in reply to
Compare Inventory to Database and Vice-Versa
So what have you tried and what didn't work? What Perl documentation have you read? Have you looked through the Tutorials section? Have you any other programming experience?
When reading through documentation take special note of anything that mentions the word "hash". Perl's hash data structure is the key to much of what you want to do. Another key Perl feature is likely to be regular expressions - see perlretut.
True laziness is hard work