For base time units, time_quantity is an integer
number. For composite units, the quantity must be expressed as a string with
multiple integer numbers separated by any punctuation character.

Example of composite units:

INTERVAL '2:2' YEAR_MONTH
INTERVAL '1:30:30' HOUR_SECOND
INTERVAL '1!30!30' HOUR_SECOND -- same as above

Time units can be used in the following contexts:

* after a + or a - operator;
* with the following DATE or TIME functions: ADDDATE(), SUBDATE(), DATE_ADD(),
DATE_SUB(), TIMESTAMPADD(), TIMESTAMPDIFF(), EXTRACT();
* in the ON SCHEDULE clause of CREATE EVENT and ALTER EVENT.
* when defining a partitioning BY SYSTEM_TIME

URL: https://mariadb.com/kb/en/date-and-time-units/https://mariadb.com/kb/en/date-and-time-units/