I have to agree with Peter - what do we need a database for ?
Quality is in the eyes of the beholder. The only real judge is yourself. Why would I want a database that tells me some movie is quality 3 - what does that say ? nothing - its totally useless information.
Not only related to this topic but in general - I wonder how come so many people seem to have so litle faith in themselves that they allways need everybody else to tell them if they should use this or that. You see it everywhere on the forums, should I use this or that encoder? should I use constant or variable? should I use this or that burningsoftware? etc etc and so on - it goes on forever.
I would NEVER trust anyone to tell me how to or what to do. I allways try things and judge for myself and I allways get the result I want.
Basically, try, try and try again. In time you will get the knowledge and experience from trial and error, that will make it simple for you to allways deside what works best for you under different circumstances.