Oracle: how to add minutes to a timestamp?

Question

I need to add 30 minutes to values in a Oracle date column. I do this in my SELECT statement by specifying

to_char(date_and_time + (.000694 * 31)

Answer 1

Oracle now has new built in functions to do this:

select systimestamp START_TIME, systimestamp + NUMTODSINTERVAL(30, 'minute') end_time from dual