<?php

class Qs_Db_Obj extends Qs_Sys_Db_Obj
{
    public function getLastUpdated()
    {
        $days = 0;

        try {
            $sql = 'SELECT DATEDIFF(NOW(), MAX(`changed`)) '
                 . 'FROM `' . $this->_getTableName($this->_tableAlias) . '` '
                 . 'WHERE 1';
            $days = $this->db->fetchOne($sql);
        } catch (Exception $e) {
            // nothing to do
        }

        return (int) $days;
    }
}