Difference between storing sysdate and to_date(to_char(sysdate, 'DD Mon YYY

Question

What is the difference between storing sysdate or to_date(to_char(sysdate, 'DD Mon YYYY HH:MI AM'),'DD Mon YYYY HH:MI AM') in a date data type column?
When I column value is set with sysdate the following query gives no records
select *
from Test
WHERE Updatedon = to_date('22 Sep 2012 07:55 PM','DD Mon YYYY HH:MI AM');
when I run the same query with out where clause I am getting the records with that time or storing with to_date(to_char(sysdate, 'DD Mon YYYY HH:MI AM'),'DD Mon YYYY HH:MI AM') gives records.
Can someone explain the difference please?

Answer 1

Hi,
Welcome to the forum!
user8765044 wrote:
What is the difference between storing sysdate or to_date(to_char(sysdate, 'DD Mon YYYY HH:MI AM'),'DD Mon YYYY HH:MI AM') in a date data type column?Remember that all DATEs include hours, minutes and seconds , as well as year, month and day.
to_date(to_char(sysdate, 'DD Mon YYYY HH:MI AM'),'DD Mon YYYY HH:MI AM')is equivalent to
TRUNC (SYSDATE, 'MI')To see why, consider what
to_char(sysdate, 'DD Mon YYYY HH:MI AM'),does. It creates a string out of the year, month, day, hours and minutes of SYSDATE, but it ignores the seconds. If you convert that string into a DATE, the seconds will default to 00.
When I column value is set with sysdate the following query gives no records
select *
from Test
WHERE Updatedon = to_date('22 Sep 2012 07:55 PM','DD Mon YYYY HH:MI AM');
when I run the same query with out where clause I am getting the records with that time or storing with to_date(to_char(sysdate, 'DD Mon YYYY HH:MI AM'),'DD Mon YYYY HH:MI AM') gives records.Whenever you get confusing results with DATEs, display the full DATE, including hours, minutes and seconds.
To change the default DATE format in your session, so that the hours, minutes and seconds appear automatically, use ALTER SESSION. For example:
ALTER SESSION  SET NLS_DATE_FORMAT = 'DD-Mon-YYYY HH:MI:SS AM';