File Upload and Delete multiple rows by selecting checkboxes using PHP

Index Page :
<html>
<head></head>
<body>
<form name="frm" method="post" action="submit.php" enctype="multipart/form-data">
<table>
<tr>
<td> Student Name </td>
<td><input type="text" name="stu_name"/><td>
<tr>
<tr>
<td> Student Email </td>
<td><input type="text" name="stu_email"/><td>
<tr>
<tr>
<td> Student Phone </td>
<td><input type="text" name="stu_phone"/><td>
<tr>
<tr>
<td> Student Photo </td>
<td><input type="file" name="stu_photo"/><td>
<tr>
<tr colspan="2">
<td><input type="submit" value="submit data" name="submit"></td>
</tr>
</table>
</form>
<form name="frm1" method="post" action="submit.php" enctype="multipart/form-data">
<table>
<tr>
<td><input type="checkbox" name="check_all"/>
<td>ID</td>
<td> Name</td>
<td> Email</td>
<td> phone</td>
<td>photo </td>
</tr>
<?php
$con = mysql_connect("localhost","root","");
mysql_select_db("pan_test",$con);
$query = mysql_query("select * from stu_info");
while($row = mysql_fetch_array($query)){
$id = $row['id'];
$name = $row['name'];
$email = $row['email'];
$phone = $row['phone'];
$photo = $row['photo'];
echo "<tr>";
echo "<td><input type='checkbox' name='checkbox[]' value='$id'/></td>";
echo "<td>$name</td>";
echo "<td>$email</td>";
echo "<td>$phone</td>";
//echo "<td><img src='uploads/$photo'/><td>";
echo "</tr>";
}

?>
<tr colspan="2">
<td><input type="submit" value="submit data" name="submit1"></td>
</tr>
</body>
</html>

submit.php

<?php
$con = mysql_connect("localhost","root","");
mysql_select_db("pan_test",$con);
if($_REQUEST['submit']){
$name= $_REQUEST['stu_name'];
if(empty($name)){
echo "missing";
}
$mail= $_REQUEST['stu_email'];
$phone=$_REQUEST['stu_phone'];
$photo= $_FILES['stu_photo'] ['name'];
$target = 'uploads/'.basename($_FILES['stu_photo'] ['name']);
move_uploaded_file($_FILES['stu_photo'] ['tmp_name'],$target);

$query = mysql_query("insert into stu_info(name,email,phone,photo) values('$name','$mail','$phone','$photo')");
header('location: index.php');
}
else if($_REQUEST['submit1']){
print_r($_REQUEST);
$checkbox= $_REQUEST['checkbox'];
for($i=0;$i<count($_REQUEST['checkbox']);$i++){
echo $id= $checkbox[$i];
$query = mysql_query("delete from stu_info where id=$id");

}
}

?>