What are the classifications and characteristics of data models?

According to different application levels, data models are divided into conceptual data model, logical data model and physical data model.

1, conceptual data model

Its characteristic is a user-oriented and real-world-oriented data model, which describes the conceptual structure of a unit; Have strong semantic expression ability, and can express all kinds of semantic knowledge in application conveniently and directly; Simple and clear, easy for users to understand; Conceptual model is a work full of subjective colors.

2. Logical data model

It directly reflects the needs of business departments and plays an important guiding role in the physical implementation of the system. You can outline the data blueprint of the enterprise through entities and relationships; The logical model provides a mechanism for users to define integrity constraints to reflect the specific semantic constraints that data involved in a specific application must abide by.

3. Physical data model

Its characteristic is to express the cognitive object intuitively in the form of physical objects or drawings; Each logical data model has its corresponding physical data model when it is implemented; Describing the organizational structure of data on storage media is not only related to the specific DBMS, but also related to the operating system and hardware.

Extended data:

Data model structure is mainly divided into data structure, data operation and data constraint.

1. The data structure mainly describes the types, contents, attributes and relationships of data. Data types, such as records in DBTG network model, data items, relationships in relational model, etc. Data structure is the basis of data model, and different data structures have different operations and constraints.

2. Data operations mainly describe the types and ways of operations on corresponding data structures. Is a collection of operation operators, including several operation and inference rules, used to operate a database composed of valid instances of the target type.

3. Data constraints mainly describe the syntax, semantic relations, constraints and dependencies between data in the data structure, as well as the rules of data dynamic change, so as to ensure the correctness, validity and compatibility of data. Constraints can be divided into data value constraints and data connection constraints according to different principles; Static constraints and dynamic constraints; Entity constraints and reference constraints between entities, etc.

Baidu Encyclopedia-Data Model

Baidu Encyclopedia-Conceptual Model

Baidu Encyclopedia-Logical Model

Baidu encyclopedia-physical model