SQL返回错误表的计数

Question

此SQL正在返回表Dim的记录计数，而不是返回表BIDdetails的记录计数。我该如何解决？

BIDReportSearch.CommandText = ("SELECT BIDdetails.Origin, BIDdetails.Destination, 
Round(Sum(Dims.ChargeableWeight)) as CWeight, count(BIDdetails.Origin) as NoOfShpt 
FROM BIDdetails LEFT JOIN DIMS ON BidDetails.BID=Dims.BID 
where BIDdetails.OrgCountry<>'AE' and BIDdetails.DestCountry='AE' and 
BIDdetails.ClosingDate>=#" & dtpBIDfrom.Value & "# and BIDdetails.ClosingDate<=#" & 
dtpBIDto.Value & "# GROUP BY BIDdetails.Origin, BIDdetails.Destination 
ORDER BY Round(Sum(Dims.ChargeableWeight)) DESC") 

Answer 1

表达：

count(BIDdetails.Origin) 

只计算每个组中的BIDdetails.Origin非空值的数量。因为您实际上是按字段进行分组，所以这将是每个组中的行数。

通过在唯一标识符上使用count(distinct)，您可以在大多数数据库中获得您想要的结果。唉，MS Access不支持count(distinct)，所以这样的查询在Access中编写起来要困难得多。您可以通过执行得到公正的count领域：

SELECT BIDdetails.Origin, BIDdetails.Destination, count(*) as NoOfShpt 
FROM BIDdetails 
where BIDdetails.OrgCountry <> 'AE' and BIDdetails.DestCountry='AE' and 
     BIDdetails.ClosingDate>=#" & dtpBIDfrom.Value & "# and BIDdetails.ClosingDate<=#" & dtpBIDto.Value & "# 
GROUP BY BIDdetails.Origin, BIDdetails.Destination; 

然后结合无论是在您的应用程序或通过加入该查询返回到原来的结果。

编辑：

这是原始查询：

SELECT d.Origin, d.Destination, 
     Round(Sum(Dims.ChargeableWeight)) as CWeight, count(d.Origin) as NoOfShpt 
FROM BIDdetails as d LEFT JOIN 
    DIMS 
    ON BidDetails.BID=Dims.BID 
where d.OrgCountry <> 'AE' and d.DestCountry='AE' and 
     d.ClosingDate> = #" & d.Value & "# and d.ClosingDate<=#" & dtpBIDto.Value & "# 
GROUP BY d.Origin, d.Destination 
ORDER BY Round(Sum(Dims.ChargeableWeight)) DESC 

还有一个办法，你先通过聚合的细节，然后再。我认为，在这种情况下更容易：

SELECT Origin, Destination, SUM(CWeight) as CWeight, COUNT(*) as NumShip 
FROM (SELECT d.id, d.Origin, d.Destination, 
      Round(Sum(Dims.ChargeableWeight)) as CWeight, count(d.Origin) as NoOfShpt 
     FROM BIDdetails as d LEFT JOIN 
      DIMS 
      ON BidDetails.BID = Dims.BID 
     where d.OrgCountry <> 'AE' and d.DestCountry='AE' and 
      d.ClosingDate> = #" & d.Value & "# and d.ClosingDate<=#" & dtpBIDto.Value & "# 
     GROUP BY d.id, d.Origin, d.Destination 
    ) as d 
GROUP BY Origin, Destination 
ORDER BY Round(Sum(CWeight)) DESC; 

d.id是指任何独有的ID是你想算什么。