Data Management Technology(2) -- Data Model

最新推荐文章于 2022-02-17 14:04:15 发布

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最新推荐文章于 2022-02-17 14:04:15 发布

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分类专栏：数据库文章标签：北航软件学院数据库 Data Model

本文链接：https://blog.youkuaiyun.com/weixin_41473206/article/details/93377284

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本文详细介绍了数据模型的概念，包括不同抽象层次的数据模型，重点讲解了概念模型中的ER模型和逻辑模型中的关系模型。ER模型通过实体、属性、关系和约束来表达信息，而关系模型则描述了数据结构、操作和约束，包括关系、键、完整性约束等。文章还探讨了从ER模型到关系模型的转换，并通过实例说明了关系代数的操作，如选择、投影、连接等。

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文章目录

1.Data Model

Model

Is the abstraction of real world
Reveal the essence of objects, help people to locate and resolve problems

Data Model

A data model explicitly determines the structure of data, and defines the operation that can be imposed, in order to represent the characteristic of the world
Data model is the core and fundamental of database
- Data model determines the function and performance of database
There exists different data models
- From different level, or different point of view
- The evolution of data model promotes the database progress
Conceptual model
- documents and organizes the data for communication between functional and technical people
Logical model
- describes data semantics, data relationships, data constraints and data operation in database
Physical model
- describes how data is organized in storage device

Different level of abstraction

2.Conceptual Model - ER Model

Is the most popular conceptual model
Gives us a language to specify
- what information the db must hold
- what are the relationships among components of that information
View the world as a collection of entities

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