I don't see any other way aside from post 2. Personally, I don't see a need for from/to fields. If you want to know what they paid for something in the past, you just look at the invoices table. The qty and price they paid (price came from CustomerProduct) is easily found. Of course, it would be different if you wanted a reminder to review the price at some point, but the whole operation doesn't seem that sophisticated as opposed to by the seat of someone's pants so to speak. Still, you wouldn't need a 'from' field for that - just a review date field.
The idea that a percentage field (which would simplify this) is out of the question seems bizarre. If the nominal price is $1 and customerA is getting it for 75 cents, he's getting a 25% discount. How can that be out of the question?? It would also tell me as the business owner how much I'm giving up, and the more you know about your business, the better it's chances of success.
Last edited by Micron; 10-30-2020 at 01:27 PM.
Reason: clarification
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.