# OVER Clause

The clause defining the row window used by a window function.

## What does **OVER Clause** do in a relational database?

**OVER Clause** — The clause defining the row window used by a window function.

```sql
SELECT order_id,
       SUM(total_amount) OVER (PARTITION BY customer_id) AS customer_total
FROM purchase_order;
```

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

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/over-clause