Bug 201013 [Automation][Regression]Invalid group key column name: _{$TEMP_GROUP_1$} occurs when preview attached report[1102]
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
|| odiQuery instanceof ICandidateQuery
				|| odiQuery instanceof JointDataSetQuery;
		if ( odiQuery instanceof IPreparedDSQuery )
		{
			if ( ( (IPreparedDSQuery) odiQuery ).getResultClass( ) != null )
				return new ResultMetaData( ( (IPreparedDSQuery) odiQuery ).getResultClass( ) );
			else
				return null;
		}
		else if ( odiQuery instanceof JointDataSetQuery )
		{
			return new ResultMetaData( ( (JointDataSetQuery) odiQuery ).getResultClass( ) );
		}
		else
		{
			return new ResultMetaData( ( (ICandidateQuery) odiQuery ).getResultClass( ) );
		}
	}
	/*
	 * @see org.eclipse.birt.data.engine.impl.IQueryExecutor#execute()
	 */
	public void execute( IEventHandler eventHandler ) throws DataException
	{
		logger.logp( Level.FINER,
				QueryExecutor.class.getName( ),
				"execute",
				"Start to execute" );
		if ( this.isExecuted )
			return;
		ExecutorHelper helper = new ExecutorHelper( this.parentHelper );