sql question

We have a datetime year to second field that contains start_time and an interval day to second field that contains elapsed_time. A representative value from those two fields is: start_time 2009-01-26 10:36:29 elapsed_time 0 00:01:25 Is there a way that I can add those 2 values to come up with an end_time as a datetime year to second type ? Thanks, Floyd