Node.js ：

?引进express框架
设置跨域访问请求
写端口号和监听端口
连接数据库，并且定义pool连接池存放数据
把数据库执行命令(增删查改)放在 pool.getConnection((err, connection) => { ...});里面就行?

?增加：

查找：?

前端：?

跟上一篇文章一样运行即可，操作一样~

完整代码：

//1.固定的，引进express框架
const express = require('express')
const app = express()

//2.设置跨域访问请求
app.all('*', function (req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Headers", "X-Requested-With");
    res.header("Access-Control-Allow-Methods", "PUT,POST,GET,DELETE,OPTIONS");
    res.header("X-Powered-By", ' 3.2.1')
    res.header("Content-Type", "application/json;charset=utf-8");
    next();
});

//3.端口号
const port = 3000
//3.1 监听端口
app.listen(port, () => {
    console.log(`Example app listening at http://localhost:${port}`)
})


//4.连接数据库
var mysql = require('mysql');
var pool = mysql.createPool({
    host: 'localhost',
    user: 'root',
    password: '',
    database: 'chat'
});

//5.根据参数添加数据到数据库
//把数据库执行命令放在pool.getConnection((err, connection) => {
//    ...
// });?就行?
app.get('/insert/:id/:userid/:content/:sayTime',(req,res)=>{
  pool.getConnection((err,connection) => {//连接池
      var addSql = 'INSERT INTO `chat`(`id`,`userid`,`content`,`sayTime`) VALUES(?,?,?,?)';
      var addSqlParams = [req.params.id,req.params.userid,req.params.content,req.params.sayTime];
      //增
      connection.query(addSql, addSqlParams, function (err, result) {
          if (err) {
              console.log('[INSERT ERROR] - ', err.message);
              return;
          }
          console.log(result)
          res.send("添加数据成功！！");//添加成功后，输出这条数据在页面！
          //释放连接
          connection.release();
      });
  });
});


//5.1 根据id查询数据库里面的数据
app.get("/list/:id",(req,res)=>{
    pool.getConnection((err,connection) =>{
        let searchSql = 'SELECT * from `chat` WHERE `id` = ? '
        let searchParams = [req.params.id]
        connection.query(searchSql,searchParams,(err,result) =>{
            res.send(result)
            connection.release()
        })
    });
});