What I built!
If you've ever tried to level up your SQL skills, you know the problem: reading documentation is boring, and most practice tools feel like homework. I wanted something to build something that felt more like a game — fast, satisfying, and actually challenging!
So I built SQLQuiz — an interactive SQL quiz app with 62 questions across three difficulty tiers, a built-in SQL cheat sheet, and a personal performance dashboard--and it's launched!
What exactly is it!?!?
What It Is
SQLQuiz is a dark-themed, browser-based SQL practice app. You pick a quiz mode, answer multiple choice questions against a fictional company_db database, and get instant feedback with detailed explanations.
Three free quiz modes:
🟢 Easy — Core SELECT fundamentals: filtering, sorting, WHERE clauses, LIMIT, DISTINCT
🔵 Intermediate — Aggregates, GROUP BY, JOINs, subqueries, window functions, CASE
Two premium quiz modes:
🏆 Master — All 40 beginner + intermediate questions shuffled into one full gauntlet
🔴 Advanced — 20 deep questions on CTEs, recursive queries, window frames, transactions, indexes, and query performance
Every question includes:
A hint before you answer
A full explanation after you confirm
A "Save for Later" button on wrong answers so you can revisit them!
The Tech Stack
I kept this simple, drawing mostly on knowledge of early web development basics.
Vite — blazing fast dev server and build tool
Vanilla JavaScript — no React, no Vue, no unnecessary complexity
Supabase — auth (email/password signup + login) and a profiles table with an is_premium flag
Gumroad — one-time payment for Premium access
Basic CSS — for the dark theme, animations, and responsive layout
The Premium Analytics Dashboard
One thing I'm proud of is the My Dashboard feature. Here you can see your performance over time! What it features:
Quiz History — every quiz you've taken, score, mode, date, and letter grade
Wrong Answer Heatmap — your 10 most-missed questions with a relative frequency bar
Topic Breakdown — accuracy percentage per SQL topic (SELECT, JOINs, CTEs, Window Functions, etc.) sorted worst-first so you know exactly what to study.
⚠️ Everything stored in localStorage so there's zero backend logic for the analytics, and quiz progress. The Supabase database only stores one thing per user: your username/email/password, and premium status!
Try It
The app is live and the free tier has no time limits — you can take the Easy and Intermediate quizzes as many times as you want.
https://master-sql-quiz.netlify.app/
Premium is a one-time purchase for lifetime access to the Master Quiz, Advanced Quiz, and the full analytics dashboard.
If you're preparing for a technical interview, working through a data analytics bootcamp, or just want to sharpen your SQL — give it a shot and let me know what you think in the comments.
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