Build billing on flow-capture

Hello.
I read this maillists.There are already was topic about building billing
system on flow-tools.But there are was another epproach to problem.
In that topic people try to parse and store information into
SQL-backend, but I want store into SQL information, which I need and
store all information into files as already releesed.


I want change flow-capture to build billing.
Include in flow-capture utility work's with MySQL or PostgreSQL or other
backend.

And flow-capture will write date into SQL & file both, but I want write
into
sql-database only IP and sum of bytes.

I want use data from flow-capture to update client's record's into
SQL-table.

Where into source of flow-capture information writing into file?
Or Where I can include sending data into SQL-database?