Bug 201396 Exception is thrown out when a chart use the list shared result set [0005]
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryResults.java
this.rootQueryResultID = rootQueryResultID;
		this.selfQueryResultID = selfQueryResultID;
	}
	
	/**
	 * Set current queryresult ID for sub query. Sub query result ID can not be
	 * generated independently, and it is needs to be attached with its parent
	 * query.
	 * 
	 * @param selfQueryResultID
	 */
	void setID( String selfQueryResultID )
	{
		this.setID( null, selfQueryResultID );
	}
	
	/**
	 * If current query results is associated with a sub query, its result
	 * iterator needs to know which group level this sub query belongs to.
	 * 
	 * @return group level of sub query
	 */
	int getGroupLevel( )
	{
		return queryService.getGroupLevel( );
	}
	
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryService#isClosed()
	 */