# CASE Expression

An expression that chooses a result by evaluating conditions in order.

## What does **CASE Expression** do in a relational database?

**CASE Expression** — An expression that chooses a result by evaluating conditions in order.

```sql
SELECT order_id,
       CASE
           WHEN total_amount >= 100 THEN 'large'
           ELSE 'standard'
       END AS size
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/case-expression