Solve real business mysteries using SQL.
Start investigatingCase Brief
The Tuesday Anomaly
Revenue is down 34% every Tuesday for 8 weeks.
CEO suspects a competitor. Data team disagrees. You have orders, customers, and discounts.
Tables
orders
id, customer_id, total_amount, day_of_week
customers
id, name, email, tier
discount_codes
id, code, valid_from, valid_until
Query
Results
press ▶ Run to execute
Not another SQL tutorial.
We don't teach syntax. We train reasoning.
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DebugWho
How investigations work
- Step 01
Read the case
A real business problem. No instructions, no hand-holding.
- Step 02
Explore the tables
Real schemas, thousands of rows. Nothing is pre-cleaned for you.
- Step 03
Write queries
SELECT, JOIN, aggregate. Your only tool is SQL.
- Step 04
Follow the clues
Socratic hints nudge your thinking — they never hand you the query.
- Step 05
Find the anomaly
The pattern that doesn't belong. That's the real signal.
- Step 06
Submit your conclusion
State what happened and why. Right, or you missed something.
- Step 07
Climb the ranks
Every solve earns points toward your detective rank — Intern to Chief — and lights up your skill map.
Real tables. Real anomalies.
Thousands of rows, not sanitized sample data. The bug is really in there.
orders
48,112 rows
Most days look normal — until they don't.
customers
9,466 rows
A few of them shouldn't be possible.
payments
51,209 rows
Some don't match any order.
promo_engine
37 rows
One rule never stopped firing.
refund_report
1,284 rows
A handful arrived before the sale.
Four tiers. One real ladder.
Cut your teeth on routine cases, then take on tricky, complex, and cold cases.
Routine
50 pts
Filters, aggregates, GROUP BY. Find what's obviously wrong.
Tricky
100 pts
JOINs, subqueries, timezones. The bug hides in the relationship.
Complex
200 pts
Window functions, CTEs. The bug hides in a pattern over time.
Cold Case
400 pts
Multi-table, open-ended. Nobody tells you which table lies.
Pick a case.
Six real investigations, from a five-minute find to a 70-minute cold case.
The Ghost Order
847 orders in the system reference customer IDs that don't exist in the customers table. They have valid products, real payment amounts, but no matching customer. Who placed them?
The Vanishing Inventory
Five products show zero stock in the system. The warehouse team insists they're physically there. The system and reality disagree. Find which record is lying.
The Coupon Cascade
Finance spots ~₹4.18L in unplanned coupon discounts from code BETA30. It was issued to 12 beta testers. The redemption log shows 430 uses. Something is very wrong.
The Timezone Ghost
Revenue dashboard shows Monday mornings spike hard every single week. Finance suspects a batch process or fraud. The data says organic Sunday and Monday traffic are identical. So where is the Monday spike actually coming from?
The Cohort Cliff
Month-3 retention for most cohorts runs 60-70%. Except March 2024 — it's 0%. Something specific happened to users who signed up that month.
The Quiet Cartel
Four vendors always win procurement contracts in rotation. Their bids are always within 2% of each other. Vendor A wins 48% of contracts. The same procurement officer approves all.
This is how real analysts think.
You're not learning SQL. You're learning how to think with data.
Built for real investigation.
A real editor, not a toy box
Full syntax highlighting, autocomplete, and the keyboard shortcuts you already use daily.
Thousands of rows, one bug in there somewhere
No sanitized sample tables. Every schema is built to hide its anomaly in real data.
Nothing you tried gets lost
Every query you ran is saved, so you can retrace exactly how you found it.
Hints that make you think, not skip ahead
AI asks the next question instead of writing the query. You still have to solve it.
Finally, SQL problems that feel like real work.
I found the bug before I even knew what JOIN was.
The hints never give it away. It forces you to actually think.
Simple pricing.
Start free. Upgrade when the cases get harder.
Pro
PopularSave $199 vs. paying monthly — or $29/month
- All cases, all levels
- Unlimited hints
- CSV export
- Full skill map
- Early access to new cases
Some people watch SQL tutorials.
Others solve real business mysteries.
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