sub get_cmd {
    # returns an array of sth->fetchrow_hashref
    my $cmd = shift;
    my $line = shift || 'keine Angabe';
    my $data = [];
    my $sth = $dbh->prepare($cmd) || die "Zeile: $line" . $dbh->errstr;
    my $rv = $sth->execute        || die "Zeile: $line" . $dbh->errstr;
    while( my $ref = $sth->fetchrow_hashref() ){
        push @{ $data }, $ref;
    }
    $sth->finish();
    return $data;
} # get_cmd