Mysql按小时，按日，按周，按月，按季度，按年分组统计数据
按小时：select from_unixtime(create_time,"%Y%m%d%H") as hours,count(id) as counts from table group by hours;按日：select from_unixtime(create_time,"%Y-%m-%d") as days,count(id) as counts from table group by ...
