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  • 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
              
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