用DatabaseMetaData.getColumns获取了Oracle数据库的某个表Column的属性，
用next输出时所有Column的属性已经打印完了，
但是他还会至少多循环两遍，所有的Column的属性从新打一遍

比如一个表两个字段，执行一遍，按正常来说有两个打印，
但是有四个，重复两遍

特别奇怪的事有些表没有这种情况

请问这是什么情况？

@Override
    public void getColumnsInfo() {

        // 创建一个数据库连接
        Connection connection = null;
        // 创建一个结果集对象
        ResultSet rs = null;

        OperateOracle oracle = new OperateOracleImpl();

        try {
            connection = oracle.getOracleConnection();

            DatabaseMetaData metaData = connection.getMetaData();
            rs = metaData.getColumns(null,null,tableName,null);

            while (rs.next()){

                String isPk = "false";
                String tableName_ = rs.getString("TABLE_NAME");
                String columnName = rs.getString("COLUMN_NAME");
                int dataType = rs.getInt("DATA_TYPE");
                String isAutoincrement = rs.getString("IS_AUTOINCREMENT") == "NO" ? "false" : "true";
                int columnSize = rs.getInt("COLUMN_SIZE");
                String isNullable = rs.getString("IS_NULLABLE") == "NO" ? "false" : "true";
                String remarks = rs.getString("REMARKS");
                int index = rs.getInt("ORDINAL_POSITION");

//                if(map.containsKey(columnName)){
//                    isPk = "true";
//                }

                System.out.println("\t<attribute attrName=\"" + tableName_ + "_" + columnName + "\" isFakeColumn=\"false\" " +
                        "dataType=\"" + dataType + "\" " + "isPrimaryKey=\""+ isPk + "\" " + "isAutoIncrement=\"" + isAutoincrement + "\" " +
                        "maxlength=\"" + columnSize + "\" " + "columnName=\"" + columnName + "\" " +
                        "isNullable=\"" + isNullable + "\" " + "index=\"" + index + "\" " +
                        "tableName=\"" + tableName_ + "\"/>");
            }

            System.out.println("</attributes>\n" +
                    "\n" +
                    "</dataSetConf>");
            //map.clear();

        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            oracle.ReleaseResource(connection,rs);
        }
    }

这是表数据问题，本身就存在重复，代码没啥问题。