# Database Relationship Types

* **One-to-One**: A user has one profile (e.g., `/users/1/profile`).
* **One-to-Many**: An author has many books (`/authors/1/books`).
* **Many-to-Many**: Projects and team members (`/projects/1/team-members`)

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### Relate&#x64;**:**

* **Rails**
  * [**Routes setup (BACKEND style guide)**](https://aaron-mota.gitbook.io/aarons-style-guide/api/broken-reference) (i.e. `routes.rb`)
  * [**Controller Setup (BACKEND style guide)**](https://aaron-mota.gitbook.io/aarons-style-guide/api/broken-reference) (e.g. `projects_controller.rb`)
