If your date is of DATE type, you can change the date in Oracle as follows:
select myDateField +1 from myTable : This adds one day to the selected date
select myDateField +(1/24) from myTable : This adds one hour to the selected date
select myDateField +(1/(24*60)) from myTable : This adds one minute to the selected date
select myDateField +(1/(24*60*60)) from myTable : This adds one second to the selected date
