Combine several query tables in one new table with sales totals

Combine several query tables in one new table with sales totals

Hi,

I have several query tables, one for each office sales:

e.g.

1. New York

Timestamp - office - product code - sales amount

29/09/2012 - newy york - ab100 - 100 USD
29/09/2012 - new york - ab200 - 120 USD
28/09/2012 - new york - ab100 - 100 USD

2. Atlanta

Timestamp - office - product code - sales amount

29/09/2012 - atlanta - ab100 - 100 USD
29/09/2012 - atlanta - ab200 - 120 USD
28/09/2012 - atlanta - ab100 - 100 USD

QUESTION:
I need to get a table to sum all sales of all offices on a daily base:

Timestamp - office - product code - sales amount

29/09/2012 - sum of all - ab100 - 200 (100+100) USD
29/09/2012 - sum of all - ab200 - 240 (120+120) USD
28/09/2012 - sum of all - ab100 - 200 (100+100) USD

I can not combine them in one table because of size limits.. each query table is approaching 500k rows. Can I have a query table that holds only the day totals for each product?

Thanks

PS
I extract the query tables from several tables with the following code:

SELECT
"ActivityDt","BarcodNumber","LocationName1","SalesFees"

FROM "Customers1"
WHERE "LocationName" = 'xxx'

UNION ALL

SELECT
"ActivityDt","BarcodNumber","LocationName1","SalesFees"

FROM "Customers2"
WHERE "LocationName" = 'xxx'

Maybe I could extract the totals directly from the tables instead of going trough the query tables?

DATA TABLES --> QUERY TABLES --> TOTALS QUERY TABLE
vs.
DATA TABLES --> TOTALS QUERY TABLE