Shulou(Shulou.com)06/01 Report--

The editor in this issue will bring you an introduction to the relational database and analyze and describe it from a professional point of view. I hope you can get something after reading this article.

Relational database is a database created on the basis of relational model, which deals with the data in the database with the help of mathematical concepts and methods such as set algebra. All kinds of entities in the real world and the relationships between them are represented by relational models. The relation model was first put forward by Edgar Cod in 1970 and cooperated with the Twelve laws of Cod. Although there are some criticisms of this model nowadays, it is still the traditional standard of data storage. The standard data query language SQL is a language based on relational database, which performs the retrieval and operation of data in relational database.

The relational model consists of three parts: relational data structure, relational operation set and relational integrity constraints.

1. Relational database

In a given application domain, the set of all entities and their relationships forms a relational database.

2. The type and value of relational database

The type of relational database is called relational database schema, which is the description of relational database, the definition of several domains, and several relational schemas defined on these domains; the value of relational database is the set of relationships corresponding to these relational patterns at a certain time, which is usually referred to as relational database.

3. Relational database structure

Single data structure-relationship

Entities in the real world and all kinds of relationships between them are represented by relationships.

Logical structure of data-two-dimensional table

From the user's point of view, the logical structure of the data in the relational model is a two-dimensional table.

However, this simple data structure of the relational model can express rich semantics and describe the entities and the relationships between entities in the real world.

The above is the introduction of the relational database shared by the editor. If you have similar doubts, it will not hinder your understanding with reference to the above analysis. If you want to know more about it, please follow the industry information.

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