我在MS Access查询中遇到此错误:The number of columns in the two selected tables or queries of a union query do not match.
列数匹配清楚,当我运行UNION查询一次挑选任何2个集时,它工作正常。当我在查询中包含更多2选择时,它会显示此错误。
SELECT "Applied" as Application_Status, Count(*) AS [CountOfApplication Status]
FROM [EDB Applicants - ALL]
WHERE [EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Dec Date]>Date()-366
UNION
SELECT "Hold" as Application_Status, Count(*) AS [CountOfApplication Status]
FROM [EDB Applicants - ALL]
WHERE [EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Dec Date]<=Date()-366 And [EDB Applicants - ALL].[Application Status]="Hold"
UNION
SELECT "Withdraw" as Application_Status, Count(*) AS [CountOfApplication Status]
FROM [EDB Applicants - ALL]
WHERE [EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Date of Enrollment Change]<=Date()-366 And [EDB Applicants - ALL].[Application Status] In ("Declined","Withdrew Application","Withdrew After Enrollment")
答案 0 :(得分:1)
我不知道原始问题的原因,但您可以重写查询以消除联盟:
select Application_Status, COUNT(*)
from (select (case when [EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Dec Date]>Date()-366
then 'Applied'
when [EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Dec Date]<=Date()-366 And [EDB Applicants - ALL].[Application Status]="Hold"
then 'Hold'
when [EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Date of Enrollment Change]<=Date()-366 And [EDB Applicants - ALL].[Application Status] In ("Declined","Withdrew Application","Withdrew After Enrollment")
then 'Withdraw'
end) as Application_Status, [EDB Applicants - ALL].*
from [EDB Applicants - ALL]
) t
where Application_Status is not null
group by Application_Status
没错,在MS Access中你必须使用IIF(),但同样的想法适用:
select Application_Status, COUNT(*)
from (select iif([EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Dec Date]>Date()-366,
'Applied',
iif([EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Dec Date]<=Date()-366 And [EDB Applicants - ALL].[Application Status]="Hold",
'Hold',
iif([EDB Applicants - ALL].[Application Year].Value Like "2012" And [EDB Applicants - ALL].[Application Date]<=Date()-366 And [EDB Applicants - ALL].[Date of Enrollment Change]<=Date()-366 And [EDB Applicants - ALL].[Application Status] In ("Declined","Withdrew Application","Withdrew After Enrollment")
'Withdraw', '')))) as Application_Status, [EDB Applicants - ALL].*
from [EDB Applicants - ALL]
) t
where Application_Status <> ''
group by Application_Status