I'm not sure where you need cryptography for this though, since it's your own database.
Using cryptography for confirmation of paid items is what I intend, as cryptography can be used to verify a legitimate payment & point out a fake one.
possible?
I do not think you really need cryptography in a closed system such as yours. Maybe just one-way hash functions if you want to protect your data from hacking attempts. Cryptography is used in a decentralized system to protect against unauthorized modification of data and prevent double spending. It is a security mechanism that ensures the validity of information and transactions in the blockchain network.
If I understand your problem correctly, to verify the legitimacy of the payment, you can simply check your database to ensure that the transaction is recorded there. And since you are the only one authorized to confirm payments and write data to your database, you do not need cryptography.