PDO, $_GET e SELECTing dal database MySQL

Prova questo;

connection.php

try{
$db = new PDO('mysql:host=localhost;dbname=database_name;charset=utf8mb4', 'database_username', 'database_password');
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
}
catch (PDOException $ex){
echo $ex->getMessage();return false;
}

function retrieve($query,$input) {
 global $db;
 $stmt = $db->prepare($query);
 $stmt->execute($input);
 $stmt->setFetchMode(PDO::FETCH_OBJ);   
 return $stmt;
}

Per recuperare i dati, chiama la funzione retrieve()

Pagina di recupero, diciamo display.php

require 'connection.php';
$getid = $_GET["id"];
$result=retrieve("SELECT paste FROM pasteinfo WHERE id=?",array($getid));
$row=$result->fetch();
//To get paste column of that id
$paste=$row->paste;
echo $paste;