Update of date column keeping HH:MM:SS

Question

I am using the query below to update another parition but I am loosing time asssociated with
the data. Can somebody show me how to keep the time and only modify YYYYMMDD part of
the date
update xxx.tab1 set create_date='20110522' where
create_date >= to_date('2011/01/14', 'yyyy/mm/dd') and
create_date < to_date('2011/01/15', 'yyyy/mm/dd');

Answer 1

example
update xxx.tab1
set create_date=to_date('20110522','YYYYMMDD') + (create_date - trunc(create_date))
where create_date >= to_date('2011/01/14', 'yyyy/mm/dd')
and create_date < to_date('2011/01/15', 'yyyy/mm/dd');This adds a number value to your date. This number value happens to be the time portion of the create_date column.