取每个task_id分组中更新日期最新的一行
采用join的方式完成

select  a.task_id,a.theme_id,a.time_unix
from    table_xxx a
join    (select  task_id,max(time_unix) as max_timefrom    table_xxxwhere   date <= '${date}'and     date >= '${date}' - 3and     theme_id > 0group bytask_id) b
on      date <= '${date}'
and     date >= '${date}' -3
and     a.task_id = b.task_id
and     a.time_unix = b.max_time
) t2