MDX

Question

考虑到维度中的开始日期和结束日期，我需要在日期范围内计算按日期分组的度量。 objective是统计一段时间内某学校每天活跃的学生人数

以下 SQL 代码适用于数据仓库（多维数据集的来源）。

SELECT 
     t.[date]
    ,count(distinct a.SKStudent) as Students
FROM DM.DimTime t
    CROSS JOIN DM.FactStudents a 
    INNER JOIN DM.DimStudents m ON a.SKStudent = m.SKStudent
    INNER JOIN DM.DimSchool e ON a.SKSchool = e.SKSchool
WHERE t.[date] between '20170502' and '20170512'
    and e.SchoolCode = 123456
    and t.[date] between m.[StartDate] and m.[EndtDate]
GROUP BY t.[data]

结果集如下：

+--------------+----------+ 
| date         | Students |
+--------------+----------+ 
| 2017-05-02   |    567   |
| 2017-05-03   |    567   |
| 2017-05-04   |    568   |
| 2017-05-05   |    570   |
| 2017-05-06   |    570   |
| 2017-05-07   |    570   |
| 2017-05-08   |    573   |
| 2017-05-09   |    573   |
| 2017-05-10   |    571   |
| 2017-05-11   |    568   |
| 2017-05-12   |    568   |
+--------------+----------+

我试着做了MDX代码。以下是我尝试过的。我不知道如何使用 CASE 语句中的逻辑（在 '???' 标记之间）过滤日期：

WITH SET DateRange AS 
    [Dim Time].[Date].&[20170502]:[Dim Time].[Date].&[20170512]
MEMBER StudentsByDay AS 
    AGGREGATE(DateRange, 
        ???CASE WHEN DateRange.CURRENTMEMBER 
                    BETWEEN [Dim Students].[Start Date] 
                        AND [Dim Students].[End Date] 
                THEN [Measures].[Students Count]
            ELSE NULL END???)
SELECT 
    NON EMPTY { [StudentsByDay] } ON COLUMNS,
    NON EMPTY { [DateRange] } ON ROWS
FROM [Education]
WHERE ( [Dim School].[School Code].&[123456] )

Answer 1

MDX 不像 SQL 那样灵活。我建议将以下条件放入您的 FactStudents table:

t.[date] between m.[StartDate] and m.[EndtDate]

并像单独的措施一样使用或替换现有的措施。

你需要以下东西：

事实 table 带有 DateID、StudentID 字段（参见下面的代码）；
与Student和Date dims相关的度量组；
在 StudentID 字段上使用 DistinctCount 聚合的度量。

事实代码：

SELECT 
     t.[date] as DateID
    ,a.[SKStudent] as StudentID
FROM DM.DimTime t
    CROSS JOIN DM.FactStudents a 
    INNER JOIN DM.DimStudents m ON a.SKStudent = m.SKStudent
    INNER JOIN DM.DimSchool e ON a.SKSchool = e.SKSchool
WHERE e.SchoolCode = 123456
    and t.[date] between m.[StartDate] and m.[EndtDate]

MDX - 如何根据维度中的开始和结束日期按日期聚合

MDX - How to aggregate by date considering start and end date in a dimension

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