questao3.php

<?php
class MyUserClass
{
    public function getUserList()
    {
        $dbconn = new DatabaseConnection('localhost','user','password');
        if ($dbconn->connect_error) { 
            // Supondo que a classe DatabaseConnection tenha tratado as funções de erro no banco
            die("Conexão falhou: " . $dbconn->connect_error);
            $dbconn->close();
        } 
        $results = $dbconn->query('select name from user');
        sort($results);
        $dbconn->close(); 
        return $results;
    }
}