Update a WordPress user account first_name and last_name if it is missing with their WooCommerce billing_first_name and billing_last_name if available.

fix-missingnames.sql

/* Get all the users missing a first_name. */
SELECT * FROM wp_usermeta AS A
WHERE A.meta_key = 'first_name'
AND A.meta_value = '';

/* Updated to first_name to their billing_first_name if available. */
UPDATE wp_usermeta AS A 
JOIN ( SELECT user_id, meta_value FROM `wp_usermeta` WHERE wp_usermeta.meta_key = 'billing_first_name' AND wp_usermeta.meta_value <> '') AS B 
ON  A.user_id = B.user_id
SET A.meta_value = B.meta_value
WHERE A.meta_key = 'first_name'
AND A.meta_value = '';

/* Get all the users missing a last_name. */
SELECT * FROM wp_usermeta AS A
WHERE A.meta_key = 'last_name'
AND A.meta_value = '';

/* Updated to last_name to their billing_last_name if available. */
UPDATE wp_usermeta AS A 
JOIN ( SELECT user_id, meta_value FROM `wp_usermeta` WHERE wp_usermeta.meta_key = 'billing_last_name' AND wp_usermeta.meta_value <> '') AS B 
ON  A.user_id = B.user_id
SET A.meta_value = B.meta_value
WHERE A.meta_key = 'last_name'
AND A.meta_value = '';