Problem when Counting results of a query

Question

Hi all
In our application, we use the Toplink Essentials Queryframework API to create queries because of JPA limitations.
Now I have a problem: I want to count the results of a existing query, i.e. I have a ReportQuery and I want to count the results of it.
I tried the following:
ReportQuery query = ...
ReportQuery countQuery = new ReportQuery(Pivot.class, builder);
countQuery.addCount(COUNT,
ExpressionBuilder.from("id", builder.subQuery(query)));
countQuery.setShouldReturnSingleValue(true);
return Integer.valueOf(session.executeQuery(countQuery).toString());
Now it seems that Toplink executes the query but the result is not correct, i.e. the count result is NOT the same as the number of results in the original query.
The subquery may contain group by's, a where clause and so on...
Anyone has an idea how to count the number of results of another query in Toplink?
It should have the same affect as a simple sql "select count(*) from (select ...)" query.
Regards
Michael

Answer 1

Not exactly sure what your doing, what does the original ReportQuery select?
You probably want to do something like the following:
originalQuery...
ReportQuery countQuery = new ReportQuery(Pivot.class, countBuilder);
countQuery.addCount("id");
countQuery.setSelectionCriteria(originalQuery.getSelectionCriteria());
You may need to also call rebuildOn() if you reuse the same selection criteria from a different query.
i.e.
countQuery.setSelectionCriteria(originalQuery.getSelectionCriteria().rebuildOn(countBuilder));
James : http://www.eclipselink.org