SQL> desc xx_time
Name Type
---------------- -------------------
STANDARD_START NUMBER(4)
STANDARD_STOP NUMBER(4)


SQL> select * from xx_time

STANDARD_START STANDARD_STOP
-------------- -------------
2100 400
1600 2300
1930 230

How to calculate time scale difference?
Means the total hours between 2100 and 400 will 7 Hours.
I want to calculate the hours in between.