select trunc(sysdate) as "000", trunc(sysdate) + 1 - interval '1' second as "235959", trunc(sysdate) + interval '1' month - 1 as "last000", trunc(sysdate) + interval '1' month - interval '1' second as "last235959" from dual;
select to_char(trunc(sysdate,'dd'),'yyyy-mm-dd hh24:mi:ss'),to_char(trunc(last_day(sysdate)+1,'dd')-1/24/60/60,'yyyy-mm-dd hh24:mi:ss') from dual;
trunc(sysdate) + 1 - interval '1' second as "235959",
trunc(sysdate) + interval '1' month - 1 as "last000",
trunc(sysdate) + interval '1' month - interval '1' second as "last235959"
from dual;