tableau-api - Tableau - 计算日期小于另一个数据源的值的平均值

Question

我正在尝试计算 Tableau 中列的平均值，但问题是我正在尝试使用来自另一个数据源的单个日期值(基于过滤器)来仅计算考试日期 <= 的平均值从其他来源过滤的日期值。

注意:参数在这里对我不起作用，因为新的日期值不断添加到集合中。

我尝试了许多不同的方法，但最简单的方法是尝试使用计算字段，从其他数据源提取过滤后的考试日期。

它成功地可以提取过滤后的日期，但公式无法按预期工作。 2个版本的计算如下:

IF DATE(ATTR([Exam Date])) <= DATE(ATTR([Averages (Tableau Test Scores)].[Updated])) THEN AVG([Raw Score]) END

IF DATEDIFF('day', DATE(ATTR([Exam Date])), DATE(ATTR([Averages (Tableau Test Scores)].[Updated]))) > 1 THEN AVG([Raw Score]) END

基本上，我正在寻找 SQL Server 中的等效项:

SELECT AVG([Raw Score]) WHERE ExamDate <= (Filtered Exam Date)

下面的工作簿显示了我想要完成的任务的示例。目前它返回所有空白，可能是由于我尝试在计算中使用多对一比较。

非常感谢任何反馈!

Tableau Test Exam Workbook

Answer 1

我能够通过使用自定义 SQL 将表连接在一起并根据我的条件计算平均值来解决此问题，以获得我想要的列结果。

直接在 Tableau 中拥有此功能仍然很棒，但无论如何都能完成工作。

编辑:

SELECT 
[AcademicYear]
,[Discipline]
--Get the number of student takers
,COUNT([Id]) AS [Students (N)]
--Get the average of the Raw Score
,CAST(AVG(RawScore) AS DECIMAL(10,2)) AS [School Mean]
--Get the number of failures based on an "adjusted score" column
,COUNT([AdjustedScore] < 70 THEN 1 END) AS [School Failures]
--This is the column used as the cutoff point for including scores
,[Average_Update].[Updated]
FROM [dbo].[Average] [Average]

FULL OUTER JOIN [dbo].[Average_Update] [Average_Update] ON ([Average_Update].[Id] = [Average].UpdateDateId)

--The meat of joining data for accurate calculations
FULL OUTER JOIN (
SELECT DISTINCT S.[Id], S.[LastName], S.[FirstName], S.[ExamDate], S.[RawScoreStandard], S.[RawScorePercent], S.[AdjustedScore], S.[Subject], P.[Id] AS PeriodId
FROM [StudentScore] S
FULL OUTER JOIN
(
--Get only the 1st attempt
SELECT DISTINCT [NBOMEId], S2.[Subject], MIN([ExamDate]) AS ExamDate
FROM [StudentScore] S2
GROUP BY [NBOMEId],S2.[Subject]
) B
ON S.[NBOMEId] = B.[NBOMEId] AND S.[Subject] = B.[Subject] AND S.[ExamDate] = B.[ExamDate]
--Group in "Exam Periods" based on the list of periods w/ start & end dates in another table.
FULL OUTER JOIN [ExamPeriod] P 
ON  S.[ExamDate] = P.PeriodStart AND S.[ExamDate] <= P.PeriodEnd
WHERE S.[Subject] = B.[Subject]
GROUP BY P.[Id], S.[Subject], S.[ExamDate], S.[RawScoreStandard], S.[RawScorePercent], S.[AdjustedScore], S.[NBOMEId], S.[NBOMELastName], S.[NBOMEFirstName], S.[SecondYrTake]) [StudentScore]  
ON 
([StudentScore].PeriodId = [Average_Update].ExamPeriodId 
AND [StudentScore].Subject = [Average].Subject 
AND [StudentScore].[ExamDate] <= [Average_Update].[Updated])
--End meat


--Joins to pull in relevant data for normalized tables
FULL OUTER JOIN [dbo].[Student] [Student] ON ([StudentScore].[NBOMEId] = [Student].[NBOMEId])
INNER JOIN [dbo].[ExamPeriod] [ExamPeriod] ON ([Average_Update].ExamPeriodId = [ExamPeriod].[Id])
INNER JOIN [dbo].[AcademicYear] [AcademicYear] ON ([ExamPeriod].[AcademicYearId] = [AcademicYear].[Id])

--This will pull only the latest update entry for every academic year.
WHERE [Updated] IN (
SELECT DISTINCT MAX([Updated]) AS MaxDate
FROM [Average_Update]
GROUP BY[ExamPeriodId])

GROUP BY [AcademicYear].[AcademicYearText], [Average].[Subject], [Average_Update].[Updated], 
ORDER BY [AcademicYear].[AcademicYearText], [Average_Update].[Updated], [Average].[Subject]