npm install mysql --save-dev

var express = require("express");//引入express
var router = express.Router();//注意Router首字母大写
var  mysql = require(‘mysql‘);
//1.连接数据库
var db = mysql.createConnection({
    host: ‘localhost‘, user: ‘root‘,
    password: ‘123456‘, database: ‘user‘
});

router.post("/",function(req,res,next){//注意 users.js中定义的路由 的路由要改成跟路由"/"
    console.log(req.body)

    db.query("select* from user", (err, data) => {
        if (err) {
            console.log("error!", err);
        } else {
            console.log("success!", data)
            res.json({
                data:data
            });
        }
    });

            
})

module.exports = router;//导出router