# One-to-Many Relationship

A relationship where one parent row can relate to many child rows.

## What is **One-to-Many Relationship** in a relational database?

**One-to-Many Relationship** — A relationship where one parent row can relate to many child rows.

```sql
CREATE TABLE purchase_order (
    order_id INTEGER PRIMARY KEY,
    customer_id INTEGER REFERENCES customer (customer_id)
);
```

Level: Novice · [More Database terms at this level](https://www.ask-codey.com/glossary/subjects/database/novice)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/one-to-many-relationship