Unbelievable! How about set operations: unions, differences and intersections? Can you still remember them? Take a look:
gluten_free_product (id, type, name, calories, price)
vegetarian_product (id, type, name, calories, price)
As you can see, we are now inside a dietician's office. We have two tables with the same columns: products that are free of gluten and vegetarian products. Each product has its own id, its type (whether it's meat, dairy, etc.), name, number of calories per portion and price.
Show all columns for the products which are gluten free and vegetarian at the same time.
Use the following template to help you build your query:
SELECT ... FROM ... INTERSECT SELECT ... FROM ...;
