Question

I have the the following Django model:

class UserProfile(models.Model):
    user = models.ForeignKey(User, unique=True)
    full_name = models.CharField(max_length=100)
    network = models.ForeignKey(Network)
    positions = models.ManyToManyField(Position, through ='Timestamp', blank=True)
    featured_video = models.ForeignKey(VideoInfo, blank=True, null=True)

From SHOW CREATE TABLE userprofile_userprofile, I get the following MySQL output:

| userprofile_userprofile | CREATE TABLE `userprofile_userprofile` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `full_name` varchar(100) NOT NULL,
  `network_id` int(11) NOT NULL,
  `featured_video_id` int(11) DEFAULT NULL,
  `bio` longtext NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `user_id` (`user_id`),
  KEY `userprofile_userprofile_fb2a452b` (`network_id`),
  KEY `userprofile_userprofile_58bbe944` (`featured_video_id`),
  CONSTRAINT `featured_video_id_refs_id_b7c2ab56` FOREIGN KEY (`featured_video_id`) REFERENCES `userprofile_videoinfo` (`id`),
  CONSTRAINT `network_id_refs_id_f5c27879` FOREIGN KEY (`network_id`) REFERENCES `network_network` (`id`),
  CONSTRAINT `user_id_refs_id_da7416c6` FOREIGN KEY (`user_id`) REFERENCES `auth_user` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=31034 DEFAULT CHARSET=latin1 |

What do the last seven lines doing here? What significance do they have?

• unique key
• key
• constraint
• engine=InnoDB
• auto-increment=31034

Answer 1

• key is creating an index
• unique key is creating an index that enforces a unique value for the column mentioned.
• constraint … Foreign Key is creating a foreign key reference, limiting values inserted to only those that already exist in
  the referenced table.
• auto_increment
  set the starting auto_increment
  column value.