webpromo,
As mentioned in the earlier post, we are looking into adding export functionality to DotNetInvoice. If you have a SQL Script that generated the data that you need, you could add a page in DotNetInvoice that would take the data from your SQL Script and add it to a file for export.
If you are in need of this feature before our next release or if it doesn't make our next release, you can email us at support@dotnetinvoice.com for a quote on custom work for this feature.
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Jeremy
DotNetInvoice Support