# Unique Index

An index that also prevents duplicate indexed value combinations.

## What is **Unique Index** in a relational database?

**Unique Index** — An index that also prevents duplicate indexed value combinations.

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/unique-index