What stages has data management technology gone through so far?

Data management technology has gone through three stages: 1. Manual management stage (before the mid-1950s), which mainly uses the human brain to manage and utilize data; 2. File system stage (1950s) late to the mid-1960s); 3. Database system stage (since the late 1960s).

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

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 and driven by application needs, data management technology has gone through three stages: manual management, file system, and database system based on the development of computer hardware and software.

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 calculation tools (abacus, slide rule) to perform calculations, and mainly 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) 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 stage

From the late 1950s to the mid-1960s, with the development of computer hardware and software, disks, magnetic drums When direct access devices began to become popular, the data processing system of this period organized the data in the computer into independent named data files, and could be accessed according to the name of the file, and the records in the file were accessed. data management technology.

Data can be stored in the computer's external memory for a long time, the data can be processed repeatedly, and it supports operations such as query, modification, insertion and deletion of files. This is the file system. The file system achieves structure within the record, but the file as a whole is unstructured.

The data is oriented to specific applications, so data sharing and independence are poor, and the redundancy is high, and the cost of management and maintenance is also high.

Database system stage

Since the late 1960s, computer performance has been further improved, and more importantly, large-capacity disks have appeared. Storage capacity has increased significantly and prices have dropped. 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 characteristic of the database is that the data is no longer just for a specific application, but for the entire organization. It has an overall structure, high sharing, reduced redundancy, and a certain relationship between programs and data. independence and 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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