Return the difference between two time expressions:
SELECT TIMEDIFF("13:10:11", "13:10:10");
The TIMEDIFF() function returns the difference between two time/datetime expressions.
Note: time1 and time2 should be in the same format, and the calculation is time1 – time2.
TIMEDIFF(time1, time2)
Extract the time part from a time expression:
SELECT TIME("19:30:10");
The TIME() function extracts the time part from a given time/datetime.
Note: This function returns “00:00:00” if expression is not a datetime/time, or NULL if expression is NULL.
TIME(expression)
Return the difference between two periods:
SELECT PERIOD_DIFF(201710, 201703);
The PERIOD_DIFF() function returns the difference between two periods. The result will be in months.
Note: period1 and period2 should be in the same format.
PERIOD_DIFF(period1, period2)