What is the core of a database system?

The core of the database system is the database management system (DBMS). It is a system software that works with the support of the operating system and solves how to organize and store data scientifically and how to obtain and maintain data efficiently; DBMS can The database is managed and controlled uniformly to ensure the security and integrity of the database.

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

The database system is an ideal data processing system developed to meet the needs of data processing. It is also a software system that provides data for actual operable storage, maintenance and application systems. It is a storage medium. , a collection of processing objects and management systems.

Database systems generally consist of 4 parts:

(1) Database (DB) refers to long-term storage in the computer, organized and shareable A collection of data. The data in the database is organized, described and stored according to a certain mathematical model. It has small redundancy, high data independence and easy scalability, and can be shared by various users.

(2) Hardware: Various physical devices that make up a computer system, including external devices required for storage. The hardware configuration should meet the needs of the entire database system.

(3) Software: including operating system, database management system and application programs.

Database management system (DBMS) is the core software of the database system. It works with the support of the operating system and solves how to organize and store data scientifically and how to obtain it efficiently. and system software that maintains data. Its main functions include: data definition function, data manipulation function, database operation management and database establishment and maintenance.

(4) Personnel: There are mainly 4 categories. The first category is system analysts and database designers: System analysts are responsible for the requirement analysis and specification of the application system. They work with users and database administrators to determine the hardware configuration of the system and participate in the outline design of the database system. Database designers are responsible for the determination of data in the database and the design of database schemas at all levels. The second category is application programmers, who are responsible for writing applications that use the database. These applications can retrieve, create, delete or modify data. The third category is end users, who use the system's interface or query language to access the database. The fourth type of user is the database administrator (data base administrator, DBA), who is responsible for the overall information control of the database. The specific responsibilities of the DBA include: specifying the information content and structure in the database, determining the storage structure and access strategy of the database, defining the security requirements and integrity constraints of the database, monitoring the use and operation of the database, and being responsible for improving the performance of the database. Database reorganization and reconstruction to improve system performance.

Database Management System (DBMS)

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 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:

• Data definition: DBMS provides data definition language DDL (Data Definition Language) for users to define the three-level schema structure, two-level image 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).

• Data operation: DBMS provides data operation language DML (Data Manipulation Language) for users to perform operations such as appending, deleting, updating, and querying data.

• Database operation management: The database operation management function is the operation control and management function of DBMS, including concurrency control, security check and access restriction control, integrity check and The organization and management of execution and running logs, transaction management and automatic recovery ensure the atomicity of transactions. These functions ensure the normal operation of the database system.

• 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 what file structure to use How to organize these data at the storage level and access methods, 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.

• Protection of database: The data in the database is a strategic resource of 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.

• Database maintenance: This part includes functions such as database data loading, conversion, dumping, database reorganization and reconstruction, and performance monitoring. These functions are performed by each user program. Finish.

• 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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