@startuml
title User Management System ER Diagram

class User {
  +id: int
  ...
}

class Role {
  +id: int
  +name: string
}

class Permission {
  +id: int
  +name: string
}

class User_Role_Permission {
  +user_id: int
  +role_id: int
  +permission_id: int
}

User --> "*" User_Role_Permission
Role --> "*" User_Role_Permission
Permission --> "*" User_Role_Permission
@enduml