Trevor, I'll leave QBCoach to give you a specific answer on this but will just explain about relationships as these are very powerful things in Quickbase as they allow you to natively do lots of things.
An example being the max function. If you are adding into a table say a record each month containing all your sales stats for each site in your organisation. You could setup a relationship one site can have many sales stats.
With this you can then create an automatic report to show sumarised sales data. Once you have create the sales data and sites relationship go to table to table relationships and add a summary field. Then select max (now you have 2 options, you can either select record id or date), ill use date and then name max date 1, click create field. then add another field this time exactly thew same but at the bottom you choose the option where date is not equal to max date 1, call it max date 2. then the same again but where it is note equal to max date 1 and where it is not equal to max date 2.
Keep going till you have 12 fields.
You then have some choices, you can either create summary fields totalling certain figures from your sales data and build a report in the sites table or you can via the table relationship create lookup fields for max date 1 - 12 and build you report in the sales data table using the filter where date is equal to max date 1 or date is equal to max date 2 etc.
This will allow a rolling 12 month report. as each time you add a new record with a more recent date the dates work their way down towards max date 12 and then drop off once you have 12 records with a greater date.
Note if using multiple sites you will need to also add Site Name is equal to related site name or something along those lines to each of your max date fields as otherwise you wont get just the specific results for your site.
You can then create a total or average for a field in the same way as above, you can then create lookup fields to pull this down to your sales data table and create a field called sales average and then sum the 12 lookup fields and divide by 12, you can then add this to your graph and it will give you a 12 month average line. Then your actual sales data line would be either above or below the rolling 12 month average.
