# GROUP BY

A clause collecting rows with equal grouping values so each group produces one result row.

## What is **GROUP BY** in a relational database?

**GROUP BY** — A clause collecting rows with equal grouping values so each group produces one result row.

```sql
SELECT customer_id, COUNT(*) AS order_count
FROM purchase_order
GROUP BY 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/group-by