Question : Calculate Running Total in a New Field

I am trying to calculate the running sum and saving the results in a new field either in the same table or a new one.  

To help explain, I've attached sample DB with the original table (tblTestData) and the desired output (Desired Output).  Basically - for each change in field PARE, calculate the running sum QTY_ONHAND - REQ_QTY  and store in field called Balance.

The table is sorted by PART and DUE_DATE.

I've also attached Excel file with function logic used to calculate the desired results.  Looking for something similar to do in Access.

Prefer a solution using queries/macros as I am not very strong w/VBA but could manage if it is not too complicated.

Thanks.

Attachments:

Desired-Result.xlsx (26 KB) (File Type Details) 

Excel File with logic to calculate running total

TestDB3.accdb (13.7 MB) (File Type Details) 

Sample Access Database with data

Answer : Calculate Running Total in a New Field

This tutorial may be useful

http://www.businessobjects.com/global/pdf/dev_zone/VS2005_Walkthroughs.pdf

mlmcc