检索插入到数据库中的最后一行

Question

我正在开发一个在线银行应用程序，这是我卡住的一部分。

- >用户在HTML页面上显示一个表单以输入他们的详细信息，以创建一个帐户。

- >然后将详细信息输入MySQL数据库，并将用户重定向到JSP页面，在那里他应该显示他的帐号（使用MySQL自动递增功能自动生成）和一个秘密的4位数字引脚（每个用户随机生成，而不是自动增量）。

从我的Servlet的doPost（）方法的代码sinppet插入在DB值和重定向到JSP是这里 -

try { 
Class.forName("com.mysql.jdbc.Driver"); 
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/inb", "root", "root"); 

//The user's password has to be converted into a salted hash before storing in the database. 
String hashed_password=CreateDigest.getPasswordDigest(request.getParameter("password")); 

PreparedStatement ps=con.prepareStatement("insert into inb.users values (NULL, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"); 
     ps.setString(1, request.getParameter("name1")); 
     ps.setString(2, request.getParameter("name2")); 
     ps.setString(3, request.getParameter("name3")); 
     ps.setString(4, request.getParameter("dob")); 
     ps.setInt(5, Integer.parseInt(request.getParameter("age"))); 
     ps.setString(6, request.getParameter("email")); 
     ps.setString(7, request.getParameter("mobnum")); 
     ps.setString(8, request.getParameter("address1")); 
     ps.setString(9, request.getParameter("address2")); 
     ps.setString(10, request.getParameter("pannum")); 
     ps.setString(11, request.getParameter("aadhar")); 
     ps.setString(12, hashed_password); 
     ps.setString(13, request.getParameter("acc_bal")); 
     ps.setInt(14, pin); 

      int i=ps.executeUpdate(); 


    //Check if records have been actually been inserted or not. 
     if (i>0) { 
      response.sendRedirect("AccountOpened.jsp"); 
     } 

    } catch (ClassNotFoundException | SQLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

现在，这是JSP代码以显示帐户没有。和用户 的引脚（last_acc_no和last_pin都在我的Servlet类，我创建没有和引脚保持最后插入的帐户的静态变量。）

<% 
String acc_no=CreateAccount.last_acc_No; 
int pin=CreateAccount.last_pin; 
%> 
<h3>Congratulations ! Your account has been created.</h3>. 
<br/><br/> 
Your Account Number Is : <b> <%= acc_no %> </b> 
<br/><br/> 
Your Secret PIN No. Is : <b> <%= pin %> </b> 

现在，我要检索的account_no上和销最后插入的用户，以便我可以在JSP页面上显示它。我无法弄清楚这个方法。

Answer 1

try { 
Class.forName("com.mysql.jdbc.Driver"); 
Connection con=DriverManager.getConnection("jdbc:mysql://localhost:3306/inb", "root", "root"); 

//The user's password has to be converted into a salted hash before storing in the database. 
String hashed_password=CreateDigest.getPasswordDigest(request.getParameter("password")); 

PreparedStatement ps=con.prepareStatement("insert into inb.users values (NULL, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)", , Statement.RETURN_GENERATED_KEYS); 
     ps.setString(1, request.getParameter("name1")); 
     ps.setString(2, request.getParameter("name2")); 
     ps.setString(3, request.getParameter("name3")); 
     ps.setString(4, request.getParameter("dob")); 
     ps.setInt(5, Integer.parseInt(request.getParameter("age"))); 
     ps.setString(6, request.getParameter("email")); 
     ps.setString(7, request.getParameter("mobnum")); 
     ps.setString(8, request.getParameter("address1")); 
     ps.setString(9, request.getParameter("address2")); 
     ps.setString(10, request.getParameter("pannum")); 
     ps.setString(11, request.getParameter("aadhar")); 
     ps.setString(12, hashed_password); 
     ps.setString(13, request.getParameter("acc_bal")); 
     ps.setInt(14, pin); 

      int i=ps.executeUpdate(); 


    //Check if records have been actually been inserted or not. 
      ResultSet rs = ps.getGeneratedKeys(); 
      if(rs.next()) 
      { 
       int id = rs.getInt(1); 
      request.setAttribute("id", id); 
      request.setAttribute("pin", pin); 
      request.getRequestDispatcher("AccountOpened.jsp").forward(request, response); 
     } 

    } catch (ClassNotFoundException | SQLException e) { 
     // TODO Auto-generated catch block 
     e.printStackTrace(); 
    } 

在JSP页面：

<h3>Congratulations ! Your account has been created.</h3>. 
<br/><br/> 
Your Account Number Is : <b> <%= request.getAttribute("id")%> </b> 
<br/><br/> 
Your Secret PIN No. Is : <b> <%= request.getAttribute("pin") %> </b> 

Answer 2

你有没有考虑在t-sql使用Return SCOPE_IDENTITY()？

是int i返回的帐号 - 应该是。这样你就不必担心它是数据库中最重要的条目。严格地说你只是想创建最后一个记录是危险的。用户A和用户B可能会在同一时间创建一个帐户，并得到纠结/交叉的帐户信息。一旦你有“int i”的accountNumber，那么你应该没有问题重新从数据库中获取这些信息？

这有帮助吗？