Pick an industry path and solve realistic problems against a real PostgreSQL database. Messy data, real stakeholders, tight deadlines. No toy datasets.
Free tier · No credit card
Each path simulates a real analyst role. Here's the loop.
Your manager pings you with a question. Deadlines are real. Requirements are vague (on purpose).
Write SQL against a database with NULLs, duplicates, refunds, and inconsistent formats planted in it.
A 5-tier validation engine checks your work and gives graduated Slack-style feedback until you nail it.
Zero setup
Just open the editor
580
Total missions
25+
Missions per path
20
Industry career paths
Real schemas, not toy data
Every path uses a star-schema database modeled on the shape of data real analyst teams work with — not hand-curated Northwind-style puzzles.
Messy on purpose
NULLs, duplicates, refunds, inconsistent formats — the data quality traps in these missions are the kinds that quietly break dashboards in the wild.
Slack-style feedback
A 5-tier validation engine returns graduated, human-sounding feedback — like a senior analyst reviewing your PR, not a green/red checkmark.
“I built caseSQL because every course I tried taught syntax in isolation. But knowingSELECTfromJOINisn’t the hard part of the job — the hard part is translating a vague business question into a query that gives a trustworthy answer from imperfect data. That’s what caseSQL teaches.”
Interview prompts from the companies you want to work at
Real archetypes from real SQL interview loops. 10 Pro missions, each tagged with the company it came from.
Drawn from early users working as analysts at real data teams.
“Every other SQL site felt like a textbook. caseSQL felt like the Monday morning of my first week on the job — messy data, a manager who didn't quite know what they wanted, and a deadline. That's the only thing that actually got me ready.
M. K.
Career changer · bootcamp grad
“I'd drilled 200+ problems on LeetCode and still froze in my first real SQL screen. After three weeks on the Marketing path I stopped freezing. The 5-tier feedback is what LeetCode never had — it tells you why you're wrong, not just that you are.
S. R.
Job seeker · prepping for analyst roles
“I'm a junior analyst a few months in and the dirty-data missions mirror what I actually see at work. Doing them on the side has made me noticeably faster at the stuff my team throws at me.
J. P.
Junior data analyst · first job
Each path has its own database, stakeholders, and challenges.
Customer behavior, campaign ROI, sales pipeline, and executive dashboards.
Variance bridges, credit risk, fraud detection, AML, and regulatory reporting.
Inventory turns, on-time delivery, supplier scorecards, and demand-forecast variance.
EHR data quality, readmissions, ED throughput, and CMS quality dashboards.
Shopify + GA4 + Stripe reconciliation, RFM segmentation, and DTC retention.
Hiring funnel, regrettable attrition, comp bands, and manager span of control.
Incident MTTR, DORA metrics, ticket SLAs, and security posture.
No installs. No toy data. Just you, a database, and a manager who needs answers.
Choose Your Path→Free tier · No credit card
Common questions before you dive in.
No. The first mission eases you in, and every mission includes progressive hints if you get stuck.
PostgreSQL, hosted on Supabase. Your queries run against a real server-side database — the same stack used by modern data teams.
Realistic industry databases with intentional messiness — NULLs, duplicates, refunds, and format inconsistencies that mirror real analyst work.
A 5-tier engine compares your results against the expected answer and gives Slack-style graduated feedback until you nail it.
There's a free tier and a Pro tier. Free covers the Starter and Easy missions across every career path (10 per path) plus 12 coding interview questions — enough to get the fundamentals down. Pro ($14.99/mo or $139/yr) unlocks the Medium, Hard, and Expert missions, the full 40-question coding interview bank, and 71 advanced general interview questions. Cancel anytime from the Stripe billing portal. See /pricing for the full breakdown.
Every Medium/Hard/Expert mission across all career paths, the full coding interview bank (questions tagged with real companies like Stripe, Meta, and Amazon), 71 advanced general interview questions across behavioral, statistics, A/B testing, product metrics, and case studies, plus priority support. $14.99/month or $139/year.