my @avgs  = $dbh->selectrow_array($avgSQL);

# CSV output method A
print join(",", @cols) . "\n";
print join(",", @avgs) . "\n";

# CSV output method B (2-columns)
print "Col,Avg\n";
printf("%s,%f\n", $cols[$_], $avgs[$_]) for 0 .. $#cols;