Yesterday's Weather
A hard SQL mock interview question on DataDriven, with an AI interviewer who asks follow-up questions and a hire or no-hire decision at the end.
- Domain
- SQL
- Difficulty
- hard
- Seniority
- L4
Interview Prompt
A FinOps team benchmarks its cost models against the simplest possible forecast: whatever a month actually cost becomes next month's prediction. Total each month's real cloud spend from `cloud_costs` and treat the prior month's total as the current month's forecast. For each month, report its year-month, its actual cost, the forecast, the percent error, and whether the actual came in over or under the forecast.
Summary
The forecast was off. By how much?
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write and run your SQL against a real database
- Answer the interviewer's follow-up questions, then get a hire or no-hire decision