我的SQL代码执行结果为空，没报错。【有好答案我可以加悬赏，求助！】

Question

我的这段SQL代码，执行了1个小时，没有报错，但是最终结果是“空”，求助。
（1）这段代码应该怎么优化？
（2）这段代码为什么执行完是空？

with sanlian as (
select uuid, att_user, intrst_user, inten_user, car_owner, top1att, top3att, top5att, hour_prf, level_prf, series_prf, spec_prf, brand_prf, place_prf, price_prf, leads_num, leads_series
from AA表
where uuid in(select distinct uuid from AA表) and substr(dt,1,7) = '2018-10'
),
fulltable as(
select uuid, age_age as age,
        sex_sex as sex,
        car_loan as car_loan,
        mortgage as mortgage,
        er_value as customer_value,
        du_level as edu_level,
        ge_name as stage,
        occupation as occupation,
        tal_status as marital_status,
        illing as loan_willing,
        city as city,
        concen as concen,
        interval_day as interval_day
from BB表
where seri = '1'
),
atttime as(
select b.uuid, a.att_time
from(
    ( select uuid, cookie from CC表) b
    join
    (select cookie, sum(att_time) as att_time
    from DD表
    where substr(dt,1,7) = '2018-10' cookie <> '0'
    group by cookie
    ) a
    on a. cookie = b.cookie
    )
),
inten as (
select b.uuid, a.ordernum
from(
    (
    select phone, sum(ordernum) as ordernum
    from EE表 
    where substr(dt,1,7) = '2018-10' and series_id = '1'
    group by phone
    ) a
join
    (
    select uuid, phone
    from FF表
    )b
on a.phone = b.phone
    )
),
fangwen as(
    select uuid, y_id, y_name, sum(y_ratio) as y_ratio, sum(n_ratio) as n_ratio
    from GG表
    where substr(dt,1,7) = '2018-10' and series_id = '1' 
    group by uuid, y_id, y_name
)

select *
from sanlian as a
left join atttime as e
on a.uuid = e.uuid
full join intention as b
on a.uuid = b.uuid
left join fangwen as f
on a.uuid = f.uuid
join fulltable as g
on a.uuid = g.uuid

最后*是35个来自a\b\e\f\g的变量。

Answer 1

参考GPT和自己的思路：

针对你的问题，我可以提供以下回答：

（1）对于代码的优化，首先建议对代码进行排查和调试，检查表之间的关联关系和查询条件是否正确，以及是否有数据丢失、重复等问题。其次，可以考虑对查询语句进行简化，避免不必要的嵌套和重复操作。另外也可以对表进行合并或者使用索引等方式来优化代码执行效率。

（2）造成结果为空的原因可能有很多，需要具体排查。可能是原始数据表中没有符合查询条件的数据，也可能是查询结果被误归为NULL或者空值，还有可能是查询结果存在错误但是没有被报错。建议根据具体情况进行调试和修改代码。