format_c@elvis ~
$ mysql -Dtest -utestuser -ppassword
Welcome to the MySQL monitor.  Commands end with; or \g.
Your MySQL connection id is 6 to server version: 3.23.49-max-nt

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> select * from config;
+-------------+--------------+
| config_name | config_value |
+-------------+--------------+
| schlüssel1  | wert1        |
| schlüssel2  | wert2        |
| schlüssel3  | wert3        |
| schlüssel4  | wert4        |
+-------------+--------------+
4 rows in set (0.00 sec)

mysql> \q
Bye

format_c@elvis ~
$ perl
use strict;
use DBI;
use Data::Dumper;
my %config = ();
my $dbh = DBI->connect('DBI:mysql:database=test','testuser','password')
        or die DBI::errstr();
my $sth = $dbh->prepare('SELECT * FROM config') or die $dbh->errstr();
$sth->execute() or die $dbh->errstr();
while (my ($key,$value) = $sth->fetchrow_array()) {
        $config{$key} = $value;
}
print Dumper(\%config);
_ _ END _ _
$VAR1 = {
          'schlüssel3' => 'wert3',
          'schlüssel1' => 'wert1',
          'schlüssel2' => 'wert2',
          'schlüssel4' => 'wert4'
        };

format_c@elvis ~
$

 $config{$key} = $value;

 ${$key} = $value;

print $config{'schlüssel1'}; #wird wert1 ausgeben

 $config{$key} = $value;