Those already comfortable with joins, CTEs, and window functions (you’d want an intermediate/advanced course). 7. Sample Query from the Course (Illustration) -- Find the top 5 customers by total payments in 2007 SELECT c.customer_id, c.first_name, c.last_name, SUM(p.amount) AS total_spent FROM customer c JOIN payment p ON c.customer_id = p.customer_id WHERE EXTRACT(YEAR FROM p.payment_date) = 2007 GROUP BY c.customer_id, c.first_name, c.last_name ORDER BY total_spent DESC LIMIT 5;

Absolute beginners, career switchers to data analytics, business intelligence aspirants, and backend developers wanting to learn SQL quickly.