How should I pass data between classes and application layers?

Question

For example, if I am creating a 3 layer application (data / business / UI) and the data layer is grabbing single or multiple records. Do I convert everything from data layer in

Answer 1

I´d add a new layer, ORM Object Relational Mapping, with the responsability to transform data from Data layer into bussiness objects collections. I think that using objects in your bussiness model is the best practice.