Oracle查询消除不考虑Null的重复项

Question

我执行了完整的外部联接，得到以下信息：

ColumnFromTable1          ColumnFromTable2
     AAA                       ABA
     AAA                       Null          <-  remove
     AAA                       ACC
     BBB                       Null
     CCC                       CDC
     Null                      EFE
     DDD                       FFF
     Null                      FFF           <-  remove
     GGG                       FFF

我真正想要的是压缩行以除去重复项，这样我的结果将是：

ColumnFromTable1          ColumnFromTable2
     AAA                       ABA
     AAA                       ACC
     BBB                       Null
     CCC                       CDC
     Null                      EFE
     DDD                       FFF
     GGG                       FFF

基本上我需要消除

AAA  Null
Null  FFF

因为我的AAA或FFF都为非空值。 但是我需要保持

BBB  Null
Null  EFE

因为没有BBB或EFE非零

我尝试修改我的完整外部联接（如果需要可以将其发布），还尝试将这些结果包装在子查询中。

在这里编辑是为此帖子简化的查询

select ColumnFromTable1, ColumnFromTable2 from Table1 t1
       full outer join Table2 t2 on t1.common_code = t2.common_code 
       group by ColumnFromTable1, ColumnFromTable2 

Answer 1

row_number()看起来很有希望：

select c1, c2
  from (
    select c1, c2, 
           row_number() over (partition by c1 order by c2) r1,
           row_number() over (partition by c2 order by c1) r2
      from t)
  where not ((c1 is null and r2 > 1) or (c2 is null and r1 > 1))

^演示

当空值不是按顺序排列时，它将消除空值。

Answer 2

将您已经在CTE中计算出的完整外部联接放入，您可以通过执行以下操作进一步过滤它：

with f (c1, c2) as (
  ... -- full outer join you already computed here
)
a (x) as ( -- repeated c1 with non-null c2
  select c1
  from f
  group by c1
  having count(c2) > 0
),
b (x) as ( -- repeated c2 with non-null c1
  select c2
  from f
  group by c2
  having count(c1) > 0
)
select *
from f
where not(c1 in (select x from a) and c2 is null)
  and not(c2 in (select x from b) and c1 is null)