# Subquery

A query nested inside another SQL statement.

## What is **Subquery** in a relational database?

**Subquery** — A query nested inside another SQL statement.

```sql
SELECT order_id
FROM purchase_order
WHERE total_amount > (
    SELECT AVG(total_amount)
    FROM purchase_order
);
```

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/subquery