php mariadb sum除以若沒有值，會出現NAN，能否顯示0？

Question

$selectTip = $pdo->query("SELECT * FROM `tips_rate`
                WHERE `tip_id` = '".$row['id']."' "
              );
              $selecttotal = mysqli_num_rows($selectTip);
              $rate = $pdo->query("SELECT SUM(star) as startotal FROM `tips_rate`
                WHERE `tip_id` = '".$row['id']."' "
              );
              $startotal = mysqli_fetch_array($rate);
              echo $startotal['startotal']/$selecttotal;

當我echo他們互除以的結果後
假設沒有值他會出現NAN...能不能顯示 0？

Answer 1

$num = $startotal['startotal']/$selecttotal;echo is_nan($num) ? 0 : $num;