how to calculate the sum of each expression in different queries in a microsoft access database?

Answer 1

in the different queries ? you can't .

but you can try to sum the result in subquery :
select sum(a.fieldinA) + (select sum(b.fieldinB) from Table1 B) from Table2 B
btw : i uses interbase, so.... maybe ms access has a different structure.

other than subquery, you must build 'Stored Procedure' to sum the result from different query.