PHP - Connection To Db From Web Page

Hi Guys,

need a little help and drawn a blank. The code that is not working is below

$result = $conn->query("SELECT * FROM MK_migration_details WHERE mig_bid='".$_SESSION['bid']."'");

I can confirm the $_SESSION['bid'] is working as echo's out on another part of the page. and the above $result works when i manually type the search criteria like below.

$result = $conn->query("SELECT * FROM MK_migration_details WHERE mig_bid='300101'");

Basically no result turn up on the page. Any ideas or advise how I can diagnose?

$shippingcost=new ShippingCost();
$shippingcost->state="Italy";
 
$shippingcost->get(); // here I have an array with cost, discount, time ecc.

$shippingcost->get("JSON"); // here I have the JSON with cost, discount, time ecc.

class ShippingCost
{
	public $state; 
	private $arrayReturned; 

	public function __construct() {  
		$this->stato="Italy"; // the default state
	}

	public function __destruct() {
	}

	public function get($format="array") {
		$this->arrayReturned=array(
			"cost" => 3.99,
			"costDiscounted" => 7.99,
			"discount" => "50%"
		);

		if (strtolower($formato)=="json")  {
			$this->arrayReturned=json_encode($this->arrayReturned);
		}
		return $this->arrayReturned;
		}
}

Hi I have been following a youtube tutorial trying to update my php knowledge and they use pdo to create the DB wrapper class and once i load my index.php through WAMP server i get the following on screen error:

SQLSTATE[HY000] [1049] Unknown database 'lr'

THIS IS THE DB CLASS FILE,

<?php
class DB {
    private static $_instance = null;
    private $_pdo, 
    $_query, 
    $_error = false, 
    $_results, 
    $_count = 0;
    
    private function __construct() {
        try {
            $this->_pdo = new PDO('mysql:host=' . Config::get('mysql/host') . ';dbname=' . Config::get('mysql/db'), Config::get('mysql/username'), Config::get('mysql/password'));
        } catch(PDOException $e) {
            die($e->getMessage());
        }
    }
    
    public static function getInstance() {
        if(!isset(self::$_instance)) {
            self::$_instance = new DB();
        }
        return self::$_instance;
    }
    
    public function query($sql, $params = array()) {
        $this->_error = false;
        if($this->_query = $this->_pdo->prepare($sql)) {
            $x = 1;
            if(count($params)) {
                foreach($params as $param) {
                    $this-> _query->bindValue($x, $param);
                    $x++;
                }
            }
            
            if($this->_query->execute()) {
                $this->_results = $this->_query->fetchAll(PDO::FETCH_OBJ);
                $this->count = $this->_query->rowCount();
            } else {
                $this->_error = true;
            }
        }
        
        return $this;
    }
    
    public function action($action, $table, $where = array()) {
        if(count($where) === 3) {
            $operators = array('=', '>', '<', '>=', '<=');
            
            $field       = $where[0];
            $operator    = $where[1];
            $value       = $where[2];
            
            if(in_array($operator, $operators)) {
                $sql = "{$action} FROM {$table} WHERE {$field} {$operator} ?'";
                
                if(!$this->query($sql,array($value))->error()) {
                    return $this;
                }
            }
        }
        return false;
    }
    
    public function get($table, $where) {
        return $this->action('SELECT *', $table, $where);
    }
    
    public function delete($table, $where) {
        return $this->action('DELETE', $table, $where);
    }
    
    public function insert($table, $fields = array()) {
        if(count($fields)) {
            $keys = array_keys($fields);
            $values = '';
            $x = 1;
            
            foreach($field as $field) {
                $values .= '?';
                if($x < count($fields)) {
                    $values .= ', ';
                }
                $x++;
            }
            
            $sql = "INSERT INTO users (`" . implode('`,`', $keys) . "`) VALUES ({$values})";
            
            if(!$this->query($sql, $fields)->error()) {
                return true;
            }
        }
        return false;
    }
        
    public function results() {
        return $this->_results;
    }
    
    public function first() {
        return $this->results()[0];
    }    
    
    public function error() {
        return $this->_error;
    }
    
    public function count() {
        return $this->_count;
    }
    
}

THIS IS THE INIT.PHP FILE

<?php
session_start();

$GLOBALS['config'] = array (
    'mysql' => array(
        'host' => '127.0.0.1',
        'username' => 'root',
        'password' => '',
        'db' => 'lr'
    ),
    'remember' => array(
        'cookie_name' => 'hash',
        'cookie_expiry' => 604800
    ),
    'session' => array(
        'session_name' => 'user'
    )
);

spl_autoload_register(function ($class) {
    require_once 'classes/' . $class . '.php';
});

require_once 'functions/sanitize.php';

and this is the index.php file

<?php
require_once 'core/init.php';

$user = DB::getInstance()->query("SELECT username FROM users WHERE username = ?", array('alex'));

    if(!$user->count()) {
        echo 'No user';
    } else {
        echo 'OK';
    }

<?php class UserQuery { public function Adduser($id,$username,$email,$password)

{

$conn = new Config();

$sql =("INSERT INTO test.user (id, username, email, password) VALUES ('$id', '$username', '$email',$password)");

$conn->exec($sql); }

}

getting an "exec doesnt exist "    error,  saying exec doesnt exist in my db file.

it doesnt need to exist does it ?

anyone any idea why ?