SQL 服务器动态列创建

Question

我有一个 table 列和值如下

如何在第二个表格列中获取结果，动态列名称为 - 首先是 "prgmg_product_id"，其余列是 "source ID 1"，"source ID 2" , "source ID 3"

Answer 1

我有一点时间把它扔在一起。我知道围绕 SO 的偏好是使用动态枢轴。我不太关心 sql 服务器中的 PIVOT。我发现语法非常迟钝。我倾向于更喜欢交叉表查询（也称为条件聚合）。额外的好处是这种方法几乎总是比动态 PIVOT 稍微快一点。

您还必须认识到，此处 post 一半以上的代码都存在设置问题。将来你应该 post ddl 和像这样的可消费格式的样本数据。这让我们更容易提供帮助。

if OBJECT_ID('tempdb..#Something') is not null
    drop table #Something

create table #Something
(
    prgmg_product_id int,
    source_id_other int
)

insert #Something (prgmg_product_id, source_id_other) values
(3310, 11478),
(3337, 10833),
(3354, 11466),
(4039, 4846),
(4039, 65454),
(4039, 65456)

declare @StaticPortion nvarchar(2000) = 
    'with OrderedResults as
    (
        select *, ROW_NUMBER() over(partition by prgmg_product_id order by source_id_other) as RowNum
        from #Something
    )
    select prgmg_product_id';

declare @DynamicPortion nvarchar(max) = '';
declare @FinalStaticPortion nvarchar(2000) = ' from OrderedResults Group by prgmg_product_id order by prgmg_product_id desc';

with E1(N) AS (select 1 from (values (1),(1),(1),(1),(1),(1),(1),(1),(1),(1))dt(n)),
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS 
(
    SELECT  ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
)

select @DynamicPortion = @DynamicPortion + 
    ', MAX(Case when RowNum = ' + CAST(N as varchar(6)) + ' then source_id_other end) as SourceID' + CAST(N as varchar(6)) + CHAR(10)
from cteTally t
where t.N <= 
(
    select top 1 Count(*)
    from #Something
    group by prgmg_product_id
    order by COUNT(*) desc
)

declare @SqlToExecute nvarchar(max) = @StaticPortion + @DynamicPortion + @FinalStaticPortion;
exec sp_executesql @SqlToExecute

Answer 2

要使用动态 SQL 实现此目的，以下内容会有所帮助：

CREATE TABLE #Prgmg (
    prgmg_product_id INT
    ,source_id_other INT
    );

INSERT #Prgmg (
    prgmg_product_id
    ,source_id_other
    )
VALUES (3310,11478)
    ,(3337,10833)
    ,(3354,11466)
    ,(4039,4846)
    ,(4039,65454)
    ,(4039,65456);

DECLARE @DYColumns NVARCHAR(1000)
    ,@DYSqlQuery NVARCHAR(4000);

--  CREATE THE COLUMNS REQUIRED
SET @DYColumns = STUFF((
            SELECT DISTINCT ',' 
                    + N'sourceID' 
                    + CAST(ROW_NUMBER() OVER (PARTITION BY prgmg_product_id ORDER BY prgmg_product_id, source_id_other) AS NVARCHAR(10))    
            FROM #Prgmg
            FOR XML PATH('')
            ), 1, 1, '');

-- CREATE THE DYNAMIC SQL AND ADD IN THE CREATED COLUMNS
SET @DYSqlQuery = '
    SELECT prgmg_product_id,' 
        +   @DYColumns 
        +   ' FROM (
                SELECT prgmg_product_id
                    ,CAST(N''sourceID'' + CAST(ROW_NUMBER() OVER (
                        PARTITION BY prgmg_product_id ORDER BY prgmg_product_id, source_id_other
                        ) AS NVARCHAR(10)) AS NVARCHAR(100)) AS Col
                    ,source_id_other
                FROM #Prgmg S1
        ) X
        PIVOT(MIN(source_id_other) FOR Col IN (' + @DYColumns + ')) P'

EXECUTE sp_executesql @DYSqlQuery;

虽然这确实为您提供了解决方案，但您应该花时间理解所使用的概念。比如Columns的创建需要使用ROW_NUMBER and the how that maps to the use of the PIVOT。

SQL 服务器动态列创建

SQL Server dynamic columns creation

sql

sql-server

pivot