Query to find out log switch frequency and history

set lines 150;
set pages 999;
set markup html on
spool log_history.html
select
to_char(first_time,'YYYY-MON-DD') day,
to_char(sum(decode(to_char(first_time,'HH24'),'00',1,0)),'9999') "00",
to_char(sum(decode(to_char(first_time,'HH24'),'01',1,0)),'9999') "01",
to_char(sum(decode(to_char(first_time,'HH24'),'02',1,0)),'9999') "02",
to_char(sum(decode(to_char(first_time,'HH24'),'03',1,0)),'9999') "03",
to_char(sum(decode(to_char(first_time,'HH24'),'04',1,0)),'9999') "04",
to_char(sum(decode(to_char(first_time,'HH24'),'05',1,0)),'9999') "05",
to_char(sum(decode(to_char(first_time,'HH24'),'06',1,0)),'9999') "06",
to_char(sum(decode(to_char(first_time,'HH24'),'07',1,0)),'9999') "07",
to_char(sum(decode(to_char(first_time,'HH24'),'08',1,0)),'9999') "0",
to_char(sum(decode(to_char(first_time,'HH24'),'09',1,0)),'9999') "09",
to_char(sum(decode(to_char(first_time,'HH24'),'10',1,0)),'9999') "10",
to_char(sum(decode(to_char(first_time,'HH24'),'11',1,0)),'9999') "11",
to_char(sum(decode(to_char(first_time,'HH24'),'12',1,0)),'9999') "12",
to_char(sum(decode(to_char(first_time,'HH24'),'13',1,0)),'9999') "13",
to_char(sum(decode(to_char(first_time,'HH24'),'14',1,0)),'9999') "14",
to_char(sum(decode(to_char(first_time,'HH24'),'15',1,0)),'9999') "15",
to_char(sum(decode(to_char(first_time,'HH24'),'16',1,0)),'9999') "16",
to_char(sum(decode(to_char(first_time,'HH24'),'17',1,0)),'9999') "17",
to_char(sum(decode(to_char(first_time,'HH24'),'18',1,0)),'9999') "18",
to_char(sum(decode(to_char(first_time,'HH24'),'19',1,0)),'9999') "19",
to_char(sum(decode(to_char(first_time,'HH24'),'20',1,0)),'9999') "20",
to_char(sum(decode(to_char(first_time,'HH24'),'21',1,0)),'9999') "21",
to_char(sum(decode(to_char(first_time,'HH24'),'22',1,0)),'9999') "22",
to_char(sum(decode(to_char(first_time,'HH24'),'23',1,0)),'9999') "23"
from v$log_history
group by to_char (first_time,'YYYY-MON-DD')
order by day;
spool off
exit