How to retain older invoice amounts when re-pricing products?
My DB has tables called 'customers' and is related to a second table 'invoices'. Each customer is one record as is each invoice.
Pricing for my product is entered in a field on the 'customers' table and calculated onto individual invoice records.
But when I updated prices, all older invoice pricing updates as well, upsetting all of last years figures. How to retain the older invoice amounts when re-pricing products? Are their option settings that will keep last year's invoice records or do I need to start a new DB for 2014?
Any help is much appreciated.