What is the first generation database system?

The first generation database system refers to a database system based on a network model or a hierarchical model. Database system refers to a system formed after introducing a database into a computer system. The first generation database system was a hierarchical and network database system developed in the 1970s.

The operating environment of this tutorial: windows7 system, mysql8 version, Dell G3 computer.

Database system refers to a system formed after introducing a database into a computer system. It generally consists of a database, a database management system (and its development tools), an application system, a database administrator and users.

The database system is a complete computer application system composed of hardware, software (operating system, database management system and compilation system, etc.), database and users. The database is the core and management object of the database system. Therefore, the meaning of the database system is no longer just a software that manages data, nor is it just a database. The database system is a system that actually operates and stores, maintains and provides data support to the application system according to the database method.

Database system stage

1. The first generation database system

was in the 1970s Hierarchical and network database systems developed in the 1990s. In 1963, the IDS system designed and developed by Bachman began to be put into operation, which could share databases for multiple COBOL programs; in 1968, network database systems such as TOTAL began to appear; in 1969, the hierarchical database system developed by McGee and others of IBM Company The IMS system is released, which allows multiple programs to share databases. In October 1969, the developers of the CODASYL database proposed a specification report for the network model database system, which made the database system begin to standardize and standardize. In 1971, the Database Task Group under the American Database System Language Association conducted systematic research and discussion on network database methods and proposed several reports called the DBTG report. The DBTG report identified and established many concepts, methods and methods of network database systems. technology, it proposes a three-level abstraction model, that is, the external model that describes the part of the data structure required by the application, the conceptual model that describes the data structure of the entire object system, and the internal model that describes the data storage structure, which solves the problem of data independence. The problem marks the theoretical maturity of the database. Because of this, many experts believe that database technology originated in the late 1960s.

2. The second generation database system

is a relational database system. In 1970, Codd of IBM published a paper entitled "Relational Model for Large Shared Database Data", proposing the relational data model and pioneering the relational database method and relational database theory. Due to its theoretical perfection and structural simplicity, the relational method has played a vital role in the development of database technology and successfully laid the theoretical foundation for relational database technology. The 1970s was an era of theoretical research on relational databases and development of prototype systems. Research on relational database systems has achieved a series of results, mainly including the following aspects:

(1) It laid the theoretical foundation of the relational model and provided a normative description of the relational model that is generally accepted by people.

(2) Proposed relational data languages, such as relational algebra, relational calculus, SQL language, QBE, etc. These descriptive languages ​​changed the process-oriented style of previous programming languages ​​and network and hierarchical database languages. They were welcomed by end users for their advantages of being easy to learn and understand, and laid the foundation for the standardization of database languages ​​in the 1980s.

(3) A large number of prototypes of relational database systems have been developed, and a series of key technologies such as query optimization, concurrency control, and fault recovery have been overcome in system implementation. It not only greatly enriches the database management system implementation technology and database theory, but more importantly, promotes the vigorous development and widespread application of relational database system products.

3. The third generation database system

Since the 1980s, database theory and application have entered a mature development period. With the development of computing technology and computer networks, the field of computer applications has expanded rapidly, and the field of database applications has also continued to expand. The great achievements of database technology in the commercial field have stimulated the rapid growth of demand for databases in other fields. On the one hand, new database application fields, such as computer-aided design/management (CAD/CAM), process control, office automation systems, geographic information systems (GIS), computer manufacturing systems (CIMS), etc., have opened up new areas for database applications. world; on the other hand, new demands for management in practical applications also directly promote the research and development of database technology.

Traditional databases represented by relational databases are already difficult to meet the needs of new fields, because new applications require the database to handle more complex data, such as processing time-related attributes, and even require the database to handle Be dynamic and proactive.

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

The most important database type in the third generation database system is the object-oriented database system (OODBS for short). It is the product of the combination of database technology and object-oriented programming methods. It is both a DBMS and It is an object-oriented system.

Therefore, it has both DBMS features, such as persistence, auxiliary management, data sharing (concurrency), data reliability (transaction management and recovery), query processing and schema modification, etc., as well as object-oriented features. Features such as types/classes, encapsulation/data abstraction, inheritance, object identification, composite objects, and extensibility.

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