数据库设计-ERD。建模问题
希望有人能够快速建议我建模 ERD 的最佳方法（我使用的是 IDEF1X 和 ERWin，而不是 Chen Notation），尽管这并不重要。
基本上，我有三个实体
- 组织
- 人员
- 受托人
业务规则规定受托人可以是个人或组织。
我的问题是，与受托人有两个主要的外键关系是否正确。组织之一>受托人和第二个从人>受托人。受托人的 FK 字段之一将始终为 NULL，具体取决于受托人是个人还是组织。
或者在个人和组织（person_organization）之间建立某种关联表并根据 person_Organization > 创建 PK、FK 关系会更好吗？受托人。
第二种选择似乎更好，因为可能还有其他实体也需要链接到组织和个人。
希望这是有道理的。
提前非常感谢
Hopefully someone may be able to quickly advise the best way for me to model my ERD (I'm using IDEF1X & ERWin not Chen Notation) although it doesn't really matter.
Basically I have Three Entities
- Organisation
- Person
- Trustee
Business rules state that a Trustee can be either a person or organisation.
My question is, would it be correct to have two primary, foreign key relationships to Trustee. One from Organisation > Trustee and the second from Person > Trustee. Where one of the FK fields of Trustee will always be NULL depending on if the Trustee is a person or organisation.
Or would it be better to have some sort of associative table between person and organisation (person_organisation) and create a PK, FK relationship from person_Organisation > Trustee.
The second option seems better as there might be other entities that also need to link to both Organisation and person.
Hopefully that makes sense.
Many many thanks in advance
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好吧，这也应该有效：
EDIT
Well, this should work too:
在我看来，受托人只是一个人在组织中可以扮演的角色的一个例子。实际上，我们正在讨论一个三向关联 Person_Organization_Role，其中所有三个都是主键。现在，可以分解为 Person_Organization > PO_Role，但我的偏好是不要走那么远。
It seems to me that Trustee is just one example of a role a person can play in an organisation. So really, we're talking about a three-way association Person_Organization_Role where all three are the primary key. Now, that could be broken down into Person_Organization > PO_Role, but my preference is not to take things that far.