我无法得到我的jquery ajax帖子来连接我的php页面

php
<?php

include 'connection.php';
echo "reached page";
$stmt = $conn->prepare("INSERT INTO flagged ( ID,URL,COUNT,comment)VALUES ( :id,    :url, :count,:COMMENT )"); 
$stmt->bindParam(':id', $id);
$stmt->bindParam(':url', $url);
$stmt->bindParam(':count', $count);
$stmt->bindParam(':COMMENT', $comment);

$id = NULL;
$url = $_POST['url']);
$count = 1;
$comment = $_POST['data']);
$stmt->execute();

?>
php
<?php

include 'connection.php';
echo "reac