WordPress bulk add, modify, remove duplicate custom fields

1. How to add new custom fields in batches

insert into wp_postmeta (post_id, meta_key, meta_value)
select ID, '新自定义字段', '自定义字段值' from wp_posts where post_type = 'post';

2. Modify custom field names in batches

UPDATE 'wp_postmeta' SET 'meta_key'='新的自定义域名称' WHERE 'meta_key' = '旧的自定义域名称';

3. Remove duplicate custom fields

1. By directly modifying the database command

delete from wp_postmeta
where meta_id in (
       select *
       from (
               select meta_id
               from wp_postmeta a
               where a.meta_key = 'views'
               and meta_id not in (
                       select min(meta_id)
                       from wp_postmeta b
                       where b.post_id = a.post_id
                       and b.meta_key = 'views'
               )
       ) as x
);

Notice:

views represents the field you want to modify, wp_posta is a table in the database, and the custom field is stored in this table. Please pay attention to the previous wp_, which is the prefix that WordPress sets when creating the database. If your prefix is ​​not wp _ instead of bb _, then wp_ postmeta needs to be changed to bb _postmeta 

2. Use php code to remove duplicate fields

If you have no way to operate the database through phpMyAdmin, then you can use the following method.

1. Create a new file named remove-duplicate-custom-fields.php in the root directory of the website, copy the following code to the file, and save:

<?php
define('WP_USE_THEMES', false);
require('wp-blog-header.php');
 
    define( 'WP_DEBUG_DISPLAY', true ); 
    ini_set( 'display_errors', true );
    $allposts = get_posts('numberposts=-1&post_type=post&post_status=any');
    $keys = array('views','test_meta');//要检索的自定义字段
    foreach ( $keys as $key ) {
        foreach( $allposts as $postinfo) {
            // 获取（上面所填写的）自定义字段的值
            $postmeta = get_post_meta($postinfo->ID, $key);
 
            if (!empty($postmeta) ) {
                // 删除这篇文章的（上面所填写的）自定义字段
                delete_post_meta($postinfo->ID, $key);
 
                // 插入一个且只有一个（上面所填写的）自定义字段
                update_post_meta($postinfo->ID, $key, $postmeta[0]);
            }
        }
    }
?>

Pay attention to modify the fields in line 8. In this example, the two fields 'views' and 'test_meta' are deleted, please modify them yourself (multiple fields are separated by half-width English commas).

2. Access http://your domain name/remove-duplicate-custom-fields.php through the browser, wait for a while, and the redundant duplicate fields can be deleted!