Rangesum() works when you have a static number of values, but in your case the number of values are different for each row.
The best solution is to use SubField() like below
SubField(Value, ',') AS Value
Sum(Value) AS Value
Group by ID;
DROP TABLE Temp;
Hope this helps you.
Yeah, this Is exactly how I was doing it but instead of Sum I was using another formula to get the product of the values of the field in question. But since my table had tons of fields it was rather cumbersome to add each field to the GroupBy. Besides grouping is expensive operation in my short experience.
That's why I wanted someting more concise (and elegant) like using RangeSum on a single field.