我已经成功地在我的自定义帖子类型中添加了一个元框（请参见下面的代码），现在我需要添加另一个元框。使用此框，我想显示/编辑另一个名为wp\\u project\\u bids\\u mitglied的表中的值。此表包含一行post ID和一行值（0,1,2），我想在后端编辑/显示这些值。如何更改代码以实现此目标？谢谢

function add_custom_meta_box() {
add_meta_box(
    \'custom_meta_box\', // $id
    \'Dauer\', // $title
    \'show_custom_meta_box\', // $callback
    \'project\', // $page
    \'normal\', // $context
    \'high\'); // $priority
}
add_action(\'add_meta_boxes\', \'add_custom_meta_box\');

// Field Array
$prefix = \'custom_\';
$custom_meta_fields = array(


array(
    \'label\'=> \'Select Box\',
    \'desc\'  => \'Fotoauftrag Dauer angeben\',
    \'id\'    => $prefix.\'dauer\',
    \'type\'  => \'select\',
    \'options\' => array (
        \'one\' => array (
            \'label\' => \'1-3\',
            \'value\' => \'a\'
        ),
        \'two\' => array (
            \'label\' => \'3-6\',
            \'value\' => \'b\'
        ),
        \'three\' => array (
            \'label\' => \'6-9\',
            \'value\' => \'c\'
        ),
        \'four\' => array (
            \'label\' => \'>9\',
            \'value\' => \'d\'
                  )
    )
)
);

// The Callback
function show_custom_meta_box() {
global $custom_meta_fields, $post;
// Use nonce for verification
echo \'<input type="hidden" name="custom_meta_box_nonce" value="\'.wp_create_nonce(basename(__FILE__)).\'" />\';

// Begin the field table and loop
echo \'<table class="form-table">\';
foreach ($custom_meta_fields as $field) {
    // get value of this field if it exists for this post
    $meta = get_post_meta($post->ID, $field[\'id\'], true);
    // begin a table row with
    echo \'<tr>
            <th><label for="\'.$field[\'id\'].\'">\'.$field[\'label\'].\'</label></th>
            <td>\';
            switch($field[\'type\']) {
                // case items will go here
                // text



case \'select\':
echo \'<select name="\'.$field[\'id\'].\'" id="\'.$field[\'id\'].\'">\';
foreach ($field[\'options\'] as $option) {
    echo \'<option\', $meta == $option[\'value\'] ? \' selected="selected"\' : \'\', \' value="\'.$option[\'value\'].\'">\'.$option[\'label\'].\'</option>\';
}
echo \'</select><br /><span class="description">\'.$field[\'desc\'].\'</span>\';
break;
            } //end switch
    echo \'</td></tr>\';
} // end foreach
echo \'</table>\'; // end table
}

// Save the Data
function save_custom_meta($post_id) {
global $custom_meta_fields;

// verify nonce
if (!wp_verify_nonce($_POST[\'custom_meta_box_nonce\'], basename(__FILE__)))
    return $post_id;
// check autosave
if (defined(\'DOING_AUTOSAVE\') && DOING_AUTOSAVE)
    return $post_id;
// check permissions
if (\'page\' == $_POST[\'post_type\']) {
    if (!current_user_can(\'edit_page\', $post_id))
        return $post_id;
    } elseif (!current_user_can(\'edit_post\', $post_id)) {
        return $post_id;
}

// loop through fields and save the data
foreach ($custom_meta_fields as $field) {
    $old = get_post_meta($post_id, $field[\'id\'], true);
    $new = $_POST[$field[\'id\']];
    if ($new && $new != $old) {
        update_post_meta($post_id, $field[\'id\'], $new);
    } elseif (\'\' == $new && $old) {
        delete_post_meta($post_id, $field[\'id\'], $old);
    }
} // end foreach
}