SELECT b.id, b.title, 
	CASE WHEN b.id NOT IN (SELECT ib.book_id FROM issued_book ib) 
	OR (b.id IN (SELECT ib.book_id FROM issued_book ib) AND ib.date_return IS NOT NULL) THEN 'В наличии' 
	ELSE 'Нет в наличии' 
	END AS Наличие
FROM book b
LEFT JOIN issued_book ib ON ib.book_id = b.id