	SELECT if(t2.`year` > 0, concat(t2.`year`, '年', t2.`day`, '天'), concat(t2.`day`, '天')) as period from (
SELECT TIMESTAMPDIFF(YEAR,t1.firstDay,t1.today) AS `year`,DATEDIFF(DATE_SUB(t1.today,INTERVAL TIMESTAMPDIFF(YEAR,t1.firstDay,t1.today) YEAR), t1.firstDay) AS `day`  
FROM (SELECT `value` AS firstDay, now() AS today FROM zt_config WHERE `owner` = 'system' AND `key` = 'installedDate') AS t1
) t2