I have a database tracking registrations of software products with two related tables,
"registered_products" and "people". I need to pull a list of email addresses from the
people table BUT I only want to pull people records who own very specific combinations of
products from the registered_products table.
Let's say I want people who own both Product A AND Product B... My first guess is to write
a query like this:
registered_products on people.person_id = registered_products.person_id
registered_products.product_type = "Product A" and
registered_products.product_type = "Product B"
However, this does not work, no rows are returned. When I think about it, that makes
sense, because rows are evaluated one at a time, and no single product row can
simultaneously have two values for the column "product_type".
I need to only get results from a person record that has two related registered_product
rows, one with a value of "Product A" and one with "Product B".
What is the best way to write a query to do this?