MySQL Compute time difference

MySQL calculates the time difference function for two dates: Timestampdiff

Grammar:
Timestampdiff (interval, DATETIME_EXPR1, DATETIME_EXPR2)

interval Value:  
SECOND sec  
MINUTE min
HOUR hours
Day days
MONTH Month

Year years

Description
Returns an integer difference between a date or datetime expression Datetime_expr1 and datetime_expr2. The unit of the result is given by the interval parameter.

Example:
SELECT Timestampdiff (MONTH, ' 2016-09-01 ', ' 2016-10-01 ');

From for notes (Wiz)

MySQL Compute time difference