What are all the different book publishers?
SELECT DISTINCT publisher FROM book_club
SELECT DISTINCT publisher FROM book_club
[{'Publisher': 'Alyson'}, {'Publisher': "St. Martin's Press"}, {'Publisher': 'William Morrow'}, {'Publisher': 'Mysterious Press'}, {'Publisher': 'International Polygonics'}, {'Publisher': 'Banned Books'}, {'Publisher': 'Naiad Press'}, {'Publisher': 'Crossing Press'}]