在数据库中插入文件名

Question

使用MY_Upload类

在数据库中插入文件名

控制器

$this->load->library('upload');

        //Configure upload.
        $this->upload->initialize(array(
            "upload_path"   => './public/uploads/album/',
            "allowed_types" => 'mp3',
            "max_size" => '2194304000',
            "overwrite" => 'FALSE'
        ));

        //Perform upload.
        if($this->upload->do_multi_upload("files")) {


            $arr = array(

                    'fx_title' => ?????,
                    'alb_id'  => $id,
                    'user_id'  => $user_id

            );

            $this->db->insert('nmp3_faixas', $arr);
        }    

我应该在fx_title中添加什么值？