JSP数据库综合练习

一.问题概述

        实现了数据库的增删改查和分页显示。

        分页显示:mysql

String cmd = "select * from t_user limit "+firstResult+","+pageSize;
mysql> SELECT * FROM table LIMIT 5,10; // 检索记录行 6-15 

--为了检索从某一个偏移量到记录集的结束所有的记录行，可以指定第二个参数为 -1： 

mysql> SELECT * FROM table LIMIT 95,-1; // 检索记录行 96-last. 

--如果只给定一个参数，它表示返回最大的记录行数目： 

mysql> SELECT * FROM table LIMIT 5; //检索前 5 个记录行 

--换句话说，LIMIT n 等价于 LIMIT 0,n。
                  分页显示:sql server 
select top 10 * from table --这是选出前10条

select top 100 *from table where id not in(select Top 50 id from table)

--这是选出第51到100条,使用存储过程也好。

        文档结构如下：

            image

二.代码实现 

<!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>Insert title here</title>

</head>

<body>

<form action="insert.jsp" method="post">

<table>

	<tr>

		<td>用户名：</td>

		<td><input type="text" name="username"></td>

	</tr>

	<tr>

		<td>密码：</td>

		<td><input type="text" name="password"></td>

	</tr>

	<tr>

		<td colspan="2"><input type="submit" value="提交"/> </td>

	</tr>

</table>

	

</form>

</body>

</html>
<%@page import="java.sql.Statement"%>

<%@page import="java.sql.DriverManager"%>

<%@page import="java.sql.Connection"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%

	String username = request.getParameter("username");

	String password = request.getParameter("password");

	

	String cmd = "insert into t_user (username,password) values('"+username+"','"+password+"')";

	int count = 0;

	try{

		Class.forName("com.mysql.jdbc.Driver");

		String url= "jdbc:mysql://127.0.0.1/db_user";

		String uid = "root";

		String pwd = "root";

		Connection conn = DriverManager.getConnection(url,uid,pwd);

		Statement st = conn.createStatement();

		count = st.executeUpdate(cmd);

		conn.close();

	}catch(Exception e){

		e.printStackTrace();

	}

	if(count>0) response.sendRedirect("list.jsp");

	else response.sendRedirect("error.jsp");

%>
<%@page import="java.sql.ResultSet"%>

<%@page import="java.sql.Statement"%>

<%@page import="java.sql.DriverManager"%>

<%@page import="java.sql.Connection"%>

<%@ 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>Insert title here</title>

</head>

<body>

	<a href="fill.html">添加新人员</a>

	<br />

	<table border="1">

		<tr>

			<td>ID</td>

			<td>username</td>

			<td>password</td>

			<td>操作</td>

		</tr>

		<%

	String pageNum = request.getParameter("pageNum");

	int rowCount = 0;//数据库表总纪录数

	int pageSize = 3;//每页显示纪录数，假设为3

	int pageCount =0;//共有多少页

	//pn做pageNum的中间变量使用的

	int pn = 1;

	if(null != pageNum && pageNum.length()>0)

		pn = Integer.parseInt(pageNum);

	

	

	try{

		Class.forName("com.mysql.jdbc.Driver");

		String url = "jdbc:mysql://127.0.0.1/db_user";

		String uid = "root";

		String pwd = "root";

		Connection conn = DriverManager.getConnection(url,uid,pwd);

		

		Statement st2 = conn.createStatement();

		String cmd2 = "select count(*) from t_user ";

		ResultSet rs2 = st2.executeQuery(cmd2);

		if(rs2.next()){

			rowCount = rs2.getInt(1);

		}

		rs2.close();

		

		pageCount = rowCount%pageSize ==0 ? (rowCount/pageSize) : (rowCount/pageSize+1);

		if(pn < 1 ) pn = 1;

		if(pn >pageCount) pn = pageCount;

		

		int firstResult = (pn-1)*pageSize;

		

		

		Statement st = conn.createStatement();

		/*MySql数据库有limit关键字，注意用法

		第一个参数是从0开始的，不是一

		SELECT * FROM table LIMIT 5,10; // 检索记录行 6-15 

		*/

		String cmd = "select * from t_user limit "+firstResult+","+pageSize;

		ResultSet rs = st.executeQuery(cmd);

		while(rs.next()){

			

%>

		<tr>

			<td><%=rs.getInt(1) %></td>

			<td><%=rs.getString(2) %></td>

			<td><%=rs.getString(3) %></td>

			<td>

				<a href="edit.jsp?id=<%=rs.getInt(1) %>">编辑</a> 

				<a href="delete.jsp?id=<%=rs.getInt(1) %>"> 删除</a>

			</td>

		</tr>

		<%			

		}

		conn.close();

		

	}catch(Exception e){

		e.printStackTrace();

	}

%>

		<tr>

			<td colspan="4">共有<%=rowCount %>条记录，每页显示<%=pageSize %>条记录，共显示<%=pageCount %>页，当前是第<%=pn %>页。

			</td>

		</tr>

		<tr>

			<td colspan="4"><a href="list.jsp?pageNum=1">第一页</a> 

				<a href="list.jsp?pageNum=<%=pn-1 %>">上一页</a> 

				<a href="list.jsp?pageNum=<%=pn+1 %>">下一页</a> 

				<a href="list.jsp?pageNum=<%=pageCount %>">最后页</a>

			</td>

		</tr>

	</table>

</body>

</html>



<%@page import="java.sql.ResultSet"%>

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@page import="java.sql.Statement"%>

<%@page import="java.sql.DriverManager"%>

<%@page import="java.sql.Connection"%>    

<!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>Insert title here</title>

</head>

<body>

<%

String id = request.getParameter("id");

String username = "";

String password = "";

try{

	Class.forName("com.mysql.jdbc.Driver");

	String url= "jdbc:mysql://127.0.0.1/db_user";

	String uid = "root";

	String pwd = "root";

	Connection conn = DriverManager.getConnection(url,uid,pwd);

	Statement st = conn.createStatement();

	String cmd = "select * from t_user where id="+id;

	ResultSet rs = st.executeQuery(cmd);

	if(rs.next()){

		username = rs.getString(2);

		password = rs.getString(3);

	}

	conn.close();

}catch(Exception e){

	e.printStackTrace();

}

%>

<form action="update.jsp" method="post">

<input type="hidden" name="id" value="<%=id %>"/>

<table>

	<tr>

		<td>用户名：</td>

		<td><input type="text" name="username" value="<%=username %>"></td>

	</tr>

	<tr>

		<td>密码：</td>

		<td><input type="text" name="password" value="<%=password %>"></td>

	</tr>

	<tr>

		<td colspan="2"><input type="submit" value="提交"/> </td>

	</tr>

</table>

	

</form>

</body>

</html>



<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@page import="java.sql.Statement"%>

<%@page import="java.sql.DriverManager"%>

<%@page import="java.sql.Connection"%>

<%

	int count = 0;

	String id = request.getParameter("id");

    if(null != id && id.length()>0){

	

		String cmd = "delete from t_user where id="+id;

		try{

			Class.forName("com.mysql.jdbc.Driver");

			String url= "jdbc:mysql://127.0.0.1/db_user";

			String uid = "root";

			String pwd = "root";

			Connection conn = DriverManager.getConnection(url,uid,pwd);

			Statement st = conn.createStatement();

			count = st.executeUpdate(cmd);

			conn.close();

		}catch(Exception e){

			e.printStackTrace();

		}

    }

	if(count>0) response.sendRedirect("list.jsp");

	else response.sendRedirect("error.jsp");

%>



<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@page import="java.sql.Statement"%>

<%@page import="java.sql.DriverManager"%>

<%@page import="java.sql.Connection"%>

<%

	int count = 0;

	String id = request.getParameter("id");

	String username = request.getParameter("username");

	String password = request.getParameter("password");

	if(null != id && id.length()>0){

	

		String cmd = "update t_user set username='"+username+"',password='"+password+"' where id="+id;

		try{

			Class.forName("com.mysql.jdbc.Driver");

			String url= "jdbc:mysql://127.0.0.1/db_user";

			String uid = "root";

			String pwd = "root";

			Connection conn = DriverManager.getConnection(url,uid,pwd);

			Statement st = conn.createStatement();

			count = st.executeUpdate(cmd);

			conn.close();

		}catch(Exception e){

			e.printStackTrace();

		}

	}

	if(count>0) response.sendRedirect("list.jsp");

	else response.sendRedirect("error.jsp");

%>



<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

  <display-name>db</display-name>

  <welcome-file-list>

    <welcome-file>index.html</welcome-file>

    <welcome-file>index.htm</welcome-file>

    <welcome-file>index.jsp</welcome-file>

    <welcome-file>default.html</welcome-file>

    <welcome-file>default.htm</welcome-file>

    <welcome-file>default.jsp</welcome-file>

  </welcome-file-list>

</web-app>



        

	      

	    

	  

	  

	    
      
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          原文地址：https://www.cnblogs.com/hxsyl/p/3435462.html