class Category(models.Model):
    name = models.CharField(max_length=255)

class Post(models.Model):
    title = models.CharField(max_length=255)
    description = models.TextField()
    post = models.TextField()
    pub_date = models.DateField()
    categories = models.ManyToManyField(Category, blank=True)

BEGIN;
CREATE TABLE `posts_category` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `name` varchar(255) NOT NULL
)
;
CREATE TABLE `posts_post` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `title` varchar(255) NOT NULL,
    `description` longtext NOT NULL,
    `post` longtext NOT NULL,
    `pub_date` date NOT NULL
)
;
CREATE TABLE `posts_post_categories` (
    `id` integer AUTO_INCREMENT NOT NULL PRIMARY KEY,
    `post_id` integer NOT NULL,
    `category_id` integer NOT NULL,
    UNIQUE (`post_id`, `category_id`)
)
;
ALTER TABLE `posts_post_categories` ADD CONSTRAINT `post_id_refs_id_2bd0ebb3` FOREIGN KEY (`post_id`) REFERENCES `posts_post` (`id`);
ALTER TABLE `posts_post_categories` ADD CONSTRAINT `category_id_refs_id_65af7dcb` FOREIGN KEY (`category_id`) REFERENCES `posts_category` (`id`);
COMMIT;

UNIQUE (`post_id`, `category_id`)