wordpress create meta box with multiple entries

This is answering of how to save multi-dimensional array values and some how solves your problem in some level

You should use arrays.

I am doing this in many implementations in my Scripts. Lets see how:

HTML/PHP First:

<?php    $countries = get_post_meta($post->ID, 'countries' true);?><div class="EntriesContainer" data-count="<?php echo count($countries); ?>" id="itemsList">    <?php        $cnt = 0;        foreach($countries as $country)        {            ++$cnt;    ?>    <div class="newItem">        <input name="countries[<?php echo $cnt; ?>][name]" type="text" />' +        <input name="countries[<?php echo $cnt; ?>][population]" type="text" />        <input name="countries[<?php echo $cnt; ?>][flag_url]" type="text" />    </div>    <?php        }    ?></div><input type="button value="Add new Country" class="button" id="addNewItem" />

JavaScript:

jQuery(document).ready(    function($)    {        $('#addNewItem').on(            'click.myThemeOrPluginName',            function(e)            {                e.preventDefault();                var ttlItems = parseInt($('#itemsList').attr('data-count'));                ++ttlItems;                var $newItem = '<div class="newItem>' +                               '<input name="countries[' + ttlItems + '][name]" type="text" />' +                               '<input name="countries[' + ttlItems + '][population]" type="text" />' +                               '<input name="countries[' + ttlItems + '][flag_url]" type="text" />' +                               '</div>';                $('#itemsList').append($newItem);            }        );    });

Then in save_post action hooked function you will get via the $_POST an array that will look like that:

array(    'countries' => array(        [1] => array(            name => 'Greece'            population => '11000000',            flag_url => '../el_GR.png'        )        [2] => array(            name => 'Italy'            population => '????',            flag_url => '../it_IT.png'        )    ))

This is the general idea. Customize based on your requirements :)

You should consider Custom Post Types (http://codex.wordpress.org/Post_Types).

In this case, you could create a new type : country, that contains the post title (Name of country) and you could add 2 custom fields : population (text field), and flag (image field).

Then, you could add as many countries as you want, just like Posts.