public function delete($product_id, array $options = array())
    {
        $result = null;
        $this->hook->attach('sku.delete.before', $product_id, $options, $result, $this);

        if (isset($result)) {
            return (bool) $result;
        }

        $sql = 'DELETE FROM product_sku WHERE product_id=?';

        if (!empty($options['combinations'])) {
            $sql .= ' AND LENGTH(combination_id) > 0';
        }

        if (!empty($options['base'])) {
            $sql .= ' AND LENGTH(combination_id) = 0';
        }

        $result = (bool) $this->db->run($sql, array($product_id))->rowCount();
        $this->hook->attach('sku.delete.after', $product_id, $options, $result, $this);
        return (bool) $result;
    }