Members , signups and Coupons

select
A.date,
A.mid,
B.referral,
C.couponname
from

(select
distinct m.id as mid,
date(m.created_at + interval '8' hour) as date
from members m
where m.created_at+interval 8 hour >= '2019-05-01 00:00:00') A

left join
(select
distinct ma.member_id as mid,
ma.recommender as referral
from member_appendixes ma) B
on B.mid = A.mid

left join
(select
distinct c.member_id as mid,
c.comment as couponname
from coupons c) C
on C.mid = B.mid