I am designing a database that includes the simple (!) functionality
of producing invoices (not an accounting package). I understand the
convention is to have a table for invoice headers and one for invoice
transactions. My question is what are the advantages of this approach
rather than just having one table for invoice transactions. The
printed invoice (an Access report) can have the invoice headings
(date, invoice no customer address etc) in the report header and the
invoice transactions in the report detail. What would be wrong with
that?

Gordon