my code

Controller :
function perkategori(){

		$arsesi = array(
			'sesi_id' => $this->input->get('list')
		);
		$this->session->set_userdata($arsesi);
		redirect('categoryproduct');
	}

	function listcategory(){

		if($this->session->userdata('sesi_id') == false){
			redirect(base_url(),'redirect');
			return false;
		}
		$data['categoryHead'] = $this->M_home->listCategory();
		$this->load->view('frontend/template/header', $data);
		$data['productsLast'] = $this->M_home->listProductLast();
		$data['productsLast2'] = $this->M_home->listProductLast2();
		$data['category'] = $this->M_home->listCategory();

		$config['base_url'] = base_url().'categoryproduct/'.$this->session->userdata('sesi_id');
		$config['total_rows'] = $this->M_home->listProductPerCategory_num_rows();
		$config['per_page'] = 12;
		$config['first_link']		= 'First';
		$config['last_link']		= 'Last';
		$config['next_link']		= 'Next';
		$config['prev_link']		= 'Prev';
		$config['use_page_numbers'] = TRUE;
		$page = ($this->uri->segment(3)) ? $this->uri->segment(3) : 0;
		$this->pagination->initialize($config);
		$data['listCategory'] = $this->M_home->listProductPerCategory($config['per_page'],$page);


		$this->load->view('frontend/category', $data);
		$this->load->view('frontend/template/footer');
}
Model :
function listProductPerCategory($limit1='',$limit2=''){
		$data = array();
			$sql = "SELECT category.category, product.id, product.picture, product.name, product.part_no FROM product, category
					WHERE category.id=product.id_category AND product.id_category = ".$this->session->userdata('sesi_id').
					" ORDER BY product.part_no ASC LIMIT ".$limit2;
			if($limit1){
				$sql .= ",".$limit1;
			}
			$hasil = $this->db->query($sql);
			if($hasil->num_rows() > 0){
				$data = $hasil->result();
			}
			$hasil->free_result();
			return $data;
}

function listProductPerCategory_num_rows(){
	$this->db->select('*');
	$this->db->from('product');
	$this->db->join('category', 'product.id_category = category.id');
	$this->db->where('product.id_category', $this->session->userdata('sesi_id'));
	$data = $this->db->get();
	return $data->num_rows();
}