Master SQL through our step-by-step interactive course. Start writing queries immediately in our browser-based environment — no installation required.
Run SQL directly in your browser with our SQLite WASM engine. No installation needed.
See how JOINs work with animations. Understand query execution with visual explain plans.
Get immediate validation on your queries. Learn from mistakes in a safe sandbox environment.
SQL (Structured Query Language) is the universal language for working with data. Whether you're a data analyst extracting insights from a data warehouse, a backend developer building APIs, or a product manager querying dashboards, SQL is an essential skill that powers modern businesses. In fact, SQL consistently ranks among the top 10 most in-demand technical skills across job postings worldwide.
Unlike many programming languages that come and go, SQL has remained the standard for relational databases for over 50 years. Learning SQL is a long-term investment in your career. It's used by PostgreSQL, MySQL, SQL Server, Oracle, and even analytics platforms like BigQuery, Snowflake, and Redshift. The syntax you learn here transfers directly to virtually any database system you'll encounter.
Beyond just retrieving data, SQL allows you to transform, aggregate, and analyze information in powerful ways. From simple lookups to complex analytical queries involving window functions and recursive CTEs, mastering SQL opens doors to roles in data engineering, business intelligence, software development, and data science.
Our interactive SQL course is designed to take you from absolute beginner to confident practitioner. The curriculum is structured progressively, building on concepts as you advance:
SELECT, WHERE, ORDER BY, LIMIT, and filtering with AND/OR. These commands form the backbone of every SQL query you'll ever write.INNER JOIN, LEFT JOIN, and other join types. Summarize data with GROUP BY, HAVING, and aggregate functions like COUNT, SUM, and AVG.IN/EXISTS) and powerful window functions like RANK(), LAG(), LEAD(), and SUM() OVER(). These are essential for analytics and reporting.CROSS JOIN, self-joins for hierarchical data, indexing strategies for performance, transactions (BEGIN, COMMIT, ROLLBACK), Common Table Expressions (CTEs with WITH), and views for reusable query logic.Each lesson in SQL Boy follows a proven "learn-by-doing" approach that cognitive science research shows is far more effective than passive reading:
This approach ensures you're not just passively reading—you're actively writing SQL and building muscle memory. Making mistakes is encouraged; research shows that struggling with problems before seeing solutions leads to deeper understanding and better retention.
SQL Boy's curriculum is built on three evidence-based learning principles:
Instead of re-reading examples, you're challenged to write queries from memory. This "testing effect" strengthens neural pathways and improves long-term retention compared to passive review.
Rather than drilling one concept repeatedly, our lessons mix different types of problems. This "interleaved practice" forces your brain to identify which technique applies, building flexible problem-solving skills.
Delayed feedback weakens learning. Our instant validation loop lets you correct misconceptions immediately, before they become ingrained habits.
Our SQL tutorials are designed to meet learners wherever they are in their journey:
Never written a line of SQL? Start with Chapter 1 and follow the structured path. We explain everything from scratch, assuming no prior database knowledge.
Know basic SQL but want to master JOINs, window functions, and CTEs? Jump directly to the relevant chapters and fill in your knowledge gaps.
Preparing for FAANG, MAANG, or data science interviews? Practice the SQL concepts that hiring managers test most frequently, from basic queries to complex analytics.
A free, no-setup resource for classroom use. Teachers can assign specific lessons; students can practice at their own pace without software installation headaches.
No! SQL Boy runs entirely in your browser using SQLite compiled to WebAssembly. There's nothing to download, no database to configure, and no accounts required to start learning.
We use SQLite syntax, which closely follows the ANSI SQL standard. The vast majority of what you learn here—JOINs, aggregations, window functions, CTEs—transfers directly to PostgreSQL, MySQL, SQL Server, and other major databases.
Most learners complete all 11 chapters in 10-20 hours of focused practice. You can go at your own pace—lessons are self-contained and your progress is saved automatically.
Yes, completely free. All lessons, all chapters, no paywalls. We believe quality SQL education should be accessible to everyone, regardless of their financial situation.
The best time to learn SQL was yesterday. The second best time is now. Click on any lesson above to begin your journey. Whether you're aiming to analyze data more effectively, ace technical interviews, or build better applications, SQL mastery is within your reach. Let's get started!