Modeling a many-to-many relationship in SQLAlchemy ORM - Part 1

Types of relationships

QUIZ QUESTION: :

See if you can match each of these examples with the correct relationship type.

ANSWER CHOICES:

A passport belongs to a person

An account has one user

A school teaches many subjects, and a subject is taught in many schools

A class has many students

A teacher has many students

Example	What type of relationship?
One-to-one
One-to-many
One-to-one
Many-to-many
One-to-many
Many-to-many

SOLUTION:

Example	What type of relationship?
One-to-one	A passport belongs to a person
One-to-one	An account has one user
One-to-many	A class has many students
One-to-many	A teacher has many students
One-to-one	A passport belongs to a person
One-to-one	An account has one user
Many-to-many	A school teaches many subjects, and a subject is taught in many schools
One-to-many	A class has many students
One-to-many	A teacher has many students
Many-to-many	A school teaches many subjects, and a subject is taught in many schools

Keys in relationships; association tables

Takeaways

• In one-to-many and one-to-one, the foreign key is established on the child model.
• In many-to-many, a special association table exists to join the two tables together, storing two foreign keys that link to the two foreign tables that have a relationship with each other.