现有 表A,B,C,D,其中以user_id作为各表关联条件 如果想通过ABCD表形成漏斗数据(A表为最大漏斗D表为最小漏斗)
select count(distinct a.user_id),count(distinct b.user_id),count(distinct c.user_id),count(distinct d.user_id)
from
(select user_id
from a
) as a
left join
(
select user_id
from b
) as b
on a.user_id=b.user_id
left join
(
select user_id
from c
) as c
on b.user_id=c.user_id
left join
(
select user_id
from d
) as d
on c.user_id=d.user_id
以表c为例 请问下关联条件处写 b.user_id=c.user_id 或 a.user_id=c.user_id 从数据差异或运行效率上会有差别吗