make the day part of the first date to be 1, make the day part of the second date to be 31 or 30 (or add 1 to the month part and make the day part 1), and use "between". So for example, if your inputs are "2000-01" and "2000-07", you
do
between #2000-01-01# and #2000-07-31#
or
between #2000-01-01# and #2000-08-01#