How to properly set POST value from AJAX? - php

Question

I want to pass the value from jquery to php using AJAX, the problem is the value in the php is not properly set.
Here is my sample codes:
Button trigger to pass data into jquery.
<button class="btn btn-info add-percentage"
data-landing_id-percentage="'.$row['hidden_id'] .'"
data-toggle="add-percentage"><i class="glyphicon glyphicon-time"></i></button>
Below is the ajax and jquery code.
<script>
$(".add-percentage").click(function(){
var landing_id = $(this).data('landing_id-percentage');
$.ajax({
url: 'ajax/readPercentage.php',
type: 'POST',
data: {
landing_id: landing_id
},
success: function(msg) {
alert('Email Sent'+msg);
$('#add-percentage').modal('show');
readRecords();
}
});
});
<script>
The result below in the php code is the landing_id is not properly set.
readPercentage.php
<?php
$data = '
<table class="table table-bordered table-hover table-striped" id="ModalMyTable">
<thead>
<tr class="success">
<th ><center>No.</center></th>
<th ><center>Percentage ID</center></th>
<th ><center>Landing ID</center></th>
<th><center>Percentage</center></th>
<th><center>Date Added</center></th>
</tr>
</thead>';
if(isset($_POST['landing_id'])){
$landing_id = $_POST['landing_id'];
$query = mysqli_query($conn, "SELECT
percentage.percent_id,
percentage.landing_id,
percentage.percentage,
percentage.date_recorded
FROM
percentage
WHERE percentage.landing_id = '$landing_id'");
$number = 1;
while($row = mysqli_fetch_assoc($query)) {
$data .= '
<tr>
<td><center>' . $number . '</center></td>
<td><center>' . $row['percent_id'] . '</center></td>
<td><center>' . $row['landing_id'] . '</center></td>
<td><center>' . $row['percentage'] . '%</center></td>
<td><center>' . date("M. d, Y", strtotime($row['date_recorded'])) . '</center></td>
</tr>';
$number++;
}
}else{
$data .='<tr><td colspan="6">Landing id is not properly set!</td></tr>';
}
$data .= '</table>
<script>
{
$(document).ready(function(){
$("#ModalMyTable").DataTable();
readRecords();
});
}
</script>
';
echo $data;
?>
I hope some one can help me in my problem. Thanks in advance.