查询当天的数据
DateDiff(create_time,sysdate())=0
根据时间随机查询当天的数据
select * from **** where time BETWEEN #{createTime}and DATE_SUB(#{createTime},INTERVAL -1 DAY) order by create_time desc limit 1 //查询当天的数据,并对此排序,然后获取最新一条数据