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SQL Essentials

Ask questions of real data: SELECT, JOIN, GROUP BY and window functions on a store's orders database.

8 lessons7 hours301k learnersCertificate with Pro

Code you'll write

JOINssql

SELECT c.name, o.ordered_at, o.total
FROM customers AS c
JOIN orders AS o ON o.customer_id = c.id
WHERE o.total > 100
ORDER BY o.ordered_at DESC
LIMIT 10;

GROUP BYsql

-- Revenue per month
SELECT strftime('%Y-%m', ordered_at) AS month,
       COUNT(*)      AS orders,
       SUM(total)    AS revenue
FROM orders
GROUP BY month
HAVING revenue > 5000
ORDER BY month;

Window functionssql

SELECT name, department, salary,
       RANK() OVER (PARTITION BY department ORDER BY salary DESC) AS rank
FROM employees;