What are the characteristics of the data model?

The characteristics of the data model are: 1. Conceptual data model, which is user-oriented and real-world oriented; 2. Logical data model, which directly reflects the needs of the business department; 3. Physical data model, which has the following characteristics: Express the characteristics of the recognized object intuitively in the form of physical objects or drawings.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

The data model is divided into conceptual data model, logical data model and physical data model according to different application levels.

1. Conceptual data model

is characterized by a user-oriented and real-world data model that describes the conceptual structure of a unit; it has strong semantic expression ability and can be expressed conveniently and directly Various semantic knowledge in applications; simple, clear, and easy for users to understand; conceptual models are artifacts full of subjective color.

2. The logical data model

is characterized by directly reflecting the needs of the business department and playing an important guiding role in the physical implementation of the system; it can outline the data blueprint of the enterprise through entities and relationships; logic The 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 comply with.

3. Physical data model

is characterized by the ability to intuitively express cognitive objects in the form of physical objects or drawings; each logical data model has its corresponding physical data model when implemented. ; Describes the organizational structure of data on storage media, which 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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