MTV模型(django):
        M:模型层(models.py)
        T:templates
        V:views
    MVC模型:
        M:模型层(models.py)
        V:视图层(views.py)
        C:控制器(Controller) urls.py
    本质:django的MTV也是MVC

# 1、第一种django的orm自动创建
        class Book(models.Model):
            name = models.CharField(max_length=32)
            authors = models.ManyToManyField(to='Author')

        class Author(models.Model):
            name = models.CharField(max_length=32)


# 2、第二种纯手动创建第三张表
        class Book(models.Model):
            name = models.CharField(max_length=32)

        class Author(models.Model):
            name = models.CharField(max_length=32)

        class Book2Author(models.Model):
            book = models.ForeignKey(to='Book')
            author = models.ForeignKey(to='Author')
            info = models.CharField(max_length=32)


# 3、第三种半自动创建第三张表
        class Book(models.Model):
            name = models.CharField(max_length=32)
            authors = models.ManyToManyField(to='Author', through='Book2Author', through_fields=('book', 'author'))

        class Author(models.Model):
            name = models.CharField(max_length=3)
            book = models.ManyToManyField(to='Book', through='Book2Author', through_fields=('author', 'book'))

        class Book2Author(models.Model):
            book = models.ForeignKey(to='Book')
            author = models.ForeignKey(to='Author')
            info = models.CharField(max_length=32)

对应的数据格式：name=jason&password=123
后端获取数据：request.POST
ps:django会将urlencoded编码的数据解析自动放到request.POST

        form表单传输文件的编码格式
        后端获取文件格式数据:request.FILES
        后端获取普通键值对数据:request.POST