Is it possible to setup Unique Key's for DFF inside a Value Set?

Summary:

Hi Community,

Our customer is looking forward to create a table of important setup for them inside a value set. This table stores specific codes for cities and postal codes, but it requires some validations, therefore it is not good to use Manage Geographies for it, but we are exploring the possibility of a value set.

1- We have created the value set and added columns to it via value set values FF —> FND_VS_VALUES_B.

2- However, the logic of the table is missing: Postal Code & City should be unique keys, meaning, it is supposed not to be able to add another combination of Postal Code & City that is the same as another value already saved. Postal Code & City combinations at the moment are possible to be saved, and no error is shown.