Tutorials, guides, and insights to help you master SQL
What happens when your database crashes in the middle of a payment? Learn how SQL Transactions and ACID properties keep your data safe.
Stop writing nested subquery nightmares. Learn how to use Common Table Expressions (CTEs) to make your SQL readable, modular, and powerful.
Why is my query slow? The answer is usually indexes. Learn how database indexes work, when to create them, and how they speed up your SQL.
Master ROW_NUMBER, RANK, and running totals with interactive visualizations. See exactly how window functions process your data row by row.
Unlock the power of nested queries. Learn when to use subqueries in SELECT, WHERE, and FROM clauses with practical, runnable examples.
Learn how GROUP BY transforms rows into meaningful summaries. Watch data collapse into groups with interactive animations and master COUNT, SUM, AVG, and HAVING.
Stop guessing what JOINs do. Learn Inner, Left, and Cross Joins with live, interactive examples and animations running right in your browser.
Ever wondered why you can't use a column alias in a WHERE clause? It's all about the order of execution. Learn how SQL actually runs your code.
Is your database crawling? Learn the 3 most common reasons for slow SQL queries and how to use the EXPLAIN command to fix them.
Welcome to the SQL Boy blog! Learn why we built SQL Boy and how it can help you master SQL faster than ever before.