Could you please show me the publishers with a book published in 1989?
select publisher from book_club where year = 1989
Could you please show me the publishers with a book published in 1990?
select publisher from book_club where year = 1990
Which publishers published books in 1989 and 1990?
select publisher from book_club where year = 1989 intersect select publisher from book_club where year = 1990