I don't think you have a question about Net::SNMP::Interfaces which is a module specifically for access the network interface OIDs and doesn't concern itself with SNMP traps at all.

However the code above is designed to be run by the snmptrapd and is passed the information about the trap on STDIN, you will need to read the documentation of your SNMP server to find out how to configure the trap handling to have the script run. In order to have the trap information put into a database you would replace the parts that send the mail message with a database insert using the DBI.

You'll probably find that because this is a more general question and not one about a particular CPAN module that you will get more and better answers somewhere like Perlmonks or comp.lang.perl.misc

/J\