下面是一段代码，类似于我在导入数据后用来修复问题的代码：

<?php
define(\'MY_METABOX_ID\', \'my_metabox_id\');
define(\'MY_METABOX_PREFIX\', \'my_metabox_prefix_\');
define(\'MY_CUSTOM_POST_TYPE\', \'my_custom_post_type\');

// Include WordPress
define(\'WP_USE_THEMES\', false);
define(\'WP_DEBUG\', 1);
require_once(\'../wp-load.php\');

// extract all MY_CUSTOM_POST_TYPE posts
$q = new WP_Query(\'post_type=\' . MY_CUSTOM_POST_TYPE . \'&nopaging=true\');

// for each post
while($q->have_posts()) {
    $q->next_post();

    $p = $q->post;
    $id = $p->ID;

    // check if the field already exists, take action only if it does not
    if (!get_post_meta($id, MY_METABOX_ID . \'_fields\', true)) {

        // crete the content
        $fields = array(
            MY_METABOX_PREFIX . \'field1\',
            MY_METABOX_PREFIX . \'field2\',
            MY_METABOX_PREFIX . \'field3\',
        );

        //add the meta field
        add_post_meta($id, MY_METABOX_ID . \'_fields\', $fields);
    }
}
echo \'DONE!\';