SELECT DISTINCT p.id AS id, p.precio AS precio, p.tipo_libro, p.url_ebook, p.autor AS autor, p.activo AS activo FROM producto AS p JOIN producto_categoria AS pd2 ON( p.id = pd2.producto_id AND pd2.categoria_id = '16' ) WHERE p.activo = 1 AND p.tipo_libro > 0 GROUP BY p.id