InfoPath Merge Forms and Data Aggregation

[egrigg9000]

I would like to use InfoPath and SharePoint in order to generate and
display some data. The results should be aggregated. The problem I'm
having is the InfoPath merge forms seems to be optimized for
concatenating fields rather than adding them up. For example, if you
have:

billy's expense report >> meals >> $20
fred's expense report >> meals >> $10

The results of "merge forms" is a single form with both billy and
fred's meal line items listed, rather than an item that says

combined expense report >> meals >> $30

The literature I'm (now) looking at seems to confirm this behavior,
such as at
http://office.microsoft.com/en-us/assistance/HA011294451033.aspx ,
where the example in purple shows SharePoint representing the
information as bars. I am looking to aggregate data.

The reason for me posting to this newsgroup is to a) make sure I didn't
miss anything, that InfoPath really does work this way, and b) ask for
suggestions on how to do this, other than creating my own database or
e-mailing excel files back and forth.

 

[egrigg9000]

As a follow-up, it would be great to know if there is a way to leave
all the forms separate, but run a SQL query on whatever implicit behind
the scenes database is at work here, in order to do these types of
roll-up reports that I need. I assume this is possible, the trick is
knowing how the db is organized and how to reference it. Any help
appreciated. Thank you.