Perl does not support directly inserted SQL statement, as some lauguages do, like Pro*c etc. There might be new concepts to you when you learn DBI. Looking at your SQL statement, I think there is at least one thing you want to pay special attention to: prepared statement and placehold. Eventually, your code should look similar to this:

use DBI;

my $dbh= DBI->connect("dbi:mysql:test", "", "", {RaiseError => 1, Auto
+Commit => 0});

my $addprod = $dbh->prepare("insert into products (pname, unit, qty, c
+ost) values (?, ?, ?, ?)");

...
$addprod->execute('apple', 'kg', 1, 1.99);
...
$dbh->commit();#commit for each unit of work, or rollback, for really 
+simple cases, you can turn on AutoCommit
...
$dbh->disconnect();
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