将两个表的结果作为行，将第三个表连接为其他列答案

【问题标题】：Results from two tables as rows, joining a third for additional columns将两个表的结果作为行，将第三个表连接为其他列
【发布时间】：2018-07-26 12:45:42
【问题描述】：

尝试从 3 个表中提取数据：warpall, warpalq, warcmdt

我希望将来自warpall/warpalq 的数据作为同一结果中的行返回（所以首先是warpall 数据，然后是下面的warpalq 数据），加入warcmdt，因为它有我需要的描述返回。我无法合并它们，因为 warpalq 中没有我需要的一个字段。

有人可以建议如何解决这个问题吗？

select clntpm, pal#pm, clsspm, clsqpm, **commpm**  from warpall
where <criteria>

select clntpq, pal#pq, clsspq, clsqpq from warpalq
where <different criteria>

join warcmdt on warcmdt.clntcd = warpall.clntpm and warcmdt.commcd = 
warpall.commpm

--- 编辑

我现在的语法是；

select 
  * from (select substr(warpall.clntpm,1,2) as clntwf, 
substr(warpall.pal#pm,1,10) as pal#wf, commpm, substr(warpall.clsspm,1,2) as 
clsswf, warpall.clsqpm * 1 as clsqwf from warpall

where locnpm <> 'ASSEMBLED PALLET'
and commpm <> 'ASSEMBLED PALLET'
and clsqpm <> 0

union all

select substr(clntpq,1,2) as clntwf, substr(pal#Pq,1,10) as pal#wf, null 
commpm, substr(clsspq,1,2) as clsswf, clsqpq * 1 as clsqwf from warpalq
where clsqpq <> 0
) as t9
inner join 
  warcmdt as t3
on 
  t3.clntcd = t9.clntwf  and t3.commcd = t9.commpm

【问题讨论】：

标签： sql join union db2-400

【解决方案1】：

知道了。 As400/db2 需要 '0' 用于空列。

select 
clntwf, commpm, fdsccd, clsqf, pal#wf, dtcdpm, clsswf, srb#pm, descsc
from (select substr(warpall.clntpm,1,2) as clntwf,
substr(warpall.pal#pm,1,10) as pal#wf, commpm, 
substr(warpall.clsspm,1,2) as clsswf, warpall.clsqpm * 1 as clsqwf, 
srb#pm, dtcdpm from warpall

where locnpm <> 'ASSEMBLED PALLET'
and commpm <> 'ASSEMBLED PALLET'
and clsqpm <> 0

union all

select substr(clntpq,1,2) as clntwf, substr(pal#pq,1,10) as pal#wf, '0', 
substr (clsspq,1,2) as clsswf, clsqpq * 1 as clsqwf, '0', '0' from warpalq
where clsqpq <> 0
) as t9
Inner join
warcmdt as t3
on 
t3.clntcd = t9.clntwf 
and 
t3.commcd = t9.commpm
inner join
warclss as t4
on
t4.clsssc = t9.clsswf

order by pal#wf asc

【讨论】：