以下内容全是我个人理解写出，如有不对，请立刻练习本人进行更改。以免被刚入门的被我带入坑里。
—node是什么？我想大家应该都知道。
node是前端未来干掉后端的一种语言，是用JavaScript来编写后端代码的一种语言。前端走后端的路让后端无路可走。是前端人员走向全栈开发的一条路。
—学习node要掌握什么呢？学习它就需要掌握一下几个方面，这是我现在学习的时候需要掌握的东西，算是很基本的东西了。
一、node的安装
二、数据库的安装和使用（sql命令）
三、node最底层基本写法
四、koa框架
五、Sequelize功能模块使用
六、读写文件
node的安装在这里就不讲了，网上一搜就都能搜到的，不想搜也可以点击这个连接，去看下node安装这些都有详细的介绍。
数据库的安装在网上也能够搜索到，安装数据库可以看下这个博客，这里写的挺详细的，从安装数据库到navicat MySQL的安装都有 查看请点击这里↓↓↓↓↓↓↓
sql的命令离不开增删改查
mydb：数据库名
user：表名
text：对应的属性名
2：要插入的数据
id：主键
age：对应的属性
增： INSERT INTO `mydb`.`user` (`text`) VALUES (‘2‘);
删：DELETE FROM user WHERE id=1
改：UPDATE `mydb`.`user` SET `age`=‘22‘ WHERE `id`=‘1‘;
查：select * from user
以上就是数据操作的主要四个，其他命令可以百度一下，一抓一大把。
接下来进入最主要的地方了，开是接触放弃的地方了，底层的基本用法
+开始需要把数据库放进去才能够使用
$ cnpm install mysql
接下来引入你本地的数据库
// 连接数据库var mysql ?????= require(‘mysql‘);var connection = mysql.createConnection({host ????: ‘localhost‘,user ????: ‘root‘,password : ‘123456‘,database : ‘node‘}); 接下来开始捣鼓你的数据库（我的数据库放了一下的数据名）
接下来对下面的数据进行操作（用上面已经连接上的数据库）
node底层写法：
var http = require(‘http‘);// 连接数据库var mysql ?????= require(‘mysql‘);var connection = mysql.createConnection({host ????: ‘localhost‘,user ????: ‘root‘,password : ‘123456‘,database : ‘node‘}); // 请求下数据库connection.connect(); ??var http = require("http");var url = require("url");// 调用方法function start() { ?function onRequest(request, response) {} ?http.createServer(onRequest).listen(8888);
端口号是8888去进行请求}start();新增数据方法
// 新增数据const hello = function (response, data) { ?connection.query(`INSERT INTO log ?(content, summary, user, day) VALUES ("${data.content}", "${data.summary}", "${data.user}","${data.day}");`, function (error, results, fields) { ???if (error) throw error; ?????// 请求成功，返回格式 ?????response.writeHead(200, {"Content-Type": "application/json"}); ?????// 返回给页面的数据 ?????response.write(JSON.stringify(results.insertId)); ?????// 请求结束 ?????response.end(); ?});}获取列表
// ?获取列表const hello2 = function (response, data) { ?connection.query(`select * from log`, function (error, results, fields) { ???if (error) throw error; ?????response.writeHead(200, {"Content-Type": "application/json"}); ?????response.write(JSON.stringify(results)); ?????response.end(); ?});}删除事件
// 删除id=4const hello4 = function (response,data){ ?console.log(data) ?connection.query(`DELETE FROM log WHERE id=${data.id}`,function (error,results,fields) { ???if (error) throw error; ???response.write("ok"); ???response.end(); ?})}分页写法
// 分页写法const hello3 = function (response, page, size) { ?console.log(‘page, size‘, page, size) ?connection.query(`select * from log ?limit ${size} offset ${(page-1)*size} `, function (error, results, fields) { ???if (error) throw error; ?????response.writeHead(200, {"Content-Type": "application/json"}); ?????response.write(JSON.stringify(results)); ?????response.end(); ?});}调用的话直接调用方法就可以（这里还需要注意是get请求还是post请求）
// 调用方法function start() { ?function onRequest(request, response) { ???// /hello ???var pathname = url.parse(request.url).pathname.split(‘/‘); ???// /hello3/1/10 ???// 接收数据 ???if (request.method === ‘POST‘) { ?????request.on(‘data‘, function(data) { ???????// 把数据转换成json格式 ???????let data1 = JSON.parse(data.toString()) ???????console.log(‘data: ‘, data1.toString(), data1) ???????// 接收到的接口调用什么方法 ???????switch(pathname[1]) { ?????????case ‘hello‘: { hello(response, data1) } break; ?????????case ‘hello2‘: { hello2(response, data1) } break; ?????????case ‘hello3‘: { ????????????// 用拼接的方式（get）获取数据方法 ???????????// let page = pathname[2] ???????????// let size = pathname[3] ???????????// console.log(pathname) ???????????// 用接收体来调用数据（post） ???????????hello3(response, data1.page, data1.size) ??????????} break; ?????????case ‘hello4‘: { hello4(response, data1) } break; ?????????// 调用weitch方法 ?????????default: response.end(); ???????} ?????}) ???}完整的使用代码
var http = require(‘http‘);// 连接数据库var mysql ?????= require(‘mysql‘);var connection = mysql.createConnection({host ????: ‘localhost‘,user ????: ‘root‘,password : ‘123456‘,database : ‘node‘}); // 请求下数据库connection.connect(); ??var http = require("http");var url = require("url");// 新增数据const hello = function (response, data) { ?connection.query(`INSERT INTO log ?(content, summary, user, day) VALUES ("${data.content}", "${data.summary}", "${data.user}","${data.day}");`, function (error, results, fields) { ???if (error) throw error; ?????// 请求成功，返回格式 ?????response.writeHead(200, {"Content-Type": "application/json"}); ?????// 返回给页面的数据 ?????response.write(JSON.stringify(results.insertId)); ?????// 请求结束 ?????response.end(); ?});}// ?获取列表const hello2 = function (response, data) { ?connection.query(`select * from log`, function (error, results, fields) { ???if (error) throw error; ?????response.writeHead(200, {"Content-Type": "application/json"}); ?????response.write(JSON.stringify(results)); ?????response.end(); ?});}// 删除id=4const hello4 = function (response,data){ ?console.log(data) ?connection.query(`DELETE FROM log WHERE id=${data.id}`,function (error,results,fields) { ???if (error) throw error; ???response.write("ok"); ???response.end(); ?})}// 分页写法const hello3 = function (response, page, size) { ?console.log(‘page, size‘, page, size) ?connection.query(`select * from log ?limit ${size} offset ${(page-1)*size} `, function (error, results, fields) { ???if (error) throw error; ?????response.writeHead(200, {"Content-Type": "application/json"}); ?????response.write(JSON.stringify(results)); ?????response.end(); ?});}// 调用方法function start() { ?function onRequest(request, response) { ???// /hello ???var pathname = url.parse(request.url).pathname.split(‘/‘); ???// /hello3/1/10 ???// 接收数据 ???if (request.method === ‘POST‘) { ?????request.on(‘data‘, function(data) { ???????// 把数据转换成json格式 ???????let data1 = JSON.parse(data.toString()) ???????console.log(‘data: ‘, data1.toString(), data1) ???????// 接收到的接口调用什么方法 ???????switch(pathname[1]) { ?????????case ‘hello‘: { hello(response, data1) } break; ?????????case ‘hello2‘: { hello2(response, data1) } break; ?????????case ‘hello3‘: { ????????????// 用拼接的方式（get）获取数据方法 ???????????// let page = pathname[2] ???????????// let size = pathname[3] ???????????// console.log(pathname) ???????????// 用接收体来调用数据（post） ???????????hello3(response, data1.page, data1.size) ??????????} break; ?????????case ‘hello4‘: { hello4(response, data1) } break; ?????????// 调用weitch方法 ?????????default: response.end(); ???????} ?????}) ???} ???// Get ???if (request.method === ‘GET‘) { ?????response.end(‘aaaaa‘); ???} ?} ??http.createServer(onRequest).listen(8888);}start();
开始化简模式。学习使用koa框架
安装koa
npm intall koa2npm intall koa-router
在页面引入
const Koa = require(‘koa‘)const bodyParser = require(‘koa-bodyparser‘)const Router = require(‘koa-router‘)
来个简单例子
const Koa = require(‘koa‘);//引入koa ?const app = new Koa(); ?//方法放到app下 ?app.use(async ctx => { ???ctx.body = ‘Hello World‘; ?}); ?//执行方法 ?app.listen(3000);//app创建端口号koa主要的就是request的请求方法，response响应，因为太多就不在这讲了，想了解的 戳这里↓↓↓↓↓
app.use(async ctx => { ???console.log(ctx.request.href)//获取到地址，换个方法就可以获取前台传得数据 ???ctx.response.body = "aaaaa"//返回值});来上面的去看文档慢慢敲就行了，Sequelize功能模块使用来讲一下
var Sequelize = require(‘sequelize‘);var mysql = new Sequelize(‘node‘, ‘root‘, ‘123456‘, { ???host: ‘localhost‘, ???dialect: ‘mysql‘, ???pool: { ???????max: 5, ???????min: 0, ???????idle: 10000 ???},})看数据库的导入方式就不一样了，接下来我们使用的可能多数都是这样的，样式了。
//数据表里面的内容var Log = mysql.define(‘log‘, { ???id: { ???????primaryKey: true, ???????type: Sequelize.INTEGER, ???}, ???content: Sequelize.STRING, ???summary: Sequelize.STRING, ???user: Sequelize.STRING, ???day: Sequelize.STRING, ?}, { ???freezeTableName: true, // Model 对应的表名将与model名相同 ???timestamps: false ?});使用方法查询数据
Log.findAll({ ???????where: { ???????????$and: [ ???????????????{ id: {gt: 32} }, ????????????????//大于多少 ???????????????{ id: {lt: 35} } ???????????????//小于等于多少 ???????????] ???????}, ???????raw: true ???}).then(res => { ???????console.log(res.length) ???//一共多少条 ???for(var i=0 ;i<res.length;i++){//遍历出来显示 ???????Log.create( ???????{ ???????????content: res[i].content, ???????????summary: res[i].summary, ???????????user: res[i].user, ???????????day: res[i].day ???????} ???) ???} ???})整体使用
const main = async function() {//查询所有 ???let res = await Log.findAll({ ???????raw: true ???})//写入 ???let newDatas = res.map(item => ({ ???????a: item.content, ???????b: item.summary, ???????c: item.user, ???????d: item.day, ???}))//往新表里插入多条数据 ???await Aaa.bulkCreate(newDatas)//删除数据 ???await Aaa.destroy({ where: { ???????id: 2 ???}})//修改数据 ???await Aaa.update({ ???????a: ‘item.content‘, ???????b: ‘item.summary‘, ???????c: ‘item.user‘, ???????d: ‘item.day‘, ???}, { ???????where: { ???????????id: 3 ???????} ???})}main()接下来进行三军会师，用三种方法写成最简单的代码来调用数据
开始在app文件中
const Koa = require(‘koa‘)const bodyParser = require(‘koa-bodyparser‘)const router = require(‘./controllers‘)//引入使用包const app = new Koa()app.use(bodyParser())//调用koabadyparser方法app.use(router.routes())app.listen(3000)//引入文件，创建端口
在controllers文件中写入方法并进行调用
const Router = require(‘koa-router‘)const router = new Router()const services = require(‘./services‘)//查询所有数据router.get(‘/‘, async (ctx, next) => { ???let res = await services.hello1() ???ctx.body = res});//返回值hello worldrouter.get(‘/hello‘, (ctx, next) => { ???ctx.body = "hello world"});//新增数据router.post(‘/hello2‘, async (ctx, next) => { ???let obj = ctx.request.body ???let res = await services.hello2(obj) ???let eee = { ???????content : res.content, ???????summary : res.summary ???} ???ctx.body = { ???????statusCode: 200, ???????result:eee ???}})//删除数据router.post(‘/hello3‘, async (ctx, next) => { ???let obj = ctx.request.body ???let res = await services.hello3(obj) ???ctx.body = { ???????statusCode: 200, ???}})//查询数据router.post(‘/hello4‘, async (ctx, next) => { ???let obj = ctx.request.body ???let res = await services.hello4(obj) ???ctx.body = res})//更改数据router.post(‘/hello5‘, async (ctx, next) => { ???let obj = ctx.request.body ???let res = await services.hello5(obj) ???ctx.body = res})//调用module.exports = router在services.js文件中
const Log = require(‘./models‘)const hello = async function (obj) { ???//放个查询方法 ???let logs = await Log.Log.findAll({ ???????where: { ???????????$and: [ ???????????????{id: { $gt: obj.id }}, ???????????????{id: { $lte: obj.css }} ???????????] ???????} ???}) ???return logs}//查询所有数据大于0的const hello1 = async function () { ???let loge = await Log.Log.findAll({ ???????where: { ???????????id: { gt: 0}, ???????} ???}) ???return loge}//新增数据const hello2 = async function (obj) { ???let loge = await Log.rizhi.create({ ???????????content:obj.content, ???????????summary:obj.summary, ???????????user:obj.user, ???????????day:"2015-10-7" ???}) ???return loge}//删除数据const hello3 = async function (obj) { ???let loge = await Log.rizhi.destroy({ ??????????where:{ ???????????????id : obj.id ???????????} ???????}) ???return loge}查询数据const hello4 = async function (obj) { ???let ass = { ???????content : obj.content, ???????summary : obj.summary, ???????user : obj.user, ????} ???if(!obj.content){ ??????delete ass.content ???} ???if(!obj.summary){ ???????delete ass.summary ???} ???if(!obj.user){ ???????delete ass.user ???} ???let loge = await Log.rizhi.findAll({ ???????????????????where:ass ???????}) ???return loge}//更改数据const hello5 = async function (obj) { ???let ass = { ???????content : obj.content, ???????summary : obj.summary, ???????user : obj.user, ????} ???let loge = await Log.rizhi.update(ass,{ ???????????????????where:{ ???????????????id : obj.id ??????????} ????}) ????let cha = await Log.rizhi.findAll({ ???????where: { ???????????id: obj.id, ???????} ???}) ???return cha}需要调用的方法module.exports = { ???hello,hello1,hello2,hello3,hello4,hello5}最后将表格的内容模块导入到models.js中
const mysql = require(‘./mysql‘)//导入数据库const Sequelize = require(‘sequelize‘)//log表内数据格式var Log = mysql.define(‘log‘, { ???id: { ???????primaryKey: true, ???????type: Sequelize.INTEGER, ???}, ???content: Sequelize.STRING, ???summary: Sequelize.STRING, ???user: Sequelize.STRING, ???day: Sequelize.STRING,}, { ???????freezeTableName: true, // Model 对应的表名将与model名相同 ???????timestamps: false}); ?//日志表内数据格式var rizhi = mysql.define(‘rizhi‘, { ???id: { ???????primaryKey: true, ???????type: Sequelize.INTEGER, ???}, ???content: Sequelize.STRING, ???summary: Sequelize.STRING, ???user: Sequelize.STRING, ???day: Sequelize.STRING,}, { ???????freezeTableName: true, // Model 对应的表名将与model名相同 ???????timestamps: false});调出两个表module.exports = {Log,rizhi}这就是一个完整的的node项目了，增删改查，以后就需要自己去扩展了
读写文件的话，就免不了书把txt，excel、sql、之间的数据转换，以后在讲。。。。。。
node.js从入门到放弃（一）
原文地址：https://www.cnblogs.com/yishifuping/p/9783917.html