my $ordered_schema = sprintf(
    "%s%s",
    $header . "\n",
    sub {
        my $ordered_columns;
        for my $column (sort keys %columns) {
            $ordered_columns .= $columns{$column} . "\n";
        }
        return $ordered_columns;
    }->(),
);

##</code><code>##

my $ordered_schema = join "\n", $header, map $columns{ $_ } sort keys %columns;

##</code><code>##

my $ordered_schema = sprintf(
    "%s%s",
    $header . "\n",
    do {
        my $ordered_columns;
        for my $column (sort keys %columns) {
            $ordered_columns .= $columns{$column} . "\n";
        }
        $ordered_columns; ## Update: return statement removed. Thanks Choroba.
    },
);