PHP开发一个简单的成绩录入系统

预览界面
源码：
<!DOCTYPE html>
<html>
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style type="text/css">
        table{
            text-align: center;
        }
    </style>
</head>
<body>
    <form action="" name="number" method="post">
        Input the number of student:&nbsp;
        <input type="number" name="stuNum"/>&nbsp;
        <input type="submit" value="OK" name="submitStu"/>
    </form>
</body>
</html>

<?php
    if(isset($_POST['submitStu'])){
        $stuNum=$_POST['stuNum'];
        if($stuNum>=0){
            echo '<div>';
            echo '<form action="" method="post" name="form1">';
                echo '<table border="1" >';
                    echo '<tr><td>Sno:</td><td>Name:</td><td>Score:</td></tr>';
                    for($i=0;$i<$stuNum;$i++){
                        echo '<tr><td><input type="text" name="XH[]"/></td><td><input type="text" name="XM[]"/></td><td><input type="text" name="CJ[]"/></td></tr>';
                    }
                    echo '<tr><td colspan="3"><input type="submit" value="OK" name="bt_stu"/></td></tr>';
                echo '</table>';
            echo '</form>';
            echo '</div>';
        }else{
            echo "Please input corrent num";
        }
    }
?>

<?php

    if(isset($_POST['bt_stu'])){
        $XH=$_POST['XH'];
        $XM=$_POST['XM'];
        $CJ=$_POST['CJ'];
        array_multisort($CJ,$XH,$XM);
        $sum[]=null;
        for($i=0;$i<count($XH);$i++){
            $sum[$i]=array($XH[$i],$XM[$i],$CJ[$i]);   //里面每一个元素都是一个数组
        }
        echo '<div>The score has been sort:</div><br>';
        echo '<div>';
            echo '<table border="1">';
                echo '<tr><td>Sno:</td><td>Name:</td><td>Score:</td></tr>';
                    for($i=0;$i<count($sum);$i++){
                        echo "<tr><td>{$sum[$i][0]}</td><td>{$sum[$i][1]}</td><td>{$sum[$i][2]}</td></tr>";
                    }
                    /*foreach($sum as $value){
                        list($stu_num,$stu_name,$stu_score)=$value;
                        echo "<tr><td>$stu_num</td><td>$stu_name</td><td>$stu_score</td></tr>";
                    }*/
            echo '</table>';
        echo '</div>';
    }

?>