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
ArrayList queryList = report.getQueries();
		int counter = 0;
		for (int i = 0; i < queryList.size(); i++) {
			IQueryDefinition query = (IQueryDefinition) queryList.get(i);
			assert query != null;
			
			String queryId = (String)report.getQueryIDs( ).get( query );
			List resultSetList = (List) mapQueryIDToResultSetName.get(queryId);
			if (resultSetList == null) {
				continue;
			}
			
			ReportItemDesign reportItem = (ReportItemDesign) mapQueryToReportItem
					.get(query);
			if( reportItem == null )
			{
				continue;
			}
			String displayName = null;
			if (reportItem.getName() != null) {
				displayName = reportItem.getName() + "_" + counter;
			} else {
				displayName = "ELEMENT_" + reportItem.getID() + "_" + counter;
			}
			counter++;
			
			this.mapQueryToDispName.put( query, displayName );
			
			Iterator resultSetIter = resultSetList.iterator();
			while (resultSetIter.hasNext()) {