0

我有一张像

 ID     option
 1      optionA
 1      optionB
 1      optionC
 1      optionD

我想要这样的结果：

ID    A        B       C       D
1  optionA  optionB optionC optionD

做这个的最好方式是什么？

我尝试过的查询是

select * from TableName PIVOT (option for ID = 2674 )) as abc

这将不起作用，因为 PIVOT 需要聚合函数..

我也尝试过这样的 COALESCE

declare @t table(num VARCHAR(100))
insert into @t 
    select choice FROM QuestionAnswers where QuestionID=2674
select num from @t
declare @s varchar(8000)
select  @s = COALESCE(@s + ',', '') + num
from    @t
exec('select '+@s)

但这也不起作用..

4

2 回答 2

4

这种类型的数据转换称为数据透视。在 SQL Server 2005+ 中，有一个函数可以为您执行此数据轮换。但是，您可以通过多种方式执行此数据转换。

这是一个PIVOT适用于您的示例数据的查询：

select *
from
(
  select id, [option], right([option], 1) col
  from yourtable
) src
pivot
(
  max([option])
  for col in (a, b, c, d)
) piv

请参阅SQL Fiddle with Demo。

这也可以使用带有CASE表达式的聚合函数来执行：

select id,
  max(case when col = 'a' then [option] else null end) a,
  max(case when col = 'b' then [option] else null end) b,
  max(case when col = 'c' then [option] else null end) c,
  max(case when col = 'd' then [option] else null end) d
from
(
  select  id, [option], right([option], 1) col
  from yourtable
) src
group by id

请参阅SQL Fiddle with Demo。

您可以在表上执行多个连接：

select a.id,
  a.[option] a,
  b.[option] b,
  c.[option] c,
  d.[option] d
from yourtable a
left join yourtable b
  on a.id = b.id
  and right(b.[option], 1) = 'b'
left join yourtable c
  on a.id = c.id
  and right(c.[option], 1) = 'c'
left join yourtable d
  on a.id = d.id
  and right(d.[option], 1) = 'd'
where right(a.[option], 1) = 'a'

请参阅带有演示的 SQL Fiddle

最后，如果要转换为列的值未知，则可以使用动态 sql 来完成：

DECLARE @colsName AS NVARCHAR(MAX),
    @cols AS NVARCHAR(MAX),
    @query  AS NVARCHAR(MAX)

select @colsName = STUFF((SELECT distinct ', ' + QUOTENAME(right([option], 1)) +' as '+ right([option], 1)
                    from yourtable
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')

select @cols = STUFF((SELECT distinct ', ' + QUOTENAME(right([option], 1))
                    from yourtable
            FOR XML PATH(''), TYPE
            ).value('.', 'NVARCHAR(MAX)') 
        ,1,1,'')


set @query = 'SELECT id, ' + @colsName + ' from 
             (
                select id, [option], right([option], 1) col
                from yourtable
            ) x
            pivot 
            (
                max([option])
                for col in (' + @cols + ')
            ) p '

execute(@query)

请参阅带有演示的 SQL Fiddle

所有查询的结果是：

| ID |       A |       B |       C |       D |
----------------------------------------------
|  1 | optionA | optionB | optionC | optionD |
于 2013-01-29T11:41:43.153 回答
0 
CREATE TABLE Product(Cust VARCHAR(25), Product VARCHAR(20), QTY INT)
GO
-- Inserting Data into Table
INSERT INTO Product(Cust, Product, QTY)
VALUES('KATE','VEG',2)
INSERT INTO Product(Cust, Product, QTY)
VALUES('KATE','SODA',6)
INSERT INTO Product(Cust, Product, QTY)
VALUES('KATE','MILK',1)
INSERT INTO Product(Cust, Product, QTY)
VALUES('KATE','BEER',12)
INSERT INTO Product(Cust, Product, QTY)
VALUES('FRED','MILK',3)
INSERT INTO Product(Cust, Product, QTY)
VALUES('FRED','BEER',24)
INSERT INTO Product(Cust, Product, QTY)
VALUES('KATE','VEG',3)
GO
-- Selecting and checking entires in table
SELECT *
FROM Product
GO
-- Pivot Table ordered by PRODUCT
SELECT PRODUCT, FRED, KATE
FROM (
SELECT CUST, PRODUCT, QTY
FROM Product) up
PIVOT (SUM(QTY) FOR CUST IN (FRED, KATE)) AS pvt
ORDER BY PRODUCT
GO
-- Pivot Table ordered by CUST
SELECT CUST, VEG, SODA, MILK, BEER, CHIPS
FROM (
SELECT CUST, PRODUCT, QTY
FROM Product) up
PIVOT (SUM(QTY) FOR PRODUCT IN (VEG, SODA, MILK, BEER, CHIPS)) AS pvt
ORDER BY CUST
GO
-- Unpivot Table ordered by CUST
SELECT CUST, PRODUCT, QTY
FROM
(
SELECT CUST, VEG, SODA, MILK, BEER, CHIPS
FROM (
SELECT CUST, PRODUCT, QTY
FROM Product) up
PIVOT
( SUM(QTY) FOR PRODUCT IN (VEG, SODA, MILK, BEER, CHIPS)) AS pvt) p
UNPIVOT
(QTY FOR PRODUCT IN (VEG, SODA, MILK, BEER, CHIPS)
) AS Unpvt
GO
-- Clean up database
DROP TABLE Product
GO

参考http://blog.sqlauthority.com/2008/06/07/sql-server-pivot-and-unpivot-table-examples/

已编辑

DECLARE @Product TABLE (ID int, _option varchar(10) )

-- Inserting Data into Table
INSERT INTO @Product
(
    ID,
    _option
)
SELECT 1, 'optionA' UNION ALL
SELECT 1, 'optionB' UNION ALL
SELECT 1, 'optionC' UNION ALL
SELECT 1, 'optionD' 

SELECT 
    optionA, optionB, optionC, optionD
FROM (
SELECT ID, _option
FROM @Product) up
PIVOT (SUM(ID) FOR _option IN (optionA, optionB, optionC, optionD)) AS pvt
于 2013-01-29T11:35:41.713 回答