SQL returning the count from wrong table - sql

Question

This SQL is returning the record count of table Dims instead returning the record count of table BIDdetails. How can I fix?
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

The expression:
count(BIDdetails.Origin)
simply counts the number of non-NULL values of BIDdetails.Origin in each group. Because you are actually grouping by the field, that would be the number of rows in each group.
You can get what you want in most databases by using count(distinct) on a unique identifier. Alas, MS Access doesn't support count(distinct) so such a query is much harder to write in Access. You can get just the count field by doing:
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;
And then combining the results either in your application or by joining this query back into the original one.
EDIT:
This is your original query:
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
There is another approach, where you aggregate first by the details and then again. I think that is easier in this case:
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 refers to whatever the unique id is for what you want to count.