# How to create a running sum of 2 expression fields?

• ### Question

• I am struggling to get a running sum to work on a report. What I want is the following:

``Product    Qty1   Qty2  Total  RunningTotalABC123     100    200   300    300DEF321     50     100   150    450XYZ123     -100   -150  -250   150``

The total column is an expression like

```=ReportItems!Qty1.value + ReportItems!Qty2.Value```

For running total I have tried many different things, most of which tell me that it has to be in a header or footer. The obvious expression which I thought would work is

```=ReportItems!Total.Value + previous(ReportItems!Total.Value)```

but that doesnt work.

Can anyone explain what I am doing wrong here?

Cheers Dean

Saturday, May 26, 2012 4:01 AM

### All replies

• Dean,

I am not quite sure what you call a "Running Total". Is it the sum of Total, up to the current line ? If yes, then there could be an error in your table, because on the last line, it should be 200 (450 - 250).

Now, why do you use the ReportItems collection ? Wouldn't it be easier to sum the fields which contain the data ? In this case, your Total is :

`=(Fields!Qty1.Value + Fields!Qty2.Value)`

`= (Sum(Fields!Qty1.Value) + Sum(Fields.Qty2.Value))`

Tuesday, May 29, 2012 2:40 PM
• Hi Sygrien,

You are correct, it should be 200, just a type there when I typed in in :)

The problem is that Qty1 and Qty1 and not fields, they are expressions based on other fields in the report therefore they do not show up on Fields.

Regards,

Dean

Wednesday, May 30, 2012 1:24 AM
• Dean,

In any case, you can't SUM the ReportItems values. So you'll have to go back to the original definition of Qty1 and Qty2 and SUM the Fields.

Wednesday, May 30, 2012 7:09 AM