use strict;
my $tstr = 'abc äÄöÖüÜß test';

my %subsTable = (
    'ä' => 'ae', 'Ä' => 'AE', 'ö' => 'oe', 'Ö' => 'OE',
    'ü' => 'ue', 'Ü' => 'UE', 'ß' => 'ss'
);
my $notInSQL = qr{['`´",%\$]};
my $inSQL = qr{[`´",\$]};

sub blah { 
    my $str = shift; 
    my $regex = join "", map { quotemeta $_ } keys %subsTable;
    $regex = "[$regex]";
    print "Regex: $regex\n";
    $str =~ s/($regex)/$subsTable{$1}/g;
    return $str
};


print "orig : $tstr\n";
print blah($tstr)."\n";