About SQLab Hub
SQLab Hub is a 100% free site for learning SQL by writing it. You read a lesson, run its examples on a real database in your browser, and then solve practice tasks against the same data.
Who runs SQLab Hub
SQLab Hub is built, written and maintained by Rahul Kumar, an independent developer based in India. It is a one-person project, not a company: there is no editorial team, no investors and no office. When this site says “we”, it means Rahul.
You can reach him at support@sqlabhub.com. Messages are read by him personally, so a reply can take a few days.
Why it exists
Reading about a JOIN is not the same as writing one and seeing which rows come back. Most SQL articles show a query and a hand-typed result table, and you have to take the result on trust. SQLab Hub puts a database behind every example, so you can run it, change it, break it and see what happens.
The practice database is a small online store with 8 related tables: customers, orders, order items, products, payments, reviews, and the company's employees and departments. It is generated sample data, not real customer records. You can see every table and how they connect on the database schema page.
How the content is made and checked
Lessons and challenges are planned and edited by Rahul. AI writing tools are used for drafting and for the site's code, and nothing is published on the strength of a draft alone. What makes a page reliable is that its SQL is executed, not that someone says it is right:
- Lesson examples. In the lessons rebuilt since October 2026, each example query is run against the practice database when the page is generated, and the result table on the page is that real output. A query that errors or returns nothing stops the page from being generated.
- Challenges. Every challenge has a model solution that is run during the build to produce the expected output shown on its page. Challenges whose stored solution fails, returns no rows or does not answer its own question are held back from search engines until they are fixed.
- SQL dialect. Queries run on SQLite. Where MySQL, PostgreSQL or SQL Server behave differently, the lesson says so, but only the SQLite version is executed here.
- Dates. Each lesson shows the date its content last changed at the foot of the page. It is not bumped to make a page look fresh.
Some older lessons were written before these checks existed and are being rebuilt one at a time. If an example on any page does not behave the way the page says, that is a bug worth reporting.
Found a mistake?
Email support@sqlabhub.com with the page address and what is wrong: a query that returns something different, an explanation that does not match the code, a broken link. Confirmed errors are fixed on the page and the page's “last updated” date is changed.
The contact page lists what to include for bug reports and account or payment questions.
Who it is for
What it costs: nothing
SQLab Hub is 100% free. The lessons, the Playground, all 389 challenges, the projects and the skill tests cost nothing. There is no paid plan, no trial, and nothing to buy anywhere on the site.
You can run queries without an account. A free account is needed only to save queries, see model solutions, keep your progress and take the timed tests.
The site is paid for by advertising. Ads, where shown, are served by Google AdSense. Advertisers have no say over what the lessons teach. How advertising cookies work and how to opt out is explained in the Privacy Policy.