这是在jQuery和PHP中使用AJAX的正确方法吗？

I need some help. I'm going use AJAX (for the first time) and I'd like you to tell me whether the way I am going to show you is optimal.

Let's say that I have a select element.

<select class="update-db" data-id="25" data-original-value="2">
    <option value="1">Yellow</option>
    <option value="2" selected="selected">Red</option>
    <option value="3">Blue</option>
</select>

So here is what I do:

$(document).on('change', 'select.update-db', function() {

// Get needed data
var select = $(this);
var id = select.attr('data-id');
var originalValue = select.attr('data-original-value');
var newValue = select.val();

    // Perform the request
    $.ajax({
        method: 'POST',
        url: 'update-db.php',
        data: { id: id, 'original-value': originalValue, 'new-value': newValue }
    });

  // Then, if everything is okay, change the "original value" of the select element
  // so that we can perform the updating operation again without having to refresh the page
  .done(function() {
      select.attr('data-original-value', newValue);
  });

});

Then, on the other side, a PHP script validates everything and updates the database.

Is this the correct way of using AJAX? I feel it's not. What am I doing wrong?