pool

SELECT products.id as my_product_id, products.name as my_product_name,
group_concat(bb.name) AS book_binding_name,
group_concat(bl.name) AS book_language_name,
group_concat(ba.name) AS book_authors_name
FROM products,product_book
LEFT JOIN book_binding bb ON book_name = 'book_binding' AND bb.id = product_book.book_id
LEFT JOIN book_language bl ON book_name = 'book_language' AND bl.id = product_book.book_id
LEFT JOIN book_authors ba ON book_name = 'book_authors' AND ba.id = product_book.book_id
WHERE products.id = 'ПЧ9' and product_book.product_id = products.id group by products.id