Handle One-to-One and One-to-Many Relationships

Overview

In this lesson, we’ll delve into the intricacies of one-to-one and one-to-many relationships and learn how to manage them with TypeORM.

Relationships are the associations between different entities (tables) in a relational database. There are several types of relationships.

• One-to-one (1:1): One record in a table is related to one—and only one—record in another. For example, a user and their primary address have a one-to-one relationship.

• One-to-many (1:N): A record in one table can be related to multiple records in another. For instance, a single user might have multiple posts in a blogging application.

• Many-to-many (N:N): Multiple records in one table can be related to multiple records in another. For instance, students and courses in a school management system might have a many-to-many relationship.

Handling a one-to-one relationship

The following illustration shows a one-to-one relationship between the address and user tables. An address is linked to one user, and each user has only one primary address.