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
IBaseQueryDefinition query = (IBaseQueryDefinition)keyIter.next( );
					dispName = (String)mapQueryToDispName.get( query );
					addToResultSetList( query, dispName );
				}
			}
		}
		return resultMetaList;
	}
	/*
	 * create IResultSetItem using display name and IResultMetaData 
	 */
	private void addToResultSetList( IBaseQueryDefinition query, 
			String displayName )
	{
		assert query != null;
		assert displayName != null;
		
		ResultMetaData resultMeta = new ResultMetaData(
				getValueExpressions( query ));
		IResultSetItem resultItem = new ResultSetItem(displayName, resultMeta);
		
		resultMetaList.add( resultItem );
	}
	
	public void selectColumns( String[] columnNames )
	{
		selectedColumns = columnNames;
		currentResult = null;
	}