[英]How to insert new rows based on values in other columns in sql server?
我有一個如下的數據集:
Id A14_Comment A15_Comment A16_Comment
1 Comment1 null null
2 Comment2 Comment3 Comment4
3 null Comment5 Comment6
4 null null Comment7
我需要做的是獲得以下輸出:
Id A14_Comment A15_Comment A16_Comment Code
1 Comment1 null null A14
2 Comment2 Comment3 Comment4 A14
2 Comment2 Comment3 Comment4 A15
2 Comment2 Comment3 Comment4 A16
3 null Comment5 Comment6 A15
3 null Comment5 Comment6 A16
4 null null Comment7 A16
可以看出,我的目的是通過標記代碼來添加Code
列並復制行。 下面的查詢為我提供了需要為每行添加具有不同代碼的行的次數,但是無法找到一種有效的方法來完成其余的工作。
select Id, (
select count(*)
from (values (T.A14_Comment), (T.A15_Comment), (T.A16_Comment)) as v(col)
where v.col is not null and v.col <> ''
) from #Comments as T
任何幫助,將不勝感激。
我會用apply
:
select c.*, c.code
from #Comments c cross apply
(select c.code
from (values (c.A14_Comment, 'A14'), (c.A15_Comment, 'A15'), (c.A16_Comment, 'A16')
) v(col, code)
where col is not null
) c;
子查詢實際上是不必要的。 您可能會發現更簡單:
select c.*, v.code
from #Comments c cross apply
(values (c.A14_Comment, 'A14'), (c.A15_Comment, 'A15'), (c.A16_Comment, 'A16')
) v(col, code)
where v.col is not null
通過將表加入CTE:
with
codes as (
select 'A14' code
union all
select 'A15'
union all
select 'A16'
),
idcodes as (
select comments.id, codes.code
from comments cross join codes
)
select *
from comments c inner join idcodes i
on
c.id = i.id
and (
c.A14_Comment is not null and i.code = 'A14'
or
c.A15_Comment is not null and i.code = 'A15'
or
c.A16_Comment is not null and i.code = 'A16'
)
參見演示 。
結果:
> Id | A14_Comment | A15_Comment | A16_Comment | code
> -: | :---------- | :---------- | :---------- | :---
> 1 | Comment1 | null | null | A14
> 2 | Comment2 | Comment3 | Comment4 | A14
> 2 | Comment2 | Comment3 | Comment4 | A15
> 2 | Comment2 | Comment3 | Comment4 | A16
> 3 | null | Comment5 | Comment6 | A15
> 3 | null | Comment5 | Comment6 | A16
> 4 | null | null | Comment7 | A16
下面的查詢將給出預期的結果:
select * From (
select *,'A14' Code from #Comments where A14_Comment is not null union all
select *,'A15' Code from #Comments where A15_Comment is not null union all
select *,'A16' Code from #Comments where A16_Comment is not null) as xData order by ID,Code
ID A14_Comment A15_Comment A16_Comment Code
1 Comment1 NULL NULL A14
2 Comment2 Comment3 Comment4 A14
2 Comment2 Comment3 Comment4 A15
2 Comment2 Comment3 Comment4 A16
3 NULL Comment5 Comment6 A15
3 NULL Comment5 Comment6 A16
4 NULL NULL Comment7 A16
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