SELECT
date(created_at),
count(DISTINCT(user_id)) AS daily_users,
count(
    DISTINCT (
        CASE
        WHEN date(created_at) BETWEEN date_sub(created_at, INTERVAL 2 DAY)
        AND created_at THEN
            user_id
        END
    )
) AS users_2_day_lookback
FROM
table.users
WHERE
date(created_at) BETWEEN 'yyyy-mm-dd'
AND now()
GROUP BY
1