これを試してください::
SELECT CONCAT_WS(' ', first_name, last_name) AS name FROM `users`
WHERE CONCAT_WS(' ', first_name, last_name) LIKE "%John Doe%"
これを試してください::
SELECT CONCAT_WS(' ', first_name, last_name) AS name FROM `users`
WHERE CONCAT_WS(' ', first_name, last_name) LIKE "%John Doe%"