Show all company names.
select company_name from culture_company
Only show the companies with a book.
select t1.company_name from culture_company as t1 join book_club as t2 on t1.book_club_id = t2.book_club_id
What about the companies with a book published by Alyson?
select t1.company_name from culture_company as t1 join book_club as t2 on t1.book_club_id = t2.book_club_id where t2.publisher = 'Alyson'