Bug 177504 Engine doesn't provide SubQuery for extended item
Engine doesn't provide SubQuery for extended item, so chart can't use container's binding to execute the query. If possible, engine could provide an option for extended item to choose whether engine could create the query, so extended item won't create SubQuery by itself.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/ReportQueryBuilder.java
}
			if ( DesignChoiceConstants.INTERVAL_SECOND.equals( interval ) )
			{
				return IGroupDefinition.SECOND_INTERVAL;
			}
			if ( DesignChoiceConstants.INTERVAL_INTERVAL.equals( interval ) )
			{
				return IGroupDefinition.NUMERIC_INTERVAL;
			}
			return IGroupDefinition.NO_INTERVAL;
		}
		/**
		 * @param direction
		 *            "asc" or "desc" string
		 * @return integer value defined in <code>ISortDefn</code>
		 */
		protected int parseSortDirection( String direction )
		{
			if ( "asc".equals( direction ) ) 
				return ISortDefinition.SORT_ASC;
			if ( "desc".equals( direction ) ) 
				return ISortDefinition.SORT_DESC;
			assert false;
			return 0;
		}
		/**
		 * Transfers old expressions to column bindings and new expression.
		 * 
		 * @param item
		 *            the report design.