Deleting Custom Fields in WordPress

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While working on a project you may have had custom fields that are left behind and that are no longer in use for the current theme these unused custom fields remain in your database. I came across this exact scenario when I was upgrading a section of a website that was outdated and needed to be re-done. The previous programmer had use a plethora of custom fields and my goal was to reduce the amount of custom fields used.

Take a look at the following example. All the custom fields that are not being used

Removing Unused Custom Fields

  1. Log into to phpMyAdmin
  2. Select your database.
  3. If you use a different database prefix than the default “wp_” one, then you’ll need to change that in the example below. Replace “meta_key” with your actual custom field name.
  4. Run the following script. ( The script will run and delete any references to that custom field and the data associated with it )
DELETE FROM wp_postmeta WHERE meta_key = 'meta_key';

Alternatively you can also run an sql script that looks at meta_key and see if there are any empty values

SELECT * FROM wp_postmeta WHERE meta_key = 'meta_key';

In my scenario I needed to look for any custom field containing the words productOption running the sql script returned the following.

SELECT * FROM wp_postmeta WHERE meta_key LIKE '%productOption%';

wp-unused-fields-db

Changing Database Prefix in WordPress

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The following blog post over at DigWp.com has a great step by step tutorial on changing your database prefix in WordPress database tables. You will definitely come across this scenario when working on WordPress websites.

Change Your Database Prefix to Improve Security

What I found really helpful is that you can run an SQL command to rename all your tables at once.

RENAME table `wp_commentmeta` TO `wp_VzQCxSJv7uL_commentmeta`;
RENAME table `wp_comments` TO `wp_VzQCxSJv7uL_comments`;
RENAME table `wp_links` TO `wp_VzQCxSJv7uL_links`;
RENAME table `wp_options` TO `wp_VzQCxSJv7uL_options`;
RENAME table `wp_postmeta` TO `wp_VzQCxSJv7uL_postmeta`;
RENAME table `wp_posts` TO `wp_VzQCxSJv7uL_posts`;
RENAME table `wp_terms` TO `wp_VzQCxSJv7uL_terms`;
RENAME table `wp_term_relationships` TO `wp_VzQCxSJv7uL_term_relationships`;
RENAME table `wp_term_taxonomy` TO `wp_VzQCxSJv7uL_term_taxonomy`;
RENAME table `wp_usermeta` TO `wp_VzQCxSJv7uL_usermeta`;
RENAME table `wp_users` TO `wp_VzQCxSJv7uL_users`;