else
$query = "SELECT `Book`.*, avg((ifnull(Rating.valor,0))) as avg FROM `books` AS `Book` LEFT JOIN `ratings` AS `Rating` ON (`Rating`.`book_id` = `Book`.`id`) left join books_tags on books_tags.book_id=Book.id WHERE books_tags.tag_id=$tag group by Book.id $order1 limit $offset, $limit;";
$posts = $this->query($query);
'SELECT `Book`.*, avg((ifnull(Rating.valor,0))) as avg, concat( if(saga="","",saga), if(orden=0,"", concat (" - ",orden)) ) as ssaga FROM `books` AS `Book` LEFT JOIN `ratings` AS `Rating` ON (`Rating`.`book_id` = `Book`.`id`) WHERE 1 = 1 group by Book.id limit 3600, 20;'