Converting interval to the number of minutes:

Assume we have the following table with two DATETIME columns.
create table dt (
	d1 datetime year to second,
	d2 datetime year to second);

select d2, d1,
((extend(d2, minute to minute) - extend(d1, minute to minute)) || " ") +
60*((extend(d2, hour to hour) - extend(d1, hour to hour)) || " ")  + 
60*24*((extend(d2, day to day) - extend(d1, day to day)) || " ") +
60*24*30*((extend(d2, month to month) - extend(d1, month to month)) || " ") +
60*24*30*365*((extend(d2, year to year) - extend(d1, year to year)) || " ") mdif
from dt;