可编辑但不处理ID

I am having some hard time trying to update my database after changing the text, in return I receive the following database error: Unknown column '' in 'field list'.

the content of the element id work, but the element id doesn't seems to be retrieved.

the element id is also the name of my field in the database

database fields name:

id| _career| _location| _education
62|IT      | London   | BSc Computer science

index.php file

<div style="margin-left: 2%;">
  <p><h1 class = "_name"><?php echo $user_data['firstname'], " ", $user_data['lastname']; ?></h1></p>
  <p><h3 class = "_career"><?php echo $user_data['_career'] ?></h3></p>
  <p><h4 class = "_location"><?php echo $user_data['_location'] ?></h4></p><br>
  <p><h5 class = "_education"><?php echo $user_data['_education'] ?></span></h5></p>
</div>

datacenter.php

$(document).ready(function() {
  $('.edit').editable('./datacenter.php', {
    indicator: 'Saving...',
    tooltip: 'Click to edit...'
  });
  $('._career').editable('./datacenter.php', {
    id: 'id',
    name: 'data',
    cancel: 'Cancel',
    submit: 'OK',
    indicator: '<img src="img/indicator.gif">',
    tooltip: 'Click to edit...'
  });
  $('._location').editable('./datacenter.php', {
    id: 'id',
    name: 'data',
    cancel: 'Cancel',
    submit: 'OK',
    indicator: '<img src="img/indicator.gif">',
    tooltip: 'Click to edit...'
  });
  $('._education').editable('./datacenter.php', {
    id: 'id',
    name: 'data',
    cancel: 'Cancel',
    submit: 'OK',
    indicator: '<img src="img/indicator.gif">',
    tooltip: 'Click to edit...'
  });

});

edit.php file

<?php

require 'core/init.php';

if (logged_in() == true && user_details_check($user_data['id'], "firstname", "noname") == true || logged_in() == false) {
  header("Location:./");
}

$f = $_POST['id'];
$value = $_POST['data'];
$user_id = trim($user_data['id']);

mysqli_query($con, "UPDATE users SET `$f` = '$value' WHERE `id` = '$user_id'") or die(mysqli_error($con));

/* sleep for a while so we can see the indicator in demo */
usleep(2000);

$renderer = $_GET['renderer'] ? $_GET['renderer'] : $_POST['renderer'];
if ('textile' == $renderer) {
  require_once './Textile.php';
  $t = new Textile();
  /* What is echoed back will be shown in webpage after editing. */
  print $t->TextileThis(stripslashes($_POST['user_edited_content']));
} else {
  /* What is echoed back will be shown in webpage after editing. */
  print $_POST['data'];
}

I have been stuck on this for days, Really hope someone could please help me figure this out

The element id wasnt working, so I switch to element class.

Before:

<p><h1 class = "_name"><?php echo $user_data['firstname'], " ", 

Now:

<p><h1 id = "_name"><?php echo $user_data['firstname'], " ",

datacenter.php

Before:

$(document).ready(function() {
  $('#edit').editable('./datacenter.php', {
    indicator: 'Saving...',
    tooltip: 'Click to edit...'
  });

Now:

$(document).ready(function() {
  $('.edit').editable('./datacenter.php', {
    indicator: 'Saving...',
    tooltip: 'Click to edit...'
  });