Is a data model usually composed of data structures, data types and data operations?
Data model usually consists of three parts: data structure, data operation and integrity constraints.
Generally speaking, a data model is a strictly defined set of concepts. These concepts accurately describe the static characteristics, dynamic characteristics and integrity constraints of the system. Therefore, the data type usually consists of three parts: data structure, data operation and integrity constraints.
Related introduction:
Data Model (Data Model) is an abstraction of data characteristics. Data is a symbolic record that describes things, and model is an abstraction of the real world. The data model describes the static characteristics, dynamic behavior and constraints of the system from an abstract level, providing an abstract framework for the information representation and operation of the database system. The content described by the data model has three parts: data structure, data operations and data constraints.
The content described by the data model includes three parts: data structure, data operations, and data constraints.
1) Data structure: It mainly describes the type, content, nature and relationship between data, etc. It is a collection of target types. Target types are components of the database and can generally be divided into two categories: data types and relationships between data types. Data types include record types and data items in the DBTG (Database Task Group) network model, relationships and domains in the relational model, etc. The contact part includes the line types in the DBTG network model, etc. Data structure is the basis of data model, and data operations and constraints are basically based on data structure. Different data structures have different operations and constraints.
2) Data operations: Data operations in the data model mainly describe the operation types and operation methods on the corresponding data structure. It is a collection of operators, including several operations and inference rules, used to operate on a database composed of valid instances of the target type.
3) Data 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 stability of the data. Correct, valid and compatible. It is a collection of integrity rules to limit the database state and state changes that conform to the data model. 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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