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
protected IExtractionResults currentResult = null;
	
	/*
	 * map query id to result set name stored in DtE
	 */
	protected HashMap mapQueryIDToResultSetName;
	
	/*
	 * current result set name
	 */
	protected String resultSetName;
	/*
	 * map IBaseQueryDefinition to ReportItemDesign, namely TableItemDesign, ListItemDesign
	 * and ExtendedItemDesign
	 */
	protected HashMap mapQueryToReportItem;
	
	/*
	 * map result set display name to result set name stored by DtE.
	 */
	protected HashMap mapDispNameToResultSetName;
	
	/*
	 * have the metadata be prepared
	 */
	protected boolean isMetaDataPrepared = false;
	
	/*
	 * map query to display name