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This article mainly introduces the meaning of the first generation database system, which is very detailed and has a certain reference value. Interested friends must finish reading it!

The first generation database system refers to the database system based on mesh model or hierarchical model. The database system refers to the system formed by introducing the database into the computer system. the first generation database system is the hierarchical and reticulated database system developed in the 1970s.

Database system is a system formed by introducing database into computer system, which is generally composed of database, database management system (and its development tools), application system, database administrator and users.

Database system is a complete computer application system composed of hardware, software (operating system, database management system and compiler system, etc.), database and users. Database is the core and management object of database system. Therefore, the meaning of database system is not only a software to manage data, but also not only a database, but also a system that actually runs, stores, maintains and provides data support to application systems in accordance with the database mode.

Database system phase

1. First generation database system

It is a hierarchical and reticulated database system developed in the 1970s. In 1963, the IDS system designed and developed by Bachman was put into operation, which can share the database for multiple COBOL programs; in 1968, the mesh database system such as TOTAL began to appear; in 1969, the IMS system of the hierarchical database system developed by McGee et al of IBM was published, which allows multiple programs to share the database. In 1969, CODASYL database developers put forward the network model database system specification report, so that the database system began to be standardized and standardized. In 1971, the database task force under the American Database system language Association systematically studied and discussed the network database method, and put forward several reports called DBTG report. The DBTG report identified and established many concepts, methods and technologies of the network database system, and proposed a three-level abstract model, that is, an external model to describe the data structure required by the application. The conceptual model for the description of the data structure of the whole object system and the internal model for the description of the data storage structure solve the problem of data independence and mark the maturity of the database in theory. Because of this, many experts believe that database technology originated in the late 1960s.

two。 The second generation database system

It's a relational database system. In 1970, Codd of IBM Company published a paper entitled "Relational Model of large-scale shared Database data", which put forward the relational data model and initiated the relational database method and relational database theory. Because of its theoretical perfection and simple structure, relational method plays an important role in the development of database technology, and successfully lays a theoretical foundation for relational database technology. The 1970s is the era of relational database theory research and prototype system development. The research of relational database system has made a series of achievements, including the following aspects:

The main contents are as follows: (1) the theoretical foundation of the relational model is established, and the specification of the generally accepted relational model is given.

(2) Relational data languages are proposed, such as relational algebra, relational calculus, SQL language, QBE and so on. These descriptive languages have changed the process-oriented style of previous programming languages and mesh and hierarchical database languages, and have been welcomed by end-users for their advantages of being easy to learn and understand, which laid the foundation for the standardization of database languages in the 1980s.

(3) A large number of relational database system prototypes are developed to overcome a series of key technologies such as query optimization, concurrency control, fault recovery and so on. It not only enriches the database management system implementation technology and database theory, but also promotes the vigorous development and wide application of relational database system products.

3. The third generation database system

Since the 1980s, the theory and application of database have entered a period of mature development. With the development of computing technology and computer network, the field of computer application is expanding rapidly, and the field of database application is also expanding continuously. the great achievements of database technology in the commercial field have stimulated the rapid growth of database demand in other fields. On the one hand, new database application fields, such as computer aided design / management (CAD/CAM), process control, office automation system, geographic information system (GIS), computer manufacturing system (CIMS), etc., have opened up a new field for the application of database; on the other hand, the new requirements of management in practical application have also directly promoted the research and development of database technology.

The traditional database represented by relational database has been difficult to meet the needs of the new field, because the new application requires the database to deal with complex data, such as dealing with time-related attributes, and even requires the database to be dynamic and proactive.

In this way, there must be new database technology to meet the practical needs, in order to meet the needs of modern applications, database technology must be well integrated with other modern data processing technologies (such as object-oriented technology, timing and real-time processing technology, artificial intelligence technology, multimedia technology) to form a "new generation of database technology", which can also be called "modern database technology". Such as temporal database technology, real-time database technology and multimedia database technology.

The most important database type in the third generation database system is object-oriented database system (objectorienteddatabasesystem, referred to as OODBS), which is the product of the combination of database technology and object-oriented programming method. It is not only a DBMS, but also an object-oriented system.

Therefore, it not only has DBMS characteristics, such as persistence, auxiliary management, data sharing (concurrency), data reliability (transaction management and recovery), query processing and schema modification, but also has object-oriented characteristics, such as type / class, encapsulation / data abstraction, inheritance, object identification, composite objects and extensibility.

The above is all the contents of this article "what does the first generation database system mean?" Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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