What are the classifications of models in the database?

Classification of models in the database: 1. Conceptual data model, which is user-oriented and real-world oriented data model, describing the conceptual structure of a unit; 2. Logical data model, which can outline the enterprise through entities and relationships. Data blueprint; 3. Physical data model, which has the characteristics of intuitively expressing cognitive objects in the form of physical objects or drawings.

Classification of models in the database:

1. Conceptual data model

Characteristics are

• User-oriented, real-world oriented data model, describing the conceptual structure of a unit;

• has strong Semantic expression ability can express various semantic knowledge in applications conveniently and directly;

• Simple, clear, and easy for users to understand;

• Conceptual models are subjective artifacts.

2. The logical data model

is characterized by

• #directly reflecting the needs of the business department , plays an important guiding role in the physical implementation of the system;

• 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 the data involved in a specific application must adhere to.

3. The physical data model

is characterized by

• being intuitive in the form of physical objects or drawings Express the characteristics of the cognitive object;

• Each logical data model has its corresponding physical data model when implemented;

• Description 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 information:

The data model structure is mainly divided into data structure, data operation, and data constraints .

1. Data structure mainly describes the type, content, nature of data and the relationship between data. Data types, such as record types, data items in the DBTG network model, relationships in the 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 operation types and operation methods on the corresponding data structures. It is a collection of operation operators, including several operations and inference rules, used to operate on the database composed of valid instances of the target type.

3. Data constraints mainly describe the syntax and word meaning relationships between data in the data structure, the constraints and dependencies between them, and the rules for dynamic changes in data to ensure that the data is correct, effective and compatible. Constraints can be divided according to different principles into data value constraints and data connection constraints; static constraints and dynamic constraints; entity constraints and reference constraints between entities, etc.

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