考虑以下表格:
mysql> select * from vCountryStatus;
+-------------+------------+------+---------+--------+-----------------+
| CountryName | CountryISO | Code | Status | Symbol | CurrencyName |
+-------------+------------+------+---------+--------+-----------------+
| Brazil | BR | 55 | LIVE | BRL | Brazilian Real |
| France | FR | 33 | offline | EUR | Euro |
| Philippines | PH | 63 | LIVE | PHP | Philippino Peso |
+-------------+------------+------+---------+--------+-----------------+
3 rows in set (0.00 sec)
我想基于这张表构建一个哈希表。为此我会进行以下步骤:
#!/usr/bin/perl
use DBI;
use Data::Dumper;
my $dbh = DBI->connect("dbi:mysql:database=db", "user", "password", {RaiseError => 1, AutoCommit => 0, FetchHashKeyName => "NAME_lc"}) || die "DB open error: $DBI::errstr";
my $sth = $dbh->prepare("select * from vCountryStatus");
$sth->execute;
my $hash = $sth->fetchall_hashref('countryiso');
print Dumper($hash);
这是它生成的输出结果:
$VAR1 = {
'PH' => {
'symbol' => 'PHP',
'status' => 'LIVE',
'countryname' => 'Philippines',
'countryiso' => 'PH',
'currencyname' => 'Philippino Peso',
'code' => '63'
},
'BR' => {
'symbol' => 'BRL',
'status' => 'LIVE',
'countryname' => 'Brazil',
'countryiso' => 'BR',
'currencyname' => 'Brazilian Real',
'code' => '55'
},
'FR' => {
'symbol' => 'EUR',
'status' => 'offline',
'countryname' => 'France',
'countryiso' => 'FR',
'currencyname' => 'Euro',
'code' => '33'
}
};
问题是: 为什么哈希表的键(countryiso)在哈希表内部的值中被重复使用?
我希望得到以下输出:
$VAR1 = {
'PH' => {
'symbol' => 'PHP',
'status' => 'LIVE',
'countryname' => 'Philippines',
'currencyname' => 'Philippino Peso',
'code' => '63'
},
'BR' => {
'symbol' => 'BRL',
'status' => 'LIVE',
'countryname' => 'Brazil',
'currencyname' => 'Brazilian Real',
'code' => '55'
},
'FR' => {
'symbol' => 'EUR',
'status' => 'offline',
'countryname' => 'France',
'currencyname' => 'Euro',
'code' => '33'
}
};
能否使用fetchall_hashref DBI方法?或者我必须沿用传统的方法,遍历每一行并即时构建哈希表?
my $hash = $dbh->selectall_hashref("select * from vCountryStatus", 'countryiso');
- Tim Bunce