Summarizing from multiple records

[Herb]

I have tables named Posting and Donations. There can be any number of Donations within a Posting. Donations represent checks identified by Donor ID, Date and Check Number. Checks are assigned to a Team Member (another table.) However, Checks can be "split" meaning shared by multiple Team members. In a split, the application creates multiple Donation records (1 for each team member sharing the donation) with amounts reduced to reflect the sharing - the Donation amounts for the same check number will always total the Check Amount of check.

I want to produce a report and an extract (e.g. CSV) of the checks in a Posting that ignores any splits. My question is what's the best way to accomplish this - via Db schema (how?) or via a report rollup?

Thank you.

[Herb]

I figured out how to do the roll-up on a list view. I can now produce the desired report on a Layout, and give the user the option to extract to a tab-delimited file.

This has raised another roll-up question: I want to display to the user the Count of the number of lines in the roll-up. The roll-up is defined in a sub-summary Part. How can I get at such a Count?

Thank you.