Your query:
select DATE_FIELD
from table
where DATE_FIELD >= to_date(to_char(sysdate, 'yyyy/mm/dd'), 'yyyy/mm/dd') and
DATE_FIELD <= to_date(to_char(sysdate, 'yyyy/mm/dd')+1, 'yyyy/mm/dd')
----------------------------------------------------------^
I don't know what this would work anywhere, because to_char( . . . ) + 1
should fail. Well, I could imagine an arcane setting that would recognize the 'yyyy/mm/dd'
date format and convert the string back to a date to add 1.
I would suggest the much simpler:
where DATE_FIELD >= trunc(sysdate) and DATE_FIELD < trunc(sysdate + 1)