jsp数据库基础之--从MySQL数据库更新数据

川长思鸟来 2022-09-25 09:26 3阅读 0赞

项目地址：https://gitee.com/martinHuang/jsp-basic/

终于进入数据库基础的最后一个环节，那就是更新数据了。这个操作对于初学者来说会稍微麻烦一些，要先从数据库中把我们想要的数据查询出来，然后再对数据进行更新。

我们开始吧~基本的原理跟之前增、查、删是一样一样的~可以相互参考

1、在WebContent下新建update\_0.jsp文件，用于输入ID

![20160818180531676][]

输入如下内容

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>往数据库更新数据</title>
    </head>
    <body>
       <form action="update_1.jsp" method="post">
          <input type="text" name="id" placeholder="请输入id">
          <input type="submit" value="确定">
       </form>
    </body>
    </html>

2、再在WebContent文件夹下新建update\_1.jsp文件，用于根据update\_0.jsp传来的id号查询数据

![20160818180506613][]

输入如下内容

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <%@ page import="com.Database.*" %>
    <%@ page import="java.sql.*"%>
    <%
       String id = request.getParameter("id");
       conDB DB = new conDB();
       String sql = "select * from personinfo where id = "+id;
       DB.connectDB();
       Statement state = DB.getConnection().createStatement();
       ResultSet set = state.executeQuery(sql);
       set.next();
    %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <title>I更新第一步 查询数据</title>
    </head>
    <body>
      <form action="FormAction/update.jsp" method="post">
         <label>ID</label>
         <input type="text" name="id" value="<%out.print(set.getString("id"));%>">
         <label>name</label>
         <input type="text" name="name" value="<%out.print(set.getString("name"));%>">
         <label>birthProvince</label>
         <input type="text" name="pro" value="<%out.print(set.getString("birthProvince"));%>">
         <input type="submit" value="提交">
      </form>
    </body>
    </html>
    <%state.close();%>

3、在FormAction文件夹下新建update.jsp文件，用于更新的核心操作。

最后文件目录应该是这样的

![20160818181211402][]

在update.jsp文件中输入如下内容

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <%@ page import="com.Database.*" %>
    <%@ page import="java.sql.*" %>
    <%
       request.setCharacterEncoding("utf-8");
       String id = request.getParameter("id");
       String name = request.getParameter("name");
       String pro = request.getParameter("pro");
       String sql = "update personinfo set name = '"+name+"',birthProvince = '"+pro+"' where id = "+id;
       conDB DB = new conDB();
       DB.connectDB();
       Statement state = DB.getConnection().createStatement();
       int flag = state.executeUpdate(sql);
       if(flag > 0)
       {
    	   out.print("<script>alert('更新成功！');window.location.href='../update_0.jsp'</script>");
       }
       else
       {
    	   out.print("<script>alert('更新失败！');window.location.href='../update_0.jsp'</script>");
       }
       state.close();
    %>

4、运行测试

![20160818181340998][]

我输入1

![20160818181449890][]

![20160818181536719][]

查询成功~

我把福建改成上海

![20160818181353748][]

点击提交

![20160818181557235][]

数据库中

![20160818181611381][]

OK！！

[20160818180531676]: /images/20220718/4edff968b6dc49428847a3fb703d59d8.png
[20160818180506613]: /images/20220718/011d3ededad14505934caa3a672d4805.png
[20160818181211402]: /images/20220718/5bdbd529b27c46259c66919863f402a0.png
[20160818181340998]: /images/20220718/e3938e7fb27d4709adfacd050ba573e3.png
[20160818181449890]: /images/20220718/eaa76a4e456a400192d3df6bffc5e251.png
[20160818181536719]: /images/20220718/dca8dcd706e64f2697fd11c120daa070.png
[20160818181353748]: /images/20220718/9bfc43594c2a4985834e59bfd527590d.png
[20160818181557235]: /images/20220718/988384542f644098a39832a6d9a48100.png
[20160818181611381]: /images/20220718/ae4f049fee054ce194eddace0dec9b3e.png