Access Database Query Grouping - ms-access

Question

I have an Access 2003 database I've been asked to try and amend. My MS Access skills are limited hence this question.
The query looks like this:
SELECT
TBL_PropertyProgramMember.PropertyId,
Max(TBL_PropertyProgramMember.To) AS MaxOfTo,
TBL_PropertyProgramMember.BookingPriority
FROM
TBL_PropertyProgramMember
GROUP BY
TBL_PropertyProgramMember.PropertyId,
TBL_PropertyProgramMember.BookingPriority;
I need to return unique PropertyIds, the maximum To value for each property, and the BookingPriority associated with that maximum To value. Using the above grouping, I get multiple results if there property is listed more than once with different a different BookingPriority.
As I'm using grouping, I can't remove the BookingPriority grouping without Access throwing an error.
I'm sure this is to do with grouping, but I can't work out how to fix it. Just getting the maximum or minimum BookingPriority won't fix the problem because the value can change.

Answer 1

You have to compute your maximum (without returning your BookingPriority) and then join back to the results again, something like this:-
SELECT
TBL_PropertyProgramMember.PropertyID,
M.MaxTo,
TBL_PropertyProgramMember.BookingPriority
FROM
(
SELECT
TBL_PropertyProgramMember.PropertyID,
Max(TBL_PropertyProgramMember.To) AS MaxTo
FROM
TBL_PropertyProgramMember
GROUP BY
TBL_PropertyProgramMember.PropertyID
) AS M
INNER JOIN
TBL_PropertyProgramMember
ON (M.MaxTo = TBL_PropertyProgramMember.To)
AND (M.PropertyID = TBL_PropertyProgramMember.PropertyID);
You will need to handle cases where there is more than one record having the same maximum "To" column for a given BookingPriority.