Database + interface for data import/export from/to flat files

We need a tool consisting of:
- a database;
- an interface,

to perform the following tasks:
a) Import data from a flat file with specified fields to populate/update a customer table in the DB;
b) Import data from a flat file with specified fields to:
b1) populate a table in the DB containing data relative to customers;
b2) generate flat files with specified fields as an output to other softwares;
b3) handle a simple logic to manage some operations on the data (basically, simple math operations to updated counters, and trigger events when certain thresolds are reached)

Preferred tools: Python (django?) + PostgreSQL
The source code needs to be fully documented/commented
Working environment: Windows