help with model / db

[eluser]Unknown[/eluser]

Database Model : http://i.stack.imgur.com/cYorn.jpg

Can any one guid me on how to implement the following database design using codeigniter? I would like to know if i have to extend the sub model to the base model which is the adclassifieds. Is there any orm that i can use to achieve it?

i am very new to CI framework.

[eluser]InsiteFX[/eluser]
See Datamapper in the Ignited Code forums...