from django.db import models

class User(models.Model):

    username = models.CharField(max_length=12, unique=True)

    serial = models.IntegerField()

class UserSite(models.Model):

    user = models.ForeignKey(User, to_field="username")

    data = models.IntegerField()

class Place(models.Model):

    name = models.CharField(max_length=50)

class Restaurant(Place):

    pass

class Manager(models.Model):

    retaurant = models.ForeignKey(Restaurant)

    name = models.CharField(max_length=50)