Bug 200500 Error happens while share result set from item behind it.[0005]
Description: Error happens while share result set from item behind it. Build number:2.2.1.v20070820 Steps to reproduce: 1. New sample data source and dataset. 2. Drag the dataset to Layout and name it t1. 3. Insert a table before t1 and share result set from t1. 4. Preview. Expected result: If this situation isn't supported by Engine, at least we should provide friendly error message. Actual result: Error happened while running the report. Error log:n/a
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryResults.java
* Returns the PreparedQuery that contains the execution plan for producing
	 * this. A convenience method for the API consumer.
	 * 
	 * @see org.eclipse.birt.data.engine.api.IQueryResults#getPreparedQuery()
	 */
	public IPreparedQuery getPreparedQuery()
	{ 
		return queryService.getPreparedQuery( );
	}
	
	/*
	 * @see org.eclipse.birt.data.engine.api.IQueryResults#getResultMetaData()
	 */
	public IResultMetaData getResultMetaData( ) throws DataException
	{
		if ( queryService == null )
			throw new DataException( ResourceConstants.RESULT_CLOSED );
		
		try
		{
			return queryService.getResultMetaData( );
		}
		catch ( DataException e )
		{
			throw e;
		}
	}
	
	/*
	 *