如何使用 DBD::CSV 获取列名行？

Question

我正在使用DBD::CSV 来显示 csv 数据。我的代码是：

#! perl
use strict;
use warnings;
use DBI;

my $dbh = DBI->connect("dbi:CSV:", undef, undef, {
    f_dir            => ".",
    f_ext            => ".txt/r",
    f_lock           => 2,
    csv_eol          => "\n",
    csv_sep_char     => "|",
    csv_quote_char   => '"',
    csv_escape_char  => '"',
    csv_class        => "Text::CSV_XS",
    csv_null         => 1,
    csv_tables       => {
        info => {
            file => "countries.txt"
        }
    },  
    FetchHashKeyName => "NAME_lc",
}) or die $DBI::errstr;

$dbh->{csv_tables}->{countries} = {
  skip_first_row => 0,
  col_names => ["a","b","c","d"],
  raw_header => 1,
};

my $sth = $dbh->prepare ("select * from countries limit 1");
$sth->execute;
while (my @row = $sth->fetchrow_array) {
  print join " ", @row;
  print "\n"
}

country.txt 文件是这样的：

ISO_COUNTRY|COUNTRY_NAME|REGION_CODE|REGION_NAME
AF|Afghanistan|A|Asia
AX|"Aland Islands"|E|Europe
AL|Albania|E|Europe

但是当我运行这个脚本时，它会返回

AF Afghanistan A Asia

我希望它返回：

ISO_COUNTRY COUNTRY_NAME REGION_CODE REGION_NAME

有谁知道如何使用 DBD::CSV 模块来实现这一点？

还有一个问题是col_names属性设置为什么没有生效？ 如何使其返回以下内容？

 a b c d

Answer 1

$sth->{NAME}、$sth->{NAME_lc} 和 $sth->{NAME_uc} 返回对包含名称的数组的引用。

my $sth = $dbh->prepare("select * from countries limit 1");
$sth->execute;
print "$_\n" for @{ $sth->{NAME} };