Perhaps this is a simple thing that my brain is having trouble with but I felt I should bounce this off a few of you here.
In a database I am building, I would like to ensure older Invoices and their line items do not change in price when my item information is updated. Say prices go up next year for a few of my items. I do not want the invoices from the past being updated with the new prices. Just new invoices created after the price change should reflect the new prices.