About AltQuery
Master SQL through practice. Free forever. No login required.
Our Mission
We believe learning SQL should be accessible to everyone. AltQuery provides a completely free, no-signup-required platform where you can practice SQL at your own pace. Whether you're preparing for interviews, learning for a new job, or just curious about databases, we've got you covered.
Why Choose AltQuery?
1050+ Questions
Comprehensive question bank covering everything from basic SELECT statements to advanced window functions and CTEs.
Instant Feedback
Run queries in your browser and get immediate validation. Know instantly if your answer is correct.
AI Assistant
Stuck? Ask our AI assistant for hints, explanations, or corrections. Learn at your own pace.
Monaco Editor
VS Code's powerful editor with syntax highlighting, autocomplete, and keyboard shortcuts.
No Setup Required
Everything runs in your browser. No installation, no configuration, no database setup needed.
100% Free
No paywalls, no premium tiers, no hidden costs. All 1050+ questions are completely free forever.
How It Works
Browse Questions
Explore 1050+ questions organized by difficulty (Easy, Medium, Hard) and topic (SELECT, JOINs, Window Functions, etc.). Use filters to find exactly what you want to practice.
Understand the Problem
Read the detailed question description, review the database schema, and check the expected output. Each question includes helpful hints and context.
Write Your Query
Use the Monaco Editor (same as VS Code) to write your SQL query. Enjoy autocomplete for table and column names, syntax highlighting, and keyboard shortcuts like Ctrl+Enter to run.
Get Instant Feedback
Run your query and see results immediately. The system automatically validates your answer and shows whether it's correct. If not, the AI assistant can help you understand what went wrong.
Learn and Improve
Use hints, ask the AI assistant questions, and experiment with different approaches. The more you practice, the better you'll get!
Topics Covered
Fundamentals
- SELECT Basics (100 questions)
- Filtering with WHERE (150 questions)
- Aggregation & GROUP BY (150 questions)
- String Functions (50 questions)
- Date Functions (50 questions)
Advanced
- JOINs (250 questions)
- Subqueries (100 questions)
- Window Functions (100 questions)
- CTEs (50 questions)
- CASE Statements (50 questions)
Technology Stack
Frontend
- • Next.js 14 (App Router)
- • React 18
- • TypeScript
- • Tailwind CSS
- • Monaco Editor
SQL Engine
- • SQL.js (SQLite WASM)
- • In-browser execution
- • No server required
- • Instant query results
AI Assistant
- • Together AI API
- • LiquidAI/LFM2-24B-A2B
- • Context-aware hints
- • Error explanations
Tips for Success
Start with Easy Questions
Build confidence with fundamentals before tackling harder problems.
Read Hints First
Try the hint before asking the AI assistant for a more guided learning experience.
Check Expected Output
See what the result should look like, but try solving it yourself first!
Experiment Freely
Try different approaches. There's often more than one way to solve a problem.
Understand the Schema
Always review table structures and relationships before writing queries.
Practice Regularly
Consistency is key. Even 15 minutes a day will improve your SQL skills significantly.