TIMEDIFF
Subtracts to find the amount of time between two datetimes or times.
Syntax
TIMEDIFF(date1, date2)
Arguments
date1, date2: a valid time, datetime, or parsable time/datetime string. Both arguments should be of the same type.
Return Type
Time object. If date1 or date2 is not a valid time/datetime or the types don’t match, returns NULL.
Important
The TIME object can only express intervals between -838:59:59 and 838:59:59.
Examples
SELECT TIMEDIFF('2015-02-13 23:31:30', NOW()) AS time_since_graduation;
****
+-----------------------+
| time_since_graduation |
+-----------------------+
| -433:58:39 |
+-----------------------+