Oracle 双 select 问题

Question

所以我在 Oracle 上有这两个表：

客户

cl_id  cl_name
1      John
2      Maria

付款

pa_id  pa_date        pa_status   cl_id
1      2017-01-01     1           1
2      2017-01-01     1           2
3      2017-02-01     1           1
4      2017-02-01     1           2
5      2017-03-01     0           1
6      2017-03-01     1           2

我需要一个 select 语句，它可以提供客户 ID、姓名和他最后付款的状态。所以我的 select 的最终结果应该是：

cl_id  cl_name  pa_status
1      John     0
2      Maria    1

这是有效的客户端 select：

select cl_id, cl_name from CLIENT;

这是 PAYMENT select 有效的最后状态：

select * from ( select pa_status from PAYMENT ORDER BY PA_DATE DESC) where rownum = 1;

所以现在，我需要让它们协同工作。我尝试了 2 种无效的方法：

select cl_id, cl_name, (select * from ( select pa_status from PAYMENT ORDER BY PA_DATE DESC) where rownum = 1 and PAYMENT.cl_id = CLIENT.CL_ID) as last_status from CLIENT;

错误：标识符无效

还有这个：

select cl_id, cl_name, (select * from ( select pa_status from PAYMENT ORDER BY PA_DATE DESC) where rownum = 1 ) as last_status from CLIENT;

这不会给我任何错误，但只会显示 John 的相同最后状态，即最后一条记录：

cl_id cl_name  last_status
1     John     0
2     Maria    0

谁能给我提示？

谢谢

Answer 1

这会获取客户的最大日期然后获取该日期的最高付款 ID。

with max_date as (
      select max(date) as max_date, cl_id from payments group by cl_id
)
select c.cl_id, c.cl_name, p.pa_sttus from client c
join payments p
on c.cl_id = p.cl_id
where p.pa_id = (select max(p2.pa_id) from payments p2
                  join max_date md
                  on p2.cl_id = md.cl_id
                  where p.cl_id = p2.cl_id 
                  and p2.pa_date = md.max_date
                  )

Answer 2

您需要使用解析函数。这种功能可以让你把你的数据分成一些组，然后按照你的意愿对每个组的数据进行排序。

你的情况：

Select * from (
Select id, name, status, row_number () over (partition by      p.cl_id order by p.pa_date desc) as rw
From client c join payments p on p.cl_id = c.cl_id)
Inn where inn.rw = 1;

Answer 3

首先为每个clientid 取最大值。

Select cl_id, max(pa_date) as pa_date from PAYMENTS group by cl_id

现在你带你的客户 table 并加入上面的子查询

select c.cl_id, c.cl_name,
(select pa_status from PAYMENT t where t.pa_date=p.pa_date and t.cl_id=p.cl_id)
from CLIENT c join (Select cl_id, max(pa_date) as pa_date from PAYMENTS group by cl_id) p on p.cl_id=c.cl_id

Answer 4

您可以在此处使用 Oracle 的 KEEP LAST：

select cl_id, c.cl_name, last_payment.status
from client
join
(
  select 
    cl_id,
    max(pa_status) keep (dense_rank last order by pa_date) as status
  from payments
  group by cl_id
) last_payment using (cl_id);

（如果您想包括没有付款的客户，请将联接更改为 LEFT OUTER JOIN。）

Oracle 双 select 问题

Oracle double select issue

oracle

select

rownum