# Find users who have never made an API call with a status of 400 or higher

Canonical URL: <https://datadriven.io/problems/find-users-who-have-never-made-an-api-call-with-a-status-of-8ac236fc>

Domain: SQL · Difficulty: medium

## Problem

Find users who have never made an API call with a status of 400 or higher. Be careful about NULL safety in your subquery. Return user_id and username.

## Related

- [All practice problems](https://datadriven.io/problems)
- [Mock interview mode](https://datadriven.io/interview/find-users-who-have-never-made-an-api-call-with-a-status-of-8ac236fc)
- [SQL Interview Questions](https://datadriven.io/sql-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.