What are the product names that are not product category code "Herbs"?
select product_name from products where product_category_code != "Herbs"
Show the same, but for those with unit of measurement "Handful" instead.
select t1.product_name from products as t1 join ref_product_categories as t2 on t1.product_category_code = t2.product_category_code where t2.unit_of_measure = "Handul"
What about the opposite condition?
select t1.product_name from products as t1 join ref_product_categories as t2 on t1.product_category_code = t2.product_category_code where t2.unit_of_measure != "Handul"
Of these, show for the ones that are colored "white" too.
select t1.product_name from products as t1 join ref_product_categories as t2 on t1.product_category_code = t2.product_category_code join ref_colors as t3 on t1.color_code = t3.color_code where t3.color_description = "white" and t2.unit_of_measure != "Handful"