Data migration

# testdb/models.py
from django.db import models


class Author(models.Model):
    last_name = models.CharField(max_length=200)
    first_name = models.CharField(max_length=200)
    birth_date = models.DateField()

    class Meta:
        db_table = 'authors'


class Language(models.Model):
    name = models.CharField(max_length=200)

    class Meta:
        db_table = 'languages'


class Book(models.Model):
    title = models.CharField(max_length=200)
    authors = models.ManyToManyField(Author)
    available_languages = models.ManyToManyField(Language)

    class Meta:
        db_table = 'books'