How set value in select box after ajax request?

I have site with cars and i have dropbox when you can select type of adv: car, bike etc. If you select car in dropbox make Ajax will download all mares. again after select Make dropbox in model dropbox you will see models of selected car. I can go to next page and store in DB all ids.

Now when i load adv to allow edit how can i get adv type from db and make id and model id from Db and set vale after all drop box will be loaded ?

via Chebli Mohamed