答案是:Select books.*, publisher.* From books, publisher, pubRecord Where books.pub_id = publisher.id And books.isdn=pubRecord.isdn And discount is null Or discount = 0 (5)将所有“电子工业出版社”出版的图书降价10%。 Update books set price=0.9*price Where pub_id in (select id from publisher where desc=’电子工业出版社’)
