考虑下表:
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)
我正在尝试根据该表构造一个哈希。为此,我执行以下操作:
#!/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);
这是生成的输出:
$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:为什么散列的键(countryiso)在散列内的值中重复?
我更喜欢的是以下输出:
$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'
}
};
是否可以使用 fetchall_hashref DBI 方法?或者我是否必须采用传统的方式,循环遍历每一行并动态构建哈希?