Question: how to calculate time difference between two timestamps in oracle?
Answer: Calculating the time difference between two TIMESTAMP datatypes is much easier than the old DATE datatype. ... 
SELECT SUBSTR(time1,1,30) "Time1", ... 
As you can see, the results are much easier to recognize, 8752 days, 10 hours, 34 minutes, and 24 seconds. ... 
SELECT SUBSTR(time1,1,30) "Time1",