The data model should meet three requirements, which do not include

The data model should meet three requirements, which do not include: easy to be understood by people.

A data model is an abstraction of data characteristics. Data is a symbolic record describing things, and models are abstractions of the real world. The data model describes the static characteristics, dynamic behaviors and constraints of the system from the abstract level, and provides an abstract framework for the information representation and operation of the database system. The data model describes three parts: data structure, data operation and data constraint.

Since the development of database technology, there are three main data models: hierarchical data model, network data model and relational data model. Hierarchical model developed earliest, with tree structure as its basic structure, and IMS model is its typical representative. In most practical problems, the relationship between data is not a simple tree structure, and the hierarchical data model is gradually eliminated. Mesh data model expresses the relationship between data through mesh structure. This model developed earlier and has certain advantages, but it is still widely used, and the typical representative is DBTG model.

The relational model developed late. It is a model to express the relationship between entity set and data through a two-dimensional table that meets certain conditions. It has a solid mathematical and theoretical foundation and is flexible and convenient to use, so it develops rapidly.

Introduction to data model:

With the development of database science, the concept of data model is gradually deepened and improved. In the early days, data models were usually understood as data structures. Then, in some database systems, the data model is simplified into four aspects: logical structure, physical configuration, access path and integrity constraints.

The concept of modern data model holds that data structure is only one of the components of data model. The physical configuration and access path of data are concepts about data storage, which do not belong to the content of data model. In addition, the data model should not only provide the means of data representation, but also provide the types and methods of data operation, because the database is not static, but dynamic. Therefore, the data model also includes a data manipulation part.