Database mysqli instance

<?php

class Database
{
    private $instance;

    public function __construct($host, $username, $password, $name)
    {
        $this->instance = new mysqli($host, $username, $password, $name);

        if ($this->instance->connect_error) {
            throw new Exception(sprintf(
                'Connect Error (%s): %s',
                $this->instance->connect_errno, $this->instance->connect_error
            ));
        }
    }

    public function query($sql)
    {
        return $this->instance->query($sql);
    }
}