试试这个，我已经编辑了你想要的东西。

$args = array(
    \'post_type\' => \'post\',
    \'post_status\' => \'publish\',
    \'posts_per_page\' => -1,
);

$dbResult = new WP_Query($args);
while ( $dbResult->have_posts() ) {
    $dbResult->the_post();
    global $post;

    // You can pass specific post id to get post meta values 
    $fields = get_post_custom_keys($post->ID);    // all keys for post as values of array
    if ($fields) {
        foreach ($fields as $key => $value) {

            // $value will give you meta_key\'s
            $meta_value = get_post_meta($post->ID,$value,true);

            // Exclude WP System Meta Keys
            if ($value[0] != \'_\') { 
                // Meta Value
                echo $meta_value;
            }
        }
    }
}

请尝试此代码。我将按日期添加订单。希望就是工作

https://codex.wordpress.org/Class_Reference/WP_Query

$args = array(
        \'post_type\' => \'post\',
        \'post_status\' => \'publish\',
        \'posts_per_page\' => -1,
        \'orderby\'     => \'modified\',
        \'order\'       => \'DESC\',
        \'meta_key\' => \'picture_upload_1\'
    );