查询语句，按照时间排序，取前N条

mysql：

SELECT * from 

(SELECT H_TEMPERATURE,TH_TIME FROM wenshidu 

WHERE TH_TIME <= STR_TO_DATE('2016-03-16 10:04:52','%Y-%m-%d %H:%i:%s')

order by  TH_TIME desc)  as total limit 0,8;

oracle：

SELECT * from 

(SELECT H_HUMIDITY FROM HOME_MONITOR 

WHERE H_TIME <= to_date( ' 2016-03-01 10:04:52 ' ,'yyyy-MM-dd HH24:mi:ss')   

order by  H_TIME desc ) where rownum<=8;

来自为知笔记(Wiz)