How can relationships between models be established within Django ORM?

In Django ORM, relationships between models are established using special fields that define the type of connection:

• ForeignKey (one-to-many): Connects one record of a model to multiple records of another.

• OneToOneField (one-to-one): Connects one record of a model to one record of another.

• ManyToManyField (many-to-many): Allows linking multiple records of one model with multiple records of another.

Example:

from django.db import models

class Author(models.Model):
    name = models.CharField(max_length=100)

class Book(models.Model):
    title = models.CharField(max_length=200)
    author = models.ForeignKey(Author, on_delete=models.CASCADE)  # one author - many books

class Profile(models.Model):
    user = models.OneToOneField('auth.User', on_delete=models.CASCADE)  # one profile - one user

class Student(models.Model):
    name = models.CharField(max_length=100)
    courses = models.ManyToManyField('Course')  # student can attend many courses

class Course(models.Model):
    title = models.CharField(max_length=200)

Thus, using these fields, you can explicitly define and manage relationships between models in the database.