maintain databases. The database management system is a data operation software that can provide data entry, modification, and query. It has functions such as data definition, data operation, data storage and management, data maintenance, and communication, and can be used by multiple users. Users access data in the database through DBMS, and database administrators also perform database maintenance through DBMS.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
Database Management System (DBMS) is a large-scale software that manipulates and manages databases and is used to establish, use and maintain databases. 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 provides a variety of functions that enable multiple applications and users to use different methods to create, modify and query the database at the same time or at different times. It enables users to easily define and manipulate data, maintain data security and integrity, and perform concurrency control and database recovery under multi-user conditions.
DBMS can support multiple applications and users using 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.
The database management system is a data operation software that can provide data entry, modification, and query. It has functions such as data definition, data operation, data storage and management, data maintenance, and communication, and can be used by multiple users. In addition, the development of database management systems is closely related to the development of computer technology. And in recent years, computer networks have gradually become an important part of people's lives. To this end, if we want to further improve the computer database management system, technicians should continue to innovate and reform computer technology, and continuously broaden the application scope of the computer database management system, thereby truly promoting the innovation of computer database management system technology.
Main functions
1. Data definition: DBMS provides data definition language DDL (Data Definition Language) for users to define the three-level schema structure and two-level image of the database and constraints such as integrity constraints and confidentiality restrictions. DDL is mainly used to create and modify the library structure of the database. The library structure described by DDL only provides the framework of the database, and the framework information of the database is stored in the data dictionary (Data Dictionary).
2. Data operation: DBMS provides data operation language DML (Data Manipulation Language) for users to perform operations such as appending, deleting, updating, and querying data.
3. Database operation management: The operation management function of the database is the operation control and management function of the DBMS, including concurrency control, security check and access restriction control, integrity check and execution in a multi-user environment , Organization and management of running logs, transaction management and automatic recovery, that is, ensuring the atomicity of transactions. These functions ensure the normal operation of the database system.
4. Data organization, storage and management: DBMS needs to classify, store and manage various data, including data dictionary, user data, access paths, etc. It needs to determine the file structure and access method. How to organize these data at the storage level and how to realize the connection between data. The basic goal of data organization and storage is to improve storage space utilization and choose appropriate access methods to improve access efficiency.
5. Database protection: The data in the database is a strategic resource in the information society, so data protection is crucial. DBMS protects the database through four aspects: database recovery, database concurrency control, database integrity control, and database security control. Other protection functions of DBMS include the management of system buffers and some adaptive adjustment mechanisms for data storage.
6. Database maintenance: This part includes functions such as database data loading, conversion, dumping, database recombination and reconstruction, and performance monitoring. These functions are completed by each user program.
7. Communication: DBMS has related interfaces with the operating system's online processing, time-sharing system and remote job input, and is responsible for processing data transmission. For database systems in a network environment, it should also include communication functions between the DBMS and other software systems in the network and interoperability functions between databases.
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