模型和实体有什么区别 [英] what is difference between a Model and an Entity

问题描述

我很困惑不明白这句话的意思:

I am confused to understand what is the meaning of this words:

Entity、Model、DataModel、ViewModel

任何机构可以帮助我理解它们吗?谢谢大家.

Can any body help me to understanding them please? Thank you all.

推荐答案

我希望我没有错过您在 king.net 中的观点...

I hope I've not missed your point here king.net...

无论如何，假设您在谈论实体建模或实体关系建模 (ERD):

Anyway, presuming you're talking about entity modelling or entity-relationship modelling (ERDs):

• 一个实体代表任何现实世界的实体 - 例如学生，课程，
• 实体将具有属性 - 例如学生有名字、姓氏、出生日期
• 实体将具有关系 - 例如学生已注册"课程(其中学生和课程是具有属性的实体，已注册"是关系.
• 关系可以是一对一"、一对多"或多对多"——例如一名学生注册"了许多课程，同样，一门课程有"许多学生.
• 关系也有基数

添加实体之间的关系会创建一个数据模型".您已经对一些真实世界的系统和该系统中的内部实体/对象进行了建模.下一步是对其进行规范化以确保其符合规范形式".

Adding relationships between entities creates a "data model". You've modeled some real world system and the internal entities/ objects in that system. Next step is to normalise it to ensure it meets "normal form".

在 ERD 术语中，您可能有逻辑"和物理"模型.逻辑用简单的高级术语描述了数据模型，但没有提供实现它所需的技术细节.它代表系统解决方案概述.物理模型包括实际实现系统所需的技术细节(例如实现多对多"关系所需的多对多连接表").

In ERD terms, you may have "logical" and "physical" models. The logical describes the data-model in simple high-level terms that witholds the technical detail required to implement it. It represents the system solution overview. The physical model includes technical details required to actually implement the system (such as "many-to-many join tables" needed to implement "many-to-many" relationships).

这里有一些在线教程(虽然我确定肯定有数千个):

Here are some tutorials on-line (though I'm sure there must be thousands):

• http://www.maakal.com/maakalDB/Database101ERDpart1.htm
• http://www.itteam-direct.com/gwentrel.htm
• http://www.bkent.net/Doc/simple5.htm

我不太确定您在相关上下文中所说的模型"和视图模型"是什么意思.不确定您是否会将此与模型-视图-控制器范式 (MVC) 混淆.在这里，模型是一些数据组件，视图代表该数据的观察者(例如表或图形 UI 组件).网上有很多关于模型视图控制器"或MVC"的解释.

I'm not quite sure what you mean by "model" and "view model" in a related context. Not sure if you may be confusing this with Model-View-Controller paradigm (MVC). Here, a model is some data component and the view represents an observer of that data (such as a table or graph UI component). There's lots on-line explaining "model view controller" or "MVC".

希望这会有所帮助，韦恩

Hope this helps, Wayne

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