About SQLShed

SQLShed is a place to learn SQL by writing it. Each lesson explains one idea and then asks you to use it, in a workbench that runs in your browser.

You practice against realistic datasets without installing anything. There are no accounts, no server running your queries, and nothing real to break.

The course starts with SELECT, tables, data types, and filters, then builds toward joins, aggregates, CASE expressions, safe data changes, debugging, and practical analytics patterns like window functions and common table expressions. Along the way it builds habits for reading, writing, and checking SQL, which last longer than any one dialect's syntax.

SQLShed is built for beginners and early-career analysts who need practical repetition more than another abstract syntax tour. Lessons are short on purpose: read the idea, run the query, inspect the result, and fix the part that does not behave as expected.

Alongside the lessons, SQLShed includes a concise SQL reference, scannable cheatsheets, and a common mistakes section for debugging wrong or surprising results.

The freeform SQL playground runs DuckDB in the browser. You can query built-in sample datasets or register your own CSV and Parquet files locally, without uploading data to SQLShed.

The SQL engine itself, DuckDB-WASM, is downloaded from the jsDelivr CDN the first time a page needs it. jsDelivr sees that download request, like any CDN, but never your queries: they run inside your browser tab after the engine arrives.

SQLShed uses Cloudflare Web Analytics to see roughly how many people visit and which pages help. It sets no cookies. For each page view it reports the page address (never the part after #, so never a shared query), the page you came from, your browser's name and version, and how long the page took to load. It does not report anything you type into an editor. Like any web host, Cloudflare also sees the IP address each request comes from.

Found a lesson that is unclear, or one that grades a correct answer as wrong? Email hello@sqlshed.com. That feedback is the most useful thing you can send.

Measure twice. Query once.