问Codeigniter -输入后数组插入到mysql数据库中

EN

echo form_open('account/update'); 
  echo "<p><label for='gender'>Gender</label>
 <input type='text' name='gender' id='gender'  value='".$gender."'  />  
  </p>
  <p>
  <label for='age'>Age</label>
  <input type='text' name='age' id='age' value='".$age."' />
  </p>
      <p>
  <label for='bio'>Biografie</label>
  <input type='text' name='bio' id='bio' value='".$bio."' />
  </p>
      <p>
  <label for='skills'>Skills</label>
  <input type='text' name='skills' id='skills' value='".$skills."' />
  </p>

  <p><input type='submit' value='Save' /></p>";


 echo form_close(); 

function update() 
{   
    $userid = $this->session->userdata("userid");


    $datanew = array(
           'userid' => $this->session->userdata("userid"),
           'gender' => $this->input->post('gender'),
           'age' => $this->input->post('age'),
           'bio' => $this->input->post('bio') ,
           'skills' => $this->input->post('skills')
        );
$this->session->set_userdata($data);
    $this->load->model('model_account');
    $this->load->model("model_user");

    $this->model_account->profile_insert($datanew);

$this->load->view("change_avatar");
    redirect("account/show/".$this->session->userdata("userid"));
}

function profile_insert($datanew) 
{   

  $this->db->insert('profile', $datanew);

}