Min(date) 返回冲突的结果 - Tableau

Question

长期观察者，第一次发帖：

我目前正在使用 Tableau 中的 SQL 功能。我希望查询返回用户 ID (SQLCEC)、出席日期 (SQL 日期) 和用户第一次出席 (FirstAttendanceDate)。

SELECT [Attendees$].[CEC] AS [SQLCEC]

, [Attendees$].[Date] AS [SQL Date]
, [Data2].[FirstAttendanceDate]       

FROM [Attendees$]
INNER JOIN(SELECT [Attendees$].[Name]
,                  MIN([Attendees$].[Date])As [FirstAttendanceDate]
                   From [Attendees$]
                   Group By [Attendees$].[Name])AS [Data2]
ON [Attendees$].[Name] = [Data2].[Name]
WHERE [Attendees$].[CEC] IN ("jakyles","ajannett")
ORDER BY [Attendees$].[CEC],[Attendees$].[Date]

代码返回如下结果：

SQLCEC    SQL Date          FirstAttendanceDate
ajannett  12/9/2014 0:00    12/9/2014 0:00
ajannett  4/14/2015 0:00    12/9/2014 0:00
ajannett  6/23/2015 0:00    12/9/2014 0:00
jakyles   12/9/2014 0:00    12/9/2014 0:00
jakyles   5/12/2015 0:00    12/9/2014 0:00
jakyles   6/23/2015 0:00    6/23/2015 0:00

我试图弄清楚为什么我的 FirstAttendanceDate 列为用户 jackyles（这不是我想要的）返回“6/23/2015”，而用户 ajannett 正在返回所需的结果。我是一个相当新的 SQL 用户。我从根本上错过了什么吗？感谢您的帮助！

Answer 1

我的猜测，没有看到您的原始表格，与 Name 列的内容有关，而不是 CEC 列。我怀疑如果您将 Name 列添加到结果集中，那么最后两行该列的内容对于 name 列将是不同的，即使它们对于 SQLCEC 列是相同的。

我唯一的建议是将查询中的引用从名称更改为 CEC：

SELECT [Attendees$].[CEC] AS [SQLCEC]
, [Attendees$].[Date] AS [SQL Date]
, [Data2].[FirstAttendanceDate]       

FROM [Attendees$]
INNER JOIN(SELECT [Attendees$].[CEC]
,                  MIN([Attendees$].[Date])As [FirstAttendanceDate]
                   From [Attendees$]
                   Group By [Attendees$].[CEC])AS [Data2]
ON [Attendees$].[CEC] = [Data2].[CEC]
WHERE [Attendees$].[CEC] IN ("jakyles","ajannett")
ORDER BY [Attendees$].[CEC],[Attendees$].[Date]

Answer 2

我想通了。

SELECT [Attendees$].[CEC] AS [SQLCEC]

, [Attendees$].[Date] AS [SQL Date]
, [Data2].[FirstAttendanceDate]       

FROM [Attendees$]
INNER JOIN(SELECT [Attendees$].[CEC]
,                  MIN([Attendees$].[Date])As [FirstAttendanceDate]
                   From [Attendees$]
                   Group By [Attendees$].[CEC])AS [Data2]
ON [Attendees$].[CEC] = [Data2].[CEC]
WHERE [Attendees$].[CEC] IN ("jakyles","ajannett")
ORDER BY [Attendees$].[CEC],[Attendees$].[Date]

我加入的是名字而不是 CEC。