PHP PDO: Object auto-deconstructs after calling function - php

Question

I've got a situation, where the object created in the top position in my PHP file, gets deconstructed before reaching the end of the PHP code on that file
File1.php:
//* This is all in the same PHP file *//
<?php
session_start();
include 'includes/user.inc.php';
$userOBJ = new User; //Declaring the object
?>
//*** jQuery and HTML code here ***//
<?php
if($userOBJ->isAdmin($_SESSION['session_u-name']) == true){
AdminControl();
}
// This code gets done without any problem
function AdminControl(){
echo "<a id='dbControlAdmin' onclick='changeDisplayAdm()'>Database
Control</a>";
}
?>
//*** More HTML and jQuery Code here ***//
<?php
$userOBJ->getUsersName(); //The object is no longer available when reaching this code
?>
In the Object Class I have this function as the deconstructor:
public function __destruct(){
echo "<b style='color: red;'>Status:</b> Database Connection->Disconnect";
}
This are the functions that are called through the Object:
public function isAdmin($user){
$userToGet = $user;
$stmt = $this->Connect()->prepare("SELECT admin_db FROM user_secure WHERE username_db=?");
$stmt->execute([$userToGet]);
foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
$value = $row["admin_db"];
if($value == 1){
return true;
} else {
return false;
}
}
}
public function getUsersName(){
$stmt = $this->Connect()->prepare("SELECT username_db FROM user_secure");
$stmt->execute();
while($row = $stmt->fetchAll(PDO::FETCH_ASSOC)){
echo "<option value='" . $row['username_db'] . "'>" . $row['username_db'] . "</option>";
}
}
}
When I run the website, in the top left corner appears this message
Status: Database Connection->Disconnect
Which is the instruction that the object has in the __destruct function, and the website deploys a PHP error where that last function call is: $userOBJ->getUsersName();
The error is:
Notice: Undefined index: username_db in C:\wamp64\www\NewKali\includes\user.inc.php on line 57
I don't get where the __destruct function is called or why it is called! Hope that you can help me.
Thank you for your time!

Answer 1

rename column username_db into a column, which actually exists on the server.

Answer 2

OWNER EDIT:
I changed $row['username_db'] to $row["username_db"] and it worked... (Also changed a few other things)
My final code in the function was this:
public function getUsersName(){
$stmt = $this->Connect()->prepare("SELECT * FROM user_secure");
$stmt->execute();
foreach ($stmt->fetchAll(PDO::FETCH_ASSOC) as $row) {
$value = $row["username_db"];
echo "<option value='" . $value . "'>" . $value . "</option>";
}
}

Answer 3

You're setting $userOBJ = new User twice.