To avoid problems with commas and quoting, use Text::CSV_XS or Text::xSV written by tilly; here it is an example using the first module:

use Text::CSV_XS;

$csv = Text::CSV_XS->new({ 'quote_char'  => '"',
                           'escape_char' => '"',
                           'sep_char'    => ',',
                           'binary'      => 0,
                           'eol'         => "\r\n"
                         });

while (my @row = $sth->fetchrow_array) {
  if ($csv->combine(@row)) {
    print $csv->string;
  } else {
    my $err = $csv->error_input;
    print "combine() failed on argument: ", $err, "\r\n";
  }
}
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