At this stage, storing and managing data is inseparable from the database. For example, schools need to use databases to store student and teacher information; companies need to use databases to store company profiles and employee information. After the data is stored in the database, the database management system will organize and manage the data.
The database management system (DBMS) is one of the core software of the database, which is the data management software located between the user and the operating system, which is used to establish, use and maintain the database.
Data management is to classify, organize, code, query and maintain various data. It mainly goes through three stages, namely the manual management stage, the file system stage and the database system stage. Each stage is developed to reduce data redundancy, enhance data independence, and facilitate data manipulation.
Data redundancy refers to the duplication of data, or it can be said that the same data is stored in different data files.
1. Manual management stage
Before the advent of computers, people mainly used paper and computing tools (such as abacus and slide rules) to record and calculate data, and rely on the brain to manage and utilize data.
In the mid-1950s, when computers were just beginning to sprout, there were no storage devices such as disks that specialized in managing data, but only external storage such as paper tapes, cards, and magnetic tapes. Therefore, computers can only be limited to scientific and technological aspects, mainly used for scientific computing.
That is to say, in the manual management stage, data is mainly stored on media such as paper tapes, magnetic tapes, etc., or recorded directly by hand.
The characteristics of the manual management phase are as follows:
- Data cannot be stored for a long time
- Inconvenient to query data
- Data cannot be shared, and redundancy is large
- Data is not independent
2. File system stage
In the late 1950s to the mid 1960s, direct access devices such as disks and magnetic drums in computers became popular. At this point, the data can be stored on the computer’s disk. These data are stored in the form of files, which are then managed by the file system.
Figure 1 is the file system under Windows.
There are many folders in Figure 1, and each folder has many files, which is the file system. The file system accesses the data in the file through the storage path and file name of the file, and we can view, modify, add and delete these files.
Compared with the manual management stage, the file system makes data management simple, and there is no need to search through boxes and cabinets for a file. However, the data in these files is not structured and managed, and it is still inconvenient to query.
The characteristics of the file system phase are as follows:
- Data can be stored for a long time
- Data is managed by the file system
- Large data redundancy and poor sharing
- poor data independence
- Unable to deal with emergencies (file deletion, disk failure, etc.)
3. Database System Phase
In the late 1960s, with the development of network technology and the advancement of computer software/hardware, database technology appeared. This stage is the so-called database system stage.
The database system stage uses a special database to manage data. Users can create a database in the database system, then create tables in the database, and finally store data in these tables. Users can directly query the data in the table through the database management system.
Compared with the file system, the database system implements data structure. In a file system, the data inside an independent file is generally structured, but there is no connection between the files, so there is no structure as a whole. Although the database system is often divided into many separate data files, it pays more attention to the interconnection between the data files in the same database.
The characteristics of the database system phase are as follows:
- Data is uniformly managed and controlled by a database management system
- High data sharing, low redundancy
- Strong data independence
- Small data granularity
Data granularity is the granularity of the data in the database. The higher the degree of refinement, the smaller the granularity; the lower the degree of refinement, the larger the granularity.
Each stage of data management experience has its own background and characteristics, and data management technology is constantly improving in the development. The comparison of the three stages is shown in the following table.
|3 Stages of Data Management||Human management (mid 1950s)||File systems (late 50’s to mid 60’s)||Database systems (late 1960s)|
|application background||Scientific Computing||scientific computing, management||Management of large-scale data and distributed data|
|hardware background||No direct access storage device||Tape, Disk, Drum||Large-capacity disks, rewritable optical discs, tape drives on demand, etc.|
|software background||No special management software||Utilize the operating system’s file system||Powered by DBMS|
|Data processing method||batch processing||Online real-time processing, batch processing||Online real-time processing, batch processing, distributed processing|
|data manager||User/Program Management||file system proxy||DBMS management|
|Data application and its extension||Difficult to expand for an application||For a certain application system, it is not easy to expand||Facing a variety of application systems, easy to expand|
|data sharing||No sharing, great redundancy||Poor sharing and high redundancy||Good sharing and low redundancy|
|data independence||data independence||Good physical independence, poor logical independence||It has a high degree of physical independence and good logical independence|
|data structure||Data has no structure||There is structure in the record, and the whole has no structure||Unified data model, overall structure|
|data security||application protection||file system protection||Complete security protection provided by DBMS|