用MySQL+node+vue做一个学生信息管理系统（五）：学生信息增删改的实现

先实现增加信息：
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post参数的获取：express中接受post请求参数需要借助第三方包 body-parser
下载npm install body-parser

//引入body-parser模块
const bodyParser = require('body-parser');
//拦截所有请求,配置body-parser模块
//extended:false 方法内部使用querystring模块处理请求参数的格式,并且把参数保存在req当中
//extended:true 方法内部使用第三方模块qs处理请求参数的格式
app.use(bodyParser.urlencoded({extended:false}));
//接收请求
app.post('/add',(req,res)=>{//接收请求参数console.log(req.body);
})

req.body可以拿到全部的post请求参数，是一个json对象，以键值对的形式保存，键是input的name，值就是表单输入的内容，接下来只需要获取到值并且保存在MySQL数据库当中就行

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通过结构赋值把需要的值拿到，然后插入到数据库，最后重定向到主页面

//接收请求
app.post('/add',(req,res)=>{//接收请求参数const { id, name, sex,class1}= req.body;var  addSql = 'INSERT INTO student(id,name,sex,class) VALUES(?,?,?,?)';var  addSqlParams = [id,name,sex,class1];connection.query(addSql,addSqlParams,function (err, result) {if(err){console.log('[INSERT ERROR] - ',err.message);return;}        console.log('--------------------------INSERT----------------------------');//console.log('INSERT ID:',result.insertId);        console.log('INSERT ID:',result);        console.log('-----------------------------------------------------------------\n\n');  });res.redirect('/index.html');
})

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删除功能的实现：
思路：点击删除按钮的时候创建一个ajax对象，发送请求del，并且携带post学号的参数，post请求参数就是学号，在创建button按钮的时候把学号赋值给button按钮的id属性，点击button按钮时vue的e.target可以获取到触发事件的对象，e.target.id就可以获取到按钮的id属性,删除完之后如果使用node的redirect重定向因为是同一个页面而不会生效，我们需要在html文件中写location.href重定向才行

代码：
init.vue

<template><div id="init"><div class="div2"><div class="div21">学号</div><div class="div21">姓名</div><div class="div21">性别</div><div class="div21">班级</div><div class="div21"></div><div class="div21"></div></div><div class="div3" v-for="item in people"><div class="div31">{{item.id}}</div><div class="div31">{{item.name}}</div><div class="div31">{{item.sex}}</div><div class="div31">{{item.class}}</div><div class="div31"><router-link to='/update'>更改</router-link></div><div class="div31"><button @click="del" :id="item.id">删除</button></div></div><div class="div4"><router-link to='/add'>增加</router-link></div></div>
</template><script>export default {data(){return{msg:'66',people:[]}},mounted:function(){var xhr = new XMLHttpRequest();xhr.open('POST','http://localhost:3000/init');xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xhr.send();var that = this;xhr.onload = function(){that.people = JSON.parse(xhr.responseText);}},methods:{del:function(e){console.log('del'+e.target.id);var xhr = new XMLHttpRequest();xhr.open('POST','http://localhost:3000/del');xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xhr.send('id='+e.target.id);location.href='http://localhost:3000/index.html'}}
}</script><style scoped="scoped">#init{width: 800px;margin: auto;border: 1px solid transparent;}.div2{width: 100%;height: 50px;display: flex;}.div21{text-align: center;line-height: 50px;border: 1px solid aqua;flex: 1;}.div3{width: 100%;height: 50px;display: flex;}.div31{border: 1px solid aqua;text-align: center;line-height: 50px;flex: 1;}</style>

const express = require('express');
const app = express();
const path = require('path');
//引入body-parser模块
const bodyParser = require('body-parser');
//拦截所有请求,配置body-parser模块
//extended:false 方法内部使用querystring模块处理请求参数的格式,并且把参数保存在req当中
//extended:true 方法内部使用第三方模块qs处理请求参数的格式
app.use(bodyParser.urlencoded({extended:false}));//开放静态资源访问，只需要输入文件名即可，不需要输入文件夹
app.use(express.static(path.join(__dirname,'src')));app.all("*",function(req,res,next){//设置允许跨域的域名，*代表允许任意域名跨域res.header("Access-Control-Allow-Origin","*");//允许的header类型res.header("Access-Control-Allow-Headers","Origin,X-Requested-With,Accept,Content-type");res.header("Access-Control-Allow-Credentials",true);//跨域允许的请求方式res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");res.header("Content-Type","application/json;charset=utf-8")if (req.method.toLowerCase() == 'options')res.sendStatus(200);  //让options尝试请求快速结束elsenext();
});//引入MySQL模块
var mysql      = require('mysql');
//创建MySQL的连接
var connection = mysql.createConnection({host     : 'localhost',user     : 'root',password : '1234',database : 'students'
});//连接MySQL
connection.connect();//接收请求
app.post('/add',(req,res)=>{//接收请求参数const { id, name, sex,class1}= req.body;var  addSql = 'INSERT INTO student(id,name,sex,class) VALUES(?,?,?,?)';var  addSqlParams = [id,name,sex,class1];connection.query(addSql,addSqlParams,function (err, result) {if(err){console.log('[INSERT ERROR] - ',err.message);return;}        console.log('--------------------------INSERT----------------------------');//console.log('INSERT ID:',result.insertId);        console.log('INSERT ID:',result);        console.log('-----------------------------------------------------------------\n\n');  });res.redirect('/index.html');
})app.post('/update',(req,res)=>{res.send('update');
})app.post('/del',(req,res)=>{const {id}=req.body;var delSql = 'DELETE FROM student where id='+id;//删connection.query(delSql,function (err, result) {if(err){console.log('[DELETE ERROR] - ',err.message);return;}        console.log('--------------------------DELETE----------------------------');console.log('DELETE affectedRows',result.affectedRows);console.log('-----------------------------------------------------------------\n\n');  });
})app.post('/init',(req,res)=>{//query操作可以对数据库进行操作connection.query('SELECT * from student', function (err, result, fields) {if(err){//err.message会返回错误的信息console.log('[SELECT ERROR] - ',err.message);return;}console.log('--------------------------SELECT----------------------------');console.log(result);res.send(result);console.log('------------------------------------------------------------\n\n');  });})app.listen(3000);

修改数据思路：更改替换为<button id=“upd” @click=“upd” :id=“item.id”>更改
当点击更改按钮时，把数据保存在本地，同时也把这个数据发送给后台，在update.vue组件当中提取本地数据，给location.hash=‘/update’赋值，也会造成路由的变化。但是由于路由的组件是一加载完页面就加载了全部的路由，所以保存数据之后update组件当中的数据还是空，所以需要使用location.reload();重新刷新页面读取数据

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app.js代码

var id = 0;
app.post('/server',(req,res)=>{console.log('server');id=req.body.id;console.log(id);
})app.post('/update',(req,res)=>{console.log('update');const {name,sex,class1}=req.body;var modSql = 'UPDATE student SET name = ?,sex = ?,class = ? WHERE Id = ?';var modSqlParams = [name,sex,class1,id];//改connection.query(modSql,modSqlParams,function (err, result) {if(err){console.log('[UPDATE ERROR] - ',err.message);return;}        console.log('--------------------------UPDATE----------------------------');console.log('UPDATE affectedRows',result.affectedRows);console.log('-----------------------------------------------------------------\n\n');});res.redirect('/index.html');
})

init.vue代码

upd:function(e){console.log('upd');sessionStorage.setItem('id',e.target.id);var xhr = new XMLHttpRequest();xhr.open('POST','http://localhost:3000/server');xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xhr.send('id='+e.target.id);location.hash='/update';location.reload();}

完整代码：
app.js：

const express = require('express');
const app = express();
const path = require('path');
//引入body-parser模块
const bodyParser = require('body-parser');
//拦截所有请求,配置body-parser模块
//extended:false 方法内部使用querystring模块处理请求参数的格式,并且把参数保存在req当中
//extended:true 方法内部使用第三方模块qs处理请求参数的格式
app.use(bodyParser.urlencoded({extended:false}));//开放静态资源访问，只需要输入文件名即可，不需要输入文件夹
app.use(express.static(path.join(__dirname,'src')));app.all("*",function(req,res,next){//设置允许跨域的域名，*代表允许任意域名跨域res.header("Access-Control-Allow-Origin","*");//允许的header类型res.header("Access-Control-Allow-Headers","Origin,X-Requested-With,Accept,Content-type");res.header("Access-Control-Allow-Credentials",true);//跨域允许的请求方式res.header("Access-Control-Allow-Methods","PUT,POST,GET,DELETE,OPTIONS");res.header("Content-Type","application/json;charset=utf-8")if (req.method.toLowerCase() == 'options')res.sendStatus(200);  //让options尝试请求快速结束elsenext();
});//引入MySQL模块
var mysql      = require('mysql');
//创建MySQL的连接
var connection = mysql.createConnection({host     : 'localhost',user     : 'root',password : '1234',database : 'students'
});//连接MySQL
connection.connect();//接收请求
app.post('/add',(req,res)=>{//接收请求参数const { id, name, sex,class1}= req.body;var  addSql = 'INSERT INTO student(id,name,sex,class) VALUES(?,?,?,?)';var  addSqlParams = [id,name,sex,class1];connection.query(addSql,addSqlParams,function (err, result) {if(err){console.log('[INSERT ERROR] - ',err.message);return;}        console.log('--------------------------INSERT----------------------------');//console.log('INSERT ID:',result.insertId);        console.log('INSERT ID:',result);        console.log('-----------------------------------------------------------------\n\n');  });res.redirect('/index.html');
})var id = 0;
app.post('/server',(req,res)=>{console.log('server');id=req.body.id;console.log(id);
})app.post('/update',(req,res)=>{console.log('update');const {name,sex,class1}=req.body;var modSql = 'UPDATE student SET name = ?,sex = ?,class = ? WHERE Id = ?';var modSqlParams = [name,sex,class1,id];//改connection.query(modSql,modSqlParams,function (err, result) {if(err){console.log('[UPDATE ERROR] - ',err.message);return;}        console.log('--------------------------UPDATE----------------------------');console.log('UPDATE affectedRows',result.affectedRows);console.log('-----------------------------------------------------------------\n\n');});res.redirect('/index.html');
})
app.post('/del',(req,res)=>{console.log('del');const {id}=req.body;var delSql = 'DELETE FROM student where id='+id;//删connection.query(delSql,function (err, result) {if(err){console.log('[DELETE ERROR] - ',err.message);return;}        console.log('--------------------------DELETE----------------------------');console.log('DELETE affectedRows',result.affectedRows);console.log('-----------------------------------------------------------------\n\n');  });
})app.post('/init',(req,res)=>{console.log('init');//query操作可以对数据库进行操作connection.query('SELECT * from student', function (err, result, fields) {if(err){//err.message会返回错误的信息console.log('[SELECT ERROR] - ',err.message);return;}console.log('--------------------------SELECT----------------------------');console.log(result);console.log('------------------------------------------------------------\n\n');res.send(result);});})app.listen(3000);

index.html：

<!DOCTYPE html>
<html><head><meta charset="utf-8"><title></title></head><body><div id="app"></div><script src="./bundle.js" type="text/javascript" charset="utf-8"></script></body>
</html>

app.vue

<template><div id="app"><router-view></router-view></div>
</template><script></script><style scoped="scoped"></style>

init.vue：

<template><div id="init"><div class="div2"><div class="div21">学号</div><div class="div21">姓名</div><div class="div21">性别</div><div class="div21">班级</div><div class="div21"></div><div class="div21"></div></div><div class="div3" v-for="item in people"><div class="div31">{{item.id}}</div><div class="div31">{{item.name}}</div><div class="div31">{{item.sex}}</div><div class="div31">{{item.class}}</div><div class="div31"><button id="upd" @click="upd" :id="item.id">更改</button></div><div class="div31"><button @click="del" :id="item.id">删除</button></div></div><div class="div4"><router-link to='/add'>增加</router-link></div></div>
</template><script>export default {data(){return{msg:'66',people:[]}},mounted:function(){var xhr = new XMLHttpRequest();xhr.open('POST','http://localhost:3000/init');xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xhr.send();var that = this;xhr.onload = function(){that.people = JSON.parse(xhr.responseText);}},methods:{del:function(e){console.log('del'+e.target.id);var xhr = new XMLHttpRequest();xhr.open('POST','http://localhost:3000/del');xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xhr.send('id='+e.target.id);location.href='http://localhost:3000/index.html'},upd:function(e){console.log('upd');sessionStorage.setItem('id',e.target.id);var xhr = new XMLHttpRequest();xhr.open('POST','http://localhost:3000/server');xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');xhr.send('id='+e.target.id);location.hash='/update';location.reload();}}
}</script><style scoped="scoped">#init{width: 800px;margin: auto;border: 1px solid transparent;}.div2{width: 100%;height: 50px;display: flex;}.div21{text-align: center;line-height: 50px;border: 1px solid aqua;flex: 1;}.div3{width: 100%;height: 50px;display: flex;}.div31{border: 1px solid aqua;text-align: center;line-height: 50px;flex: 1;}</style>

router.js：

import Vue from 'vue'
import Router from 'vue-router/dist/vue-router.js'
import init from '../components/init.vue'
import app from '../components/app.vue'
import add from '../components/add.vue'
import del from '../components/del.vue'
import update from '../components/update.vue'
Vue.use(Router);export default new Router({routes: [{path: '/',redirect:'/init'},{path: '/init',component: init},{path: '/add',name:'add',component: add},{path: '/del',name:'del',component: del},{path: '/update',name:'update',component: update},]
})

update.vue：

<template><div id="update"><form action="http://localhost:3000/update" method="post"><div class="div1"><div class="div11">学号</div><div class="div12"><input type="text" name="id" placeholder="请输入学号" id="num" disabled="disabled"></div></div><div class="div1"><div class="div11">姓名</div><div class="div12"><input type="text" name="name" placeholder="请输入姓名"></div></div><div class="div1"><div class="div11">性别</div><div class="div12"><input type="text" name="sex" placeholder="请输入性别"></div></div><div class="div1"><div class="div11">班级</div><div class="div12"><input type="text" name="class1" placeholder="请输入班级"></div></div><br><button type="submit">更改</button></form></div>
</template><script>window.onload=function(){var k = sessionStorage.getItem('id');console.log(k);if(k){var num = document.querySelector('#num');num.value=k;}
}</script><style>#update{width: 60%;height: 600px;margin: auto;border: 1px solid royalblue;}.div1{margin-top: 10px;margin-left: 10px;}
</style>