search filter in php

<html>

<body>
<form action="" method="GET">
<input type="text" name="rollno" placeholder="Enter Value" id=""/>
<input type="submit" value="Search"/>
<table>
<tr><th>Name</th><th>Email</th><th>Address</th><th>ID</th></tr>

<?php

if (isset($_GET['rollno']))
{
$roll=$_GET['rollno'];
$query=mysql_query("select * from employees_record where rollno='$roll'");
while($result=mysql_fetch_array($query))
{
?>
<tr>
<td><?php echo $result ['name'];?></td>

<td><?php echo $result ['name'];?></td>

<td><?php echo $result ['name'];?></td>

<td><?php echo $result ['name'];?></td>
</body>

</html>