I have a database with the following columns: store number, date (YMD) &
costs. The database covers several years. I need a formula to sum all costs
for a any particular store and for each month.

example: What is the sum of all costs for store 2143 for the month of Jan
in 06?

2143 1/2/06 27.50
2143 1/5/06 84.75
2143 4/5/06 47.50