At one time I was trying to learn how to accomplish some stuff like this in oop. No one could give an answer. As stated, I am yet to see any complex database example done in oop. By now there should be tons of examples on the web. I just do not see examples like a real business would use. In any order entry system there should be a way to auto fill things like ship to fields and such as this. You talk about seperation of presentation layer and server php layer (I forget exact phrase). But the minute ajax or whatever is used for something complex, suddenly it's alright to mix everything up. I just want to see just one concrete example of oop where you can enter an order or something and do complex lookups. I do not disagree with oop. But for me to want to completely learn oop in php, I need to see and know how to accomplish at least a lookup. I don't see how it's possible without having some html and php combined within the same php file. Unless, php has it's own dropdown that isn't covered in the php manual. Otherwise, the second you have that dropdown contained in a php page, well you just broke your own rule of html and php seperation. And if this is true, but you have to use a dropdown to do a lookup, then oop doesn't exist. Therefore it's a paradox.
I recently dabbled in a little java / jsp. Guess what, yes there are classes, but all of the examples still have to combine some html and java on the same page in order to accomplish a lookup in a dropdown. At least the examples I ran across. Isn't the truth about oop this: It takes some genuine oop techniques but a mix of procedural code is required. I mean java is supposed to be a lot more oop than php, but yet a lot of the java examples looks like my php code.