mysql - 棱镜数据模型 : Primary key as a combination of two relational models

Question

我在 Prisma 数据建模中遇到问题，我必须限制用户只能为产品提交一条评论。我有针对非约束情况的以下设计。

Should Customer and Product be combined into a primary key in ProductReview model, or should this constraint be imposed at the application server level, and not at the database level?

现在的数据模型(非约束版本):

type Product {
  id: ID! @unique
  title: String!
  reviews: [ProductReview!]! @relation(name: "ProductReviews", onDelete: CASCADE)
}

type Customer {
  id: ID! @unique
  email: String @unique
}

type ProductReview {
  id: ID! @unique
  forProduct: Product! @relation(name: "ProductReviews", onDelete: SET_NULL)
  byCustomer: Customer!
  review: String!
  ratinng: Float!
}

Answer 1

看起来 Prisma v2 引入了复合主键:

https://newreleases.io/project/github/prisma/prisma/release/2.0.0-preview023

该链接的示例:

model User {
  firstName String
  lastName  String
  email     String

  @@id([firstName, lastName])
}

所以在给定的问题示例中，应该可以添加到ProductReview:

@@id([id, forProduct])