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SQL and Data Wrangling
Unscored tasks with hints and instant feedback. Practice results never become credentials.
Short lesson
Git recovery toolkit · 10 min
git stash for quick context switches, git reflog to find lost commits, git bisect run to find the first bad commit, git worktree add for parallel work.
L3Fix the revenue queryspot
This query should return revenue per region for 2026, highest first. Click each wrong line.
Sign up to practiseL3Write a jointext
Tables: orders(id, customer_id, amount) and customers(id, name, country). Write SQL returning each country with its total order amount.
Sign up to practiseL5Knowledge checkmcq
You need each customer's running total of orders by date. Which SQL feature fits best?
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