Relational ranking use cases

This example uses ranking to return only the 5 tallest pupils:

		DataSelection query = buildClassroomDataSelection();

		//get all the result items
		List resultItems = query.getResultItems();
		//we asked for height to be the fourth result item/column, so we won't check:
		DataItem height = (DataItem) resultItems.get(3);

		//create a ranking step filter which returns the top 5 heights:
		DataItemRankFilter top5Step = new DataItemRankFilter(DataItemRankFilter.TOP, 5, true);
		height.addStep(top5Step);

		//execute the query

The result is: