PDO Class scope call to undefined method - php

Question

I'm trying to create a simple class based on my database PDO class that I can say "get this id" and it will print the info. I'm trying to do this in "qu" but get the following error: "Call to undefined method qu::get()".
There's probably a mixture of problems so any help here would be awesome. Thanks a lot!!
class db {
protected static $conn;
private function __construct(){}
public static function connect() {
if (!isset(self::$conn)) {
self::$conn = new PDO('mysql:host=localhost;dbname=database', DB_USER, DB_PASSWORD);
}
return self::$conn;
}
}
class qu {
private $db;
function quconn (&$db){
$this->db = &$db;
}
private static function getq($id){
$sql="SELECT * FROM table WHERE id=:id";
$stmt = self::quconn()->prepare($sql);
$stmt->execute(array(':id'=> $id));
$result = $stmt->fetchAll(PDO::FETCH_ASSOC);
return $result;
}
}
//$data = db::connect()->query("SELECT * FROM table")->fetchAll(); // this works
$data = qu::getq("22"); //can i use something like this? this causes the error
print_r($data);

Answer 1

function getq of class qu should be marked with public access modifier.
Otherwise the following row will fail as getq is a private function
$data = qu::getq("22");
Second and issue in this code
function quconn (&$db){
$this->db = &$db;
}
As you enter function quconn from a static content $this is unavailable.
Use self::$db instead.
For class qu follow the same structure of class db wich is a singleton mnagament class.
I also suggest to clarify yourself differences between $this and self, static contest etc..
Php offiacial documentation offers al lot about
Also i don't think you need passing-by-reference method:
try to rewrite the quconn function as follows:
function quconn ($db){
self::$db = $db;
}
By the way i don't thing the class qu is well "engineered"
Even if you correct the passing-by-reference-problem this instruction won't work:
$stmt = self::quconn()->prepare($sql);
You are invoking the prepare function on the result of the invocation to quconn, which doesn't return anything...
I suggest:
$stmt = db::connect()->prepare($sql);
this get the PDP instance and call the prapare method....