# Entity Integrity

The rule that every relation has a primary key whose values are unique and non-NULL.

## What is **Entity Integrity** in a relational database?

**Entity Integrity** — The rule that every relation has a primary key whose values are unique and non-NULL.

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/entity-integrity