How It Works
Become a data detective in three steps. No prior experience required.
Pick an Investigation
Browse Cases by difficulty and SQL topic. Each is self-contained with real data and a mystery to crack.
Query the Database
Write SQL in the browser. No setup needed. Get hints from Chief Fox when you get stuck.
Crack the Case
Use your results to name the suspect and close the case. Earn XP and level up your rank.
54 cases. Five ranks.
One detective: you.
A complete path from your first WHERE clause to window functions, told as one career on the force. Drills sharpen each skill, exams earn your promotions, and every rank comes with a certificate.
Recruit
FIRST CASERookie
SELECT · WHERE · LOGICDetective
AGGREGATES · NULLS · CASTSenior
JOINS · SUBQUERIES · CTESChief
WINDOW FUNCTIONSConcepts when the story needs them
JOINs show up when suspects and alibis stop matching. Nothing is taught in a vacuum.
Exams that mean something
Pass the level exam to earn your promotion and a shareable certificate for each rank.
Streaks and a global leaderboard
Daily streaks, XP rankings, public detective profiles. Friendly pressure included.
Then prove it for real
Guided cases teach you. Investigations test you. A full mystery across six tables, three acts, and a ticking clock. When you think you have it, you make one accusation.
- No hints, no training wheels. Just you, the schema, and the evidence.
- Real multi-table schemas. Staff records, sensor logs, shipping manifests, phone records.
- One accusation. Name the perpetrator and their role. Get it wrong, live with it.
Off duty? Query anything.
Seven real datasets, 44 tables, no objectives and no hints. The fastest way to make SQL stick is asking your own questions about data you actually care about.
IMDB Top 250
Which director has the highest average rating across their films?
Metro Crime
200 cases of homicide, fraud and theft. Which detective closes the most?
Spotify Wrapped
A full year of listening history. Which artist gets skipped the most?
Pokemon
All 1,025 base forms across 9 generations. Which type rules the stat charts?
NBA 2024-25
Official season data. Which team has the biggest home-court advantage?
Steam Games
424 of Steam's most popular games. Do free games really get worse reviews?
Then go and get the job
SQL interview practice for the interviews you are actually sitting. Data analyst interview questions tagged by company, a rapid SQL quiz for the concepts behind them, and a map of the data roles worth aiming at.
- Meta
- Amazon
- Netflix
- Airbnb
- Spotify
- Snapchat
- Robinhood
- Lyft
- Coinbase
Interview Prep
Questions modelled on the loops at Google, Meta, Amazon and Netflix. Each opens in a real editor with the schema and a target output, checks your answer, then reveals a worked solution and the insight most candidates miss.
Quickfire
Multiple choice, one idea at a time, with an instant explanation for every answer. SQL behaviour and query performance through to statistics, A/B testing, data modelling and the modern data stack.
Data Roles
Data Analyst, BI Analyst, Analytics Engineer, Data Scientist, Data Engineer and ML Engineer. Where each sits on the analyze-to-build spectrum, the skill mix each one needs, and the SQL each one actually writes.