PHP Multiple Checkbox; - php

Question

I have problem, I am trying to create a form with a few checkboxes, each assigned a different value, i just can update value first and last, between not working, can you help me?
Check.php
<div class="top-on">
<div class="top-on1">
<p class="text-center"> <?php echo $row['username'];?></p>
<br>
<select class="form-control col-sm-12" name="edit_level">
<?php
global $pdo;
$sql = $pdo->query("SELECT * FROM level");
while ( $row_c = $sql->fetch(PDO::FETCH_ASSOC) ) {
?>
<option <?php if($row_c["level"]==$row["level"])
{
echo "selected=\"selected\"";
}?>
value="<?php echo $row_c['level']?>"> <?php echo $row_c['name'];?> </opition>
<?php } ?>
</select>
</div>
<label style="float: right;">
<input type="checkbox" class="checkbox" name="idlevel[]" value="<?php echo $row['id'];?>"> </label>
<div class="clearfix"> </div>
</div>
page Control.php
function edit_level(){
global $pdo;
$sql1="SELECT * From user ";
$stmt1 = $pdo->query($sql1);
if(isset($this->btnlevel))
{
for($i=0;$i<$stmt1->rowCount();$i++){
$elve=$this->idlevel[$i];
$sql ="UPDATE user SET level='$this->editlevel' WHERE id='".$elve."'";
$upt = $pdo->prepare($sql);
$upt->execute();
}
}
}