Using = with to_date function fails to get the results

Question

Hello ALl,
I have table for visits information. my table has two fields survey_id (Number) and visit_date(date).
the visit_date also contain the visit time HH:MI:SS.
when I query the table to find the information for one day and using the following qyery:
select survey_id,visit_date
from my_table
where visit_date=to_date('26/04/2010','DD/MM/YYYY');
The result is no data found
but When I used another query such as
select survey_id,visit_date
from my_table
where visit_date>to_date('25/04/2010','DD/MM/YYYY');
there are some records in date 26/04/2010.
In other words, always when I query the table for one day using
visit_date=to_date(:my_date,'DD/MM/YYYY');
there is no data returned although there is data in the table.
is the problem because the time HH:MI:SS exisits in visit_date field.
any help please.
Edited by: M.Jabr on May 5, 2010 6:12 AM

Answer 1

Oracle stores dates as a numeric (I think 9 digit) format which includes the time.
When you use the = operator with a truncated string, it assumes zeros for the time elements.
So your first query is looking for visits which were at exactly midnight.
So your options are to use the trunc function as suggested or to use the 'between' syntax.