As you can see this is a working query. and now I want to add first and second field (int) value on 3rd field like $f_name + $m_name = value; with loop. how could i do that?

addition.php

<?php
  if(isset($_POST['Submit'])){
  
  for($i=0;$i<$count;$i++){
  $name = $_POST['name'];
  $f_name = $_POST['lastname'];
  $m_name = $_POST['email'];
  
  // This is a query for uploading multiple values in single query.
  $sql1="UPDATE computer SET s_name='$name[$i]', f_name='$f_name[$i]', m_name='$m_name[$i]' WHERE roll='$id[$i]'";
  $result1=$db->dbc->query($sql1);
  }
?>