What are the characteristics of relational databases?

The main features of relational databases: 1. Centralized control of data; 2. High data independence; 3. Good data sharing; 4. Small data redundancy; 5. Data structure; 6. Unified Data protection features.

Relational database is a database based on the relational database model. It uses concepts and methods such as set algebra to process data in the database. It is also a Organized into a set of formally descriptive tables that are essentially special collections of data items that can be accessed or recalled in many different ways without the need for reorganization Database table.

The definition of a relational database results in a table of metadata or a formal description of tables, columns, ranges, and constraints. Each table (sometimes called a relationship) contains one or more data types represented by columns. Each row contains a unique data entity of the type defined by the column.

When creating a relational database, you can define the range of possible values ​​for a data column and further constraints that may apply to that data value.

The SQL language is the standard user and application interface to the relational database. The advantage is that it is easy to expand, and after the initial database creation, a new data type can be added without modifying all existing applications. Mainstream relational databases include oracle, db2, sqlserver, sybase, mysql, etc.

Main features of relational database

1) Centralized control of data. In the file management method, files are scattered, and each user or each process has its own file. There is generally no connection between these files. 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) High 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) Good data sharing. The data in the database can be used by multiple users, and each user is only connected with a part of the data in the database; user data can overlap, and users can access data at the same time without affecting each other, which greatly improves the efficiency of the database.

4) Data redundancy is small. 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) The data is structured. The entire database is composed of a certain structural form. The data is interrelated within the records and between record types. Users can access the data through different paths.

6) Unified data protection function, in the case of multiple users sharing data resources, strict inspection of user data, stipulating passwords or access rights for the database, and denying illegal users access to the database to ensure Data security, consistency and concurrency control.

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