this.dataType = DataType.UNKNOWN_TYPE;
	ColumnReferenceExpression( String rowInd, String columnName )	{		logger.entering( ColumnReferenceExpression.class.getName( ),				"ColumnReferenceExpression" ,columnName);		assert( columnName != null || columnName.length() == 0 );		m_columnName = columnName;		m_columnIndex = -1;		rowIndicator = rowInd; 		logger.exiting( ColumnReferenceExpression.class.getName( ),				"ColumnReferenceExpression" );	}