How to use Data Tables and Data Mappers? Are they necessary?
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I have had experience with frameworks before, but never really got into models much. I don't know if this is the case for all frameworks or just zend, but currently I am learning Zend Framework.

I have been crawling through sample applications and trying to read huge articles, but I couldn't find a short and clear answer to what confuses me. 

What is the relationship between the 3 classes? (model, modelmapper, datatable) 

Let's say I have a database table called `users` and it has 3 fields `userID, userName, userPassword` What would be an example code? 

and is it necessary to build the model part of my application in this way? Would it be a bad practice if I just had functions to retrieve data from the database and return results as arrays? 

Please consider that this is a very simple application that has users,their image galleries, and messaging functionality. 

Thanks in advance.