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我试图了解这里发生了什么。

我正在使用 Perl 和 DBI::Oracle 连接到我的 Oracle XE 数据库。我想在我的数据库查询中获取 UTF 编码字符作为返回值。不幸的是，我的期望没有得到满足。如果您仔细查看返回值，就会清楚这一点（从第 4 行开始）。对于变音符号“ä”，我得到的不是 c3a4，而是 e4。

有人可以向我解释为什么会发生这种情况吗

user@pc:~$ cat charset_test.pl
use DBI;
use Data::Dumper;
binmode STDOUT, ":utf8";

my $dbname = "DB:1521/XE";
my $user   = "system";
my $passwd = "password";
$dbh = DBI->connect("dbi:Oracle:$dbname", $user, $passwd);
sub sql{
    my $sql = shift;
    $dbh->{RaiseError} = 1;
    $sth = $dbh->prepare($sql);
    $sth->execute;
    my @dbrow = $sth->fetchrow_array;
    return $dbrow[0];
}

printf( " 0: NLS_LANG           %s \n", $ENV{'NLS_LANG'});
printf( " 1: pack ae            %s \n", unpack( 'H*', "ä" ) );
printf( " 2: sql rawtohex ae    %s \n",               sql("select rawtohex(ae)   from (select UTL_I18N.RAW_TO_CHAR ('c3a4', 'AL32UTF8') as ae from dual)"));
printf( " 3: sql rawtohex('ae') %s \n",               sql("select rawtohex('ä')  from dual") ) ;
printf( " 4: sql 'ae'           %s",    Dumper(       sql("select 'ä'            from dual") ) );
printf( " 5: sql 'ae'           %s \n",               sql("select 'ä'            from dual") ) ;
printf( " 6: pack sql ae        %s \n", unpack( 'H*', sql("select ae             from (select UTL_I18N.RAW_TO_CHAR ('c3a4', 'AL32UTF8') as ae from dual)")));
printf( " 7: pack sql 'ae'      %s \n", unpack ('H*', sql("select 'ä'            from dual") ) );

exit;
user@pc:~$ NLS_LANG=AMERICAN_AMERICA.UTF8 perl charset_test.pl
 0: NLS_LANG           AMERICAN_AMERICA.UTF8
 1: pack ae            c3a4
 2: sql rawtohex ae    C3A4
 3: sql rawtohex('ae') C3A4
 4: sql 'ae'           $VAR1 = "\x{e4}";
 5: sql 'ae'           ä
 6: pack sql ae        e4
 7: pack sql 'ae'      e4
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