Bug 124251 the data cann't been exported.
Description: the data cann't been exported. Steps to reproduce: 1. new a report 2. new a datasource and a data set(DS_A) 3. use an external library 4. drag a table to the report layout from the imported library 5. insert an another table into the layout of the report and bind the data set(DS_A) 6. preview in the 'Web Viewer' and export the data Actual result: The data can been exported. Expect result: The data can been exporteded
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTask.java
}
		
		if ( queryResultName != null )
		{
			try
			{
				IQueryResults queryResults = dataEngine.getQueryResults( queryResultName );
				
				assert queryResults.getResultIterator() != null;
				
				currentResult = new ExtractionResults( queryResults.getResultIterator() 
						, selectedColumns, getValueExpressions( rptItem.getQuery( ) ) );
				return currentResult;
				
			}
			catch ( BirtException e )
			{
				e.printStackTrace();
			}
		}
		else
		{
			DataSetID parentId = dataSetId.getParentID( );
			assert parentId != null;
			try
			{
				queryResultName = parentId.getDataSetName( );
				DataSetID parId = parentId;
				while( queryResultName == null && parId != null )
				{