Hi,
I am very interested and willing to develop 3-tier app. I have read many articles and go thru samples code. I found that, most of the articles/sample code only illutrate simple entity such as customer, product for easier understanding. It is fine.
However, I still not very clear on designing data class that may involve 2 or more tables such as Order (Order + OrderDetails).
There are more things that I would like to clarify but I just don't know how to start. For example,
1. How to have A DATA CLASS that acess multiple tables? View?
2. If client want to increase the product unit price, what should business and data object do? Should I have increaseprice methos in data class?
n etc.

Pls provide more info.
Real world sample will be appreciated.

Thank you