SELECT
	`client_id` as `clientId`,
	( SELECT COUNT(*) FROM `clients` WHERE `client_id` = clientId AND `date` >= '2020-01-01 00:00:00' AND `date` <= '2020-02-01 00:00:00' ) AS `second_month`,
	( SELECT COUNT(*) FROM `clients` WHERE `client_id` = clientId AND `date` >= '2019-12-01 00:00:00' AND `date` <= '2020-01-01 00:00:00' ) AS `third_month`
FROM
	`clients`
WHERE
	`date` >= '2020-02-01 00:00:00'
	AND `date` <= '2020-03-01 00:00:00' HAVING `second_month` > 0 AND `third_month` > 0