Question

长时间观察者，第一次海报：

我目前正在使用Tableau中的SQL功能。我想查询返回userid（SQLCEC），出勤日期（SQL日期），以及用户第一次参加（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]

代码返回以下结果：

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

我想弄清楚为什么我的FirstAttendanceDate专栏要回归＆＃34; 6/23/2015＆＃34;用户ajannett返回所需的结果时，用户jackyles（这不是我想要的）。我是SQL的新用户。我是否从根本上遗漏了一些东西？谢谢你的帮助！

Answer 1

我的猜测是，在没有看到原始表的情况下，与“名称”列的内容有关，而不是与CEC列相关。我怀疑如果将Name列添加到结果集中，那么最后两行的该列的内容对于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Name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

我能够弄明白。

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]

我加入了名字而不是CEC。

最小（日期）返回冲突的结果 - Tableau

2 个答案: