Code Igniter覆盖了DB Active Record

<?php
class spj_DB_active_record extends CI_DB_active_record {

    function update($table = \'\', $set = NULL, $where = NULL, $limit = NULL) {
        if (is_array($set) && empty($set[\'modified\'])) {
            $this->load->helper(\'date\');
            $data[\'modified\'] = date(\'Y-m-d H:i:s\',now());
        }

        log_message(\'debug\',\'TEST UPDATE \'.date(\'Y-m-d H:i:s\',time()));

        return parent::update($table, $set, $where, $limit);
    }

    function insert($table = \'\', $set = NULL) {
        if (is_array($set) && empty($set[\'modified\'])) {
            $this->load->helper(\'date\');
            $data[\'modified\'] = date(\'Y-m-d H:i:s\',now());
        }
        if (is_array($set) && empty($set[\'created\'])) {
            $this->load->helper(\'date\');
            $data[\'created\'] = date(\'Y-m-d H:i:s\',now());
        }

        log_message(\'debug\',\'TEST INSERT \'.date(\'Y-m-d H:i:s\',time()));
        return parent::insert($table, $set);
    }
}