从案例研究创建 ERD 图

Question

我正在尝试为众筹服务创建 ERD 图。我不确定我是否正确理解了实体以及它们之间的关系。

任务是创建规则（关系的句子）和查找需要的实体。

项目所有者呼吁 public 参与以资助他们的创新想法，即产品。 public 预购产品，该产品按初始价格提供。

实体和关系是什么？

Answer 1

我认为您错过了一些实体和关系。

The system has many projects.
A project has exactly one owner.
A project has exactly one product.
A product has exactly one price.
A product has zero or more orders.
An order has exactly one backer.
A backer may have many orders.
An order has (?) payments.
A project has a derived attribute of "total funding", which is calculated by adding up the value all the orders (or payments?)

从案例研究创建 ERD 图

Creating ERD Diagram From Case Study

mysql

database

erd

relationship