逻辑数据模型和概念数据模型有什么区别？ [英] What is the difference between logical data model and conceptual data model?

问题描述

逻辑数据模型和概念数据模型之间有什么区别？

解决方案

在概念数据模型中，您只需要担心高级设计-应该存在哪些表以及它们之间的连接。在此阶段中，您将识别模型中的实体及其之间的关系。

当您明确定义每个表中的列时，逻辑模型紧随概念建模之后。在编写逻辑模型时，您可能还会考虑要设计的实际数据库系统，但前提是它会影响设计（即，如果没有触发器，则可能要删除一些冗余列等）。

还有一个物理模型，详细说明了逻辑模型并为每列分配了类型/长度等。

What is the difference between logical data model and conceptual data model?

解决方案

In the conceptual data model you worry only about the high level design - what tables should exist and the connections between them. In this phase you recognize entities in your model and the relationships between them.

The logical model comes after the conceptual modeling when you explicitly define what the columns in each table are. While writing the logical model, you might also take into consideration the actual database system you're designing for, but only if it affects the design (i.e., if there are no triggers you might want to remove some redundancy column etc.)

There is also physical model which elaborates on the logical model and assigns each column with it's type/length etc.

Here is a good table and picture that describes each of the three levels.

|----------------------|------------|---------|----------|
| Feature              | Conceptual | Logical | Physical | 
|----------------------|------------|---------|----------|
| Entity Names         | X          | X       |          |
| Entity Relationships | X          | X       |          |
| Attributes           |            | X       |          |
| Primary Keys         |            | X       | X        |
| Foreign Keys         |            | X       | X        |
| Table Names          |            |         | X        |
| Column Names         |            |         | X        |
| Column Data Types    |            |         | X        |
|----------------------|------------|---------|----------|

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