The main features of relational databases are: 1. Centralized control, maintenance and management of data. 2. Data independence; the data in the database is independent of the application, including the physical independence and logical independence of the data, which provides convenience for the use, adjustment, optimization and further expansion of the database, and improves the stability of the database application system. . 3. Data sharing can be used by multiple users, and each user only has contact with a part of the data in the database. 4. Reduce data redundancy; data is not application-oriented, but system-oriented. 5. Data structuring. 6. Unified data protection function.
The operating environment of this tutorial: Windows 7 system, Dell G3 computer.
Main features of relational database
1) Centralized control of data
In the file management method, the files are dispersed, and each user or Each process has its own files, and these files are generally not connected. Therefore, they cannot be controlled, maintained and managed according to a unified method. The database overcomes this shortcoming well and can centrally control, maintain and manage relevant data.
2) Data independence
The data in the database is independent of the application, including the physical independence and logical independence of the data, which provides convenience for the use, adjustment, optimization and further expansion of the database. , improving the stability of the database application system.
3) Data sharing
The data in the database can be used by multiple users, and each user is only related to part of the data in the database; user data can overlap, and users can access it at the same time The data does not affect each other, which greatly improves the efficiency of database use.
4) Reduce data redundancy
The data in the database is not application-oriented, but system-oriented. Data is uniformly defined, organized, stored and managed centrally, which avoids unnecessary data redundancy and improves data consistency.
5) Data structuring
The entire database is structured in a certain structural form. Data is interrelated within records and between record types. Users can access data through different paths.
6) Unified data protection function
When multiple users share data resources, strict inspection of user data is carried out, passwords or access rights are specified for the database, and illegal users are rejected Enter the database to ensure data security, consistency and concurrency control
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