Chronoform v4 and DB save

Hello everyone, I explain my problem to you,
I built a form to enter a serial number.
It consists of 8 numbers but I would like the user to enter the data individually (see image)
the fields are called:
camp0, camp1, camp2, camp3, camp4, camp5, camp6, camp7
once I clicked on submit I would like to generate a "bar_code" and "lot" variable which consists of assembling a part of fields:
bar_code = camp0 + camp1 + camp2 + camp3
lot = camp4 + camp5 + camp6 + camp7
Once created I would like "bar_code" and "lot" to be saved in the DB.
Then:
1. How can I create the variables to combine the various values?
2. How can I customize the saving of data in my DB?
Thank you

I have add Custom code on Submit:

<?php
$bar_code = $_POST["camp0"].$_POST["camp1"].$_POST["camp2"].$_POST["camp3"];
$lotto = $_POST["camp4"].$_POST["camp5"].$_POST["camp6"].$_POST["camp7"];
?>

This is for solve problem n.1