Two Wallets
A medium Data Modeling mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- Data Modeling
- Difficulty
- medium
- Seniority
- L5
Interview Prompt
We run an online education marketplace with two user types: students paying for access, and instructors paying for listing and promotion features. Both subscribe to different plan tiers and keep several payment methods on file, each stored as an opaque gateway token plus the card brand and last four digits for display, never full card numbers. Finance also needs to reconstruct how many subscribers we had in any past month, so design the data model behind billing.
Summary
Two user types. Multiple payment methods. One messy billing table.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your data modeling solution with real code execution
- Get instant feedback and a hire/no-hire decision