作业四：增删查改

科技2025-10-12 12

初始数据库截图

UserBean.java

package com.media.bean; public class UserBean { private String username; private String password; private int gender; private int age; private int status; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } public int getGender() { return gender; } public void setGender(int gender) { this.gender = gender; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public int getStatus() { return status; } public void setStatus(int status) { this.status = status; } }

注册页面 index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>$Title$</title> </head> <body> <form method="post" action="register.jsp"> 用户名:<input type="text" name="username"><br> 密码: <input type="text" name="password"><br> 性别: <input type="text" name="gender"><br> 年龄: <input type="text" name="age"><br> <button type="submit">注册</button> </form> </body> </html>

使用Statement在数据库增加用户

<%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Connection" %> <%@ page import="java.sql.Statement" %> <%@ page import="com.media.bean.UserBean" %><%-- Created by IntelliJ IDEA. User: 和 Date: 2020/10/7 Time: 8:38 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="user" class="com.media.bean.UserBean"></jsp:useBean> <jsp:setProperty name="user" property="*"></jsp:setProperty> <% //user对象实例化 //UserBean user = new UserBean(); //给对象赋值 //user.setUsername(request.getParameter("username")); //user.setPassword(request.getParameter("password")); //数据库操作 //1 加载驱动程序 Class.forName("com.mysql.jdbc.Driver"); //如果执行到此位置报错标识驱动的jar包没有加载成功 //2 建立数据库连接 10.3.22.1 String url = "jdbc:mysql://127.0.0.1:3306/book?user=root&password=root";//book 为数据库名 //String url = "jdbc:mysql://127.0.0.1:3306 Connection connection = DriverManager.getConnection(url);//获得连接对象 //alt + 回车自动导入类如果报此行有问题说明数据库的连接地址或用户名和密码有问题 //3 创建Statement对象执行sql语句 alt+enter 自动引入缺失的类 Statement stmt = connection.createStatement(); // sql 插入语句值是字符串必须使用单引号 String sql = "insert into user (username,password,gender,age) values('"+user.getUsername()+"','"+user.getPassword()+"',1,23)"; //String sql = "update user set status = 3 where id = 11"; //String sql = "delete from user where id = 11"; 执行sql语句时id 保证数据库中存在该数据 //使用Statement 对象执行sql语句增删改的数据库操作使用executeUpdate int count = stmt.executeUpdate(sql); //如果报此行有错误数码上一行的sql语句是有问题的请检查数据库 if(count == 0 ){ out.print("注册失败"); //如果能执行到此位置表示数据库操作是成功数据库的数据是没有发生变化否则的肯定有异常 }else{ out.print("注册成功"); } %>

使用PreparedStatement语句增加用户

<%@ page import="javax.swing.plaf.nimbus.State" %> <%@ page import="com.mysql.jdbc.PreparedStatement" %> <%@ page import="java.sql.*" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="user" class="com.media.bean.UserBean"></jsp:useBean> <jsp:setProperty name="user" property="*"></jsp:setProperty> <% lass.forName("com.mysql.jdbc.Driver");//报错，说明驱动包没有完成 //建立数据库连接 18.3.22.1 String url ="jdbc:mysql://127.0.0.1:3306/book"; Connection connection = DriverManager.getConnection(url,"book","book"); String sql = "insert into user(username,password,gender,age) values (?,?,?,?)"; PreparedStatement temt = (PreparedStatement) connection.prepareStatement(sql); temt.setString(1,request.getParameter("username")); temt.setString(2,request.getParameter("password")); temt.setString(3,request.getParameter("gender")); temt.setInt(4, Integer.parseInt(request.getParameter("age"))); ResultSet rs = temt.executeQuery(); %>

增加用户admin3，如图所示

使用Statement执行,实现删除操作

<%@ page import="java.sql.Connection" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Statement" %> <jsp:setProperty name="user" property="*"></jsp:setProperty> <% lass.forName("com.mysql.jdbc.Driver"); String url ="jdbc:mysql://127.0.0.1:3306/book?user=root&password=root"; Connection connection = DriverManager.getConnection(url); Statement stmt = connection.createStatement(); String sql="delete from user where id = 4 "; int count = stmt.executeUpdate(sql); if(count == 0){ out.print("删除失败"); }else{ out.print("删除成功"); } %>

使用PreparedStatement语句,实现删除操作

<%@ page import="java.sql.*" %><%-- Created by IntelliJ IDEA. User: 吧 Date: 2020/10/6 Time: 14:12 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>主页</title> </head> <body> <% //加载数据库驱动 Class.forName("com.mysql.jdbc.Driver"); //建立数据库连接 String url = "jdbc:mysql://localhost:3306/book"; Connection connection = DriverManager.getConnection(url,"root","root"); //预定义对象 String sql = "delete from user where id = ? ";//使用问号代替参数 PreparedStatement pstm = connection.prepareStatement(sql); pstm.setInt(1);

删除admin1

使用Statement语句，实现修改用户

<%@ page import="java.sql.Connection" %> <%@ page import="java.sql.Driver" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="javax.swing.plaf.nimbus.State" %> <%@ page import="java.sql.Statement" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="user" class="com.media.bean.UserBean"></jsp:useBean> <jsp:setProperty name="user" property="*"></jsp:setProperty> <% lass.forName("com.mysql.jdbc.Driver"); String url ="jdbc:mysql://127.0.0.1:3306/book?user=root&password=root"; Connection connection = DriverManager.getConnection(url); Statement stmt = connection.createStatement(); String sql = "update user set status = 3 where id= 2"; int count = stmt.executeUpdate(sql); if(count == 0){ out.print("修改失败"); }else{ out.print("修改成功"); } %>

使用PreparedStatement语句,实现修改操作

<%@ page import="javax.swing.plaf.nimbus.State" %> <%@ page import="java.sql.*" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="user" class="com.media.bean.UserBean"></jsp:useBean> <jsp:setProperty name="user" property="*"></jsp:setProperty> <% Class.forName("com.mysql.jdbc.Driver");//报错，说明驱动包没有完成 //建立数据库连接 18.3.22.1 String url ="jdbc:mysql://127.0.0.1:3306/book"; Connection connection = DriverManager.getConnection(url,"book","book"); String sql="update user set status=? where status=?"; PreparedStatement pstm=connection.prepareStatement(sql); pstm.setInt(2,3); %>

未修改数据库代码运行时修改后的数据库使用Statement查询用户

使用PreparedStatement查找用户

<%@ page import="java.sql.Connection" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.PreparedStatement" %> <%@ page import="java.sql.ResultSet" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>主页</title> </head> <body> <% Class.forName("com.mysql.jdbc.Driver"); String url = "jdbc:mysql://localhost:3306/book"; Connection connection = DriverManager.getConnection(url,"root","root"); String sql = "select * from user where username = ? and password = ? ";//使用问号代替参数 PreparedStatement temt = connection.prepareStatement(sql); temt.setString(1,request.getParameter("username")); temt.setString(2,request.getParameter("password")); ResultSet rs = temt.executeQuery(); while (rs.next()) { out.print(rs.getString("username")+"-"+rs.getString(2)+"<br>"); } %> </body> </html>

所有用户查找到的用户

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