DB ROW update with AJAX - php

Question

i am troubleshooting with update row using AJAX. When i click submit button, the value of poke increases +1 and i need it to update in DB also. Everything needs to work with AJAX.
Currently my code works only +1 to poke input with ajax but DB row still not updating.
HTML:
<?php
$result = $mysqli->query("SELECT * FROM users") or die($mysqli->error);
while ($users = $result->fetch_assoc()) {
?>
<form class="table" name="table" id="table" method="post" enctype="multipart/form-data" autocomplete="off" data-counter="<?php echo $users['id']?>">
<div class="Table-row" id="table">
<div class="Table-row-item" data-header="Header1"><input class="clear" type="text" name="first_name" id="first_name" value="<?php echo $users['first_name'] ?>"></div>
<div class="Table-row-item" data-header="Header2"><input class="clear" type="text" name="last_name" id="last_name" value="<?php echo $users['last_name'] ?>"></div>
<div class="Table-row-item" data-header="Header3"><input class="clear" type="text" name="email" id="email_<?php echo $users['email']?>" value="<?php echo $users['email'] ?>"></div>
<div class="Table-row-item" data-header="Header4"><input class="clear" type="text" name="poke" id="poke_<?php echo $users['id']?>" value="<?php echo $users['poke']?>"></div>
<div class="Table-row-item" data-header="Header5"><input class="poke" type="submit" value="Poke" id="submit" name="submit"></div>
<input class="clear" type="hidden" id="hidden" name="hidden" value="<?php echo $users['email']?>">
</div>
</form>
<?php
} ?>
PHP:
<?php
require 'db.php';
if (isset($_POST['submit'])) {
$poke = $mysqli->escape_string($_POST['poke']);
$email = $mysqli->escape_string($_POST['email']);
$mysqli->query("UPDATE users SET poke='$poke' WHERE email='$email'") or die($mysqli->error);
}
AJAX:
$(document).ready(function () {
$('form').on('submit', function (e) {
var id = $(this).attr('data-counter');
e.preventDefault();
$.ajax({
type: "post",
data: $(this).serialize(),
url: "update.php",
success: function () {
var counter = parseInt($("#poke_"+id).val()); // Use form's inner #poke
counter++;
$("#poke_"+id).val(counter);
alert("form was submited on: " + id);
}
});
return false;
});
});

Answer 1

Not enough info. You need to do more diagnostics.
E.g: Dump the SQL statement to the output so you can check it is what you expect it to be.
And run the SQL in, e.g. phpAdmin to check if it updates.
You may have a problem in the email string, which could be caused by, say, different character encodings between AJAX and the DB. Probably both should use UTF8.