Оператор SQL не получает определение переменной

В этом сценарии есть два оператора sql, первый обрабатывает все поля txt, а PDO получает идентификатор строки:

$last_id = $conn->lastInsertId():

Второй оператор sql находится в закрытом классе и должен вставить URL-адрес двух файлов в одну строку (как и первый оператор).

Первый SQL-оператор выполняется нормально.
Второй — нет, и я думаю, что это потому, что он не понимает, что такое $ last_id.

Какие-нибудь предложения, чтобы заставить работать второй PDO?

 <?php
require('../dbcon2.php');
//Connection 1
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$stmt = $conn->prepare("INSERT INTO listings (title, address, lot_size, zoning, build_size, sale_price, lease_price, comment, transaction, date_added) VALUES (:title, :address, :lot_size, :zoning, :build_size, :sale_price, :lease_price, :comment, :transaction, now())");
$stmt->bindParam(':title', $_POST['title']);
$stmt->bindParam(':address', $_POST['address']);
$stmt->bindParam(':lot_size', $_POST['lot_size']);
$stmt->bindParam(':zoning', $_POST['zoning']);
$stmt->bindParam(':build_size', $_POST['build_size']);
$stmt->bindParam(':sale_price', $_POST['sale_price']);
$stmt->bindParam(':lease_price', $_POST['lease_price']);
$stmt->bindParam(':comment', $_POST['comment']);
$stmt->bindParam(':transaction', $_POST['transaction']);
$stmt->execute();
$last_id = $conn->lastInsertId();
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
//Create class
class CropAvatar {
private $src;
private $data;
private $file;
private $dst;
private $type;
private $extension;
private $srcDir = '../0images/listimg/orig';
private $dstDir = '../0images/listimg/mod';
private $msg;

function __construct($src, $data, $file, $last_id) {
$this -> setSrc($src);
$this -> setId($last_id);
$this -> setData($data);
$this -> setFile($file);
$this -> crop($this -> src, $this -> dst, $this -> data);
}
private $last_id;
public function setId($last_id) {
$this->id = $last_id;
}
private function setSrc($src) {
if (!empty($src)) {
$type = exif_imagetype($src);
if ($type) {
$this -> src = $src;
$this -> type = $type;
$this -> extension = image_type_to_extension($type);
$this -> setDst();
}
}
}
private function setData($data) {
if (!empty($data)) {
$this -> data = json_decode(stripslashes($data));
}
}
private function setFile($file) {
$errorCode = $file['error'];
if ($errorCode === UPLOAD_ERR_OK) {
$type = exif_imagetype($file['tmp_name']);
if ($type) {
$dir = $this -> srcDir;
if (!file_exists($dir)) {
mkdir($dir, 0777);
}
$currdate=date('YmdHis');
$extension = image_type_to_extension($type);
$src = $dir . '/' . $currdate . $extension;
if ($type == IMAGETYPE_GIF || $type == IMAGETYPE_JPEG || $type == IMAGETYPE_PNG) {
if (file_exists($src)) {
unlink($src);
}
$result = move_uploaded_file($file['tmp_name'], $src);
$listing_img="http://www." . $Website . ".com/0images/listimg/mod/" . $currdate . $extension;
//Process file upload
$allowedExtsf = array("pdf");
$tempf = explode(".", $_FILES["flyer"]["name"]);
$extensionf = end($tempf);
if (($_FILES["flyer"]["type"] == "application/pdf")
&& ($_FILES["flyer"]["type"] <2000000000)
&& in_array($extensionf, $allowedExtsf))
{
$flyername=$_FILES["flyer"]["name"];
if ($_FILES["flyer"]["error"] > 0)
{
echo "Return Code: " . $_FILES["flyer"]["error"] . "<br>";
}
else
{
if (file_exists("../flyers/" . $_FILES["flyer"]["name"]))
{
echo $_FILES["flyer"]["name"] . " already exists. ";
}
else
{
move_uploaded_file($_FILES["flyer"]["tmp_name"],"../flyers/" . $_FILES["flyer"]["name"]);
}
}
$ad_link="http://www." . $Website . ".com/flyers/" . $_FILES["flyer"]["name"];
//Connection 2
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$sql="UPDATE listings SET ad_link='$ad_link', listing_img='$listing_img' WHERE id=$last_id";
$conn->exec($sql);
}
catch(PDOException $e)
{
echo $sql . "<br>" . $e->getMessage();
}
$conn = null;
}
//Error handling
if ($result) {
$this -> src = $src;
$this -> type = $type;
$this -> extension = $extension;
$this -> setDst();
} else {
$this -> msg = 'Failed to save file';
}
} else {
$this -> msg = 'Please upload image with the following types: JPG, PNG, GIF';
}
} else {
$this -> msg = 'Please upload image file';
}
} else {
$this -> msg = $this -> codeToMessage($errorCode);
}
}

private function setDst() {
$dir = $this -> dstDir;

if (!file_exists($dir)) {
mkdir($dir, 0777);
}

$this -> dst = $dir . '/' . date('YmdHis') . $this -> extension;
}

private function crop($src, $dst, $data) {
if (!empty($src) && !empty($dst) && !empty($data)) {
switch ($this -> type) {
case IMAGETYPE_GIF:
$src_img = imagecreatefromgif($src);
break;

case IMAGETYPE_JPEG:
$src_img = imagecreatefromjpeg($src);
break;

case IMAGETYPE_PNG:
$src_img = imagecreatefrompng($src);
break;
}

if (!$src_img) {
$this -> msg = "Failed to read the image file";
return;
}

$dst_img = imagecreatetruecolor(220, 220);
$result = imagecopyresampled($dst_img, $src_img, 0, 0, $data -> x, $data -> y, 220, 220, $data -> width, $data -> height);

if ($result) {
switch ($this -> type) {
case IMAGETYPE_GIF:
$result = imagegif($dst_img, $dst);
break;

case IMAGETYPE_JPEG:
$result = imagejpeg($dst_img, $dst);
break;

case IMAGETYPE_PNG:
$result = imagepng($dst_img, $dst);
break;
}

if (!$result) {
$this -> msg = "Failed to save the cropped image file";
}
} else {
$this -> msg = "Failed to crop the image file";
}

imagedestroy($src_img);
imagedestroy($dst_img);
}
}
private function codeToMessage($code) {
switch ($code) {
case UPLOAD_ERR_INI_SIZE:
$message = 'The uploaded file exceeds the upload_max_filesize directive in php.ini';
break;

case UPLOAD_ERR_FORM_SIZE:
$message = 'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form';
break;

case UPLOAD_ERR_PARTIAL:
$message = 'The uploaded file was only partially uploaded';
break;

case UPLOAD_ERR_NO_FILE:
$message = 'No file was uploaded';
break;

case UPLOAD_ERR_NO_TMP_DIR:
$message = 'Missing a temporary folder';
break;

case UPLOAD_ERR_CANT_WRITE:
$message = 'Failed to write file to disk';
break;

case UPLOAD_ERR_EXTENSION:
$message = 'File upload stopped by extension';
break;

default:
$message = 'Unknown upload error';
}

return $message;
}

public function getResult() {
return !empty($this -> data) ? $this -> dst : $this -> src;
}

public function getMsg() {
return $this -> msg;
}
}
$crop = new CropAvatar($_POST['avatar_src'], $_POST['avatar_data'], $_FILES['avatar_file'], $last_id);
$response = array(
'state'  => 200,
'message' => $crop -> getMsg(),
'result' => $crop -> getResult()
);
echo json_encode($response);
?>