Question: how to subtract hours and minutes in oracle?
Answer: In Oracle, when you add or subtract a number to a date, the unit is days. So SYSDATE + 1 adds 1 day. To add some other increment, you just multiply or divide appropriately, i.e. SYSDATE - 1/24 subtracts an hour, SYSDATE - 1/24/60 subtracts a minute, etc.