What three stages has the development of database management technology gone through?

Data management technology refers to the classification, encoding, storage, retrieval and maintenance of data. It is the central issue of data processing; with the continuous development of computer technology, driven by application needs, computer hardware , On the basis of software development, data management technology has gone through three stages: manual management, file management, and database management.

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

Data management technology specifically refers to the sum of a series of activities for people to collect, organize, store, process, disseminate and utilize data. It has gone through three stages of manual management, file management and database management. . Each stage of development is marked by the continuous reduction of data storage redundancy, continuous enhancement of data independence, and more convenient and simpler data operations, each with its own characteristics.

Manual management stage

Before the advent of computers, people used conventional means to record, store and process data, that is, using paper to record and use computing tools (abacus, slide rule) to perform calculations and primarily use the human brain to manage and utilize these data.

By the mid-1950s, computers were mainly used for scientific calculations. At that time, there were no direct access devices such as disks, only external storage such as paper tapes, cards, and magnetic tapes. There were also no operating systems and specialized software for managing data. The way of data processing is batch processing. The characteristics of the management data at this stage are:

(1) The data is not saved. Because computers were mainly used for scientific calculations at that time, the need for data storage was not urgent.

(2) The system does not have special software to manage data. Each application program must include the storage structure, access method and input method of data. When programmers write applications, they also have to arrange the physical storage of data, so the burden on programmers is heavy.

(3) Data is not shared. Data is program-oriented, and a set of data can only correspond to one program.

(4) The data is not independent. Programs depend on data, and if the logical or physical structure such as data type, format, or input/output methods changes, the application program must be modified accordingly.

File system management stage

From the late 1950s to the mid-1960s, with the development of computer hardware and software, direct access devices such as disks and drums Beginning to become popular, the data processing system of this period is a data management technology that organizes data in the computer into independent named data files, which can be accessed by file name and access records in the file. Data can be stored in the computer's external memory for a long time, the data can be processed repeatedly, and operations such as query, modification, insertion and deletion of files are supported. This is the file system. The file system data management diagram is shown in the figure below. The file system achieves structure within the record, but the file as a whole is unstructured. Its data is oriented to specific applications, so data sharing, independence, and redundancy are poor, and the cost of management and maintenance is also high.

Database system management stage

Since the late 1960s, computer performance has been further improved. More importantly, large-capacity disks have appeared, and the storage capacity has been greatly increased and Prices drop. On this basis, it is possible to overcome the deficiencies in file system management of data and meet and solve the requirements for data sharing by multiple users and multiple applications in practical applications, so that the data can serve as many applications as possible. This gives rise to data management technologies such as databases. The characteristics of the database are that the data is no longer only for a specific application, but for the entire organization. It has an overall structure, high sharing, reduced redundancy, and a certain degree of independence between programs and data. Unified control over data.

Features of this stage:

(1) Data structuring. When describing data, it is necessary to describe not only the data itself, but also the connections between the data. Data structuring is one of the main features of the database and the essential difference between the database system and the file system.

(2) High data sharing, low redundancy and easy expansion. The data is no longer specific to a certain application, but to the entire system. The data can be shared and used by multiple users and multiple applications, and it is easy to add new applications, so the data is highly shareable and easy to expand. Data sharing can greatly reduce data redundancy.

(3) High data independence.

(4) Data is managed and controlled uniformly by DBMS. The database is shared by multiple users and applications, and access to data is often concurrent, that is, multiple users can access data in the database at the same time, or even store the same data in the database at the same time. In order to ensure the security of database data For correct and effective operation of the database system, the database management system provides the following four aspects of data control functions.

Data security control: Prevent data leakage and damage caused by illegal use of data, and ensure data security and confidentiality.

Data integrity control: The system ensures the correctness, validity and compatibility of data by setting some integrity rules.

Concurrency control: When multiple users access or modify the database at the same time, prevent mutual interference and provide incorrect data to users and damage the database.

Data recovery: When the database is damaged or the data is unreliable, the system has the ability to restore the database from an error state to the correct state at a recent moment.

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