具有独立 where 子句的多列 - SQL Pivot？

是否可以采用以下方式构建的表格：

ID    Month     Info1 Info2
1      1          A     B
1      2          C     D
1      3          E     F
2      3          G     H
2      4          I     J

最终形成这样的表格：

ID    JanInfo1 JanInfo2 FebInfo1 FebInfo2 MarInfo1 MarInfo2 AprInfo1 AprInfo2
1        A        B        C        D        E        F        NULL    NULL
2       NULL      NULL    NULL     NULL      G        H         I       J

我研究过使用枢轴但无法让它们工作。

我目前每个月都使用 CROSS APPLY 表值函数。

有一个更好的方法吗？

编辑：添加了现有查询 - 尝试简化显示：

-- Get the unique IDs
DECLARE @PersonIds TABLE
(
    UploadID UNIQUEIDENTIFIER,
    PersonId VARCHAR(200),
    RecordYear INT
)
INSERT INTO @PersonIds
    SELECT DISTINCT UploadID, PersonId, RecordYear
    FROM [VERTICALTABLE] 
    WHERE UploadID = @PTPUploadID
            AND RecordYear = @RecordYear
        GROUP BY  UploadID, PersonId, RecordYear

-- Flatten via functions
INSERT INTO [FLATTABLE](PersonID, JanuaryCoverage, FebruaryCoverage, MarchCoverage, AprilCoverage, MayCoverage, JuneCoverage, 
        JulyCoverage, AugustCoverage, SeptemberCoverage, OctoberCoverage, NovemberCoverage, DecemberCoverage)

    SELECT PID.PersonID, M1.Covered, M2.Covered, M3.Covered, M4.Covered, M5.Covered, M6.Covered,
        M7.Covered, M8.Covered, M9.Covered, M10.Covered, M11.Covered, M12.Covered
    FROM @PersonIds AS PID
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 1, PID.PersonId) AS M1
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 2, PID.PersonId) AS M2
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 3, PID.PersonId) AS M3
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 4, PID.PersonId) AS M4
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 5, PID.PersonId) AS M5
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 6, PID.PersonId) AS M6
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 7, PID.PersonId) AS M7
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 8, PID.PersonId) AS M8
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 9, PID.PersonId) AS M9
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 10, PID.PersonId) AS M10
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 11, PID.PersonId) AS M11
    OUTER APPLY GetMonthInfpo(@PTPUploadID, @RecordYear, 12, PID.PersonId) AS M12
    WHERE UploadID = @PTPUploadID 
        AND RecordYear = @RecordYear

函数看起来像

ALTER FUNCTION GetMonthInfpo( 
(   
    @UploadID UNIQUEIDENTIFIER,
    @Year INT,
    @Month INT,
    @PersonID VARCHAR(200)
)
RETURNS TABLE 
AS
RETURN 
(
    SELECT COUNT(*) AS 'Covered'
    FROM [VERTICALTABLE] 
    WHERE UploadID = @UploadID
        AND RecordYear = @Year
        AND RecordMonth = @Month
        AND PersonId = @PersonID
)

您不需要多个子查询。答案很简单——使用集合论。从您的第一个表 ID/Month/Info1/Info2 中执行 ID/Month + (1+2) /Info 的简单联合 - 例如：

select ID, cast(Month as varchar(10)) + cast('_1' as varchar(10)) ComposedMonth, Info1 Info 
from tbl
union all
select ID, cast(Month as varchar(10)) + cast('_2' as varchar(10)), Info2 
from tbl

然后使用该数据集（以视图或临时表的形式呈现）pivot clause.

select * 
from vw_tbl t
pivot (max(Info) for ComposedMonth in ([1_1], [1_2]...)) p
-- or if you will cast month to text
-- pivot (max(Info) for ComposedMonth in ([Jan_1], [Jan_2]...)) p

组合字符串是轻松旋转的关键。