Understand platform economics.

Connect usage, payments and costs to understand business performance.

The brief

The business question: Calculate success rates and usage costs, prevent join fan-out, and reconcile split payments with refunds.
What you’ll deliver: Safe ratios, reconciled revenue and usage contribution margins.Exported as a report with business questions, checked SQL, result evidence and your written findings. Labeled Draft until every milestone has a finding.
Skills: Ratios · Reconciliation · Multi-table analysis
Scope: Intermediate level · 4 milestones · 6 tables

Available data

Request usage, fictional model rates, invoices, payments, and refunds. Rates are invented for learning, not real provider prices.

How the tables connect:payments.invoice_id → invoices.idrefunds.invoice_id → invoices.id

ai_accounts4 columns · 6 rows · id, plan, region, signed_up_at

idintegerPK
plantext
regiontext
signed_up_attext

First 5 of 6 rows · original sample data

#	id	plan	region	signed_up_at
1	1	pro	US	2025-01-01
2	2	free	US	2025-01-02
3	3	team	EU	2025-01-02
4	4	pro	IN	2025-01-03
5	5	free	EU	2025-01-04

ai_requests7 columns · 12 rows · id, account_id, model, requested_at, …

idintegerPK
account_idinteger
modeltext
requested_attext
input_tokensinteger
output_tokensinteger
statustext

First 5 of 12 rows · original sample data

#	id	account_id	model	requested_at	input_tokens	output_tokens	status
1	1	1	swift	2025-01-01 10:00:00	1000	200	success
2	2	1	reason	2025-01-02 11:00:00	2000	600	success
3	3	2	swift	2025-01-02 12:00:00	500	0	error
4	4	3	reason	2025-01-02 13:00:00	8000	2000	success
5	5	3	swift	2025-01-03 14:00:00	4000	1000	success

model_rates3 columns · 2 rows · model, input_per_million, output_per_million

modeltextPK
input_per_millionreal
output_per_millionreal

First 2 of 2 rows · original sample data

#	model	input_per_million	output_per_million
1	swift	1	4
2	reason	3	12

invoices4 columns · 6 rows · id, account_id, period, billed_amount

idintegerPK
account_idinteger
periodtext
billed_amountreal

First 5 of 6 rows · original sample data

#	id	account_id	period	billed_amount
1	1	1	2025-01	20
2	2	3	2025-01	80
3	3	4	2025-01	20
4	4	6	2025-01	80
5	5	1	2025-02	20

payments3 columns · 7 rows · id, invoice_id, amount

idintegerPK
invoice_idinteger
amountreal

First 5 of 7 rows · original sample data

#	id	invoice_id	amount
1	1	1	10
2	2	1	10
3	3	2	80
4	4	3	15
5	5	4	80

refunds3 columns · 4 rows · id, invoice_id, amount

idintegerPK
invoice_idinteger
amountreal

First 4 of 4 rows · original sample data

#	id	invoice_id	amount
1	1	1	2
2	2	1	3
3	3	2	10
4	4	4	5

Open a table to see its columns and sample rows. You do not need to read every table before starting a milestone.

Each run starts with the original sample data. Changes to tables do not carry over to later runs or milestones. Findings are optional for continuing — required only for a complete report.

Milestones

Start

Ratios, ROUND & NULLIF

Calculate safe ratios and round your results.

Not started

Multi-grain joins without fan-out

Combine metrics at different levels without multiplying totals.

Not started

Revenue & payment reconciliation

Reconcile revenue with payments and identify differences.

Not started

AI usage cost & contribution margin

Compare usage revenue with costs to calculate contribution margin.

Not started

Project report

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