Question

从这样的表格中：

CREATE TABLE dbo.mytable 
(
     [ID] int, 
     [Category] INT, 
     [Lh] varchar(30), 
     [Sev] INT, 
     [Risk] INT
)

insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (5, 2, 'Impossible', 4, 10)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 2, 'Unlikely', 3, 13)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 3, 'Possible', 3, 18)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 5, 'Likely', 3, 23)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 6, 'Possible', 3, 18)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (7, 2, 'Impossible', 5, 15)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (8, 2, 'Very Unlikely', 5, 20)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (9, 2, 'Unlikely', 6, 30)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (10, 2, 'Impossible', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (10, 6, 'Impossible', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 1, 'Impossible', 4, 10)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 2, 'Very Unlikely', 5, 20)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 4, 'Impossible', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (13, 2, 'Impossible', 6, 21)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (14, 2, 'Impossible', 6, 21)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (15, 1, 'Very Unlikely', 3, 6)
insert into mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (15, 2, 'Impossible', 5, 15)

我正在尝试创建一个看起来像这样的结果集（请记住，可能有任意数量的类别，但每个类别总是有3个组件）：

ID  Cat_1_Lh    Cat_1_Sev   Cat_1_Risk  Cat_2_Lh    Cat_2_Sev   Cat_2_Risk  Cat_3_Lh    Cat_3_Sev   Cat_3_Risk  Cat_4_Lh    Cat_4_Sev   Cat_4_Risk  Cat_5_Lh    Cat_5_Sev   Cat_5_Risk  Cat_6_Lh    Cat_6_Sev   Cat_6_Risk
5                                       Impossible      4           10                                              
6                                       Unlikely        3           13      Possible        3           18                                          Likely          3           23      Possible        3           18
7                                       Impossible      5           15                                              
8                                       Very Unlikely   5           20                                              
9                                       Unlikely        6           30                                              
10                                      Impossible      3           6                                                                                                                   Impossible      3            6
12  Impossible      4           10      Very Unlikely   5           20                                          Impossible      3           6                       
13                                      Impossible      6           21                                              
14                                      Impossible      6           21                                              
15  Very Unlikely   3           6       Impossible      5           15

我已经查看并尝试修改此处提供的一系列pivot和unpivot解决方案，其中包含动态和静态列定义，但没有一个看起来像他们有最慢的工作机会所以我不知道哪些建议可以用于解决方案。

我非常感谢有关哪种流程/机制最适合这种情况的一些指导。

提前致谢。

Answer 1

如果你不介意动态

Declare @SQL varchar(max) = ''
Declare @BaseCols varchar(max) ='
,Cat_#_Lh   = max(case when Category=# then LH   else '''' end)
,Cat_#_Sev  = max(case when Category=# then cast(Sev  as varchar(25)) else '''' end)
,Cat_#_Risk = max(case when Category=# then cast(Risk as varchar(25)) else '''' end)
'
Select @SQL = @SQL + Replace(@BaseCols,'#',Category) from (Select Distinct Category from myTable) A 
Set @SQL = 'Select ID'+@SQL + ' From myTable Group By ID Order by ID'
Exec(@SQL)

返回

Answer 2

解决此问题的一种天真的方法是编写这样的查询

;with cte_lh as (
select Id, max([1]) as Cat_1_lh,max([2]) as Cat_2_lh,max([3]) as Cat_3_lh,max([4]) as Cat_4_lh,max([5]) as Cat_5_lh,max([6]) as Cat_6_lh from mytable 
pivot(max(Lh) for Category in ([1],[2],[3],[4],[5],[6])) as p
group by id
), cte_sev as (
select id,  max([1]) as Cat_1_Sev,max([2]) Cat_2_Sev,max([3]) Cat_3_Sev,max([4]) Cat_4_Sev,max([5]) Cat_5_Sev,max([6]) Cat_6_Sev from mytable
pivot (max(sev) for category in ([1],[2],[3],[4],[5],[6])) as p
group by id
), cte_risk as (
select id,  max([1]) Cat_1_Risk,max([2]) Cat_2_Risk,max([3]) Cat_3_Risk,max([4]) Cat_4_Risk,max([5]) Cat_5_Risk,max([6]) Cat_6_Risk from mytable
pivot (max(risk) for category in ([1],[2],[3],[4],[5],[6])) as p
group by id
) select * from cte_lh lh join cte_sev sev on lh.id = sev.id
join cte_risk risk on lh.id = risk.id

我们可以在动态sql中创建列并添加列并在列列表变化时创建动态sql。

Answer 3

这需要使用动态查询来完成，即使使用技巧，仍然不支持动态数量的列。以下是创建表的动态SQL示例。我把它留给你。

DECLARE @stmt nvarchar(max) = '
DECLARE @tbl TABLE
(
    '

DECLARE @mytable TABLE
(
     [ID] int, 
     [Category] INT, 
     [Lh] varchar(30), 
     [Sev] INT, 
     [Risk] INT
)

insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (5, 2, 'Impossible', 4, 10)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 2, 'Unlikely', 3, 13)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 3, 'Possible', 3, 18)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 5, 'Likely', 3, 23)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (6, 6, 'Possible', 3, 18)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (7, 2, 'Impossible', 5, 15)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (8, 2, 'Very Unlikely', 5, 20)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (9, 2, 'Unlikely', 6, 30)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (10, 2, 'Impossible', 3, 6)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (10, 6, 'Impossible', 3, 6)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 1, 'Impossible', 4, 10)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 2, 'Very Unlikely', 5, 20)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (12, 4, 'Impossible', 3, 6)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (13, 2, 'Impossible', 6, 21)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (14, 2, 'Impossible', 6, 21)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (15, 1, 'Very Unlikely', 3, 6)
insert into @mytable ([ID], [Category], [Lh], [Sev], [Risk]) values (15, 2, 'Impossible', 5, 15)

DECLARE @categories TABLE
(
    [Category] INT
)

INSERT @categories SELECT DISTINCT [Category] FROM @mytable ORDER BY [Category]

WHILE ((SELECT TOP 1 [Category] FROM @categories ORDER BY [Category]) IS NOT NULL)
BEGIN
    DECLARE @category int = (SELECT TOP 1 [Category] FROM @categories ORDER BY [Category])
    SET @stmt = @stmt + '[Cat_' + CAST(@category AS VARCHAR(max)) + '_Lh] VARCHAR(MAX)
    ,[Cat_' + CAST(@category AS VARCHAR(max)) + '_Sev] INT
    ,[Cat_' + CAST(@category AS VARCHAR(max)) + '_Risk] INT
' + CASE
        WHEN (SELECT count(*) FROM @categories) > 1 THEN '  ,'
        ELSE ')'
        END
DELETE TOP (1) FROM @categories
END

SET @stmt = @stmt + '

SELECT * FROM @tbl [tbl]'

EXEC sp_executesql @stmt

SQL Server Pivot使用多组列

3 个答案: