[snip]

my $rows = $dbh->selectall_hashref('select id, name, price from products');
$dbh->disconnect;

my $sum = 0; 
my $i = 0;

foreach (@$rows) {
    $_->{odd} = $i++ % 2;
    $sum += $_->{price};
}

$t->param(ROWS => $rows, TOTAL => $sum);