Software Design Problem: VPN Accounts

[eluser]parham90[/eluser]
Yes, The subscription_type table is the services table. My problem, however, is not the cost, but the number of days. Let's say that the user has paid for 30 days subscription, but has mistakenly chosen 10 days subscription. He tells the admin to change it for him. Now, if the admin changes the subscription_type_id to the other one, yes, the cost and such could be obtain by looking it up in the table containing types of subscriptions and their associated prices. However, the start_date and the end_date somehow have to be calculated, and the end_date needs to be changed. Just now though, something occurred to me. When the admin confirms the new subscription, the number of days for that particular subscription could be obtained (E.G. 30 days) and then added to the start_date, and then the end_date could be replaced by the new result. That could work?