mysql：
SELECT * from (SELECT H_TEMPERATURE FROM WENSHIDU
WHERE TH_TIME >=date_sub(NOW(), interval 1 hour) AND TH_TIME<= NOW()
order by TH_TIME desc ) as data limit 0,1;
查询语句，取得当前系统时间，算时间区间
原文：http://www.cnblogs.com/samwang88/p/304463f1d2f086a4dcd45998eb3cd67e.html
