from django.db import models

class Author(models.Model):

    name = models.CharField(max_length=100)

    age = models.IntegerField()

    friends = models.ManyToManyField("self", blank=True)

class Publisher(models.Model):

    name = models.CharField(max_length=255)

    num_awards = models.IntegerField()

class Book(models.Model):

    isbn = models.CharField(max_length=9)

    name = models.CharField(max_length=255)

    pages = models.IntegerField()

    rating = models.FloatField()

    price = models.DecimalField(decimal_places=2, max_digits=6)

    authors = models.ManyToManyField(Author)

    contact = models.ForeignKey(Author, models.CASCADE, related_name="book_contact_set")

    publisher = models.ForeignKey(Publisher, models.CASCADE)

    pubdate = models.DateField()

class Store(models.Model):

    name = models.CharField(max_length=255)

    books = models.ManyToManyField(Book)

    original_opening = models.DateTimeField()

    friday_night_closing = models.TimeField()

    area = models.IntegerField(null=True, db_column="surface")

class DepartmentStore(Store):

    chain = models.CharField(max_length=255)

class Employee(models.Model):

    # The order of these fields matter, do not change. Certain backends

    # rely on field ordering to perform database conversions, and this

    # model helps to test that.

    first_name = models.CharField(max_length=20)

    manager = models.BooleanField(default=False)

    last_name = models.CharField(max_length=20)

    store = models.ForeignKey(Store, models.CASCADE)

    age = models.IntegerField()

    salary = models.DecimalField(max_digits=8, decimal_places=2)

class Company(models.Model):

    name = models.CharField(max_length=200)

    motto = models.CharField(max_length=200, null=True, blank=True)

    ticker_name = models.CharField(max_length=10, null=True, blank=True)

    description = models.CharField(max_length=200, null=True, blank=True)

class Ticket(models.Model):

    active_at = models.DateTimeField()

    duration = models.DurationField()