加入3个表时出错

Question

我试图在加入3个表后计算不同客户的数量。这是下面的查询。

我收到错误"mismatched input 'd' expecting ) near ')' in from source"

select count(distinct(a.customer)) 
from (
    (select *
     from tab1
     where tab in (1)) c 
join (
    (select *
     from tab1
     where tab in (2)) a
     join
        (select *
         from tab1
         where tab in (3)) b
     on a.customer = b.customer) d
on c.customer = d.customer)

Answer 1

您的查询中有额外的括号，这会产生误导。改为下面

select count(distinct a.customer) 
from (
    select *
     from tab1
     where tab in (1)) c 
join (
    select *
     from tab1
     where tab in (2)) a on a.customer = c.customer
     join
        (select *
         from tab1
         where tab in (3)) b on c.customer = b.customer;