The nature of the database is determined by the "data model" it adopts. The data model is a tool used in database design to abstract the real world. It is a formal framework used in the database to provide information representation and operation methods; the data model is the core and foundation of the database system.
The operating environment of this tutorial: Windows 7 system, mysql version 5.8, Dell G3 computer.
The nature of the database is determined by the "data model" it adopts.
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The data model (Data Model) is an abstraction of data characteristics. It describes the system from an abstract level. Static characteristics, dynamic behaviors and constraints provide an abstract framework for information representation and operation of database systems. The content described by the data model has three parts, namely data structure, data operations and data constraints.
The content described by the data model includes three parts: data structure, data operations, and data constraints
①Data structure: The data structure in the data model mainly describes the type, content, and nature of the data and the connections between data, etc. Data structure is the basis of data model, and data operations and constraints are based on data structure. Different data structures have different operations and constraints.
②Data operations: Data operations in the data model mainly describe the operation types and operation methods on the corresponding data structure.
③Data constraints: Data constraints in the data model mainly describe the syntax and word meaning connections between data in the data structure, the constraints and dependencies between them, and the rules for dynamic changes in data to ensure the accuracy of the data. , effective and compatible.
Types of data models:
Three basic data models have been produced in the process of data development, they are hierarchical model, network model and relational model .
1. Hierarchical model
organizes data into a one-to-many relationship structure, and uses a tree structure to represent entities and the relationships between entities.
2. Network model
Use connection instructions or pointers to determine the network connection relationship between data, which is a many-to-many data organization method.
3. Relational model
Organize data in the form of record groups or data tables to facilitate storage and transformation using the relationships between various entities and attributes, without hierarchies or pointers. , is a very effective data organization method to establish the relationship between spatial data and attribute data
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