Bug 161191 Null is inserted when drag columns to query text with ctrl key pressed
Description: Null is inserted when drag columns to query text with ctrl key pressed Steps to reproduce: 1. New a data source. 2. New a dataset. 3. Press and hold ctrl key, select OFFICECODE and CITY columns, drag to query text. Expected result: "CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted in query text. Actual result: "null,CLASSICMODELS.OFFICES.OFFICECODE,CLASSICMODELS.OFFICES.CITY" is inserted
data/org.eclipse.birt.report.data.oda.jdbc.ui/src/org/eclipse/birt/report/data/oda/jdbc/ui/editors/SQLDataSetEditorPage.java
}
			}
		} );
	}
	
	/**
	 * 
	 * @param event
	 */
	private void populateEventData( TypedEvent event )
	{
		TreeItem[] selection = availableDbObjectsTree.getSelection( );
		
		if ( selection == null || selection.length == 0 )
			selection = selectionMac;
		
		String identifierQuoteString;
		try
		{
			identifierQuoteString = metaDataProvider.getMetaData( )
					.getIdentifierQuoteString( );
		}
		catch ( SQLException e )
		{
			identifierQuoteString = "";
		}
		if ( selection.length > 0 )
		{
			String data = "";
			for ( int i = 0; i < selection.length; i++ )