use enwiki_p;

SELECT user_name, user_editcount, user_registration, rev_timestamp AS 'Last edit', ug1.ug_group

FROM `user`

LEFT JOIN user_groups ug1

    ON user_id = ug1.ug_user AND ug1.ug_group IN ('massmessage-sender')

​

JOIN revision_userindex

    ON rev_id = (SELECT rev_id FROM revision_userindex

                 WHERE user_id = rev_user

                 ORDER BY rev_timestamp DESC

                 LIMIT 1)

WHERE rev_timestamp <= 20120613000000

    AND ug1.ug_group IS NOT NULL

    ;