数据库：什么设计指出两种可能性？ [英] Database : what design to point on two possibilities?

问题描述

我正在设计一个新项目的数据模型。

其中一个要求规定某些对象可以指向某人或公司。

最聪明的方法是什么？

我已经考虑过一个表链接 这样（用优秀的

解决方案

我建议您制作公司和个人子类型引用相同的超类型（actor）。请注意，您不需要单独的person_id，company_id，因为actor必须是一个或其他，不能同时使用。像这样：

I am designing a datamodel for a new project.

One of the requirements specifies that some objects can point either a person or a company.

What is the smartest way to achieve that?

I have thought about a table link "actor" like this (drawn with the excellent yUML.me BTW) :

In the actor table, according to actor_type, person_id or company_id is a foreign key on its corresponding table or is NULL. This way, when one_table wants to retrieve details about the actor, I start by checking the actor_type field and retrieve either person_id or company_id.

It is working, but I am looking for a better design. Here is the link for editing the diagram

解决方案

I suggest you make company and person subtypes that reference the same supertype (actor). Note that you don't need separate person_id, company_id because an actor must be one or other and cannot be both. Like this:

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