    public function getAllInvoiceItems($sale_id, $return_id = NULL)
    {
        $this->db->select('sale_items.*, tax_rates.code as tax_code, tax_rates.name as tax_name, tax_rates.rate as tax_rate, products.image, products.details as details, product_variants.name as variant, products.hsn_code as hsn_code, products.second_name as second_name')
            ->join('products', 'products.id=sale_items.product_id', 'left')
            ->join('product_variants', 'product_variants.id=sale_items.option_id', 'left')
            ->join('tax_rates', 'tax_rates.id=sale_items.tax_rate_id', 'left')
            ->group_by('sale_items.id')
            ->order_by('id', 'asc');
        if ($sale_id && !$return_id) {
            $this->db->where('sale_id', $sale_id);
        } elseif ($return_id) {
            $this->db->where('sale_id', $return_id);
        }
        $q = $this->db->get('sale_items');
        if ($q->num_rows() > 0) {
            foreach (($q->result()) as $row) {
                $data[] = $row;
            }
            return $data;
        }
        return FALSE;
    }
