# Join Condition

The predicate deciding which rows from joined sources match.

## What is **Join Condition** in a relational database?

**Join Condition** — The predicate deciding which rows from joined sources match.

```sql
SELECT customer.email, purchase_order.order_id
FROM customer
INNER JOIN purchase_order
    ON purchase_order.customer_id = customer.customer_id;
```

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

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/join-condition