jsp中如何根据input type=radio标签选择数据库表？

Question

我在mysql数据库中有两张表，一张给学生，一张给老师。两个表都有相同的列。

下面的代码只将数据插入到教师表中。如果用户选择教师单选按钮，则注册数据应存储在教师表中。如果用户选择学生电台，则注册数据应存储在学生表中。

单选按钮无法选择数据库表，它只能在 mysql 学生表中插入数据，我选择教师单选按钮

enter image description here

String gender = request.getParameter("gender");
if (gender != null) {
    String table = gender.equals("teacher") ? "teacher2" : "student";
    // replace dots with your values
    String query = "INSERT INTO " + table + "(firstname,lastname,username,password,confirmpassword,email,month,day,year,gender) VALUES ('"+name+"','"+abc+"','"+cde+"','"+pass+"','"+confpass+"','"+emails+"','"+months+"','"+day+"','"+year+"','"+gender+"')";
    st.executeUpdate(query);
} // Here is also error but it insert data in table of only student. 

问题也在这里

st.executeUpdate(query);

index.jsp

<form  method="GET " action="statement2.jsp" autocomplete="on"> 
   <input type="radio" name="gender" value="teacher" checked/> Teacher
   <input type="radio" name="gender" value="Student"/>Student
   <input type="submit" value="Login" /> 
   <input type="button" onclick="location.href='reg.jsp';" value="Sign Up" />
</form> 

statement2.jsp

<%
   String name=request.getParameter("first");
   String abc=request.getParameter("last");
   String cde=request.getParameter("user");
   String pass=request.getParameter("password");
   String confpass=request.getParameter("confirmpass");
   String emails=request.getParameter("email");
   String months=request.getParameter("month");
   String day=request.getParameter("day");
   String year=request.getParameter("year");

   String gender = request.getParameter("gender");
   if (gender != null) {
   String table = gender.equals("teacher") ? "teacher2" : "student";
// replace dots with your values
   String query = "INSERT INTO " + table + "(firstname,lastname,username,password,confirmpassword,email,month,day,year,gender) VALUES ('"+name+"','"+abc+"','"+cde+"','"+pass+"','"+confpass+"','"+emails+"','"+months+"','"+day+"','"+year+"','"+gender+"')";
  st.executeUpdate(query);}     // problem is here

 %>

---

reg.jsp

<form  method="GET" action="statement2.jsp" autocomplete="on"> 
    <h1> Sign up </h1> 
    <p> 
    <label for="firstnamesignup" class="fname" data-icon="u">First Name:</label>
    <input id="firstnamesignup" name="first" required="required" type="text" placeholder="First" />
    </p>
    <p> 
     <label for="lastnamesignup" class="lname" data-icon="u">Last Name:</label>
     <input id="lastnamesignup" name="last" required="required" type="text" placeholder="Last" />
     </p>
     <p> 
     <label for="usernamesignup" class="uname" data-icon="u">Username:</label>
     <input id="usernamesignup" name="user" required="required" type="text" placeholder="Username" />
     </p>
     <p> 
     <label for="passwordsignup" class="youpasswd" data-icon="p">Password:</label>
     <input id="passwordsignup" name="password" required="required" type="password" placeholder="Password"/>
     </p>
     <p> 
     <label for="passwordsignup_confirm" class="password" data-icon="p">Confirm Password:</label>
     <input id="passwordsignup_confirm" name="confirmpass" required="required" type="password" placeholder="Password"/>
     </p>
     <p> 
     <label for="emailsignup" class="youmail" data-icon="e" >Email:</label>
     <input id="emailsignup" name="email" required="required" type="email" placeholder="example@domain.com"/> 
     </p>
     <p> 
     <label>Date of Birth:</label>
     <select name="month" onChange="changeDate(this.options[selectedIndex].value);">
     <option value="na">Month</option>
     <option value="1">January</option>
     <option value="2">February</option>
     <option value="3">March</option>
     <option value="4">April</option>
     <option value="5">May</option>
     <option value="6">June</option>
     <option value="7">July</option>
     <option value="8">August</option>
     <option value="9">September</option> 
     <option value="10">October</option>
     <option value="11">November</option>
     <option value="12">December</option>
     </select>
     <select name="day" id="day">
     <option value="na">Day</option>
     </select>
     <select name="year" id="year">
     <option value="na">Year</option>
     </select>
     <script language="JavaScript" type="text/javascript">
     function changeDate(i){
     var e = document.getElementById('day');
     while(e.length>0)
     e.remove(e.length-1);
     var j=-1;
     if(i=="na")
     k=0;
     else if(i==2)
     k=28;
     else if(i==4||i==6||i==9||i==11)
     k=30;
     else
     k=31;
     while(j++<k){
     var s=document.createElement('option');
     var e=document.getElementById('day');
     if(j==0){
     s.text="Day";
     s.value="na";
     try{
     e.add(s,null);}
     catch(ex){
     e.add(s);}}
     else{
     s.text=j;
     s.value=j;
     try{
     e.add(s,null);}
     catch(ex){
     e.add(s);}}}}
     y = 1998;
     while (y-->1908){
     var s = document.createElement('option');
     var e = document.getElementById('year');
     s.text=y;
     s.value=y;
     try{
     e.add(s,null);}
     catch(ex){
     e.add(s);}}
     </script> 
     </p>
     <p> 
     <label>Gender:</label>
     <select name="Gender">
     <option value="male">Male</option>
     <option value="female">Female</option>
     </select>
     </p>
     <p class="signin button"> 
     <input type="submit" value="Register"/> 
     </p>
 </form>

---

db conn.jsp

       <%@page import="com.mysql.jdbc.Connection"%>
       <%@page import="com.mysql.jdbc.Statement"%>
       <%@page import="java.sql.ResultSet"%>
       <%@page import="java.sql.DriverManager"%>
       <%@page contentType="text/html" pageEncoding="UTF-8"%>
       <!DOCTYPE html>
       <html>
       <head>
       <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
       <title>JSP Page</title>
       </head>
       <body>
       <h1>Hello World!</h1>

       <%@ page import ="java.sql.*" %>
       <%
        Connection c1 = null;
        Statement st = null;
        ResultSet rs = null;
        Class.forName("com.mysql.jdbc.Driver");
        c1 = (Connection) DriverManager.getConnection("jdbc:mysql://localhost:3306/teacher","root", "abcde");

        System.out.println("Couldn't find the driver!");
        System.out.println("Couldn't connect: print out a stack trace and exit.");
        System.out.println("We got an exception while creating a statement:" + "that probably means we're no longer connected.");

        st = (Statement) c1.createStatement();
             System.out.println("Statement Created Successfully");
             {
         System.out.println("We got an exception while creating a statement:" + "that probably means we're no longer connected.");

         }

         if (c1!= null) {
         System. out.println("Hooray! We connected to the database!");
         } else {
         System.out.println("We should never get here.");
         }}
        %>

Answer 1

首先是一些最佳实践：

1. 当您想在服务器上创建/更新数据时，使用 form method=POST
2. 对 INSERT/UPDATE 使用 PreparedStatement 而不是 Statement

现在，回到单选按钮的问题： 发送要存储在表中的数据的页面是 reg.jsp，在提交时调用 statement2.jsp。 reg.jsp 中没有 name="gender" 的单选按钮，实际上在 index.jsp 中。

你有两个选择：

1. 您将单选按钮的选定值传递给 reg.jsp；在这里你在表单中使用了一个隐藏字段，这种方式被传递给 statement2.jsp
2. 您在 reg.jsp 中添加单选按钮。

Answer 2

首先，对于这种情况，您不需要具有相同列的多个表。只需使用一个包含当前所有列的表，然后创建一个名为 user_type 的附加 column。 user_type column 的值应该是 teacher 或 student 取决于您从用户端获得的输入。 如下更改查询

INSERT INTO new_table_name
(firstname,lastname,username,password,confirmpassword,email,month,day,year,gender,user_type)
VALUES ('"+name+"','"+abc+"','"+cde+"','"+pass+"','"+confpass+"',
'"+emails+"','"+months+"','"+day+"','"+year+"','"+gender+"','"+USER_TYPE_SELECTED+"')";