sql不使用外键Java从两个表中获取数据

Question

嗨，我想不使用外键从两个表中获取数据。我试着做一个循环，但运气不太好。我正在尝试使用order2表中的personid从personnew表中获取具有相同personid的数据。。这是我的代码任何建议谢谢ResultSetMetaData rsmd=rs.getMetaData（）； int numberCols=rsmd。getColumnCount（）； 结果集rs=stmt。executeQuery（“从订单2中选择*）

         int customerid = 0;

         for (int i=1; i<=numberCols; i++)
        {
           if (rs.next()){
            int id = rs.getInt(3);
            System.out.println(id);
            System.out.println("_______");  
            customerid=id;
            List<Integer> x = new ArrayList<Integer>();
            x.add(id);
           }
        }

        while(rs.next())
        {
            int id = rs.getInt(1);
            String restName = rs.getString(2);
            String cityName = rs.getString(3);
            System.out.println(id + "\t\t" + restName + "\t\t" + cityName);
        }

         rs = stmt.executeQuery("select * from PERSONNEW WHERE PERSONID=" +customerid );

        for (int i=1; i<=numberCols; i++)
        {

        }

        while(rs.next())
        {
            int id = rs.getInt(1);
            String restName = rs.getString(2);
            String cityName = rs.getString(3);
            System.out.println("PERSON " + id + "\t\t" + restName + "\t\t" + cityName);
        }
        rs.close();
        stmt.close();
        `