Relational Database
freeCodeCamp
Master SQL database concepts with freeCodeCamp's interactive Relational Database course. Build practical projects and gain valuable skills!
More resources on SQL
SQL in 10 Minutes, Sams Teach Yourself
Ben Forta's short lessons cover the core of standard SQL: SELECT, filtering, joins, subqueries, views, and stored procedures, with examples for several database engines. Finishing gives you working query skills without database-administration detail.
w3schools.com/sql
W3Schools SQL offers a beginner-friendly, interactive guide to SQL, with tutorials and reference covering core SQL commands, clauses, joins, functions, and data manipulation. It includes runnable examples and a “Try it Yourself” editor to practice directly in the browser.
use-the-index-luke.com
A practical guide to database indexing and query optimization, offering clear explanations of how indexes work, how to design them, and tutorials with SQL examples across major relational databases.
sqlzoo.net
SQLZoo.net is an interactive SQL learning resource offering free tutorials and hands-on practice with live databases. It provides step-by-step lessons and coding exercises on SQL topics (SELECT, JOIN, aggregation, etc.) with immediate feedback.
SQL Tutorial
Learn SQL with Mode's free tutorial! Master database querying and analysis with hands-on lessons from the Mode Team.
PostgreSQL Tutorial
A structured set of free PostgreSQL lessons covering SQL syntax, joins, subqueries, indexes, stored procedures, and administration, each with a sample database and runnable examples. After working through it you can write and tune everyday Postgres queries.