private KeyValuePair transferColumn(ColumnMapping column,ResultSet records,int i,KeyValuePair pair){
        ResultSetMetaData metaData = null;
        try {
            metaData = records.getMetaData();
            if(R.entity.type.transfer.equalsIgnoreCase(column.getType())){
                if(column.getSrc_name().equalsIgnoreCase(metaData.getColumnName(i))){
                    pair.setKey(column.getTar_name());
                    pair.setValue(getColumnValue(records,i));
                    log.debug(String.format("transfer %s to %s", column.getSrc_name(), column.getTar_name()));
                }
            }else if(R.entity.type.exclude.equalsIgnoreCase(column.getType())){
                pair = null;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return pair;
    }