Write code people can read
Code is read far more often than it is written. Spend the extra thirty seconds on a clear variable name, a short comment, or breaking a long function in half — every reader in the future will benefit. Stick to your community's official style guide.
Test your code
Automated tests are not optional once a project is bigger than a weekend script. They catch bugs before users do and let you refactor with confidence. Start with a handful of tests for the most important behaviours and grow the suite as you grow the project.
Where to go next
You now know enough SQL to build small, real projects. The fastest way to keep learning is to pick a project you actually want to use — a personal site, a budget tracker, a small game — and build it. Read other people's code, contribute to an open-source project, and never stop asking "why".
Take the quiz
When you feel comfortable with the material, take the SQL quiz. Pass it and you can unlock your official Play with Coding SQL Mastery Certificate.