task3.sql

-- Problem 9: Retrieve the top 3 categories with the highest total sales amount
-- Write an SQL query to retrieve the top 3 categories with the highest total sales amount.
-- The result should include the category ID, category name, and the total sales amount.
-- Hint: You may need to use subqueries, joins, and aggregate functions to solve this problem.

SELECT Categories.category_id, Categories.category_name, SUM(Orders.total_amount) AS total_sales
FROM Categories
JOIN Products ON Categories.category_id = Products.category_id
JOIN Order_Items ON Products.product_id = Order_Items.product_id
JOIN Orders ON Order_Items.order_id = Orders.order_id
GROUP BY Categories.category_id, Categories.category_name
ORDER BY total_sales DESC
LIMIT 3

-- Problem 10: Retrieve the users who have placed orders for all products in the Toys & Games
-- Write an SQL query to retrieve the users who have placed orders for all products in the Toys & Games
-- The result should include the user ID and username.
-- Hint: You may need to use subqueries, joins, and aggregate functions to solve this problem.

SELECT Users.user_id, Users.username
FROM Users
JOIN Orders ON Users.user_id = Orders.user_id
JOIN Order_Items ON Orders.order_id = Order_Items.order_id
JOIN Products ON Order_Items.product_id = Products.product_id
JOIN Categories ON Products.category_id = Categories.category_id
GROUP BY Users.user_id, Users.username
HAVING COUNT(DISTINCT Products.product_id) = (SELECT COUNT(DISTINCT product_id) FROM Products WHERE category_id = 5);

-- Problem 11: Retrieve the products that have the highest price within each category
-- Write an SQL query to retrieve the products that have the highest price within each category.
-- The result should include the product ID, product name, category ID, and price.
-- Hint: You may need to use subqueries, joins, and window functions to solve this problem.
SELECT product_id, product_name, category_id, price
FROM (SELECT *, ROW_NUMBER() OVER (PARTITION BY category_id ORDER BY price DESC) AS price_rows
FROM Products) AS Ranked_Prices
WHERE price_rows = 1;

-- Problem 12: Retrieve the users who have placed orders on consecutive days for at least 3 days
-- Write an SQL query to retrieve the users who have placed orders on consecutive days for at least 3 days.
-- The result should include the user ID and username.
-- Hint: You may need to use subqueries, joins, and window functions to solve this problem.