Perl DBI fetchall_hashref - mysql

Question

Consider the following table:
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)
I am trying to construct a hash based on this table. For this I do the following:
#!/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);
Here is the output this generates:
$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'
}
};
The question is: why is the key of the hash (countryiso) repeated in the values inside the hash?
What I would prefer is the following output:
$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'
}
};
Is it possible using fetchall_hashref DBI method? Or do I have to go the traditional way, looping through each row and constructing the hash on the fly?

Answer 1

No, it cannot be done using fetchall_hashref. But you can iterate over the hash values and delete the key:
delete $_->{countryiso} for values %$hash;

Answer 2

I had this same problem but was using multiple keys on fetchall_hashref, so I had to go deeper in the hash references. Not exactly rocket science, but here it is:
(...)
my #keys=('key1','key2','key3');
my $result_ref=$sth->fetchall_hashref(\#keys);
remove_key_values($result_ref,\#keys);
(...)
sub remove_key_values {
my ($href_values,$aref_keys) = (#_);
foreach my $hk (keys %$href_values) {
foreach my $ak (#$aref_keys) {
if ($ak eq $hk) {
delete $href_values->{$hk};
}
}
if (exists $href_values->{$hk} and ref($href_values->{$hk}) eq 'HASH') {
remove_key_values($href_values->{$hk},$aref_keys);
}
}
}