Gambar yang diupload tidak masuk di data database mysql

saya ingin mengupload file gambar di database, dan nanti bisa ditampilkan di frontend. Tapi, dari data yang diinput berupa teks dan gambar yang bisa terbaca di database hanya yang teksnya saja sedangkan yang gambar tidak muncul. berikut ini source code upload gambar :

<div class="form-group">
                               <label class="col-sm-2 col-sm-2 control-label"><?php if($this->thisPage!="inspirasimu"){?><span class="asterik">*</span><?php } ?> Gambar</label>
                                <div class="col-sm-8">
                                    <div class="fileupload fileupload-new" data-provides="fileupload">
                                        <div class="fileupload-preview fileupload-exists thumbnail" style="max-width: 200px; max-height: 150px; line-height: 16px;"></div>
                                        <div>
                                            <span class="btn btn-default btn-file">
                                                <span class="fileupload-new"><i class="fa fa-paperclip"></i> Pilih Gambar</span>
                                                <span class="fileupload-exists"><i class="fa fa-undo"></i> Ganti</span>
                                                <input type="file" name="arsitekImage" class="default" value="<?=set_value("arsitekImage");?>" />
                                            </span>
                                            <a href="#" class="btn btn-danger fileupload-exists" data-dismiss="fileupload"><i class="fa fa-trash-o"></i> Hapus</a>
                                        </div>
                                    </div>
                                </div>
                            </div>

dan tampilannya begini : source code bagian modulnya :

if(isset($_FILES['arsitekImage']) && $_FILES['arsitekImage']['name']!=""){
			$media->sectionId = $arsitek->sectionId;
			$media->mediaType 	= "image";
			$media->mediaStatus = "1";
			$upload_directory 	= "media/image/";
			$allowedExt 		= array("png","jpg","jpeg","gif");
			$mimeType			= array("image/jpg","image/png","image/gif");
			$media->mediaName 	= $arsitek->arsitekJudul;
			$media->mediaAlias 	= generate_alias($media->mediaName);
			$media->mediaDesc 	= "";
			$media->mediaSize	= get_size($_FILES['arsitekImage']['size']);
			$media->mediaPrimary= "1";
			$arrExt 			= explode(".", $_FILES["arsitekImage"]["name"]);
			$imgExt 			= strtolower(end($arrExt));
			$media->mediaValue 	= strtolower($detailSection['section_name'])."-".time().".".$imgExt;

			if($_FILES['arsitekImage']['size'] > 8000000){
				$error['arsitekImage'] = "Maksimal File Gambar 8 MB.";
			}
			if(!in_array($_FILES["arsitekImage"]["type"],$mimeType) && !in_array($imgExt,$allowedExt)){
				$error['arsitekImage'] = "Format gambar yang diijinkan .jpg, .png dan .gif";
			}
		}

dan source code bagian classnya:

function insert_arsitek(){
		$sql = "
			INSERT INTO _arsitek VALUES(
				'',
				'".$this->arsitekJudul."',
				'".$this->arsitekImage."',
				'".$this->arsitekDesc."',
				NOW()
			)
		";

		$this->execute($sql);
		$this->lastInsertId = $this->get_last_id();

		return $this->lastInsertId;
	}

	function update_arsitek($opt="",$field="",$value=""){
		if($opt==""){
			$sql = "UPDATE _arsitek
					SET a_judul = '".$this->arsitekJudul."',
						a_image = '".$this->arsitekImage."',
						a_desc	= '".$this->arsitekDesc."'
						WHERE a_id = '".$this->arsitekId."' ";

			$result = $this->execute($sql);
			return $result;
		}
		elseif($opt=="byField"){
			$sql = "UPDATE _arsitek SET ".$field." = '".$value."' WHERE a_id = '".$this->arsitekId."' ";
			$result = $this->execute($sql);
			return $result;
		}

	}

tampilan dashboardnya: sedangkan tampilan di databasenya : imagenya kosong. mohon bimbingannya....