What are the highest and lowest prices of products?
select max(product_price), min(product_price) from products
What are the highest and lowest prices of products, grouped by product type?
select max(product_price), min(product_price), product_type_code from products group by product_type_code
Sort the results by the product type.
select max(product_price), min(product_price), product_type_code from products group by product_type_code order by product_type_code