SET @yearsago20=DATE_FORMAT(DATE_ADD(NOW(), INTERVAL -20 YEAR), '%Y%m%d%H%i%s');

SET @monthsago3=DATE_FORMAT(DATE_ADD(NOW(), INTERVAL -3 MONTH), '%Y%m%d%H%i%s');

​

WITH old_users(ou_actor, ou_name) AS

(

  SELECT DISTINCT actor_id, actor_name

  FROM revision

  JOIN actor_revision ON actor_id = rev_actor

  WHERE rev_timestamp <= @yearsago20

)

SELECT ou_name

FROM old_users

WHERE EXISTS (SELECT 1

              FROM revision_userindex

              WHERE rev_actor = ou_actor

                AND rev_timestamp >= @monthsago3);