//create the database with name "weblab"
//create the table name student
// usn,name,marks

<?php 
    $servername = "localhost";
    $username = "root";
    $password = "";
    $dbname = "weblab";
    $conn = mysqli_connect($servername, $username, $password, $dbname);
    if (!$conn) {
        die("Connection failed: " . mysqli_connect_error());
    }
    $sql = "SELECT * FROM student";
    $result = $conn->query($sql); 
    $usn = array() ;
    echo "<table border='2'><caption>Before Sorting </caption><br>";
    echo "<tr><th>USN</th><th>NAME</th><th>Marks</th></tr>"; 
    if ($result->num_rows > 0)
    {
        while($row = $result->fetch_assoc())
        { 
            echo "<tr><td>". $row["usn"]."</td>";
            echo "<td>". $row["name"]."</td>";
            echo "<td>". $row["marks"]."</td></tr>";
            $usn[] = $row["usn"] ;
        }
    }
    $n = sizeof($usn) ;
    for($i = 0 ; $i < $n-1 ; $i++ )
    {
        $pos = $i ;
        for($j = $i + 1 ; $j < $n ; $j++ )
        {
            if( $usn[$pos] < $usn[$j])
            {
                $pos = $j ;
            }
        }
        if( $pos != $i)
        {
            $temp = $usn[$i] ;
            $usn[$i] = $usn[$pos] ;
            $usn[$pos] = $temp ;
        }
    }
    $name = [] ;
    $marks = [] ;
    $result = $conn->query($sql);
    if ($result->num_rows> 0)
    {
        while($row = $result->fetch_assoc()) 
        {
            for($i=0;$i<$n;$i++) 
            {
                if($row["usn"] == $usn[$i]) 
                {
                    $name[$i]=$row["name"];
                    $marks[$i]=$row["marks"];
                }
            }
        }
    }
    echo "<br><table border='2'><caption>After Sorting </caption><br>";
    echo "<tr><th>USN</th><th>NAME</th><th>Marks</th></tr>"; 
    for($i = 0 ; $i < sizeof($usn) ; $i++)
    {
        echo "<tr><td>". $usn[$i]."</td>";
        echo "<td>". $name[$i]."</td>";
        echo "<td>". $marks[$i]."</td></tr>";
    }
?>