For maintainability I really like Data::Table, since it allows me to work directly with column names in my table. It can also work with column numbers. It uses SQL or CSV as a data source. It also handles sorting, etc.

use Data::Table;
 
my $sum=0;
# my $t= Data::Table::fromSQL ($dbh, $sql, $vars);   # Database versio
+n
my $t= Data::Table::fromCSV("data.csv");
$sum += $_ for($t->col('exp'));
print $sum,"\n";
[download]

It should work perfectly the first time! - toma