SharePoint list column calculation based on the last entry (previous row)

Question

I am trying to add a column to my SharePoint list to caculate the change in tonnage from the last entry.

For example, assume that the last entry was made about two weeks ago (1/15) and I am making new entry today (2/1). How can I add a column that will caculate the difference between the tonnage entered on 1/15 and the tonnage being entered on 2/1?

I understand that this may be difficult to do, but please let me know if there is any possilbity. Or if there is another tool in SharePoint that will help me cacluate the change over time.

Please help.

Thanks.

Answer 1

I can't think of a way to do it with SharePoint Designer. But if you implemented an ItemAdding Event Receiver, you could look up the value of the previous entry, perform the calculation, and store the value in your column.