The Ground We Keep
A hard SQL mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- SQL
- Difficulty
- hard
- Seniority
- L5
Interview Prompt
We run periodic health checks across a fleet of services, and each check records the region it ran in. For December 2025 and January 2026, we want to know how much of each service's regional footprint holds up: of the regions a service was checked in during a month, what share get checked again for that same service in a later month. Return the service, the month, and that share as a percentage.
Summary
Every region is a claim once made. Measure how much of it endures.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your sql solution with real code execution
- Get instant feedback and a hire/no-hire decision