$stmt = $conn->prepare('SELECT * FROM table WHERE ID=?');
$stmt->bindParam(1, $_GET['id'], PDO::PARAM_INT);
$stmt->execute();
$row = $stmt->fetch(PDO::FETCH_ASSOC);
if( ! $row)
{
echo 'nothing found';
}
/*
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC); // Same here
if( ! $rows)
{
echo 'nothing found';
}
*/