I am currently teaching myself php from a tutorial. In one of the intermediary steps to developing a controller for handling a ‘DELETE’ request, I created the following:

use coreDatabase;

$config = require base_path("config.php");
$db = new Database($config['database']);
$currentUserId = 1;

if($_SERVER['REQUEST_METHOD'] === 'POST')
{

    $note = $db->query('select * from notes where id = :id', [
        'id' => $_GET['id']
    ])->find();
    
    
    authorize($note['UserId'] === $currentUserId);

    $db->query('delete from notes where id = :id', [
        'id' => $_GET['id']
    ])->find();

    header('location: /notes');
    exit();
}

This code references a Database object that I created in a preceding step of the tutorial:

namespace core;
use PDO;


class Database {
    public $_connection;
    public $statement;
    public function __construct($config, $username = 'root', $password = '')
    {
        $dsn = 'mysql:'.http_build_query($config,'',';');
        // dd($dsn);
        $this->$_connection = new PDO($dsn, $username, $password, [
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC 
        ]);
    }

    public function query($query, $params = [])
    {
        $this->$statement = $this->$_connection->prepare($query);
        $this->$statement->execute($params);
        return $this;
    }

    public function find(){
        return $this->$statement->fetch();
    }
}

when I run this code, I get the following error: Uncaught Error: Call to undefined method PDOStatement::prepare().

I have been trying for a few hours now to understand why this is occurring, but I cannot figure it out. Does anyone have an idea what might be happening here? Thank you in advance.

When I comment out the first query, it works:

if($_SERVER['REQUEST_METHOD'] === 'POST')
{

    // $note = $db->query('select * from notes where NoteId = :id', [
    //     'id' => $_GET['id']
    // ])->find();
    
    
    // authorize($note['UserId'] === $currentUserId);

    $db->query('delete from notes where NoteId = :id', [
        'id' => $_GET['id']
    ])->find();

    header('location: /notes');
    exit();
}

It also works if I comment out the second query:

    $note = $db->query('select * from notes where NoteId = :id', [
        'id' => $_GET['id']
    ])->find();
    
    
    authorize($note['UserId'] === $currentUserId);

    // $db->query('delete from notes where NoteId = :id', [
    //     'id' => $_GET['id']
    // ])->find();

    header('location: /notes');
    exit();

I can also make it work by re-instantiating the Database object between the two queries.

Somehow it works for the instructor, and his source code is identical to mine. I cannot understand why his works and mine doesn’t.

I appreciate any help that you can provide. Thank you in advance.