# One-to-Many

How a one-to-many relationship links many child rows to one parent row through a foreign key, like a customer and their orders.

Apprentice · SQL · Database · Updated October 29, 2026

The **One-to-Many** relationship is the most common type of relationship in a database. In a **One-to-Many** relationship, a row in the parent table can be related to one or more rows in the child table. The relationship is created by having the `foreign key` in a child table refer to the `primary key` of the parent table.

For example, a customer can place many orders. The `Customer` table is the parent table and the `Order` table is the child.

![A Customer can have many Orders](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/09/664d39c4234746d18e17231664ad3f5e.png "A Customer can have many Orders")

## Key terms

- [One-to-Many Relationship](https://www.ask-codey.com/glossary/one-to-many-relationship)

Source: https://www.ask-codey.com/lessons/database-relationships-one-to-many