03-advanced-exercises.sql

-- Exercise 03: Advanced SQL
-- Write your answers below each question.

-- 1. Build a monthly sales CTE and show a running total.

-- 2. Rank customers by total sales within each region using a window function.

-- 3. Find the top 3 products by profit in each category.

-- 4. Use LAG to compare each order date to the previous order date per customer.

-- 5. Calculate percent of total sales by region using a window function.

-- 6. Find the best sales month in each year.

-- 7. Compare weekend and weekday sales using periode.

-- 8. For each region, return the month with the highest profit and include the profit rank.

-- 9. Build a customer summary CTE that shows total sales, total profit, total orders,
--    and average days between first and last order for each customer.

-- 10. Create a query that compares each month's sales to the previous month and returns:
--     year, month, total sales, previous month sales, sales difference,
--     and growth percentage.