SQL Blog

Tutorials, interview prep and tips to level up your SQL skills — all free.

SQL JOINs Explained with Real Examples

INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN — explained clearly with diagrams and runnable examples on real data.

Most beginners confuse GROUP BY and HAVING. This guide explains the difference clearly, with examples you can run right here.

ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD, PARTITION BY — everything you need to know about window functions with practical examples.

A step-by-step guide to learning SQL from scratch. Free resources, practice platforms, and a curriculum to go from beginner to job-ready.

Master subqueries with clear explanations of correlated vs non-correlated subqueries, scalar subqueries, and inline views.

The WITH clause makes complex SQL readable. Learn how to use CTEs for recursive queries, running totals, and multi-step logic.

Write faster SQL queries with these proven optimization techniques — covering indexes, EXPLAIN plans, N+1 problems and more.

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