After spending almost a week on this problem, with a lot of help from an expert I have finally got a solution.
In order to create a amount that is the sum of all records for a company, month and invoice type since the beginning of time, while only displaying records for the last year, I have created a SQL command
Select
//All of the fields for the report,
movingBalance.Amount
from myInvoiceTable as mit
<join to any other tables for the report>
left join (
select customerID, sum(amount) as Amount
from myInvoiceTable
where Record_Type in ('Payment', 'Invoice','Interest')
and Date < {?Report Start Date}
group by customerID) movingBalance
on mit.customerID = movingBalance.customerID
where mit.RecordType in ('Payment', 'Invoice','Interest')
and mit.Date >= {?Report Start Date}
and mit.Date <= {?Report End Date}
There are a couple of tricks to using commands:
- For performance reasons you generally want to include ALL of the data for the report in a single command. Avoid joining multiple commands or joining one or more tables to a command.
- Filter the data in the command, NOT in the Select Expert in the report.
- Create any parameters in the Command Editor, not in the main report. Parameters created in the report won't work in the Command Editor.
This has done the trick.