java.sql.SQLException: 对只转发结果集的无效操作: last

出错代码如下：

      static String u = "user";
      static String p = "psw";
      static String url = "jdbc:oracle:thin:@localhost:1521:db_name";
      con = DriverManager.getConnection(url, u, p); 
      statement = con.createStatement();
      String query1="select * from dm_mpg_test'";
      ResultSet re1=statement.executeQuery(query1);
      //get the number of the records
      re1.last();
      System.out.println("ResultSet size:"+re1.getRow());

报错java.sql.SQLException: 对只转发结果集的无效操作: last

需将statement定义成
statement = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_UPDATABLE);
允许结果集可移动。