如何在SQL中使用PIVOT获得实际结果？

我正在使用一个查询并得到结果。但我不需要这个结果，我需要另一个结果。我知道我想要显示的结果的查询是错误的。我很困惑地询问结果是如何产生的，以及是否有其他方法可以得到这个结果

declare @temp table(
  ProductId int,
  Caption nvarchar(max),
  Value nvarchar(max)
)

insert into @temp values (6830,'Stone Cut','Full Cut')
insert into @temp values (6830,'Stone Cut','Single Cut')
insert into @temp values (6830,'Gem Type','Diamond')
insert into @temp values (6830,'Gem Type','Diamond')
insert into @temp values (6830,'Total Diamond Weight','0.34')

insert into @temp values (6831,'Stone Cut','Full Cut')
insert into @temp values (6831,'Stone Cut','Single Cut')
insert into @temp values (6831,'Gem Type','Diamond')
insert into @temp values (6831,'Gem Type','Diamond')
insert into @temp values (6831,'Total Diamond Weight','0.35')

select ProductId
  , (case when [StoneCut] is null then '' else [StoneCut] end) as [StoneCut]
  , (case when [GemType] is null then '' else [GemType] end) as [GemType]
  , (case when [TotalDiamondWeight] is null then '' else [TotalDiamondWeight] end) as [TotalDiamondWeight]
from
(
  select ProductId, Caption, Value
  from @temp
) x
pivot
(
  max(Value)
  for Caption in([StoneCut], [GemType], [TotalDiamondWeight])
)p;

它显示了一行，就像

---------------------------------------------------
ProductId | StoneCut | GemType | TotalDiamondWeight
---------------------------------------------------
 6830     |Single Cut| Diamond | 0.34

但我想要这个输出：

---------------------------------------------------
ProductId | StoneCut | GemType | TotalDiamondWeight
---------------------------------------------------
 6830     |Full Cut  | Diamond | 0.34
 6830     |Single Cut| Diamond |
 6831     |Full Cut  | Diamond | 0.34
 6831     |Single Cut| Diamond |

---

这能回答你的问题吗

select * from (
select 
 ProductId, 
 StoneCut, 
 max(GemType) over (partition by ProductId) GemType,
 max(TotalDiamondWeight) over (partition by ProductId) TotalDiamondWeight
from
(
  select 
    ProductId, 
    IIF(Caption = 'StoneCut', Value, '') StoneCut,
    IIF(Caption = 'GemType', Value, '') GemType,
    IIF(Caption = 'TotalDiamondWeight', Value, '') TotalDiamondWeight
  from @temp
) t
)t2
where StoneCut != ''

---

您可以通过使用

行编号（）

向集合中添加唯一的行来尝试此操作

您将获得所需的输出

输出：

+-----------+------------+----------+----------------------+
| productid | Stone Cut  | Gem Type | Total Diamond Weight |
+-----------+------------+----------+----------------------+
| 6830      | Full Cut   | Diamond  | 0.34                 |
+-----------+------------+----------+----------------------+
| 6830      | Single Cut | Diamond  | NULL                 |
+-----------+------------+----------+----------------------+
| 6831      | Full Cut   | Diamond  | 0.35                 |
+-----------+------------+----------+----------------------+
| 6831      | Single Cut | Diamond  | NULL                 |
+-----------+------------+----------+----------------------+

---

似乎您必须获得表中的2个分组，并将它们与UNION组合：

select
  ProductId,
  min(case when Caption = 'StoneCut' then Value end) StoneCut,
  min(case when Caption = 'GemType' then Value end) GemType,
  min(case when Caption = 'TotalDiamondWeight' then Value end) TotalDiamondWeight
from temp
group by ProductId
union 
select
  ProductId,
  max(case when Caption = 'StoneCut' then Value end) StoneCut,
  max(case when Caption = 'GemType' then Value end) GemType,
  max(case when Caption = 'TotalDiamondWeight' then Value end) TotalDiamondWeight
from temp
group by ProductId

---

请参阅您有一行，因为

ProductId

对于每一行总是相同的。当您使用运算符

MAX（）

时，就得到了一行

MAX（）

的

值。但是，如果希望有其他行，则只需区分这些行：

SELECT 
  p.ProductId
, p.TotalDiamondWeight
, p.GemType
, p.StoneCut
FROM
(
    SELECT ProductId,
           Caption,
           Value,
           ROW_NUMBER() OVER (PARTITION BY Caption ORDER BY Value) RN
    FROM @temp
) x
PIVOT
(
    MAX(Value)
    FOR Caption IN ([StoneCut], [GemType], [TotalDiamondWeight])
) p;

很好用。但是我有另一个问题，当产品id不同时，它会出错。你能更新你问题中的样本数据和预期输出吗。我将尝试修复查询。我刚刚更改了数据和预期输出。请看一看。我已经猜出了答案，请检查并确认您是否仍然得到答案。它正按照我的要求完美地工作着。非常感谢你。
SELECT 
  p.ProductId
, p.TotalDiamondWeight
, p.GemType
, p.StoneCut
FROM
(
    SELECT ProductId,
           Caption,
           Value,
           ROW_NUMBER() OVER (PARTITION BY Caption ORDER BY Value) RN
    FROM @temp
) x
PIVOT
(
    MAX(Value)
    FOR Caption IN ([StoneCut], [GemType], [TotalDiamondWeight])
) p;