Unknown column 'Array' in 'field list' while uploading image - php

Question

This is my controller
<?php
class Avatar extends MX_Controller
{
public function __construct()
{
parent::__construct();
$this->load->helper(array('form', 'url'));
$this->load->config('avatar');
$this->load->library('upload');
}
public function index()
{
// Prepare data
$data = array(
'avatar' => $this->user->getAvatar($this->user->getId()),
'max_size' => $this->config->item('max_size'),
'max_width' => $this->config->item('max_width'),
'max_height' => $this->config->item('max_height'),
'allowed_types' => $this->config->item('allowed_types'),
);
// Load the avatar page
$content = $this->template->loadPage("avatar.tpl", $data);
$title = breadcumb(array(
"ucp" => lang("ucp"),
"ucp/avatar" => lang("change_avatar", "ucp")
));
// Put it in a content box
$this->template->box($title, $content, true, "modules/ucp/css/avatar.css");
}
public function upload()
{
$this->load->model("avatar_model");
// Prepare data
$config = array(
'max_size' => $this->config->item('max_size'),
'max_width' => $this->config->item('max_width'),
'max_height' => $this->config->item('max_height'),
'allowed_types' => $this->config->item('allowed_types'),
'encrypt_name' => $this->config->item('encrypt_name'),
'xss_clean' => $this->config->item('xss_clean')
);
$this->upload->initialize($config);
if (!$this->upload->do_upload('avatar'))
$data = array('error' => $this->upload->display_errors());
else
{
$this->avatar_model->setAvatar(array('avatar' => $this->upload->data('file_name')));
$data = array('error' => 'Success');
}
$title = breadcumb(array(
"ucp" => lang("ucp"),
"ucp/avatar" => lang("change_avatar", "ucp"),
"ucp/avatar/upload" => lang("upload_avatar", "ucp"),
));
$page = $this->template->loadPage("upload.tpl", $data);
$this->template->box($title, $page, true);
}
}
and this is the model
<?php
class Avatar_model extends CI_Model
{
public function setAvatar($avatar)
{
$this->db->update('account_data', $avatar, array('id' => $this->user->getId()));
}
}
I have no idea what is wrong, the configs are just my preference right?
<?php
$config['allowed_types'] = 'jpg|png';
$config['max_size'] = 512; // KB
$config['max_width'] = 500;
$config['max_height'] = 500;
$config['encrypt_name'] = true;
$config['xss_clean'] = false;
this is what i get when i try to upload the image
A PHP Error was encountered
Severity: Notice
Message: Array to string conversion
Filename: mysqli/mysqli_driver.php
Line Number: 612
A Database Error Occurred
Error Number: 1054
Unknown column 'Array' in 'field list'
UPDATE account_data SET avatar = Array WHERE id = '11'
Filename: C:\xampp\htdocs\system\database\DB_driver.php
Line Number: 328