# Design a one-to-one relationship: each user has exactly one profile

Canonical URL: <https://datadriven.io/problems/design-a-one-to-one-relationship-each-user-has-exactly-one-c30e2f11>

Domain: Data Modeling · Difficulty: medium

## Problem

Design a one-to-one relationship: each user has exactly one profile. Create users and user_profiles tables where each profile belongs to one user.

## Related

- [All practice problems](https://datadriven.io/problems)
- [Mock interview mode](https://datadriven.io/interview/design-a-one-to-one-relationship-each-user-has-exactly-one-c30e2f11)
- [Data Modeling Interview Questions](https://datadriven.io/data-modeling-interview-questions)
- [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep)
- [Daily Challenge](https://datadriven.io/daily)

---

Source: DataDriven (https://datadriven.io). 100% free data engineering interview prep. Live code execution against Postgres 16, Python 3.11, and Spark sandboxes. No paywall, no premium tier, no signup gate.