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Detailed explanation of nodejs connection to mysql database and basic knowledge points

亚连

May 25, 2018 pm 04:36 PM

javascript mysql nodejs

This article mainly introduces nodejs to connect to mysql database. It summarizes and analyzes nodejs connection and operation of mysql database in the form of examples, configuration and mysql database query, adding data and other operational skills. Friends in need can refer to the following

The examples in this article describe nodejs connecting to mysql database and basic knowledge points. Share it with everyone for your reference, the details are as follows:

1. Several commonly used global variables

1, __filenameGet the path of the current file
2, __dirnameGet the directory of the current file
3, process.cwd()Get the directory of the current project

2. Import and export of files

1. Use require to import files

2. Use module .exportsExport the variables, methods, and objects specified in the file

3.nodeThe directory structure of the project

demo

package.json The package or module that the current project depends on
router The file that stores the route
views Modules that store views
public Static files
module Writing modules such as databases
app.js Main Entry file

4. Write the routing view separately in the router filedemo

1. View view file

const express = require("express");
const router = express.Router();
router.get("/", (req, res) => {
 res.send("hello word");
});
router.get("/article", (req, res) => {
 res.send("我是文章列表");
})
module.exports = router;

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2. Call

&#39;use strict&#39;;
const express = require("express");
const app = express();
app.use("/",require("./router/03_router"))
app.use("/app",require("./router/03_router1"))
app.listen(3000);

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in the main file 5. Useejstemplate

1. It needs to be installed but does not need to be introduced

npm install ejs --save

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2. Configure

//配置模板的文件路径
app.set("views",__dirname+"/views");
//配置模板引擎
app.set("view engine","ejs");

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in the main file. 3. Use

①. Template File

<!doctype html>
<html lang="en">
<head>
 <meta charset="UTF-8">
 <meta name="viewport"
   content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
 <meta http-equiv="X-UA-Compatible" content="ie=edge">
 <title>Document</title>
</head>
<body>
<h1>我是模板渲染的</h1>
</body>
</html>

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②, rendering template in route

&#39;use strict&#39;;
const express = require("express");
const router = express.Router();
router.get("/", (req, res) => {
 //可以直接使用res.render("03_index");
 res.render("03_index.ejs");
});
router.get("/article", (req, res) => {
 res.send("我是文章列表");
})
module.exports = router;

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③, main file

'use strict';
const express = require("express");
const app = express();
//配置模板的文件路径
app.set("views",__dirname+"/views");
//配置模板引擎
app.set("view engine","ejs");
app.use("/",require("./router/03_router"))
app.use("/app",require("./router/03_router1"))
app.listen(3000);

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6. About the use of ejstemplate files

1. Return data

...
let dataset = {
 name:"张三",
 age:20,
 books:[&#39;三国演义&#39;,&#39;西游记&#39;,&#39;红楼梦&#39;,&#39;水浒传&#39;]
}
res.render("03_index.ejs",dataset);
...

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2. Ordinary fields

<h2><%= name %></h2>
<h2><%= age %></h2>

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3. Iterate array

<ul>
 <% for(let i in books){%>
  <li><%= books[i] %></li>
 <%}%>
</ul>

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## 7. Load static files

1. Configure

//设置静态文件的加载(js,css,img)
app.use(express.static(__dirname+"/public"));

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in the main file 2. Use

<link rel="stylesheet" href="./css/bootstrap.css" rel="external nofollow" >
<script type="text/javascript" src="./js/jquery-3.1.1.min.js"></script>
<img src="./img/002.jpg">
...

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in the template

8. Use mysqldatabase

1. Create a ## in

module #db.js file

&#39;use strict&#39;;
const mysql = require("mysql");
/**
 * 将整个方法全部暴漏出去
 * @param sql sql语句
 * @param arg 传递到sql语句中的参数，可以不写
 * @param callback 回调函数，可以不写
 */
module.exports = function (sql,arg,callback) {
 //1.创建连接(根据自己的数据库配置)
 let config = mysql.createConnection({
  host:"localhost", //数据库的地址
  user:"root", //数据库用户名
  password:"root", //数据库密码
  port:"3306", //mysql数据库的端口号
  database:"mybatistest" //使用那个数据库
 });
 //2.开始连接数据库
 config.connect();
 //3.对数据库的增删改查操作
 config.query(sql,arg,(err,data)=>{
  callback && callback(err,data);
 })
 //4.关闭数据库
 config.end();
}

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2. Use query data in

router

view① , import the file

//引入数据库文件
const db = require("./../module/db");

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②, use

router.get("/", (req, res) => {
 db("select * from m_dept",(err,data)=>{
  console.log(data);
  res.render("03_index.ejs",{data:data});
 })
});

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3 in the view, add Data

①. For the front-end page, see code example

②. Obtain user data parameters through

req.query

router.get("/regist",(req, res)=>{
 //获取到输入参数，前提是input上要写name
 console.log(req.query);
 db("insert into student(name,age) values(?,?)",[req.query.username,req.query.age],(err,data)=>{
  console.log(data);
  if(data){
   res.send("成功");
  }
 })
})

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9. About the way node returns jsonIn the front-end and back-end separation development model, the data returned by the backend is generally json, and there is no need to use the ejs template engine

...
res.json({
 info:"成功",
 code:1
});
...

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The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.

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