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Code RoomMonthly recurring revenue query
MediumPrep Room Coding #4494

Monthly recurring revenue query

Vibe & agenticDatabases & SQLCode quality & reviewMid–Senior~18 min

You asked an AI assistant for a SQL query that computes monthly recurring revenue (MRR) from a subscriptions table, and it produced a clean, well-formatted query with CTEs that returns numbers in a believable range. You're not a billing-domain expert and the proration logic looks reasonable. Finance will use this for a board deck. How do you verify the query is actually correct before anyone trusts the output?

Implement
normalized_monthly_revenue_cents(subscription_lines: list[str]) → int
Examples
in[["active,monthly,4900","active,annual,120000","trialing,monthly,4900"]]out14900
in[["active,annual,100"]]out8
in[[]]out0
What a strong answer looks like

Treat the AI’s output as a draft to verify, not an answer to trust. Name the specific flaw and the input that triggers it, say how you’d catch it (tests, edge cases, reading critically), and how you’d re-prompt or decompose to get it right.

0:00 of about 18 min

Vibe & agentic: describe the solution in plain language (or narrate it) and the coach grades your approach.

Which questions mattered is sealed until you submit. Telling you now would just be handing over the edge cases.