What are the products with price higher than 1000?
select * from products where product_price > 1000
What are their order dates?
select t1.order_date from customer_orders as t1 join order_items as t2 on t1.order_id = t2.order_id join products as t3 on t2.product_id = t3.product_id where t3.product_price > 1000