数据库:关于两种可能性的设计要点是什么? [英] Database : what design to point on two possibilities?

问题描述

我正在为一个新项目设计一个数据模型.

其中一项要求指定某些对象可以指向个人或公司.

实现这一目标的最明智方法是什么?

我想过像这样的表格链接演员"(用优秀的

解决方案

我建议你创建引用相同超类型(actor)的 company 和 person 子类型.请注意，您不需要单独的 person_id、company_id，因为参与者必须是一个或另一个，并且不能同时是两者.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:

这篇关于数据库:关于两种可能性的设计要点是什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！