How do I update status into database?

<form name="form" method="post" action"admin_attendance_edit.php> 

    <table>
    <thead>
    <tr>
    <th>No.</th>
    <th>Name</th>
    <th>Status</th>
    </tr>
    </thead>
    <tbody>
					
    <?php
					
    $count=1;
	$sel_query="Select * from attendance ORDER BY attendance_id desc;";
	$result = mysqli_query($db,$sel_query) or trigger_error("Error". 
    mysqli_error($db));
															
					
	while($row = mysqli_fetch_assoc($result)) {?>
	<tr>
    <td align="center"><?php echo $count; ?></td>
	<td align="center"><?php echo $row["student_name"]; ?></td>
	<td align="center">

    <input type="hidden" name="user_id[]" value="<?php echo $row["user_id"];?>" 
    />
    <input type="hidden" name="name[]" value="<?php echo $row["student_name"]; ? 
    >" />
	<input  name="attendance[]" type="radio" value="present" />Present
	<input  name="attendance[]" type="radio" value="late"/>Late
	<input  name="attendance[]" type="radio" value="absent"/>Absent</td>									
						
	</tr>												
						
    <?php $count++; } ?>
    </tbody>
    </table>
       			
    <p><input name="submit" type="submit" value="Update" /></p> 
		
    </form>  

<?php
	
	
	if(isset($_POST['submit']))
	{	
			
    foreach ($attendance as $name=> $attendance_status)
		{
		
		$trn_date = date('Y-m-d');	
		$user_id = $_POST['user_id'][$name];
		$student_name =	$_POST['name'][$name];
		
		$update="update attendance set user_id='".$user_id."', student_name='".$student_name."' , 
										attendance_status='".$attendance_status."', date='".$trn_date."' 
										
										";
	mysqli_query($db, $update) or trigger_error( "Error!". mysqli_error($db));
	header('location: admin_attendance.php');
	
	}

Can anyone tell me anything wrong in my code.thanks.