Am trying to select a query from inception till today, then get another query from inception till last month, subtract the two queries from each other, the result will be equal to this month record.

e.g:   QUERY

            select distinct "Name",

sum("quantity") from "Table 1"

group by "Name" 

The second query should be the same, but must not include thus month record. 

then i want to further subtract the two queries to get my desire record. How will i go about it.

Thanks