I'm trying to select different types of data depending on a payment method which is a simple intersection table with columns "id" (INT PK) , "customer_id" (INT FK), "payment_method_id" (INT FK) and "date_changed" (DateTime)
Now, the customer may request the admin to change the payment method at any time, however I need to keep track of the payment method even if it's no longer in use simply because if I change the payment method halfway through the month I'll get invoiced the first half of the month using payment method 1 and the second half using payment method 2.
Now, depending on payment method, I will need to run different queries (using PHP in the backend) however, I need to find out, what payment method to use for a certain period of time.
How could I get to know if there is a payment method more recent, and more outdated, oh and I obviously cannot select the payment methods by month since they may be left unchanged for years on end before seeing a change, and since this is about invoicing my data needs to be trackable for 5 years...
How could I go about selecting the different data based on the methods I get back and their "date_changed" ?