which is better approch? More Traditional MVC or Creating libraries for code.

[eluser]pankaj[/eluser]
currently I am using MVC, where I separated my database related code in model, but I really like creating libraries lets say I am creating user authentication module. So I put all database and related code in library, like in function registration I added code for database as well as manipulating form data and in controller I am just validating the data coming from HTML Form and sending it to registration function which is written in library.

I am getting curious is it a good approach of using libraries for database as well as other code is better or using mvc is better.