SELECT * FROM logros ORDER BY completado ASC
SELECT * FROM logros ORDER BY completado DESC
$st = $con->prepare("SELECT * FROM logros WHERE nombre = :us ORDER BY campo_que_recogo_que_tenga_logro_o_no ASC");
$st = $con->prepare("SELECT * FROM logros WHERE nombre = :us ORDER BY campo_que_recogo_que_tenga_logro_o_no DESC");