CREATE TABLE book (book_id NUMBER, title CLOB, issues NUMBER, writer CLOB)
CREATE TABLE publication (publication_id NUMBER, book_id NUMBER, publisher CLOB, publication_date CLOB, price NUMBER)

List the writers who have written more than one book.
SELECT writer FROM book GROUP BY writer HAVING COUNT(*) > 1
SELECT "writer" FROM "book" GROUP BY "writer" HAVING COUNT(*) > 1