How to sum values from all custom posts metabox

Question

I got a metabox that hold a monthly budget per client...
that meta box is inside a custom post type called clients. Inside that metabox the only thing entered is numbers.

I want to get the sum of all the clients.
Any ideas?

Altough i think its pure php.. somehow using foreach - to the request of @Fahd Murtaza i am trying to add parts of my metabox... i am using alchemy as the base to create my meta boxes so would add some parts.. Hope this doesnt confuse more..

<?php
// structure of my metabox usign alchemy
$clients = new WPAlchemy_MetaBox(array
(
    'id' => '_project_description',
    'title' => __('Client Info Card', 'sagive'),
    'template' => get_stylesheet_directory() . '/metaboxes/clients-meta.php',
    'types' => array('portfolio'),
    'context' => 'normal',
    'priority' => 'high',
    'autosave' => TRUE

));

.

// call for budget section in my meta box
<p>
<label><?php _e('Clients Budget:', 'sagive'); ?></label>
    <?php $mb->the_field('client_budget'); ?>
    <input type="text" name="<?php $metabox->the_name('client_budget'); ?>" value="<?php $metabox->the_value('client_budget'); ?>"/>
</p>  

.
The rest of the code is way to long and i think not relevant to show... correct me if i am wrong and would add it via pastebin or similer..

.
THIS IS HOW I QUERY THE POSTS...

<?php 
    query_posts(array( 
        'post_type' => 'portfolio',
        'showposts' => 10 
    ) );                    
    $count_posts_portfolio = wp_count_posts( 'portfolio' )->publish;
?>

Answer 1

Asuming that you have a variable called $posts that contains all the posts (or easier: Post IDs) from some query.

You can then work with $result and process everything you need. Calling post data is easy, as the key would be the post ID.

// For other arguments look into @link http://codex.wordpress.org/Class_Reference/WP_Query
$posts = new WP_Query( 
     'post_type' => 'portfolio'
    ,'post_status' => 'publish'
);

foreach ( $posts as $post )
{
    $result[ $post->ID ]['post_data'] = $post->ID;
    $result[ $post->ID ]['meta_data'] = get_post_custom( $post->ID );
}

foreach( $result as $id => $data )
{
    // Do whatever you need to do with your meta data in here.
    print 'The title is: '.$post->post_title;

    // See your post data:
    print_r( $data['post_data'] );

    // See your meta data:
    print_r( $data['meta_data'] );
}

Answer 2

$args = array(
    'numberposts' => -1,  // all the posts
    'post_type'   => 'clients'
);
$clients = get_posts( $args );

$total = 0;
foreach( $clients as $client ) {
    $single = get_post_meta( $client->ID, 'metakey_name_here', true );
    $total += $single;
}

$total should now contain the total for all the clients. metakey_name_here is going to be whatever $metabox->the_name( 'client_budget' ) is, I presume that is set elsewhere, but I've never worked with the WP_Alchemy class, so I can't tell you definitively. If you need more functionality than get_posts() offers, WP_Query is gonna be the place I would look. Also, here's documentation on get_post_meta() in case you need it.