如何使用EAV来设计基于类、属性和值的对象？
我想设计一个系统，用户可以灵活地定义类、对象、属性和值，并且对象可以绑定到类，然后获取类的属性，然后为每个属性提供值。
我想为某些属性设置多个值，例如，如果一个对象有 2 个地点的 2 个电话号码（电话和号码是位置类的属性），我想知道 1 个对象的哪个电话对应哪个地点？什么是最好的设计？
我的设计如下：
- 类：
Id，Name - 对象：
Id，Name - ClassObject：
Id、ClassId、ObjectId - 属性：
Id、名称、ClassId - 值：
Id、ClassObjectId、属性Id，值
I want to design a system that a user can define class, object, attribute and value flexibly and objects can bound to class(es) then get attributes of class and then have values for each attribute.
I want to set multiple value for some attribute for example if an object has 2 phone number for 2 place (phone and number are attributes of Location Class) I want to know that which phone is for which place for 1 object? What is the best designing?
My design is like bellow:
- Class:
Id,Name - Object:
Id,Name - ClassObject:
Id,ClassId,ObjectId - Attribute:
Id,Name,ClassId - Value:
Id,ClassObjectId,AttributeId,Value
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回答您的设计问题：
为了将电话和地点关联起来，您必须使用附加类“地点”并将属性“电话”赋予类“地点”。 “location”类的一个实例可以有 2 个“place”类的实例。
这要求您有另外两个表：
Btw。您的元模型很有趣：它非常灵活，允许一个对象属于多个类。
因此你可以表达：
对象“Arnold Schwarzenegger”属于以下类别：BodyBuilder、Immigrnt、演员、书籍作者、商人、政治家。
另一方面，类之间没有继承/子类型关系。
您的属性定义中似乎没有显式的值类型声明。
Answer to your design question:
In order to associate the phone and place you have to use an additional class "place" and give the attribute "phone" to class "place". An instance of class "location" may have 2 instances of class "place".
This requires that you have another two tables:
Btw. Your metamodel is interesting: it is very flexible by allowing an object to belong to multiple classes.
Hence you can express:
Object "Arnold Schwarzenegger" belongs to classes: BodyBuilder, Immigrnt, Actor, Book Author, Businessman, Politician.
On the other hand you have no inheritance / subtype relationship between classes.
It seems that you have no explicit value type declaration in your attribute definition.