I have researched and researched in this forum for dSum function to create running total for my data. Although there are numerous threads in regards to this subject, I have yet to come up with the exact syntax to compute what I need based on a category and date. Please see below sample data. Note: some dates may repeat for any given PN. Please help with the syntax to compute CumQty. Would dSum work based on data from a query, as opposed to a table?

Is dSum the best option for me, or there is another option for my needs. I do intend to use this result set to perform another query, if that is a consideration at all.

It would help if you posted your effort. Given your sample, you'd need another field so records with the same date don't get the same running total.

there is a way, but as suggested, you'll need a unique identifier - an ID of some sort. see pic.
(in my pic, field3 is the same as your Qty field).

Of course the date would have to be added to the criteria as well.

Hit the sigma icon for totals. Create a new column and select "Expression" for total type.

Your new column should be:

CumQt: DSum("[Qty]","Your_Query_Name","[DemandDate]<=" & [DemandDate] & "")

CumQt: DSum("[Qty]","Your_Query_Name","[DemandDate]<=" & [DemandDate] & "")

That is not the correct syntax for a date value, which presumably this field is:

http://www.mvps.org/access/general/gen0018.htm

It also doesn't account for the duplicate date values. They will end up with the same value.

right, i didn't use all the fields there.

here's another link:
http://support.microsoft.com/kb/290136

I've tried so many different suggestions, but I am getting either blank results or #error. When do I use alias and how should the syntax be for the dates?

Check the link I posted in post 6. You need to concatenate the values.

After much research from other posts, I’ve finally gotten the results I needed. I am actually using data from another query, instead of a table. In the attached, you shall see the syntax I used. The problem I have is that my result can range from few hundred to over a thousand. The data is shown line by line, which takes forever to populate.

I am still searching for a better way to do it than using dSum. Below is the SQL.

SELECT qryProductionPlanning_1.PartNumber, qryProductionPlanning_1.DueDate, qryProductionPlanning_1.BO_Qty, Val(DSum(" BO_Qty","qryProductionPlanning_1","PartNumber ='" & PartNumber & "' and DueDate <= #" & DueDate & "#")) AS RunningSum
FROM qryProductionPlanning_1
ORDER BY qryProductionPlanning_1.PartNumber, qryProductionPlanning_1.DueDate;

might not make a difference but you could try creating another query to use as the basis for this one, but remove the fields you aren't using in your calculation.