Question

在SQL中，有没有办法添加不存在的行（基于某些组合）。

所有没有值的行：

Col-a Col-a 
Col-a Col-b 
Col-a Col-c 
...

数据库：

Col-a Col-a Val-a
Col-a Col-b Val-b
Col-b Col-a Val-c
Col-b Col-b Val-d
...

假设db中存在 Col-a Col-c 的行，我想添加Col-a, Col-c, 0，只是插入一个零值的缺失行。

示例：

1,1,50
1,2,100
2,2,100

所以这里我们缺少2,1因此加上2,1,0。我将给出一个[1,2]，其中两个值都应该存在。

预期产出：

1,1,50
1,2,100
2,1,0
2,2,100

有一种简单的方法吗？

Answer 1

你应该把它们“联合”起来......

select '' col-a, '' col-b, '' col-c, [null your_table.fields] 
union 
select '' col-a, '' col-b, '' col-c, your_table.*
from your_table

评论后的 更新以及原始问题中的结算：

你可以尝试这个sql语句..

select THeaders.col_a, THeaders.col_b, TSrcValues.col_c
from
(
  select 1 as col_a, 1 as col_b, 0 as col_c from dual
  union
  select 1 as col_a, 2 as col_b, 0 as col_c from dual
  union
  select 1 as col_a, 3 as col_b, 0 as col_c from dual
  union
  select 2 as col_a, 1 as col_b, 0 as col_c from dual
  union
  select 2 as col_a, 2 as col_b, 0 as col_c from dual
  union
  select 2 as col_a, 3 as col_b, 0 as col_c from dual
)THeaders
left join
(
  select TSrc.*
  from 
  (
    select 
    case when YourValue = 100 then 1 else case when YourValue = 200 then 2 else case when YourValue = 300 then 3 else 0 end end end col_a,
    case when YourValue = 100 then 1 else case when YourValue = 200 then 2 else case when YourValue = 300 then 3 else 0 end end end col_b,
    YourValue as col_c 
    from YourTable 
  ) TSrc
  where TSrc.col_a <> 0 or TSrc.col_b <> 0
) TSrcValues
on THeaders.col_a = TSrcValues.col_a and THeaders.col_b= TSrcValues.col_b
;

您应该在“case when”子句中个性化您的值范围

Answer 2

您的示例需要更清晰。但是，如果我理解正确，您需要找到第一列的所有唯一值，并将其与第二列的所有唯一值组合，如果该组合不存在，则插入该行：

Release

Here is a SQLFiddle显示SELECT组件正常工作

如果行不存在，如何添加组合值？

2 个答案: