my $data = [
    { col1 => 'data1', col3 => 'data3' },
    { col2 => 'data2', col3 => 'data3plus' },
];
if( ! @columns ) {
	# Collect all (potential) columns we want to write
	my %columns;
	for( @$data ) {
		$columns{ $_ } = 1
			for keys %$_;
	}
	@columns = sort keys %columns;
};

my $columns = join ",", map { qq("$_") } @columns;
my $placeholders = join ",", ("?") x @columns;

# Run the insert statement for each row in our list
my $sql_insert = qq(insert into "$table" ($columns) values ($placeholders));

##</code><code>##

#!perl -w
use strict;
use DBI;
use JSON;
use Getopt::Long;
use Pod::Usage;
use Path::Class 'file';

GetOptions(
	'table:s'    => \my $table,
	'dsn:s'      => \my $dsn,
	'user:s'     => \my $user,
	'password:s' => \my $password,
	'file:s'     => \my $json_file,
	'json:s'     => \my $json_text,
	'columns:s'  => \my @columns,
) or pod2usage(2);

my $data;
if( $json_file ) {
    $data = decode_json( file( $json_file )->slurp($json_file, iomode => '<:raw' ));
} elsif( $json_text ) {
    $data = decode_json( $json_text );
} else {
    binmode STDIN, ':raw';
	local $/;
	$data = decode_json( <STDIN> );
};

if( ref $data eq 'HASH' ) {
    # Convert single row to a set of rows
	$data = [$data]
};

if( ! @columns ) {
	# Collect all (potential) columns we want to write
	my %columns;
	for( @$data ) {
		$columns{ $_ } = 1
			for keys %$_;
	}
	@columns = sort keys %columns;
};

my $columns = join ",", map { qq("$_") } @columns;
my $placeholders = join ",", ("?") x @columns;

# Run the insert statement for each row in our list
my $sql_insert = qq(insert into "$table" ($columns) values ($placeholders));
my $dbh = DBI->connect( $dsn, $user, $password, { RaiseError => 1, PrintError => 0 });
my $sth_insert = $dbh->prepare( $sql_insert );
if( ! $sth_insert->execute_for_fetch( sub {
        my $item = shift @$data;
        if( $item ) {
            my $res = [@{$item}{ @columns }];
            return $res
        } else {
            return $item
        }
    }, \my @results)) {
    for my $err (grep { ref $_ } @results) {
	    warn $err->[1];
	};
};