在联合之后只返回一条记录

Posted 2021-04-15

将SQL接口用于AS / 400（iSeries）DB2数据库，但运行并发布托盘信息可以存储在两个表中的位置，一个用于未分配的库存(warpall)，另一个用于分配的库存(warpalq)。我需要在适用的情况下从两个表中返回记录。

warpalq只有少数几个与warpall有关的领域我需要从warpall获得的一个领域也被用来加入另一个表格，warpalq没有相关领域。

我正在使用union从一个结果集中的两个表中返回数据，然后加入其他表。

问题是，当在结果集上加入第三个表(warcmdt)时，它在commpm和fdsccd字段中具有空值/ 0，因为它在相应的表中没有数据。

有没有办法让commpm和fdsccd回到第2行的结果集？交联将是pal#pm = pal#pq，因此存在相对联系。

在下面运行SQL会返回此结果集。

select 
clntwf, commpm, fdsccd, clsqwf, pal#wf, dtcdpm, clsswf, srb#pm, descsc, 
cor#or  

from
(select substr(warpall.clntpm,1,2) as clntwf, pal#pm as pal#wf, commpm, 
substr(warpall.clsspm,1,2) as clsswf, warpall.clsqpm * 1 as clsqwf, srb#pm, 
dtcdpm, srd#pm 
from warpall

where 
locnpm <> 'ASSEMBLED PALLET'
and commpm <> 'ASSEMBLED PALLET'
and clsqpm <> 0
and clntPM <> 'D2'
and pal#pm = '1005609592'

union all

select substr(clntpq,1,2) as clntwf, pal#Pq as pal#wf, '0', 
substr(clsspq,1,2) as clsswf, clsqpq * 1 as clsqwf, '0', '0', '0' 
from warpalq

where 
clsqpq <> 0
and clntPQ <> 'D2'
and pal#pq = '1005609592'

) as t9

left outer join warcmdt as t3
on 
t3.clntcd = t9.clntwf  and t3.commcd = t9.commpm

left join
warclss as t4
on
t4.clsssc = t9.clsswf

left join
warohrh as t5
on
t5.clntor = t9.clntwf 
and t5.srn#or = t9.srd#pm

order by pal#wf asc

答案

您可以尝试使用这样的公用表表达式（CTE）：

with 
  pal (clntwf, pal#wf, commpm, clsswf, clsqwf, 
       srb#pm, dtcdpm, srd#pm) as (
    select
      substr(warpall.clntpm,1,2) as clntwf, 
      warpall.pal#pm as pal#wf, 
      warpall.commpm, 
      substr(warpall.clsspm,1,2) as clsswf, 
      warpall.clsqpm * 1 as clsqwf, 
      warpall.srb#pm, 
      warpall.dtcdpm, 
      warpall.srd#pm 
    from warpall
    where 
      warpall.locnpm <> 'ASSEMBLED PALLET'
      and warpall.commpm <> 'ASSEMBLED PALLET'
      and warpall.clsqpm <> 0
      and warpall.clntPM <> 'D2'
      and warpall.pal#pm = '1005609592'),

   alc (clntwf, pal#wf, commpm, clsswf, clsqwf, 
        srb#pm, dtcdpm, srd#pm) as (
     select 
       substr(warpalq.clntpq,1,2) as clntwf, 
       warpalq.pal#Pq as pal#wf, 
       pal.commpm, 
       substr(warpalq.clsspq,1,2) as clsswf, 
       warpalq.clsqpq * 1 as clsqwf, 
       '0', 
       '0', 
       pal.srd#pm 
     from warpalq
       join pal
         on waarpalq.pal#pq = pal.pal#wf
     where 
       warpalq.clsqpq <> 0
       and warpalq.clntPQ <> 'D2'
       and warpalq.pal#pq = '1005609592')

select 
  clntwf, commpm, fdsccd, clsqwf, pal#wf, dtcdpm, clsswf, srb#pm, descsc, cor#or  
from
  (select *
     from pal
   union all
   select *
     from alc
  ) as t9
  left outer join warcmdt as t3
    on t3.clntcd = t9.clntwf 
      and t3.commcd = t9.commpm
  left join warclss as t4
    on t4.clsssc = t9.clsswf
  left join warohrh as t5
    on t5.clntor = t9.clntwf 
      and t5.srn#or = t9.srd#pm
order by pal#wf asc

这使您可以在多个地方重复使用pal CTE而无需重新定义它。这意味着你可以将它加入alc CTE以获得commpm，后来用于加入t9和warcmdt。现在你不应该得到那个null。我还将srd#pm带到alc的warpall CTE，因为它用于t9和warohrh之间的连接。如果这不正确，您可以在pal.srd#pm CTE中用'0'替换alc。