Forms and database tables

Hi,
I would like to make my own ERP application and wordpress seems to be good for doing that. But I need to find a right plugin. What I need is to have access to any table in certain database and fill the forms elements with data get from these tables and send data from forms elements into tables. Also I would need to have the ability to make some calculations on the data being sent/received. I am thinking about following modules: formidable, abase. Have anyone done something like that before and would be able to give me some advice?