Oracle date field not comparing properly with to_date function

Question

Hi, i'm facing a very weird problem. I'm triyng to retrieve a range of records in between two dates. However, it doesn't seem to understand. What am i doing wrong?
let's say my table (MYRECORD) has this (where id is varchar and date is DATE and not timestamp) :
ID DATE
1 22-JAN-08
2 22-JAN-08
3 21-JAN-10
4 11-FEB-10
5 11-FEB-10
So, let's say iwanna get the records from 21st Jan 2010 :
select
date as ori_date from MYRECORD where
date = to_date('21/01/2010','DD/MM/YYYY')
1.)
it is not returning any record at all. I'm having problems with between dates and the to_date function as well,
so i'm trying to get the 'equal' part working first. I can't use to_char because at the end of the day,
i need to compare between dates.
what am i doing wrong? has this got anything to do with what kind of format is set up on the oracle server?
running :
SELECT value FROM v$nls_parameters WHERE parameter ='NLS_DATE_FORMAT'
returns DD-MON-RR
2.) how do we compare dates from the table according to our own specified format from our passed string? I only have READONLY access to this database
so i can't set anything up.

Answer 1

please run this
select To_date(date, 'DD/MM/YYYY HH24:MI:SS') as ori_date from MYRECORDprobably you have hour minute second info in your table, to_date('01012010','DDMMYYYY') means hour, minute and second is 00:00:00 so it wont be equal.The database field type is actually 'DATE' and not datetime. I've also ran the sql you provided to show its timestamp, but it's not showing anything as far as timestamp is concerned. It's showing only the date. So does this mean it's a real date only information?
However, it might be more efficient to do two comparisons, especially if there's an index on dt:
WHERE   dt >= TO_DATE ('21/01/2010', 'DD/MM/YYYY')
AND     dt <  TO_DATE ('22/01/2010', 'DD/MM/YYYY')
Ok. If we change the range to compare it on the same day, it won't work;
WHERE   dt >= TO_DATE ('21/01/2010', 'DD/MM/YYYY')
AND     dt <=  TO_DATE ('21/01/2010', 'DD/MM/YYYY')this also happens if we're using BETWEEN
this is real weird. It's supposed to work...i don't recall having this kind of issue on other databases. If that's the case,
each time a user passes me a date string i have to somehow add another day onto its 'to' comparison date in order for things to work.
but..i don't want to since i don't want to accidentally include the extra day's results!
Edited by: 803998 on Oct 21, 2010 8:14 PM
Edited by: 803998 on Oct 21, 2010 8:33 PM