Bug 122854 There is redundant columns in "available columns" list in "export data" dialog.
Description: There is redundant columns in "available columns" list in "export data" dialog. Steps to reproduce: 1. Preview attached design in web viewer. 2. Select the table and click on "export" button. 3. There is a "detail" column name in "available columns" list which is not data set column.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTask.java
assert dataSetId != null;
		
		String queryResultName = dataSetId.getDataSetName( );
		
		if( resultMetaList == null )
		{
			resultMetaList = new ArrayList( );
		}
		else
		{
			resultMetaList.clear();
		}
		
		if ( queryResultName != null )
		{
			try
			{
				IQueryResults queryResults = dataEngine.getQueryResults( queryResultName );
				
				assert queryResults.getResultIterator() != null;
				
				currentResult = new ExtractionResults( queryResults.getResultIterator() 
						, selectedColumns, getScriptExpressions( query.getRowExpressions()) );
				return currentResult;
				
			}
			catch ( BirtException e )
			{
				e.printStackTrace();
			}