Business object relationship

Summary

BO relationship and displaying the results in a table

Content

I have two BO's. One has Item number and other has Item Name.

I want to relate the above two BO's. and display the Item number and item name via a table in UI.

I know that we can define relationships between BO's. But is there any article that could help us understand the concept of relationship much better.

Also, i am need of defining what does delete rule and its options - cascade, restrict and set to null mean.

The data in the BO gets deleted after few mins without any hint, ( I doubt the delete rule here)