Question

我的数据库记录采用列格式：

ingredient    product
Ing1            AAA
Ing1            BBB
Ing2            AAA
Ing2            BBB
...             ...

我希望看到格式数据：

product    ingredient1      ingredient2
AAA           Ing1              Ing2
BBB           Ing1              Ing2

select *
from
(
  select product, ingredient
  from db 
) as d
pivot
(
  max(ingredient)
  for ingredient in ( ingredient1 , ingredient2)
) piv

但此查询返回空ingredient1和ingredient2。

Answer 1

我建议你使用这种类型的查询：

SELECT
    product,
    MAX(CASE WHEN ingredient = 'Ing1' THEN ingredient END) AS ingredient1,
    MAX(CASE WHEN ingredient = 'Ing2' THEN ingredient END) AS ingredient2
FROM 
    db
GROUP BY
    product;

Answer 2

在PIVOT IN([Ing1], [Ing2])中，您应该使用值的原始名称，稍后您可以在以下内容中对它们进行别名：

SELECT product, 
       [Ing1] as [Ingridient1], 
       [Ing2] as [Ingridient2]
FROM
(
  SELECT product, ingredient
  FROM #t1 
) AS d
PIVOT
(
  MAX(ingredient)
  FOR ingredient IN ([Ing1], [Ing2])
) piv

您可以在 SQL FIDDLE

查看工作示例

Answer 3

您可以将动态数据透视表编写为：

declare @Finalcollist varchar(max), @collist varchar(max)
declare @sql nvarchar(max)

select @Finalcollist = COALESCE(@Finalcollist + ', ','') 
                      + QUOTENAME(ingredient) +' AS '
                      + Replace (QUOTENAME(ingredient),'Ing','Ingredient')
from 
( SELECT DISTINCT ingredient FROM test1) T (ingredient)


select @collist = COALESCE(@collist + ', ','') 
                      + QUOTENAME(ingredient)                     
from 
( SELECT DISTINCT ingredient FROM test1) T (ingredient)

select @Finalcollist,@collist -- This givesdynamic column list

-- Now setting this @Finalcollist variable in the Dynamic SQL.
set @sql = '
select product, ' + @Finalcollist + '
from 
(select product,ingredient from test1
 )p
PIVOT(MAX (ingredient) FOR ingredient IN ( ' + @collist + ' )
) AS pvt
ORDER BY product'

--print @sql

EXECUTE sp_executesql @sql

DEMO

Answer 4

这里有一些有趣的试用版，你可以拥有尽可能多的Ing，它会增加列数。

CREATE TABLE #temp(ing nvarchar(5), pr nvarchar(5))
INSERT INTO #temp values ('Ing1','AA')
INSERT INTO #temp values ('Ing1','BB')
INSERT INTO #temp values ('Ing2','AA')
INSERT INTO #temp values ('Ing2','BB')
INSERT INTO #temp values ('Ing3','AA')

DECLARE @PivotCols VARCHAR(MAX);
SELECT @PivotCols = COALESCE(@PivotCols + ',','') + QUOTENAME(ing) FROM #temp GROUP BY ing ORDER BY ing
EXEC
(
'SELECT * FROM #temp PIVOT
(
    MAX(ing) FOR ing IN (' + @PivotCols + ')
) pvt
')

DROP TABLE #temp

这将导致;

pr    Ing1  Ing2  Ing3
----- ----- ----- -----
AA    Ing1  Ing2  Ing3
BB    Ing1  Ing2  NULL

SQL Server将列格式更改为行

4 个答案: