增删改查

科技2026-08-22 4

注册界面 index.jsp

<%-- Created by IntelliJ IDEA. User: 你 Date: 2020/9/29 Time: 13:59 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>注册页面</title> </head> <body> <form action="reginfo.jsp" method="post"> 用户名：<input type="text" name="username"> 密码；<input type="text" name="user"> 性别：<input type="text" name="gender"> 年龄：<input type="text" name="age"> <button type="submit">注册</button> </form> </body> </html>

创建包 xxxx

package xxxx; public class User { private String username; private String gender; private int age; private String password; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getGender() { return gender; } public void setGender(String gender) { this.gender = gender; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }

改实现将id=2的用户的status=1改为status=2 使用Statement实现

<%@ page import="java.sql.Connection" %> <%@ page import="java.sql.Driver" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Statement" %><%-- Created by IntelliJ IDEA. User: 你 Date: 2020/9/29 Time: 14:17 To change this template use File | Settings | File Templates. --%> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title></title> </head> <body> <jsp:useBean id="user" class="xxxx.User" scope="application"></jsp:useBean> <jsp:setProperty name="user" property="*"></jsp:setProperty> <% //UserBean user1=new UserBean(); //user.setUsername(request.getParameter("username")); //out.print(user.getUsername()); //加载驱动程序 Class.forName("com.mysql.jdbc.Driver"); //建立数据库连接 String url = "jdbc:mysql://127.0.0.1:3306/book?user=root&password=root"; Connection connection = DriverManager.getConnection(url);//获得链接对象 Statement stmt = connection.createStatement(); //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=4"; String sql="update user set status=2 where id=2"; int count = stmt.executeUpdate(sql); if(count == 0){ out.print("更新失败"); }else { out.print("更新成功"); } %>

使用PreparedStatement实现

<%@ 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 import="com.mysql.jdbc.PreparedStatement" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="User" class="xxxx.User" ></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");//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 statius=? where statius=?"; PreparedStatement pstm= (PreparedStatement) connection.prepareStatement(sql); pstm.setString(2, String.valueOf(2)); %>

删将id=5的用户删除使用Statement实现

<%@ page import="java.sql.Connection" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Statement" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="User" class="xxxx.User" > </jsp:useBean> <jsp:setProperty name="User" property="*"></jsp:setProperty> <% Class.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="insert into user(username,password,gender,age) values('"+user.getUsername()+"','"+user.getPassword()+"',1,23)"; String sql= "delete from user where id=5"; //String sql="update user set status=2 where id=1"; int count=stmt.executeUpdate(sql); if(count==0){ out.print("删除失败"); } else{ out.print("删除成功"); } %>

使用PreparedStatement实现

<%@ page import="java.sql.*" %><%-- Created by IntelliJ IDEA. User: f Date: 2020/10/8 Time: 8:06 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(5);

增添加id=1的用户使用Statement实现

<%@ page import="java.sql.Connection" %> <%@ page import="java.sql.DriverManager" %> <%@ page import="java.sql.Statement" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="User" class="xxxx.User" > </jsp:useBean> <jsp:setProperty name="User" property="*"></jsp:setProperty> <% Class.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="insert into user(username,password,gender,age) values('"+User.getUsername()+"','"+User.getPassword()+"',1,23)"; //String sql= "delete from user where id=3"; //String sql="update user set status=2 where id=1"; int count=stmt.executeUpdate(sql); if(count==0){ out.print("添加失败"); } else{ out.print("添加成功"); } %>

使用PreparedStatement实现

<%@ 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 import="com.mysql.jdbc.PreparedStatement" %> <%@ page contentType="text/html;charset=UTF-8" language="java" %> <jsp:useBean id="User" class="xxxx.User" ></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");//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 = connection.prepareStatement(sql); temt.setString(1,request.getParameter("username")); temt.setString(2,request.getParameter("password")); temt.setString(3,request.getParameter("gender")); temt.setInt(4,request.getParameter("age")); ResultSet rs = temt.executeQuery();

查查找admin1并且密码为111的用户使用Statement实现

<%@ page contentType="text/html;charset=UTF-8" language="java" %> <html> <head> <title>Title</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 = ?"; PreparedStatement ps =connection.prepareStatement(sql); ps.setString(1,request.getParameter("username")); ps.setString(2,request.getParameter("password")); ResultSet rs =ps.executeQuery(); while (rs.next()){ out.print(rs.getString("username")+"-"+rs.getString(3)+"<br>"); } %> </body> </html>

使用PreparedStatement实现

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