How to check state of a checkbox and update database accordingly

I am making a check to see if the user account is freeze, this is in my database, $r is where I am getting the user data (name, freeze account, etc).

So if the freeze account is set to be 0 then I am showing a unchecked box otherwise a checked box. It works fine, however my question is how could I save it if I checked the box to say that the user account is freeze.

I know how to write the query if they check the box to say that the user account is freeze, just calling this function :

function updatefreezeaccount(){
mysql_query("UPDATE `users` SET `freeze_account` = 1 WHERE `user_id` = '$user_id'");
}

This is my code so far :

<?php
      if ($r['freeze_account'] == 0) {
          echo '<div class="example">
          <input type="checkbox" unchecked data-toggle="toggle">
          </div>';
      } 
      else {
          echo '<div class="example">
          <input type="checkbox" checked data-toggle="toggle">
          </div>';
      }
?>

However I don't know how to make the check to see if the user has checked the box or not, any suggestion would be appreciated, thanks