$sql ="select st_year|st_month|st_day , st_bt, st_id , count(st_id) as cnt from station where st_year|st_month|st_day between $fullday_1 and $fullday_2
group by st_bt order by cnt " ;
select CONCAT(st_year,"-",st_month,"-",st_day) , st_bt, st_id , count(st_id) as cnt from station
where
TODAYS(CONCAT(st_year,"-",st_month,"-",st_day))
between TODAYS($fullday_1) and TODAYS($fullday_2)
group by st_bt order by cnt