Bug 176963 Subquery's resultSetExpressions is not consistent between generate and present time.
In generate time, subquery will add the parent query's column binding to its own resultSetExpressions. While in present time, it only has the ones of itself.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedQuery.java
if ( groupLevel != 0 )
		{	
			IGroupDefinition igd = (IGroupDefinition) ( (IBaseQueryDefinition) trans ).getGroups( )
					.get( groupLevel - 1 );
			trans = igd;
			groupName = igd.getName();
		}		
		
		Collection exprCol = new ArrayList( );
		Map resultSetExpressions = new HashMap();
		
		 
		Map map = baseQuery.getResultSetExpressions();
		if (map != null) 
		{
			Iterator it = map.keySet().iterator();
			while (it.hasNext()) {
				Object key = it.next();
				IBaseExpression icbe = (IBaseExpression)map.get(key);
				if( icbe.getGroupName().equals(groupName))
				{
					exprCol.add( icbe );
					resultSetExpressions.put(key, icbe);
				}
			}
		}
		prepareExpressions(exprCol, groupLevel, false, true, cx);
		
		String key = null;