forums contributors who contributed for the first time in Q3.sql

SELECT DISTINCT `questions_answer`.`creator_id`
FROM `questions_answer`
JOIN `users_profile` ON `users_profile`.`user_id` = `questions_answer`.`creator_id`
WHERE `questions_answer`.`created` BETWEEN '2015-07-01 0' AND '2015-10-01 0'
AND `users_profile`.`first_answer_email_sent` = 1
AND
`questions_answer`.`creator_id` NOT IN
(SELECT DISTINCT `auth_user`.`id`
FROM `questions_answer`
JOIN `auth_user` ON `auth_user`.`id` = `questions_answer`.`creator_id`
JOIN `users_profile` ON `users_profile`.`user_id` = `questions_answer`.`creator_id`
WHERE `questions_answer`.`created` BETWEEN '2010-01-01 0' AND '2015-07-01 0'
AND `users_profile`.`first_answer_email_sent` = 1)