SQL Reference

Learn SQL

Clear explanations of every SQL concept — from basic SELECT to window functions and CTEs. Each page answers real questions with working examples.

Foundations
SELECT→WHERE→ORDER BY & LIMIT→NULL Handling→
Aggregation
Aggregate Functions→GROUP BY→
Functions
String Functions→LIKE & Pattern Matching→Date & Time→Date Arithmetic→CASE WHEN→
Joins
JOINs→Advanced JOINs→Multiple JOINs→
Advanced Queries
Subqueries→Correlated Subqueries→Window Functions→Advanced Window Functions→
Expert
CTEs→Recursive CTEs→Set Operations→Analytical Patterns→Advanced Patterns→