classDiagram
    class User {
        +int Id
        +string Name
        +string Email
        +Login()
        +Register()
    }

    class Ad {
        +int Id
        +string Title
        +decimal Price
        +string Description
        +Create()
        +Delete()
    }

    class Message {
        +int Id
        +string Content
        +DateTime SentAt
        +Send()
    }

    User "1" --> "*" Ad : erstellt
    User "1" --> "*" Message : schreibt