Database Internals (opens provider site in a new tab)
Alex Petrov on storage engines and distributed algorithms. A natural companion to CMU 15-445.
SQL & Databases
Query data confidently, then learn how databases actually work.
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15 picks · 11 free · 14 providers · curated by Rowland Kuru
Editor's intro
Editor's intro
SQL is fifty years old and more useful than ever. Analysts, engineers, product managers, and marketers all end up needing it, and it's one of the fastest high-value skills to pick up: a few weeks of practice covers most of what you'll write day to day. This feed starts with interactive drills, then moves into performance and into how databases work under the hood.
Practise in the browser first so setup doesn't slow you down, then install PostgreSQL and load a real dataset you care about. Most people plateau at basic joins; the intermediate picks on window functions and indexing are what separate "can write SQL" from "writes good SQL." The advanced section is for engineers designing systems around a database.
Start here
SQLBolt
SQLBolt is a set of short, interactive lessons that each introduce one idea and then have you write queries against a small table right in the browser. There's nothing to install, no account to create, and no video to sit through — just read, type, and check. You can finish the core lessons in an afternoon, and by the end you'll be comfortable with filtering, sorting, joins, and aggregates. Follow it with SQL Murder Mystery or Select Star SQL for practice that feels less like homework.
This week added
All picks
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Beginner · 7
SELECT, WHERE, JOIN, GROUP BY. You can be genuinely useful with SQL within a couple of weeks.
Intro to SQL: Querying and Managing Data (opens provider site in a new tab)
Friendly talk-through lessons for complete beginners, with in-browser practice after each.
Free
Learn SQL (opens provider site in a new tab)
Codecademy's free SQL course. Well-paced lessons in the browser, no database setup needed.
Free
Select Star SQL (opens provider site in a new tab)
An interactive book built on one real dataset. Teaches you to think in queries.
Free
SQL Murder Mystery (opens provider site in a new tab)
Solve a crime by querying a database. A fun, surprisingly effective way to practise joins.
Free
SQLZoo (opens provider site in a new tab)
Old-fashioned but reliable practice problems with instant feedback. Good for drilling.
Free
SQL for Data Science (UC Davis) (opens partner site in a new tab)
A structured, graded introduction aimed at analysts. Good if you want a certificate.
Paid Financial aid available Partner
The Complete SQL Bootcamp (opens partner site in a new tab)
Jose Portilla's PostgreSQL course. Clear and practical, with plenty of exercises.
Paid 30-day refund Partner
Intermediate · 4
Window functions, indexing, query performance, and running a real database like PostgreSQL.
Modern SQL (opens provider site in a new tab)
Window functions, CTEs, and newer standard features, with notes on which databases support them.
Free
PostgreSQL Tutorial (official docs) (opens provider site in a new tab)
The official tutorial for the database most new projects choose. Short and authoritative.
Free
Relational Database (opens provider site in a new tab)
Real PostgreSQL, Bash, and Git in a virtual environment. Closer to actual work than browser drills.
Free
Use The Index, Luke! (opens provider site in a new tab)
Markus Winand on indexes and query performance. Every developer who writes SQL should read it.
Free Free to read online
Advanced · 3
Storage engines, transactions, replication — how databases work inside, and how to design around them.
CMU 15-445/645: Database Systems (opens provider site in a new tab)
Andy Pavlo on storage, indexing, and transactions inside a database. Lectures are free online.
Free
Database Internals (opens provider site in a new tab)
Alex Petrov on storage engines and distributed algorithms. A natural companion to CMU 15-445.
Paid New
Designing Data-Intensive Applications (opens provider site in a new tab)
Kleppmann's modern classic on replication, partitioning, and consistency. Changes how you design systems.
Paid